Reperfusion arrhythmia bursts predict larger infarct size in STEMI patients undergoing primary percutaneous coronary intervention despite optimal epicardial and microvascular flow

Background: Ventricular arrhythmia (VA) bursts are associated with larger infarct size (IS) in patients presenting with ST elevation myocardial infarction (STEMI) after achieving TIMI 3 flow with primary coronary intervention (pPCI). Inadequate microvascular reperfusion, as determined by myocardial blush grade (MBG) ≤2, has also been shown to be associated with larger IS. We hypothesized that VA burst is a marker of an unfavorable response to reperfusion resulting in larger IS in patients with optimal epicardial and optimal microvascular obstruction. Methods: 144 STEMI patients from the PREPARE study were included with 24 hour continuous, 12-lead Holter monitoring, and who achieved brisk epicardial flow restoration (TIMI 3 and MBG 3) post pPCI (figure 1). Angiographic MBG was determined in a blinded core laboratory. VA bursts were identified against subject-specific background VA rates using a previously published statistical outlier method in a blinded electrocardiography core laboratory. Delayed-enhancement cardiovascular magnetic resonance imaging (DE-CMR) was used to determine IS (median 202 days) by an independent core laboratory. Results: No significant differences were found for demographic characteristics, comorbidities, infarct location, number of diseased coronary vessels, or duration of ischemia between groups with MBG 3 and MBG 2. VA bursts were present in 140 patients. In patients with optimal epicardial and microvascular reperfusion (TIMI 3 and MBG 3), VA burst was associated with larger IS (N=120/144; median 11.6% vs 5.1%; p=0.001). Figure 1. Patient selection Figure 1. Patient selection Conclusion: In the presence of optimal epicardial and microvascular recanalization, VA bursts are associated with larger IS. VA bursts are a marker of myocellular injury, possibly due to the reperfusion process.