Incidence and predictors of ventricular arrhythmias after ST-segment elevation myocardial infarction

Sustained ventricular arrhythmias (VA) complicate 7% to 20% of acute myocardial infarctions. We hypothesized that primary angioplasty (percutaneous coronary intervention [PCI]) and contemporary medical treatment will result in a lower incidence of VA and shorten the time frame of their occurrence. Thus, an electrocardiographic monitoring period of 24 hours should be sufficient to detect more than 95% of all malignant VA.

We continuously monitored all patients with ST-segment elevation myocardial infarction (STEMI) for 48 hours.

Of the 510 patients who underwent PCI for STEMI, 24 (4.7%) developed sustained VA. Sixty percent of sustained VA occurred during the first 24 hours; and 92%, during the first 48 hours. In univariate analysis, heart rate greater than 100 beats per minute, Thrombolysis in Myocardial Infarction flow grade less than 3, elevated creatinine (≥1 mg/dL), elevated C-reactive protein (≥0.8 mg/dL), higher white blood cell count (≥12 × 10(3)/μL), use of diuretics, and lower hematocrit (≤39%) were associated with an increased risk of VA. Symptom-onset-to-balloon time of 4 hours or more in patients with postprocedural Thrombolysis in Myocardial Infarction 3 flow, treatment with β-blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, and statins were associated with a reduced risk of VA. After multivariate adjustment, independent predictors of sustained VA included total white blood cell count of 12 × 10(3)/μL or more, hematocrit of 39% or less, and lack of β-blocker medication.

In this study, we could demonstrate that primary PCI results in a lower incidence of VA compared with data from the literature but did not shorten the time frame of VA occurrence. Thus, an electrocardiographic monitoring period for VA of 48 hours should be performed in patients with STEMI.