Early Repolarization Increases the Occurrence of Sustained Ventricular Tachyarrhythmias and Sudden Death in the Chronic Phase of an Acute Myocardial Infarction
Background—We recently showed that the presence of early repolarization (ER) increases the risk of ventricular fibrillation occurrences in the early phase of acute myocardial infarction (AMI). This study aimed to clarify whether an association exists between ER and occurrences of ventricular tachyarrhythmias (VT/VF) or sudden death in the chronic phase of AMI.
Methods and Results—This study retrospectively enrolled 1,131 patients (67±12 years; 862 men) with AMIs surviving 14 days post-AMI. The primary endpoint was the occurrence of sustained VT/VF or sudden death >14 days after the AMI onset. We evaluated the presence of ER from the pre-discharge ECG (mean 10±3 days post-AMI). ER was defined as an elevation of the terminal portion of the QRS complex of >0.1 mV in inferior or lateral leads. After a median follow-up of 26.2 months, 26 patients had an episode of VT/VF or sudden death. A multivariable Cox regression analysis revealed the presence of ER (hazard ratio [HR] 5.37; 95% confidence interval [CI] 2.27-12.69; p<0.001), Killip class on admission of >I (HR 2.75; 95%CI 1.24-6.07; p=0.013), and a left ventricular ejection fraction of <35% (HR 11.83; 95%CI 5.16-27.13; p<0.001) were significantly associated with event occurrences. As features of the ER pattern, ER in the inferior leads, high-amplitude ER, a notched morphology, and ER without ST-segment elevation were associated with an increased risk of event occurrences.
Conclusions—ER observed at a mean of 10 days post-AMI may be a marker for a subsequent risk of VT/VF or sudden death.
- Received August 1, 2013.
- Revision received April 17, 2014.
- Accepted April 22, 2014.