Spontaneous Recovery of Myocardial Asynergic Segments Following Acute Myocardial Infarction. The Role of Post-Extrasystolic Potentiation Echocardiography in the Predischarge Evaluation

Aims: Predischarge identification of viable myocardium with a spontaneous recovery over time can be helpful in decision-making process following acute myocardial infarction (AMI). An intriguing hypothesis is that identification of viability in myocardial asynergic segments with or without spontaneous recovery over time may require an inotropic stimulus of a different intensity. To test this we used post-extrasystolic potentiation (PESP), which represents an inotropic stimulation of a different intensity as a function of coupling interval. Methods and results: Myocardial viability was assessed by PESP echocardiography in 86 patients with a first uncomplicated AMI. Spontenous changes in contractile function of viable but asynergic segments at predischarge were evaluated by a follow-up resting echocardiogram 1 month later. Viable myocardium of left ventricular asxynergic segments with spontaneous recovery or persistence of dysfunction showed its first significant improvement for different values of coupling interval during PESP (409±18 vs 336±23 ms (milliseconds), P <0·0001). An arbitrary cut-off value for RR interval ≥380 ms, correctly identified 91% of myocardial segments undergoing spontaneous recovery, while 99% of asynergic myocardial segments with spontaneous recovery had a threshold coupling interval ≥380 ms. Conclusion: At predischarge following AMI, asynergic but viable myocardial segments by PESP with spontaneous recovery of contraction over time require an inotropic stimulus of lesser intensity to acutely improve contraction pattern than viable and asynergic segments without this favourable outcome.