Abstract 8823: Abnormal Cardiac Innervation in Ventricular Fibrillation Patients with and Without Brugada Syndrome

Abstract

Abnormal cardiac innervation in patients with ventricular fibrillation (VF) has been reported. We investigated autonomic function in 48 successfully resuscitated VF patients using heart rate variability (HRV) as measured by Holter ECG and 123 I-metaiodobenzylguanidine ( 123 I-MIBG) scintigraphy. Eight patients were excluded because of hypertrophic cardiomyopathy (N = 2), arrhythmogenic right ventricular cardiomyopathy (N = 3), catecholamine-sensitive ventricular tachycardia (N = 1), and long QT syndrome (N = 2). Patients who could not discontinue internal remedies (N = 5) were also excluded. Fifteen patients (42 ± 14 years, 15 males) were diagnosed with Brugada syndrome (BS), and the remaining 20 patients (47 ± 6 years, 8 males) were diagnosed with idiopathic VF (IVF). QTc time was longer in the IVF patients than in the BS patients (450.1 ± 10.1 ms vs. 389.4 ± 21.0 ms, P < 0.05). RMS40 was lower in the BS patients than in the IVF patients (13.9 ± 2.2 mV vs. 20.9 ± 3.6 mV, P < 0.05). Parameters of HRV were similar in both groups, but abnormal circadian variations of HRV were observed in 53.3% of BS patients and 13.3% of IVF patients. The washout ratio was higher in the IVF patients than in the BS patients (36.3 ± 4.3 vs. 26.0 ± 2.1). The 123 I-MIBG uptake was increased in lateral regions in BS patients. Regionally reduced 123 I-MIBG uptake was observed with many variations in all patients, but no significant difference was observed between groups. These results demonstrated impairment of sympathetic innervation or enhanced activity of the sympathetic nervous system in patients with VF, particularly indicating sympathetic hypertonia in IVF and imbalance of circadian HRV in BS. These findings may have an impact on the arrhythmogenesis of such patients.