Mean follow-up was 1.0 ± 0.1 years, and 35.4% of the cohort experienced recurrent atrial fibrillation or atrial tachycardia. Recurrence occurred in 46.2% of the 13 patients with one topological obstacle and 44.4% of the 27 with four or more, compared with 23.5% of 17 patients with two and 34.4% of 180 with three. The comparison between any recurrence and no recurrence across the four groups was not statistically significant (p = 0.433), while the overall distribution of no recurrence, atrial fibrillation and atrial tachycardia also did not differ significantly (p = 0.584).

Multivariable logistic regression adjusted for age, clinical type of atrial fibrillation, left atrial diameter, left ventricular ejection fraction, CHA2DS2-VASc score and low-voltage area burden; no obstacle-count group was significantly associated with recurrence relative to the three-obstacle group, and the overall likelihood-ratio p value was 0.194. The research was conducted at Seoul National University Hospital among patients who underwent radiofrequency catheter ablation between January 2023 and January 2024. Of 336 people initially considered, the investigators excluded 78 with a history of prior ablation, 13 without a complete left atrial voltage map, four without post-ablation follow-up and four whose recurrence was typical atrial flutter.

The final sample included 42.6% with paroxysmal atrial fibrillation, 43.5% with persistent disease and 13.9% with long-standing persistent disease. High-density electroanatomic maps acquired before ablation were used to identify low-voltage myocardium, with bipolar thresholds below 0.5 mV in sinus rhythm or pacing and below 0.2 mV during atrial fibrillation. Maps were acquired during sinus rhythm or pacing in 166 patients, or 70.0%, and during atrial fibrillation in 71, or 30.0%.

Low-voltage area burden was calculated as the percentage of the total mapped left atrial surface meeting the applicable voltage threshold. The investigators modeled the atrium as a closed two-dimensional surface and defined topological obstacles as non-conductive regions that interrupt electrical propagation. Each map initially contained three fundamental obstacles: the left pulmonary vein antrum, the right pulmonary vein antrum and the mitral valve.

Discrete low-voltage regions were then added when they met a size criterion, while extensive scar connecting anatomical structures could merge separate barriers into a single continuous obstacle. Incorporating the actual ablation lines completed the topological representation. To avoid counting negligible low-voltage spots as functional barriers, the researchers derived a minimum area from the wavelength required to support a macroreentrant circuit.

They used an estimated minimum atrial action potential duration of 150 milliseconds and a conduction velocity of 0.5 meters per second, producing a wavelength of 75 millimeters. Under an assumed circular geometry, that circumference corresponded to a radius of approximately 11.9 millimeters and an area of 4.45 square centimeters, rounded to 4.5 square centimeters for classification. Low-voltage regions smaller than 4.5 square centimeters were therefore not treated as independent obstacles.

The threshold was based on literature-derived rather than patient-specific physiological estimates, and the circular assumption could underestimate the boundary length of small, irregularly shaped regions. Obstacle count was related to low-voltage burden, but the relationship was not linear. Patients with one obstacle had the highest mean burden at 36.6% ± 24.8%, and all 13 had a burden of at least 5%, compared with 24.9% of the overall cohort.

The largest group, containing 180 patients with three obstacles, had a mean burden of only 2.1% ± 3.5%. Counts differed significantly across burden quartiles (p < 0.001). The highest-burden quartile, with a mean burden of 18.9% ± 17.6%, was the only quartile containing patients from all four obstacle groups, demonstrating that extensive low-voltage tissue can form either one large confluent barrier or several discrete ones.

The lowest quartile contained only patients with three obstacles. Patients with a single obstacle also differed clinically from the rest of the cohort. They were older, with a mean age of 67.8 years, and had a larger left atrium, lower left ventricular ejection fraction and higher CHA2DS2-VASc score.

Their mean left atrial diameter was 50.1 ± 5.2 mm, compared with 44.6 ± 7.0 mm in the three-obstacle group, while mean ejection fraction was 51.7% ± 12.6% and 57.6% ± 6.5%, respectively. Valvular heart disease was the only comorbidity that differed significantly across obstacle groups (p = 0.021). These imbalances limit attempts to separate the influence of topology from that of underlying remodeling: a lone obstacle was simultaneously associated with a greater burden of low-voltage tissue and less favorable cardiac measurements.

Most patients received pulmonary vein antrum isolation alone as the standard strategy, although 81, or 34.1%, also received additional lesions at the operator’s discretion; cavotricuspid isthmus ablation was the most common. The primary outcome was atrial fibrillation or atrial tachycardia lasting at least 30 seconds, documented on a 12-lead electrocardiogram or Holter monitor, after a three-month blanking period. Atrial tachycardia was less common than atrial fibrillation among recurrent cases, and the mean cycle length in patients with atrial tachycardia was 235 milliseconds.

Across low-voltage-area quartiles, recurrence was 20.0% in the lowest quartile, 41.7% in the second, 34.5% in the third and 45.8% in the highest; the overall quartile-level comparison was statistically significant (p = 0.018). Comparisons among obstacle groups within individual quartiles were limited by small subgroups and did not show a consistent pattern of increasing recurrence with obstacle count. The investigators also examined whether the structural differences were reflected in electrocardiographic measures of fibrillatory organization.

They analyzed lead V1 from 12-lead recordings obtained at recurrence, separated QRS and T waves with NeuroKit2, extracted and preprocessed fibrillatory-wave segments, and used fast Fourier analysis to calculate dominant frequency and organization index. Dominant frequency ranged from 5.04 ± 0.87 Hz in the single-obstacle group to 5.66 ± 1.51 Hz among patients with four or more obstacles. Organization index was highest in the single-obstacle group at 0.49 ± 0.09 and lowest in the three-obstacle group at 0.45 ± 0.07.

Neither measure differed significantly by obstacle count or low-voltage-area quartile, so the global signal-derived measures did not reproduce the distinctions identified by voltage mapping. The study’s retrospective, single-center design and small extreme-count groups limit generalizability. Operator-dependent additional ablation and incompletely documented comorbidities may also have influenced outcomes.

Voltage measurements can vary with mapping rhythm, wavefront direction and electrode configuration, while low-voltage area remains an imperfect surrogate for fibrosis. The fixed action-potential-duration and conduction-velocity assumptions and circular geometry make the 4.5-square-centimeter classification method-dependent. Threshold sensitivity against alternative cutoff values was not formally tested, although a supplementary shape-based analysis suggested that the circular assumption may have a modest effect for mildly elongated regions and a greater effect for markedly elongated ones.

Taken together, the results support further investigation of atrial substrate geometry, but they do not establish obstacle count as a recurrence predictor or clinical ablation target.

Subject of Research: Association of left atrial topological obstacles and low-voltage burden with atrial fibrillation recurrence after pulmonary vein antrum isolation

Article Title: Impact of low-voltage area burden and topological obstacles on atrial fibrillation recurrence after pulmonary vein antrum isolation

Article References: Choi, J., Go, Y.-H., Kwon, S., Lee, K.-Y., Ahn, H.-J., Lee, S.-R., Kim, T., Lee, J. C., Choi, E.-K., & Oh, S. (2026). Impact of low-voltage area burden and topological obstacles on atrial fibrillation recurrence after pulmonary vein antrum isolation. Frontiers in Network Physiology, 6, 1945351. https://doi.org/10.3389/fnetp.2026.1945351

Image Credits: AI Generated

DOI: 10.3389/fnetp.2026.1945351

Keywords: atrial fibrillation, pulmonary vein antrum isolation, topological obstacles, low-voltage area, cardiac ablation, arrhythmia recurrence, atrial substrate, left atrium, electrical conduction, network physiology, Impact, low-voltage

Pulsed field ablation works on the principle of irreversible electroporation: extremely short, high-voltage electric pulses punch nanoscale pores into cell membranes, killing cardiomyocytes while largely sparing neighboring structures. Because different tissue types have different thresholds for irreversible injury, PFA is inherently tissue-selective. That selectivity is what has made it so attractive compared with thermal techniques such as radiofrequency and cryoablation, which can inadvertently damage the esophagus, the phrenic nerve, or the coronary arteries that lie close to the pulmonary veins—the trigger sites for most paroxysmal atrial fibrillation.

Early PFA platforms relied on monophasic pulses, which are simple to generate and highly efficient at electroporating cells, but they came with a well-documented set of problems. Monophasic stimulation provoked violent skeletal muscle contractions, required deep anesthesia, and drove unwanted electrochemical reactions at the electrodes, including polarization and gas formation. Biphasic waveforms—pairs of pulses with opposite polarity—were introduced to balance the delivered electrical charge, dramatically reducing muscle stimulation and electrochemical byproducts. Today, essentially every major commercial platform, from FARAPULSE to VARIPULSE to PulseSelect, uses some form of biphasic delivery.

But symmetric biphasic designs carry their own subtle biophysical trade-offs. When the second, opposite-polarity phase immediately follows the first, it can partially cancel the transmembrane potential that the first phase built up—a phenomenon known as the charge-cancellation effect. Compensating for that inefficiency requires higher electric field strengths, and pushing more energy through dense, high-frequency pulse bursts can generate unintended Joule heating, microbubble formation, and acute hemolysis. Those complications are not theoretical: silent cerebral lesions and hemolysis-related kidney injury have both emerged as safety concerns in the broader PFA literature.

The Chinese team, led by researchers at Tianjin Medical University and collaborating hospitals, took a different route. Their system delivers each pulse as an asymmetric biphasic waveform—a 7-microsecond positive phase followed by a 3-microsecond negative phase, separated by a 5-microsecond interval—at an amplitude of 1,000 volts. The catheter itself is a 10.5 French device with six adjustable splines, each carrying a single electrode. During each pulse, three electrodes act as anodes and three as cathodes. The catheter can be partially expanded into a basket shape to advance into a pulmonary vein, then fully deployed into a flower configuration with a maximum diameter of 32 millimeters at the vein’s ostium, maximizing tissue contact for ablation.

The trial, registered as ChiCTR2200062157, enrolled patients between January 2022 and December 2024. All had symptomatic paroxysmal atrial fibrillation that had failed or could not be tolerated on at least one class I or class III antiarrhythmic drug. Fifteen patients withdrew before the procedure, leaving 105 who underwent ablation and completed the prespecified 12-month follow-up. The cohort had a mean age of 63.7 years, was 60 percent male, and carried a mean CHA2DS2-VASc stroke-risk score of 1.54. Procedures were performed under general anesthesia or conscious sedation with uninterrupted oral anticoagulation and heparin to maintain an activated clotting time of at least 300 seconds.

The procedural results were striking. All 420 targeted pulmonary veins were acutely isolated—a 100 percent acute success rate—and no vein reconnected during the mandatory 20-minute waiting period after ablation. The mean ablation time, from the first PFA application to the last, was just under 219 seconds, and the mean total procedure time was about 102 minutes. Post-ablation voltage mapping, performed in roughly half the patients at the operator’s discretion, confirmed complete isolation at the pulmonary vein antra with no evidence of unintentional lesion formation elsewhere in the left atrium.

At 12 months, the Kaplan–Meier estimate of freedom from atrial arrhythmia recurrence—atrial fibrillation, flutter, or tachycardia lasting at least 30 seconds on protocol-specified monitoring—was 69.5 percent, with a 95 percent confidence interval of 60.1 to 77.5 percent. That figure sits comfortably within the range reported for other PFA technologies. The SINGLE SHOT CHAMPION trial reported 62.9 percent one-year freedom from recurrence, the PULSED AF Pivotal Trial reported 66.2 percent, and the VOLT-AF IDE study reported 81.1 percent. Importantly, no patient in the Chinese trial underwent repeat ablation during the 90-day blanking period, whereas several comparator studies permitted repeat procedures without counting them as endpoint failures—a difference the authors flag when urging caution about direct cross-study comparisons.

On the safety front, the results were equally notable. Not a single case of pulmonary vein stenosis, phrenic nerve injury, atrioesophageal fistula, stroke, cardiac tamponade, or acute kidney injury was recorded across the entire 12-month follow-up. The primary safety endpoint—a predefined serious adverse event—occurred in just one patient (0.95 percent), who experienced a transient coronary vasospasm on postoperative day three that resolved completely after intracoronary vasodilator administration. That patient had a pre-existing high-grade atherosclerotic coronary lesion, and while the authors acknowledge that a contributory role of the PFA procedure cannot be entirely excluded, the episode underscores a known pattern: ST-segment elevation during or after PFA should prompt urgent coronary angiography and nitroglycerin, and prophylactic nitrates may be worth considering when ablating near coronary arteries.

Two secondary safety signals deserve attention. Silent cerebral lesions, detected on brain MRI 12 to 48 hours after ablation, appeared in two patients (1.9 percent)—a rate lower than the 6.7 to 12.9 percent reported in some other PFA studies. The lesions disappeared completely on follow-up imaging at three and six months. The authors attribute the low rate partly to their waveform choice, noting that bench tests showed biphasic waveforms generate fewer microbubbles than monophasic ones, and that asymmetric biphasic pulses achieve better ablation depth than symmetric ones. Electrode geometry was also deliberately designed to avoid sharp edges and current-concentration hotspots that promote arcing and bubble formation. Meanwhile, laboratory hemolysis was common—87.6 percent of patients met the prespecified definition, with significant drops in haptoglobin and rises in lactate dehydrogenase and free plasma hemoglobin—but creatinine levels were unchanged and no patient developed acute kidney injury. The authors credit their asymmetric waveform, the basket-type catheter with single-sided electrodes that keeps current focused on tissue rather than blood, and a standardized peri-procedural saline hydration protocol. The study has limitations worth noting: it was single-arm with no comparator, lacked continuous implanted rhythm monitoring, enrolled a relatively modest sample, and excluded patients with significant renal impairment, so the hemolysis findings may not generalize to that population. Still, as a real-world, multicenter demonstration that a re-engineered pulse waveform and catheter geometry can deliver complete pulmonary vein isolation with an exceptionally clean safety record, the trial adds meaningful weight to the argument that the next generation of PFA will be defined as much by waveform physics as by catheter design.

Subject of Research: Clinical evaluation of an asymmetric biphasic pulsed field ablation system for paroxysmal atrial fibrillation

Article Title: Asymmetric biphasic pulsed field ablation of paroxysmal atrial fibrillation: clinical assessment

Article References: Xu, X., Li, Y., Lu, F., Li, H., & Cai, H. (2026). Asymmetric biphasic pulsed field ablation of paroxysmal atrial fibrillation: clinical assessment. Frontiers in Cardiovascular Medicine, 13, Article 1945178. https://doi.org/10.3389/fcvm.2026.1945178

Image Credits: AI Generated

DOI: 10.3389/fcvm.2026.1945178

Keywords: pulsed field ablation, atrial fibrillation, pulmonary vein isolation, irreversible electroporation, biphasic waveform, silent cerebral lesions, hemolysis, coronary vasospasm, cardiac electrophysiology, catheter ablation, clinical trial, Tianjin Medical University

The patient’s story began with two years of troubling palpitations. When his heart raced, an electrocardiogram captured an irregular narrow-complex tachycardia at 111 beats per minute, complete with right bundle branch block morphology and a leftward axis deviation of minus 21 degrees. Yet his heart was structurally sound: transthoracic echocardiography showed preserved left ventricular function and no abnormalities, and his thyroid function was normal. High-resolution, contrast-enhanced computed tomography revealed a crucial anatomical detail that would later prove decisive. His left superior and left inferior pulmonary veins did not drain into the left atrium separately, as they do in most people. Instead, they formed a single left common pulmonary vein, a variant present in a minority of the population that creates a wider, more complex target for any ablation strategy.

His first procedure was, by every conventional measure, a textbook success. Under general anesthesia with propofol and fentanyl, ventilated through a supraglottic i-gel airway, he underwent pulsed field ablation using the FARAPULSE system from Boston Scientific. The team delivered twenty-two applications to the left common pulmonary vein, ten to the right superior vein, and eight to the right inferior vein, alternating between the device’s basket and flower electrode configurations. Each application used a 2.0 kilovolt biphasic waveform with four pulse trains, and catheter contact was verified before every delivery using fluoroscopy and intracardiac echocardiography. When the team finished, electro-anatomical mapping with the EnSite NavX system confirmed that all the pulmonary veins had been acutely isolated from the left atrium. The electrical triggers responsible for his arrhythmia appeared, on the maps, to be sealed off for good.

Three months later, an external event monitor told a different story. Atrial fibrillation had returned. The team brought him back for a second procedure, this time with an esophageal temperature probe in place and access gained through the right internal jugular and right femoral veins. Using the OctaRay mapping catheter and the CARTO3 v8 system from Biosense Webster, they began reconstructing the arrhythmia in three dimensions. Almost immediately, they caught something valuable in the act: spontaneous premature atrial contractions, the stray beats that ignite atrial fibrillation, firing on the monitor in real time. Mapping placed their origin just beneath the ostium of the left common pulmonary vein on the posterior wall of the left atrium, slightly apart from the isolation line created during the first procedure.

What followed was a genuine detective story played out with millimeter precision and millisecond timing. Radiofrequency applications with a QDOT Micro catheter at 35 watts and a target ablation index of 400 transiently suppressed the premature beats but could not eliminate them permanently. Meanwhile, voltage mapping during right atrial pacing revealed that the left pulmonary vein had electrically reconnected to the atrium, with ripple mapping pinpointing the anterior carina, the ridge between the vein branches, as the earliest site of reconduction. The puzzle was this: the recurring trigger sat on the posterior wall, far from the isolation line, yet the reconnected vein was waking up first at the anterior carina. The two findings only made sense together if electricity was traveling along a concealed route outside the endocardial surface.

To test that hypothesis, the team paced from four distinct sites inside the left common pulmonary vein and measured how long each impulse took to reach the distal coronary sinus electrode. The numbers were striking. Pacing from the posterior bottom of the vein produced a conduction time of 140 milliseconds, and from the posterior roof 138 milliseconds, while pacing from the anterior ostium produced just 30 milliseconds. When the map was reconstructed with pacing from the vein, the earliest activation site matched the uneliminated trigger exactly. The pattern pointed to an epicardial connection, a subepicardial muscular bundle linking the anterior carina of the left pulmonary vein to the posterior atrial wall near the vein’s ostium, rather than a simple endocardial gap in the ablation line. The team targeted this presumed pathway at the inferior portion of the anterior carina with 35 watts and a target ablation index of 500, completed the pulmonary vein isolation, and rendered the arrhythmia non-inducible.

The anatomical suspect in this case has a name that cardiologists know well: the ligament of Marshall. This vestigial structure, a remnant of an embryonic vein, carries the Marshall bundle of myocardial fibers from the coronary sinus up the epicardial surface between the left atrial appendage and the left superior pulmonary vein. Its fibers can link the coronary sinus, the posterior and lateral left atrial wall, the ridge of the appendage, and the pulmonary vein antrum into a subepicardial conduction network that no endocardial ablation line can interrupt until lesions become fully transmural. Epicardial connections of this kind are not exotic curiosities. Studies estimate they occur in roughly 11 to 14 percent of patients with atrial fibrillation, and they are more numerous in patients with advanced disease and enlarged left atria. High-density mapping studies have shown that most cluster at the pulmonary vein carina and can extend well beyond the antral ablation line, explaining residual vein potentials and preserved atrial capture even when entrance and exit block appear complete.

Here the left common pulmonary vein becomes more than an anatomical footnote. Research by Kueffer and colleagues has found that this vein variant shows the lowest durability after pulsed field ablation, and the reasoning is anatomically elegant. In patients with a left common trunk, the ligament of Marshall lies closer to the ablation target, increasing the opportunity for epicardial fibers to bypass standard lesion sets. Intriguingly, the picture reverses with radiofrequency energy: lower recurrence rates have been reported for left common pulmonary vein patients treated with point-by-point radiofrequency, while the cryoballoon, another one-shot device like FARAPULSE, has shown reduced durability in the same anatomy. The implication is uncomfortable for the newest technology. One-shot ablation devices, which deliver energy in a fixed geometric pattern, may be inherently more vulnerable to anatomical variants than flexible, point-by-point techniques that an operator can adapt lesion by lesion.

The outcome for the patient, at least so far, is encouraging. After the second procedure he took no anti-arrhythmic drugs or beta-blockers, only a single anticoagulant for six months. Over a full year of follow-up, serial 24-hour Holter monitoring and 12-lead electrocardiography found no recurrence of atrial fibrillation, and he remained entirely asymptomatic, with annual Holter monitoring planned thereafter. The authors are candid about the limits of their evidence. This is a single case that cannot be generalized to everyone with a left common pulmonary vein, and because no electrode catheter was placed within the epicardial pathway and no ethanol was infused into the vein of Marshall, the exact route of the connection was inferred from post-pacing intervals rather than directly proven. The endocardial latency gap, a phenomenon in which conduction recovers with delayed timing, could not be definitively excluded, though the successful ablation at the anterior carina strongly supports the epicardial explanation.

Even with those caveats, the case lands at a consequential moment. Pulsed field ablation is expanding rapidly across the world on the strength of high acute isolation rates and a favorable early safety profile, sparing the esophagus and phrenic nerve from the collateral injury that thermal energy sources can cause. But durability, not acute success, is what determines whether a patient is truly cured, and long-term data relative to conventional treatment remain uncertain. The message from this case is that a perfect-looking lesion set on the inside of the heart can be quietly defeated by conduction running along the outside. For patients with a left common pulmonary vein, the authors argue, careful evaluation and explicit consideration of epicardial reconnection should be part of every ablation plan. As pulsed field technology matures, the hearts it fails to fix may teach clinicians as much as the ones it heals, and the answers may lie in structures no catheter can see from within.

Subject of Research: Epicardial connection as a mechanism of atrial fibrillation recurrence after pulsed field ablation

Article Title: Epicardial Connection as a Resource of Atrial Fibrillation Recurrence After Pulsed Field Ablation: A Case Report

Article References: Lee, K. H., Kitamura, T., Sahashi, S., Sugiyama, H., Izumi, C., & Hayashi, K. (2026). Epicardial Connection as a Resource of Atrial Fibrillation Recurrence After Pulsed Field Ablation: A Case Report. Clinical Case Reports, 14(10), Article e73282. https://doi.org/10.1002/ccr3.73282

Image Credits: AI Generated

DOI: 10.1002/ccr3.73282

Keywords: atrial fibrillation, pulsed field ablation, epicardial connection, pulmonary vein isolation, ligament of Marshall, left common pulmonary vein, electroanatomic mapping, cardiac electrophysiology, FARAPULSE, arrhythmia recurrence, case report, ablation durability

The trial enrolled 262 patients with symptomatic paroxysmal or persistent atrial fibrillation and randomised them in a 2:1 ratio to pulmonary vein isolation or to a sham procedure. The primary endpoint was the between-group difference in the change from baseline to six months in the AFEQT summary score, a well-established questionnaire measuring atrial fibrillation-related quality of life. At six months, the mean AFEQT score improved from 61 to 81 in the ablation group and from 59 to 75 in the sham group. Both improvements were clinically meaningful, but the difference in change between the groups was not statistically significant. Meanwhile, ablation demonstrated clear objective efficacy: atrial fibrillation was detected in 21 percent of ablated patients versus 41 percent of sham patients, an absolute difference of 20 percent, with a favourable safety profile.

What distinguishes PVI-SHAM-AF from earlier research is the rigor of its control condition. The sham intervention was not an inert experience but an active clinical pathway encompassing hospital admission, deep sedation and analgesia, venous access, a stay in the catheterization laboratory, cardioversion for patients who arrived in atrial fibrillation, and structured follow-up. The trial therefore tested catheter ablation against this comprehensive procedural and clinical-care package, not against no treatment at all. The investigators emphasise that the study did not evaluate conventional non-invasive ambulatory care. Within the six-month observation window, however, the superior rhythm control achieved by ablation simply did not translate into a statistically significant improvement in patient-reported quality of life beyond what the active sham pathway delivered.

Compared with the two previous sham-controlled ablation trials, SHAM-PVI and PFA-SHAM, PVI-SHAM-AF was substantially larger, exceeding the combined sample size of both predecessors. Baseline quality of life was impaired to a similar degree as in the major open-label trials CABANA and EARLY-AF. Intriguingly, while the improvement within the ablation arms was broadly consistent across all these studies, the improvement observed in the sham arm of PVI-SHAM-AF was markedly lower than in SHAM-PVI and PFA-SHAM. The editorial authors suggest this discrepancy indicates that patient management in PVI-SHAM-AF may have been more comprehensive than in the other two sham trials, intensifying the care received by the control group and thereby narrowing the apparent treatment effect on symptoms.

The findings echo a broader pattern in cardiovascular medicine. Previous reports have documented clinically relevant placebo effects in randomised trials of invasive procedures across settings as varied as resistant hypertension, percutaneous coronary intervention and vertebroplasty for osteoporotic vertebral fractures. A systematic review and meta-analysis found that only about a third of placebo-controlled trials of cardiovascular interventions demonstrated significant superiority of the invasive procedure over placebo. Against this backdrop, PVI-SHAM-AF is less an outlier than a striking confirmation that subjective, patient-reported endpoints are acutely susceptible to contextual healing, expectation and the attention that accompanies any hospital-based intervention.

Why did both groups improve so substantially? The editorial points to a likely combination of placebo and Hawthorne effects, regression to the mean, and optimised concomitant care driven by protocol-adherent assessments and intensive follow-up. Symptoms in atrial fibrillation, the authors argue, may not be determined solely by arrhythmia physiology but also by symptom perception, atrial or ventricular ectopy, anxiety and depression. Quantifying the individual contributions of these mechanisms is difficult, and PVI-SHAM-AF was not designed to isolate them. Disentangling how much of the improvement stems from the procedure itself, from heightened clinical attention, or from psychological factors remains a critical objective for future research and could reshape how symptom-directed therapies are evaluated.

Do the results mean ablation fails to relieve symptoms, or that it should be withheld from patients with preserved left ventricular function? The editorial authors firmly reject both conclusions. The trial demonstrates that ablation reduces atrial fibrillation recurrence and burden safely, and it does not challenge indications in settings where reducing arrhythmia burden may improve clinically relevant outcomes, such as tachycardia-induced or atrial fibrillation-aggravated cardiomyopathy and heart failure with reduced ejection fraction, populations that were not the focus of this study. The results are confined to patient-reported outcomes rather than morbidity or mortality, reflecting a familiar divergence in cardiology where effects on hard endpoints and on how patients feel can part ways, as seen with beta-blockers, inotropes and implantable cardioverter-defibrillators in heart failure.

Questions about patient selection and follow-up duration also deserve scrutiny. Data on the 937 patients who declined randomisation were insufficient for comparison, and willingness to accept an invasive sham procedure may have selected individuals with particular symptom burdens, expectations or treatment preferences; patients with severe symptoms might have declined to guarantee receiving ablation. Yet the mean baseline AFEQT score of 60 mirrored those in CABANA, EARLY-AF and STOP AF First, beta-blocker use remained high and balanced between groups, and no treatment effect heterogeneity by baseline score was observed. The six-month primary endpoint was chosen deliberately to minimise the impact of repeat procedures, but the authors concede it may have been too short to capture the full treatment effect, and it does not exclude longer-term benefits in rhythm control, medication use, healthcare utilisation or clinical outcomes. Twelve-month follow-up is ongoing.

For clinical practice, the implications centre on shared decision-making. PVI-SHAM-AF shows that the objective rhythm-control benefits of catheter ablation should be clearly distinguished from its effects on patient-reported quality of life at six months, information that is essential for counselling patients whose primary goal is symptom relief. The results also underscore the therapeutic power of comprehensive, attentive clinical care. Crucially, the authors stress that invasive sham procedures are research tools for delineating true treatment effects and must never be translated into clinical practice. Instead, the challenge is to identify which components of the sham-associated care pathway improved symptoms and how those elements can be incorporated into routine, non-invasive care.

Perhaps the trial’s most enduring lesson is methodological. The editorial demonstrates that randomised, blinded evaluation of an established, guideline-recommended invasive procedure is accepted by patients, accepted by many expert physicians, and feasible across multiple centres and countries. Sham-controlled designs are particularly important when evaluating subjective or patient-reported outcomes, because such endpoints are vulnerable to placebo effects, expectations, regression to the mean and the effects of intensified clinical care. Just as placebo controls are indispensable for drug therapies, the incremental effect of an invasive or surgical procedure on how patients feel cannot be reliably determined without an appropriate sham control. PVI-SHAM-AF may thus be remembered less for what it says about ablation alone and more for how it resets the standard of evidence for procedural medicine.

Subject of Research: A sham-controlled randomised trial evaluating catheter ablation for symptom relief and rhythm control in patients with symptomatic atrial fibrillation.

Article Title: PVI-SHAM-AF: what does this trial tell us about catheter ablation and symptoms in patients with atrial fibrillation?

Article References: Laufs, U., Böhm, M., Mahfoud, F., & Wachter, R. (2026). PVI-SHAM-AF: what does this trial tell us about catheter ablation and symptoms in patients with atrial fibrillation?. Clinical Research in Cardiology. https://doi.org/10.1007/s00392-026-03016-z

Image Credits: AI Generated

DOI: 10.1007/s00392-026-03016-z

Keywords: atrial fibrillation, catheter ablation, pulmonary vein isolation, sham-controlled trial, quality of life, AFEQT score, placebo effect, rhythm control, patient-reported outcomes, PVI-SHAM-AF, cardiology, clinical trial