Research Activities February 2013, No. 390
Abnormal electrocardiogram results nearly double the risk of cardiovascular-related death for patients without heart disease
Patients with an abnormal spatial QRS|T angle on an electrocardiogram (ECG) are at nearly double the risk of cardiovascular death (risk ratio of 1.82 for women and 2.21 for men), according to a new study. It also found that an abnormal QRS|T angle increased all-cause mortality risk by 30 percent for women and 87 percent for men. The QRS|T angle, which indicates whether the movement of electrical potential in the ventricle is normal or likely to result in arrhythmia, is measured on a 12-lead ECG that can give other prognostic measures of heart disease (e.g., the QT interval and ST-segment depression).
The researchers used baseline demographic, clinical, and ECG data on 7,052 individuals aged 40 and older without a history of heart disease, who were enrolled in the National Health and Nutrition Examination Survey between 1988 and 1994 and followed until death or the end of 2006. The researchers calculated the spatial QRS|T angle for each individuals. They categorized the QRS|T angle as normal (<75th percentile), borderline (≥75th but <90th percentile), or abnormal (≥95th percentile) separately for men and women. Men and women with gender-specific borderline QRS|T angles did not show significant increases in either cardiovascular or all-cause mortality. The QRS|T study was funded in part by the Agency for Healthcare Research and Quality (HS19465).
More details are in "Relations between QRS|T angle, cardiac risk factors, and mortality in the Third National Health and Nutrition Examination Survey (NHANES III)," by William Whang, M.D., M.S., Daichi Shimbo, M.D., Emily B. Levitan, Sc.D., and others in the April 2012 American Journal of Cardiology 109(7), pp.981-987.