Early and late ventricular arrhythmias complicating ST-segment elevation myocardial infarction

Background: Ventricular arrhythmias can be life-threatening complications of ST-segment elevation myocardial infarction (STEMI).

Aims: To describe the incidence, predictors and in-hospital impact of early ventricular arrhythmia (EVA, occurring<day 2 after STEMI) and late ventricular arrhythmia (LVA, occurring≥day 2 after STEMI) in patients with STEMI.

Methods: Data from 13,523 patients enrolled in a prospective registry were analysed. Logistic and Cox regressions were performed to identify predictors of EVA, LVA and in-hospital all-cause mortality. Predictors of LVA were used to build a risk score.

Results: EVA occurred in 678 patients (5%), whereas 120 patients (0.9%) experienced LVA, at a median timing of 3days after STEMI. EVA was associated with a significantly higher risk of all-cause mortality (hazard ratio: 1.44, 95% confidence interval: 1.17-1.76; P=0.001), whereas no association was observed with LVA (hazard ratio 0.86, 95% confidence interval 0.57-1.28; P=0.45). Multivariable predictors of LVA were: age≥65years; serum creatinine≥85μmol/L on admission; pulse pressure≤45mmHg on admission; presence of a Q wave on admission electrocardiogram; Thrombolysis In Myocardial Infarction flow grade<3 after percutaneous coronary intervention; and left ventricular ejection fraction≤45%. The score derived from these variables allowed the classification of patients into four risk categories: low (0-21); low-to-intermediate (22-34); intermediate-to-high (35-44); and high (≥45). Observed LVA rates were 0.2%, 0.3%, 0.9% and 2.5%, across the four risk categories, respectively. The model demonstrated good discrimination (20-fold cross-validated c-statistic of 0.76) and adequate calibration (Hosmer-Lemeshow P=0.23).

Conclusions: EVA is 5-fold more common than LVA in the setting of STEMI, and portends a higher risk of in-hospital all-cause mortality. LVA is mainly associated with the patient's baseline risk profile and surrogate markers of larger infarct size. We developed and internally validated a risk score identifying patients at high risk of LVA for whom early intensive care unit discharge may not be suitable.