Temporal repolarization inhomogeneity and reperfusion arrhythmias in patients undergoing successful primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction: Impact of admission troponin T

Abstract

Background The presence of admission cardiac troponin-T (cTnT) is a means of identifying a high-risk subgroup in patients with acute ST-segment elevation myocardial infarction (AMI). Because a substantial number of these patients has malignant ventricular arrhythmias, we hypothesized that there is a relation between cTnT status on admission and inhomogeneity of ventricular repolarization, and we tested this assumption in the setting of primary percutaneous coronary intervention (PCI). Methods Temporal fluctuations of ventricular repolarization were studied during and after primary PCI (Thrombolysis In Myocardial Infarction [TIMI] 2 and 3) in 94 consecutive patients with a first AMI by continuous beat-to-beat QT-interval measurement, performed with Holter monitoring initiated on admission. Troponin-T levels on admission were >0.1 ng/mL in 53 patients (cTnT+) and <0.1 ng/mL in 41 patients (cTnT−). There were no significant differences in baseline clinical characteristics between the groups. Results The incidence of severe reperfusion arrhythmias (RAs) was significantly higher in patients in the cTnT+ group within the first 2 hours after recanalization. The course of the QT interval revealed a significant decline ( P < .001) after recanalization of the infarcted vessel within 10 hours in both groups; however, hourly values were significantly lower and normalization of the QT parameters was more rapid in patients in the cTnT− group than patients in the cTnT+ in this period (QTc, 438.5 ± 28.3 ms vs 449.3 ± 35.3 ms [hour 1, P < .01]; 413.6 ± 35.8 ms vs 420.1 ± 39.2 ms [hour 10, P < .05]). QT-interval variability also significantly declined within 4 hours after PCI ( P < .001), and likewise, patients in the cTnT− group exhibited lower values in this period (QTSD, 29.7 ± 6.8 ms vs 33.5 ± 10.5 ms [hour 1, P < .01]; 23.0 ± 6.1 ms vs 25.9 ± 7.5 ms [hour 4, P < .01]). Conclusions Positivity of cTnT on admission is associated with a significantly higher temporal inhomogeneity of ventricular repolarization and a higher incidence of malignant RAs, which suggests more advanced microvascular injury. Early successful primary PCI ultimately results in a significant recovery of parameters of QT interval and mean RR interval in all patients, although it was significantly delayed in patients in the cTnT+ group. (Am Heart J 2003;145:484-92.)