Optimal QT interval correction formula in sinus tachycardia for identifying cardiovascular and mortality risk: Findings from the Penn Atrial Fibrillation Free study

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• 作者：Parin J. Patel ; MD^* ; ^&dagger ; ; ^{parin.patel@post.harvard.edu" class="auth_mail" title="E-mail the corresponding author} ; Yuliya Borovskiy ; MS^&dagger ; ; Anthony Killian ; RN^&dagger ; ; Ralph J. Verdino ; MD^&dagger ; ; Andrew E. Epstein ; MD ; FHRS^&dagger ; ; David J. Callans ; MD ; FHRS^&dagger ; ; Francis E. Marchlinski ; MD ; FHRS^&dagger ; ; Rajat Deo ; MD ; MTR^&dagger ;
• 关键词：CAD ; coronary artery disease ; ECG ; electrocardiogram ; HF ; heart failure ; ICD-9 ; International Classification of Diseases ; version 9 ; UPHS ; University of Pennsylvania Health System
• 刊名：Heart Rhythm
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：13
• 期：2
• 页码：527-535
• 全文大小：1246 K

文摘

The QT interval measures cardiac repolarization, and prolongation is associated with adverse cardiovascular outcomes and death. The exponential Bazett correction formula overestimates the QT interval during tachycardia.

Objective

We evaluated 4 formulas of QT interval correction in individuals with sinus tachycardia for the identification of coronary artery disease, heart failure, and mortality.

Methods

The Penn Atrial Fibrillation Free study is a large cohort study of patients without atrial fibrillation. The present study examined 6723 Penn Atrial Fibrillation Free study patients without a history of heart failure and with baseline sinus rate ≥100 beats/min. Medical records were queried for index clinical parameters, incident cardiovascular events, and all-cause mortality. The QT interval was corrected by using Bazett (QT/RR^0.5), Fridericia (QT/RR^0.33), Framingham [QT + 0.154 * (1000 − RR)], and Hodges (QT + 105 * (1/RR − 1)) formulas.

Results

In 6723 patients with a median follow-up of 4.5 years (interquartile range 1.9–6.4 years), the annualized cardiovascular event rate was 2.3% and the annualized mortality rate was 2.2%. QT prolongation was diagnosed in 39% of the cohort using the Bazett formula, 6.2% using the Fridericia formula, 3.7% using the Framingham formula, and 8.7% using the Hodges formula. Only the Hodges formula was an independent risk marker for death across the range of QT values (highest tertile: hazard ratio 1.26; 95% confidence interval 1.03–1.55).

Conclusion

Although all correction formulas demonstrated an association between QT_c values and cardiovascular events, only the Hodges formula identified one-third of individuals with tachycardia that are at higher risk of all-cause mortality. Furthermore, the Bazett correction formula overestimates the number of patients with a prolonged QT interval and was not associated with mortality. Future work may validate these findings and result in changes to automated algorithms for QT interval assessment.