Abstract 1773: Cardiac Sympathetic Nerve Abnormality predicts Sudden Cardiac Death in Patients with Ventricular Tachyarrhythmias
Background: Sympathetic nerve system (SNS) abnormality predicts cardiac death in patients with proven or suspected ischemic heart disease. We hypothesized that SNS abnormality would be associated with sudden cardiac death from arrhythmic cause in patients with ventricular tachycardia or fibrillation (VT/VF).
Methods and Results: Iodine-123 metaiodobenzylguanidine scintigraphy was performed in 83 patients (mean ± standard deviation, age: 47 ± 19 years, 63.9% males) with proven VT/VF. SNS activity was assessed from Heart/Mediastinum (H/M) ratio when the patients remained on the condition of sinus rhythm. Over 11 years of follow up (5.2 ± 3.7 years), 3 patients had sudden deaths (3.6%) and 23 patients had sustained VT/VF events (27.7%). Severe SNS abnormality, defined as H/M ratio <2.1, was strongly predictive of sudden death or recurrent VT/VF event (61.5% in 8 of 13 patients vs 21.4% in 15 of 70 patients without severe SNS abnormality, p=0.003). After adjustment for potential confounding variables such as older age (≥65), gender, structural heart diseases, cardiovascular risk factors, left ventricular dysfunction (ejection fraction ≤40%), and medications (use of beta-blocker, amiodaron, or any other anti-arrhythmic drugs), severe SNS abnormality remained predictive with a hazard ratio of 3.1 [95% confidence interval, 1.3 to 7.4 (p=0.009)].
Conclusion: These findings suggest that severe SNS abnormality is a readily available and powerful predictor of sudden death in patients with VT/VF.