The prognostic relationship of qt interval and dispersion in patients with acute st elevation myocardial infarction
Background: QT interval (QTc) prolongation and increased dispersion (cQTd) have been implicated as risk factors for sudden death. We examined their prognostic value in patients with ST-segment elevation myocardial infarction (STEMI) before and after reperfusion therapy as well as at hospital discharge. Methods: This study includes 153 STEMI patients either treated with primary percutaneous coronary intervention (PPCI) (n=70) or fibrinolysis (n=83 including 19 rescue PCI) within 6 hours of symptom onset. QTc, cQTd, and ST-segment elevation (SSTE) were measured at baseline, post-reperfusion, and hospital discharge. Composite in-hospital clinical events reported include death, shock and congestive heart failure. Results: QT metrics were not associated with the severity of ischemia, as quantified through SST elevation. Relative change in cQTd was weakly associated (R=0.19, p=0.02) with reperfusion success assessed by SST resolution at hospital discharge. Prolonged baseline QT metrics were correlated with an increased risk of clinical events with QTc >460ms and cQTd >65 correlated to a >10% risk of developing death, shock, and congestive heart failure. This risk tripled with every 40ms increase in cQTd (OR 2.88, 95% CI (1.05-7.89), p=0.039) after adjustment for age, heart rate, systolic blood pressure, and infarct site. The highest cQTd quartile (=69ms) had a composite event rate of 23.7% (p=0.027). Conclusions: Prolonged QTc and cQTd correlated to adverse clinical events in STEMI patients treated with PPCI and fibrinolysis. Although caution must be employed using arbitrary cut points; a baseline cQTd beyond an upper boundary of 65ms appears to denote significant risk of adverse in-hospital events.
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- Cardiovascular System & Hematology
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Published In
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Cardiovascular System & Hematology