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To the Editor: In their cohort study using patients from the Framingham Heart Study, Dr Cheng and colleagues¹ found that prolongation of the PR interval or first-degree atrioventricular (AV) block was associated with increased risks of atrial fibrillation (AF), pacemaker implantation, and all-cause mortality. In their AF analysis, they adjusted for electrocardiographic left ventricular hypertrophy (LVH) as a confounder, consistent with an article from the LIFE study that showed the relationship between LVH and AF.² However, a subsequent article³ from the LIFE study reported that regression of LVH was associated with reduction of sudden cardiac death, and LVH has been reported to be a risk factor for cardiovascular mortality.⁴

Therefore, LVH may play a role as a confounder in mortality analysis, but the investigators did not adjust for LVH in that analysis. Such an adjustment might provide a more accurate estimation of the mortality hazard ratio.

Financial Disclosures: None reported.

Jaewon Oh, MD; Ho Youn Won, MD; Seok-Min Kang, MD, PhD
smkang@yuhs.ac
Yonsei University College of Medicine
Seoul, South Korea

1. Cheng S, Keyes MJ, Larson MG; et al. Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block. JAMA. 2009;301(24):2571-2577. FREE FULL TEXT 2. Okin PM, Wachtell K, Devereux RB; et al. Regression of electrocardiographic left ventricular hypertrophy and decreased incidence of new-onset atrial fibrillation in patients with hypertension. JAMA. 2006;296(10):1242-1248. FREE FULL TEXT 3. Wachtell K, Okin PM, Olsen MH; et al. Regression of electrocardiographic left ventricular hypertrophy during antihypertensive therapy and reduction in sudden cardiac death: the LIFE Study. Circulation. 2007;116(7):700-705. FREE FULL TEXT 4. Havranek EP, Froshaug DB, Emserman CD; et al. Left ventricular hypertrophy and cardiovascular mortality by race and ethnicity. Am J Med. 2008;121(10):870-875. FULL TEXT | WEB OF SCIENCE | PUBMED

Letters Section Editor: Robert M. Golub, MD, Senior Editor.

JAMA. 2009;302(18):1967.

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