Premature Atrial Contraction Count Predicts A-Fib Risk
Addition of PAC to Framingham model improves risk discrimination, net reclassification
THURSDAY, Dec. 5, 2013 (HealthDay News) -- Premature atrial contraction (PAC) count improves atrial fibrillation (AF) risk model performance, according to a study published in the Dec. 3 issue of the Annals of Internal Medicine.
Thomas A Dewland, M.D., from the University of California in San Francisco, and colleagues conducted a prospective cohort study involving a random subset of 1,260 adults with prevalent AF enrolled in the Cardiovascular Health Study from 1989 to 1990. The authors sought to examine whether PAC count improves AF risk model performance. Twenty-four hour electrocardiography was used to quantify PAC count.
The researchers found that doubling of the hourly PAC count correlated with a significant increase in AF risk (hazard ratio, 1.17) and overall mortality (hazard ratio, 1.06), after adjustment. PAC count alone resulted in similar AF risk discrimination as the Framingham model at five and 10 years of follow-up, and in superior risk discrimination at 15 years. Addition of PAC to the Framingham model correlated with significant improvement in the 10-year AF risk discrimination (c-statistic, 0.65 versus 0.72; P < 0.001), net reclassification (23.2 percent; P < 0.001), and integrated discrimination (5.6 percent; P < 0.001). For PAC counts of >32 beats per hour, the specificity for predicting AF at 15 years exceeded 90 percent.
"Addition of PAC count to a validated AF risk algorithm provides superior AF risk discrimination and significantly improves risk reclassification," the authors write.