Pre-discharge atrial pacing test in evaluation of risk stratification after uncomplicated myocardial infarction.

Right atrial pacing (RAP) using three pacing stages (I: 100 BPM/5 min; II: 120 BPM/5 min; III: 140 BPM/5 min) was performed for residual myocardial ischemia, hypotensive response and related prognostic significance in 55 uncomplicated acute myocardial infarction (AMI) patients. We aimed to clarify whether early risk stratification and jeopardized myocardium score, calculated using pacing results, could predict disease severity and future major cardiac events during long-term follow-up. During RAP testing, 24 patients displayed negative and 31 patients positive RAP. The positive RAP group had a significantly higher incidence of multivessel disease, higher jeopardized myocardium scores and left ventricular end-diastolic pressure than the negative RAP group. As expected, according to pacing response the disease severity score also showed a significant difference. During the one-year follow-up, there were three recurrent angina attacks, reinfarction and two congestive heart failures in the negative RAP group. In the positive RAP group, four died, six had new or recurrent myocardial infarctions and six developed congestive heart failure. Only six patients in the positive RAP group carried the critical risk, four suffered from recurrent angina, two developed reinfarction, three developed congestive heart failure, and two died. Total major cardiac events in the positive RAP group appeared to significantly increase compared to those in the negative RAP group. Our results show that early RAP with three pacing stages is useful in predicting subsequent major cardiac events after uncomplicated myocardial infarction. We also observed that hypotensive response during positive RAP represents the best predictor of critical risk requiring further invasive studies. We believe that RAP is justified for risk strategy.