The prognostic value of the Tpeak-Tend interval in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction☆
Introduction
Myocardial infarction (MI) is a major cause of morbidity and mortality. Electrophysiological characterization of arrhythmogenic substrates in the myocardium of post-MI patients has shown clinical promise for prediction of malignant arrhythmias. Among these variables and measurements are a prolonged QT interval, signal-averaged electrocardiogram (ECG), and T wave alternans, but they all have drawback of not being useful in the acute clinical setting because their prognostic value is first manifested when measured 6 to 8 weeks post-MI.1, 2, 3, 4, 5
The interval from the peak to the end of the T wave (Tpeak-Tend interval, or TpTe) has been proposed to represent repolarization dispersion in the heart. However, to what extent TpTe expresses transmural apicobasal, left-to-right ventricle, or anterior-posterior electrical gradients influence is not clear.6, 7 A prolonged TpTe has been associated with arrhythmic events in various clinical conditions,2,8, 9, 10, 11, 12, 13 but little is known about TpTe in the acute setting of transmural myocardial ischemia and reperfusion, for example, in patients with ST-segment elevation MI (STEMI) undergoing primary percutaneous coronary intervention (pPCI). The purpose of the present study was to evaluate TpTe immediately before and after pPCI in patients with STEMI and evaluate its prognostic value.
Section snippets
Study subjects
Patients were recruited from a single tertiary catheterization laboratory of a high PCI volume center (Gentofte University Hospital, Copenhagen, Denmark: 650 pPCI and 1200 elective PCI per year performed by 5 PCI operators). Patients were included if they had (1) relevant chest discomfort, (2) ECG changes fulfilling the criteria for STEMI, (3) pPCI, and (4) a significant stenosis or occlusion requiring placement of at least 1 intracoronary stent. After pPCI, patients received usual standard of
Demographics and follow-up
Demographic, clinical, and angiographic data are summarized in Table 1. No patients were lost to follow-up. There were 10 deaths in the population, with a mean (SD) follow-up time of 683 (211) days.
TpTe and survival
The pre-pPCI TpTe was prolonged in patients that died during follow-up. However, the post-pPCI TpTe was similar between surviving and deceased patients (Table 2). Using the Youden index, the optimal cutoff point was determined to be 100 milliseconds for the pre-pPCI TpTe, with a sensitivity and
Discussion
The main findings of this study of patients with STEMI undergoing pPCI were: (1) the pre-pPCI TpTe predict all-cause mortality; (2) TpTe was not associated with infarct-related artery, LVEF, or symptom to balloon time; and (3) QT interval was prolonged after pPCI.
Conclusion
In conclusion, TpTe pre-pPCI predicted all-cause mortality in patients with STEMI undergoing pPCI. TpTe and the QT interval were increased after pPCI, whereas TpTe seems to be independent of infarct-related artery, LVEF, and symptom to balloon time. Pre-pPCI may be a new marker of increased risk in patients with STEMI undergoing pPCI, and the clinical value of this parameter should be further evaluated.
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The study was supported by the Danish Heart Foundation, John and Tove Girotti's Foundation, Danish National Research Foundation, King Christian X' Foundation and Lægernes Forsikringsforening.