AF may raise risk for sudden cardiac death

Two large population-based cohort studies that included middle-aged and elderly participants found that those who developed atrial fibrillation were at increased risk for sudden cardiac death compared with those who did not develop atrial fibrillation.

Lin Y. Chen, MD, MS, of the cardiovascular division, department of medicine, University of Minnesota Medical School, and colleagues analyzed data from 15,439 participants in the Atherosclerosis Risk in Communities (ARIC) Study and data from 5,479 participants in the Cardiovascular Health Study (CHS). ARIC participants were aged 45 to 64 years, and 55% were women and 26% black. CHS participants were aged 65 years or older at baseline, and 58% were women and 15% black. The main outcome of the researchers’ meta-analysis was physician-adjudicated sudden cardiac death and the secondary outcome was non-sudden cardiac death (defined as CHD death not meeting sudden cardiac death criteria).

“The use of two populations in which the association of AF and sudden cardiac death is replicated is a major strength of this analysis. Definitions for AF, sudden cardiac death and non-sudden cardiac death and for comorbidities were consistent across two populations, and overall findings were similar across the studies, even though participants in the Cardiovascular Health Study were nearly 20 years older than participants in the Atherosclerosis Risk in Communities Study at baseline,” Kyndaron Reineir, PhD, MPH,and Sumeet S. Chugh, MD, of The Heart Institute at Cedars-Sinai Medical Center, wrote in an accompanying editorial.

In the ARIC Study, 894 AF, 269 sudden cardiac death and 233 non-sudden cardiac death events occurred during a median follow-up of 13.1 years. In the CHS, 1,458 AF, 292 sudden cardiac death and 581 non-sudden cardiac death events occurred during the same length of follow-up.

The researchers calculated a crude incidence rate of sudden cardiac death of 2.89 per 1,000 person-years for participants with AF and 1.3 per 1,000 person-years for participants without AF in the ARIC study. The multivariable HR of AF for sudden cardiac death was 3.26 (95% CI, 2.17-4.91) and non-sudden cardiac death was 2.43 (95% CI, 1.6-3.71).

In the CHS, the crude incidence rate of sudden cardiac death was 12 per 1,000 person-years for participants with AF and 3.82 per 1,000 person-years for participants without AF. The multivariable HR of AF for sudden cardiac death was 2.14 (95% CI, 1.6-2.87) and non-sudden cardiac death was 3.1 (95% CI, 2.58-3.72).

According to the meta-analysis, the HR of AF for sudden cardiac death was 2.47 (95% CI, 1.95-3.13) and non-sudden cardiac death was 2.98 (95% CI, 2.52-3.53).

“The strength of the association between AF and sudden cardiac death was comparable to that between AF and non-sudden cardiac death,” Chen and colleagues wrote.

According to the researchers, “The present study is the first to demonstrate that incident AF is associated with an increased risk of sudden cardiac death in two independent population-based cohorts.” Further, this association was seen in both men and women and in blacks and non-blacks.

“… [T]hese findings of at least a doubling of sudden cardiac death risk in patients with AF are important and refocus our attention on improving our understanding of the intersection between AF and sudden cardiac death,” Reineir and Chugh wrote.

For more information:

Chen Lin Y. Arch Intern Med. 2012;doi:10.1001/2013.jamainternmed.744.

Reineir K. Arch Intern Med. 2012;doi:10.1001/jamainternmed.2013.1774.

Disclosure: The researchers, Chugh and Reineir report no relevant financial disclosures.