Regional heterogeneous sympathetic innervation assessed by 11C-hydroxyephedorine positron emission tomography in patients with sustained ventricular tachycardia or fibrillation

Objectives Abnormalities in cardiac sympathetic innervation and its distribution may contribute to the pathogenesis of ventricular tachycardia or fibrillation. Left stellate innervations functionally distributes to lateral and inferior wall.

Methods We studied 10 non-ischemic patients who admitted our hospital due to the documented lethal ventricular arrhythmias (ARVC: n=1, Brugada syndrome: n=2, long QT syndrome: n=2, HCM: n=3, HHD: n=2) (age 57±20 years). All patients had normal left ventricular ejection fraction (>50%) and have undergone ICD implantation for the secondary prevention as a Class-I recommendation. The distribution of sympathetic nerves in left ventricle was estimated at 17-cardiac segments by the retention index of 11C-hydroxyephedorine PET. Healthy volunteers (n = 10; age 32±10 years) were also enrolled as controls.

Results Global retention index did not differ between patients and healthy volunteers (0.120±0.046 vs 0.152±0.032, p = 0.08). When regional retention index was compared between groups, the index in inferolateral wall in patients were significantly lower than that in healthy volunteers (0.107±0.040 vs 0.150±0.032, p = 0.02,Figure). Accordingly, the coefficient of variation of 17-segment retention index in patients was higher than healthy volunteers (0.196±0.117 vs 0.101±0.035, p = 0.02).

Conclusions Cardiac regional sympathetic nerve innervation was decreased and heterogenous in patients with lethal ventricular arrhythmias, which might imply that the regional sympathetic abnormality is the key mechanism of cardiac sudden death in patients with normal systolic function.