Prolonged QT and myocardium recovery after primary PCI : a cMRI study

Background The presence of viable stunned myocardium recovering after primary angioplasty is not easy to identify in the early phase of acute myocardial infarction ( AMI ) by noninvasive bed‐side methods. We therefore aimed to assess whether a simple electrocardiogram parameter may be of help in identifying the presence of stunned viable myocardium recovering after reperfusion with primary angioplasty. Materials and methods A total of 14 consecutive patients with ST ‐elevation AMI ( STEMI ) were enrolled in the study and underwent QT duration assessment after admission: the difference between QT corrected ( QT c) in the ischaemic areas and QT c values in nonischaemic areas was therefore calculated and compared with the presence and the extension of viable stunned myocardium, assessed by comparing akinetic/dyskinetic areas at admission echocardiography with akinetic/dyskinetic areas and extension of scar at 6‐month cardiac magnetic resonance imaging ( cMRI ). Results In subjects with viable recovering myocardium, 75% had a QT c max > 440 ms (vs. 17%, P = 0·03); higher differential QT c values and smaller scar areas were found (33 ms vs. −17 ms, 14% vs. 27%, P = 0·03, 0·06 respectively). Differential QT c values > 0 were able to identify the presence of viable myocardium with an odds ratio of 35 ( P < 0·05, sensitivity 88%, specificity 83%, positive predictive power 88%, negative predictive power of 83%). Differential QT c values were related to the extension of viable recovering myocardium ( P < 0·001). Conclusion Viable myocardium recovering after primary angioplasty in STEMI may be predicted by the presence of increased QT c values in ischaemic areas in comparison with nonischaemic areas.