Towards understanding the clinical significance of QT peak prolongation: a novel marker of myocardial ischemia independently demonstrated in two prospective studies

Wong, Kenneth Y-K; Velavan, Periaswamy; Wong, Suzanne Y S; McSwiggan, Stephen J; Ogston, Simon A; Steeples, Dominic; Kennedy, Norman S; Tait, Joshua; MacWalter, Ronald S; Ball, Jeff B; Struthers, Allan D

Abstract

Background: QT peak prolongation identified patients at risk of death or non-fatal MI. We tested the hypothesis that QT peak prolongation might be associated with significant myocardial ischaemia in two separate cohorts to see how widely applicable the concept was. Methods and Results: In the first study, 134 stroke survivors were prospectively recruited and had 12-lead ECGs and Nuclear myocardial perfusion scanning. QT peak was measured in lead I of a 12-lead ECG and heart rate corrected by Bazett’s formula (QTpc). QTpc prolongation to 360ms or more was 92% specific at diagnosing severe myocardial ischaemia. This hypothesis-generating study led us to perform a second prospective study in a different cohort of patients who were referred for dobutamine stress echocardiography. 13 of 102 patients had significant myocardial ischaemia. Significant myocardial ischaemia was associated with QT peak prolongation at rest (mean 354ms, 95% CI 341-367ms, compared with mean 332ms, 95% CI 327-337ms in those without significant ischaemia; p=0.002). QT peak prolongation to 360ms or more was 88% specific at diagnosing significant myocardial ischaemia in the stress echocardiography study. QT peak prolongation to 360ms or more was associated with over 4-fold increase odds ratio of significant myocardial ischaemia. The Mantel- Haenszel Common Odds Ratio Estimate=4.4, 95% CI=1.2-16.0, p=0.023. Conclusion: QT peak (QTpc) prolongation to 360ms or more should make us suspect the presence of significant myocardial ischaemia. Such patients merit further investigations for potentially treatable ischaemic heart disease to reduce their risk of subsequent death or non-fatal MI.

Citation

Wong, K. Y., Velavan, P., Wong, S. Y. S., McSwiggan, S. J., Ogston, S. A., Steeples, D., …Struthers, A. D. (2015). Towards understanding the clinical significance of QT peak prolongation: a novel marker of myocardial ischemia independently demonstrated in two prospective studies. Journal of cardiology and current research, 2(1), 1-5. https://doi.org/10.15406/jccr.2015.02.00046

• Journal Article Type: Article
• Acceptance Date: Jan 8, 2015
• Online Publication Date: Jan 14, 2015
• Publication Date: 2015
• Deposit Date: Apr 9, 2015
• Publicly Available Date: Apr 9, 2015
• Journal: Journal of cardiology & current research
• Print ISSN: 2373-4396
• Electronic ISSN: 2373-4396
• Peer Reviewed: Peer Reviewed
• Volume: 2
• Issue: 1
• Pages: 1-5
• DOI: https://doi.org/10.15406/jccr.2015.02.00046
• Keywords: Ischaemia, Stress echocardiography, Nuclear cardiology, Imaging, Electrocardiology
• Public URL: https://hull-repository.worktribe.com/output/372147
• Publisher URL: http://medcraveonline.com/JCCR/JCCR-02-00046.pdf
• Additional Information: Copy of article: Wong KYK, Velavan P, Wong SYS, Mcswiggan S, et al. (2015) Towards Understanding the Clinical Significance of QT Peak Prolongation- A Novel Marker of Myocardial Ischemia Independently Demonstrated in Two Prospective Studies. J Cardiol Curr Res 2(1): 00046. DOI: 10.15406/jccr.2015.01.00046