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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

Authors

Kenneth Y-K Wong

Periaswamy Velavan

Suzanne Y S Wong

Stephen J McSwiggan

Simon A Ogston

Dominic Steeples

Norman S Kennedy

Joshua Tait

Ronald S MacWalter

Jeff B Ball

Allan D Struthers

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.

Journal Article Type Article
Publication Date 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
Institution 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. doi:10.15406/jccr.2015.02.00046
DOI https://doi.org/10.15406/jccr.2015.02.00046
Keywords Ischaemia, Stress echocardiography, Nuclear cardiology, Imaging, Electrocardiology
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

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