Early Reperfusion Therapy Affects Inducibility, Cycle Length, and Occurrence of Ventricular Tachycardia Late After Myocardial Infarction

Abstract

Background-This study aimed to evaluate the impact of early reperfusion during acute myocardial infarction (MI) on ventricular tachycardia (VT) inducibility, inducible VT cycle length (CL), and occurrence of spontaneous VT late after MI. Methods and Results-Five hundred six patients (440 men; age, 63Ϯ11 years) with prior MI who underwent electrophysiology study before implantation of an implantable cardioverter-defibrillator for primary or secondary prevention were assessed. Patients were classified according to the reperfusion strategy (reperfusion: thrombolysis, nϭ44, or percutaneous coronary intervention, nϭ65, versus no reperfusion, nϭ397) during acute MI. Monomorphic sustained VT was inducible in 351 (69%) patients. Inducibility in reperfused and nonreperfused patients was similar in primary prevention patients (56% versus 58%) but significantly higher for nonreperfused patients in secondary prevention patients (56% versus 79%, Pϭ0.001). Induced VTCL was shorter (247Ϯ40 versus 287Ϯ63, PϽ0.001) and very fast VT (CL Յ250 ms) was more often induced in reperfused patients (71% versus 47%, Pϭ0.001). In primary prevention patients, nonreperfusion was associated with a doubled risk for first spontaneous VT during follow-up. Conclusions-There are important differences in VT inducibility, induced VTCL, and occurrence of spontaneous VT in the chronic infarct healing phase between patients with and those without successful reperfusion during acute MI. These findings suggest differences in the chronic arrhythmogenic substrate.

Arrhythmogenesis after acute myocardial necrosis with and without preceding ischemia in rats

“…First, the second arrhythmogenic period in nonreperfused MI, characterized mainly by monomorphic VT, contrasted with the absence of significant arrhythmias in reperfused MI, beyond reperfusion arrhythmias. This finding indicates that the salvage of myocardial tissue decreases the substrate formation for monomorphic VT and is in line with clinical data demonstrating markedly decreased incidence of sub-acute and chronic-stage monomorphic VT in MI patients treated with percutaneous coronary interventions; for instance, in a post-MI cohort of ∼500 patients [38], reperfusion decreased the inducibility of monomorphic VT in electrophysiologic study, as well as the incidence of spontaneous VT during follow-up. Second, the delayed window of polymorphic Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 6/2/15 11:44 PM VT/VF after direct necrosis may correspond to in-hospital VT/VF during the sub-acute MI stage [2], occasionally observed even in the absence of ongoing ischemia, acute LV failure or electrolyte disturbances [39].…”

The Relationship between Time from Myocardial Infarction, Left Ventricular Dyssynchrony, and the Risk for Ventricular Arrhythmia: Speckle-Tracking Echocardiographic Analysis

“…13 In brief, patients were studied in a fasting, nonsedated state and after the discontinuation of antiarrhythmic medications (except for amiodarone) for five half-lives. 14 PES included up to three drive-cycle lengths (600, 500, and 400 msec) with up to three ventricular extrastimuli and burst pacing from the right ventricular apex and right ventricular outflow tract. Positive response to PES was defined as the reproducible induction of sustained monomorphic VT lasting >30 sec or requiring termination because of hemodynamic compromise.…”

Signal‐averaged electrocardiography: Past, present, and future

“…Reperfusion strategies after acute coronary occlusion, widely practiced during the past decade, have altered the characteristics of patients, when compared to earlier populations; indeed, prompt reperfusion decreases infarct size and transmurality, thereby ameliorating the substrate for monomorphic VT . This development increases the need for more accurate identification of potential candidates for ICD therapy and supports emerging views, challenging the current use of LVEF as the main variable in primary SCD prevention .…”