Prevalence and significance of accelerated idioventricular rhythm in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention.

Accelerated idioventricular rhythm (AIVR) has been considered a marker of successful reperfusion in fibrinolytic-treated patients. Evidence is limited regarding its significance in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention (PPCI). The purpose of the present study was to determine the prevalence and associated outcomes of arrhythmias and conduction disturbances occurring during PPCI. In 503 patients with ST-elevation myocardial infarction, the arrhythmias and conduction disturbances occurring from arrival at the catheterization laboratory to 90 minutes after PPCI were registered. Continuous ST-monitoring was performed to determine the interval from the first wire to complete ST resolution. The area at risk was evaluated in the acute phase and the final infarct size (FIS) after 1 month using myocardial perfusion imaging. Mortality was registered at a median follow-up of 2.9 years. The most common arrhythmias observed during PPCI were AIVR (42%), sinus bradycardia (28%), and nonsustained ventricular tachycardia (26%). The arrhythmias associated with the FIS included AIVR (unstandardized regression coefficient [B] = 5.27, p <0.001), sustained ventricular tachycardia (B = 15.7, p <0.001), and sinus bradycardia (B = -4.12, p = 0.001). Right bundle branch block was the only conduction disturbance associated with FIS (B = 7.17, p = 0.001). Patients with AIVR less often achieved spontaneous ST resolution before PPCI (13% vs 36%, p <0.001), less often had Thrombolysis In Myocardial Infarction flow 3 on admission (3% vs 33%, p <0.001), had a larger area at risk (35% vs 23% of the left ventricle, p <0.001), had a longer time to complete ST resolution (39 vs 21 minutes, p <0.001), had a larger FIS (13% vs 5% of the left ventricle, p <0.001) but had similar mortality (8.6% and 6.5%, p = 0.39) compared to patients without AIVR. In conclusion, AIVR is the most frequent arrhythmia occurring during PPCI in patients with ST-elevation myocardial infarction. However, it is not a marker of successful reperfusion but is associated with extensive myocardial damage and delayed microvascular reperfusion.