Myocardial Ischemia and Ventricular Tachycardia on Continuous Electrocardiographic Monitoring and Risk of Cardiovascular Outcomes After Non–ST-Segment Elevation Acute Coronary Syndrome (from the MERLIN-TIMI 36 Trial)

Abstract

Among patients with non-ST-segment elevation acute coronary syndromes, recurrent ischemia and ventricular arrhythmias detected on continuous electrocardiographic monitoring remain common events that are associated with worse outcomes. The relative clinical significance of both events together is not well described. We determined the risk associated with ischemia (≥1 mm ST depression lasting ≥1 minutes) and ventricular tachycardia (VT) (≥4 beats) detected on 7-day continuous electrocardiographic monitoring in 6,355 patients with non-ST-segment elevation acute coronary syndromes from the Metabolic Efficiency with Ranolazine for Less Ischemia in Non-ST-elevation Acute Coronary Syndrome-Thrombolysis In Myocardial Infarction (MERLIN-TIMI) 36 trial. The patients were categorized into 4 groups according to the presence or absence of VT and ischemia. Cardiovascular death, sudden cardiac death (SCD), myocardial infarction, and recurrent ischemia were assessed during a median follow-up of 348 days. A total of 60.0% patients had no VT or ischemia, 20.0% had VT alone, 14.7% had ischemia alone, and 5.3% had both. The patients with either VT or ischemia were at increased risk of cardiovascular outcomes. The combination of ischemia and VT identified a particularly high-risk population for cardiovascular death (10.1% vs 3.0%, p <0.001), SCD (7.8% vs 0.9%, p <0.001), and myocardial infarction (15.4% vs 6.2%, p <0.001) compared to patients with neither. The addition of arrhythmia and ischemia significantly improved the clinical model for predicting cardiovascular death or SCD (p <0.001). In patients with both ischemia and VT, 66.6% of SCD occurred within 90 days of the non-ST-segment elevation acute coronary syndromes. In conclusion, in >6,300 patients with non-ST-segment elevation acute coronary syndromes, the presence of myocardial ischemia or VT alone, and particularly in combination, was independently associated with poor cardiovascular outcomes and thus provides incremental improvement in early risk stratification.