Abstract P239

Introduction: Clockwise and counterclockwise rotations of QRS transition zone in horizontal plane are long recognized electrocardiogram (ECG) findings, but data on their prognostic values are sparse.

Hypothesis: We hypothesized that clockwise and counterclockwise rotations of QRS transition zone are associated with future cardiovascular disease (CVD) events (coronary heart disease [CHD], heart failure [HF], and stroke).

Methods: We studied 13518 middle aged (45-65 years) individuals from the Atherosclerosis Risk in Communities (ARIC) Study, a community based cohort from 1987-1989 through 2010. Given the difference in cardiovascular risk, we decided a-priori to examine women and men separately.

Results: During an average follow-up of 21.7 years, 5043 CVD events (2232 CHD events, 1910 HF events, and 901 stroke events) were observed. Compared to normal rotation, clockwise rotation was significantly associated with higher risk of CVD (Table) in Model 1 in both men and women. The association remained significant after adjusting for potential confounders only in women. In terms of individual CVD subtypes, clockwise rotation was significantly associated with CHD (hazard ratio=1.31, 95% CI =1.01-1.70) and HF (1.48, 1.18-1.85) but not with stroke (1.08, 0.74-1.58) in women in Model 4. The association between clockwise rotation and CVD risk in women was consistent across demographic and clinical subgroups. In contrast, the counterclockwise rotation was not significantly associated with cardiovascular risk overall in both sexes.

Conclusions: A clockwise QRS axis rotation was associated with cardiovascular events in some models in both sexes, but the association was more robust in women than in men. A counterclockwise rotation did not confer independent cardiovascular risk in either sex in these data. Our results suggest that the overall prognostic value of clockwise/counterclockwise rotation is modest, but clockwise rotation in women may deserve clinical attention and further studies.