Hidden Nerve Hotspots in Uninjured Heart Regions Predict Danger After Heart Attack

When a patient arrives at the hospital in the grip of a major heart attack, cardiologists race to reopen the blocked artery that is starving the heart muscle of oxygen. That culprit vessel receives all the attention, yet a new study suggests that some of the most important clues about the patient’s future lie in the parts of the heart that were never injured at all. Researchers in Japan report that overactivity of the sympathetic nerves supplying regions of the heart remote from the site of the infarction powerfully predicts which survivors of ST-elevation myocardial infarction, or STEMI, will go on to suffer further cardiac disasters. The finding, published in the European Journal of Nuclear Medicine and Molecular Imaging, adds a striking neurological dimension to risk assessment after a heart attack, one that standard clinical scores completely overlook.

The science behind the discovery rests on a nuclear medicine technique that has been refined over decades. Cardiac sympathetic nerve activity can be visualized using a radioactive tracer called iodine-123 metaiodobenzylguanidine, abbreviated 123I-MIBG. This molecule mimics norepinephrine, the chemical messenger that sympathetic nerve endings release to accelerate the heartbeat under stress. Because the tracer is taken up by the same transport machinery that recycles norepinephrine, images of its distribution reveal how well the cardiac sympathetic nervous system is functioning. Damaged or overactive nerve terminals handle the tracer abnormally, and one of the most informative measurements is the washout rate, which describes how quickly the tracer clears from the heart muscle between early and delayed scans. A high washout rate signals heightened sympathetic tone, a state long associated with arrhythmias, worsening heart function, and death in patients with heart disease.

What has remained unclear is whether the whole-heart measurement tells the whole story. Conventional practice relies on planar images, two-dimensional snapshots that average tracer behavior across the entire myocardium. The Japanese team, led by Takumi Kondo of Osaka General Medical Center, asked a more granular question: does the sympathetic activity measured specifically in the territory of the blocked artery, the culprit lesion, carry different prognostic weight than the activity in territories served by the other coronary arteries, the non-culprit regions? To find out, they prospectively enrolled 122 patients with STEMI and performed 123I-MIBG imaging with both planar and single photon emission computed tomography, or SPECT, which resolves the heart into three-dimensional regional detail.

The study design was rigorous and forward-looking. Every patient underwent imaging during the acute phase of their heart attack, and the investigators calculated a global washout rate from the planar images alongside separate average washout rates for the culprit and non-culprit territories on the SPECT images. The patients were then followed for an average of 4.2 years, with a standard deviation of 2.5 years, while the researchers tracked the occurrence of major adverse cardiac events, a composite endpoint that captures the outcomes patients and doctors fear most. During the follow-up period, 34 of the 122 patients experienced such an event, providing a substantial body of outcome data for statistical analysis.

The results delivered a genuine surprise. Both an abnormally high global washout rate on planar imaging and an increased washout rate in the non-culprit lesion were independently associated with major adverse cardiac events, even after the two measures were mutually adjusted against each other and after the analysis controlled for established clinical predictors including the widely used GRACE and TIMI risk scores. The washout rate in the culprit lesion, by contrast, showed no such independent association. In other words, sympathetic overactivity in the region of the heart that suffered the infarction did not add prognostic information, but sympathetic overactivity in the apparently healthy, remotely located myocardium did.

The explanation likely lies in the biology of the cardiac autonomic nervous system. Sympathetic nerves are distributed across the heart in a heterogeneous pattern, and injury or inflammation in one region can trigger widespread neural remodeling that extends well beyond the damaged zone. Previous histological and imaging work has documented that autonomic nerves course through the human heart in regionally variable ways, and animal studies have shown that sympathetic neuronal function and receptor populations recover on different schedules after ischemia and reperfusion. Remote sympathetic activation, sometimes amplified by interventions such as ischemic conditioning, has emerged as a therapeutic target in its own right. The new findings suggest that this remote neural disturbance is not a bystander phenomenon but an active driver of poor outcomes, plausibly by lowering the threshold for lethal ventricular arrhythmias and progressive ventricular dysfunction in tissue that remains structurally viable.

Perhaps the most clinically consequential result concerns patients who exhibit both abnormalities simultaneously. Those with both an abnormal global washout rate and an increased non-culprit washout rate faced a significantly higher risk of major adverse cardiac events than patients showing either abnormality alone, a difference that reached statistical significance with a p value of 0.025, and a dramatically higher risk than patients with neither abnormality, where the p value fell below 0.001. This dose-response-like layering indicates that the regional SPECT measurement provides genuinely incremental information on top of the conventional planar assessment. A two-tier imaging strategy, in which planar screening is followed by regional tomographic analysis, could therefore identify a small subgroup of heart attack survivors whose risk is substantially underestimated by every current scoring system.

The implications reach beyond risk prediction into treatment selection. Patients flagged as high risk by this neural signature might be candidates for more aggressive therapy, closer surveillance, earlier decisions about implantable cardioverter-defibrillators, or enrollment in trials of neuromodulation strategies aimed at calming the overactive cardiac sympathetic system. The same research group has previously shown that remote ischemic perconditioning can suppress sympathetic activation after acute myocardial infarction, and that MIBG imaging can track the effects of drugs such as nicorandil on nerve function. A measurable, regional index of sympathetic overactivity gives such interventions a concrete target and a way to verify whether they are working, potentially transforming the tracer technique from a passive prognostic tool into an active guide for therapy.

Certain caveats deserve emphasis. The study involved 122 patients at a single center in Osaka, and the imaging was performed in the acute phase, so it remains to be seen whether the non-culprit washout rate retains its predictive power when measured later, or in more diverse populations and health care systems. SPECT regional analysis also demands more expertise and processing time than a simple planar washout calculation, and questions about standardization across different cameras and centers, which have been addressed for other MIBG parameters in multicenter calibration work, will need answers for regional indices as well. Nevertheless, the core message is difficult to dismiss: after a heart attack, the nerves in the parts of the heart that were spared may matter more than the nerves in the parts that were not. As nuclear cardiology moves toward ever finer characterization of the heart’s neuroanatomy, the non-culprit territory has moved from the periphery of the image to the center of prognostic attention, and clinicians assessing STEMI survivors may soon want to look not only at where the artery was blocked, but at what the rest of the heart’s nervous system is doing.

Subject of Research: Prognostic value of regional cardiac sympathetic nerve activity measured by 123I-MIBG imaging in STEMI patients

Article Title: Cardiac sympathetic nerve activity in the non-culprit lesion predicts poor prognosis in patients with STEMI

Article References: Kondo, T., Yamada, T., Asai, M., Morita, T., Kawasaki, M., Kikuchi, A., Kawai, T., Seo, M., Nakamura, J., Fujita, T., Kokubu, Y., Oyama, F., Obayashi, H., Kurihara, H., Noda, K., Nishikawa, N., Suganami, A., Takahashi, M., Sakata, Y., & Fukunami, M. (2026). Cardiac sympathetic nerve activity in the non-culprit lesion predicts poor prognosis in patients with STEMI. European Journal of Nuclear Medicine and Molecular Imaging. https://doi.org/10.1007/s00259-026-08186-6

Image Credits: AI Generated

DOI: 10.1007/s00259-026-08186-6

Keywords: STEMI, cardiac sympathetic nerve activity, 123I-MIBG imaging, SPECT, washout rate, non-culprit lesion, major adverse cardiac events, prognosis, nuclear cardiology, GRACE risk score, TIMI risk score, myocardial infarction