Effects of Angiotensin Converting Enzyme Inhibition on Cardiac Innervation and Ventricular Arrhythmias after Myocardial Infarction

Purpose: To investigate the influence of angiotensin-converting enzyme inhibitor (ACEI) on cardiac innervation and inducible ventricular arrhythmias (VAs) in healed myocardial infarction (MI).Methods: Left anterior descending coronary artery was ligated to induce MI in 30 rabbits. After oral captopril (10mg/kg/d) for 8 weeks, electrophysiological study was performed to evaluate the incidence of inducible VAs. RT-PCR and immunohistochemistry were used to measure the cardiac innervation.Results: Eight weeks after the operation, the incidence of inducible VAs in MI-placebo group was significantly higher (58.3%, 7/12) than the sham operation group (16.7%, 2/12, P< 0.05). However, the inducible VAs in the MI-captopril group was lower (27.2%, 3/11) than the MI-placebo group (P<0.05). Proliferation and growth of nerve fibers in the MI-placebo group were mainly distributed at the periphery of the infarcted and perivascular regions of the myocardium. This MI-induced abnormal nerve fiber distribution was partly restored by the captopril treatment.Conclusion: Prolonged captopril treatment may be effective to prevent occurrence of VAs in healed MI, partly by attenuating the spatial heterogeneity of cardiac innervation.