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, 63±11 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, n=44, or percutaneous coronary intervention, n=65, versus no reperfusion, n=397) 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%, P=0.001). Induced VTCL was shorter (247±40 versus 287±63, P<0.001) and very fast Vt (CL ≤250 ms) was more often induced in reperfused patients (71% versus 47%, P=0.001). 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.