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High lean body mass predicts AF in postmenopausal women
Greater lean body mass was an independent predictor of atrial fibrillation in postmenopausal women, according to new data from the Women’s Health Initiative.
Elevated BMI is known to be a risk factor for AF, but little research had been done on the association between elevated lean body mass and AF, according to the researchers.
They evaluated 11,393 participants from the Women’s Health Initiative study of postmenopausal women aged 50 to 79 years. All participants underwent dual-energy X-ray absorptiometry to assess lean body mass, and the researchers documented incident AF via hospitalization records and Medicare diagnostic codes.
After excluding some participants because of prevalent AF or incomplete data, they analyzed 8,832 participants (mean age, 63.3 years; 77.3% white). Mean follow-up was 11.6 years, during which 1,035 cases of incident AF were documented.
After adjusting for covariates, Farnaz Azarbal, MD, from the division of cardiovascular medicine of the department of medicine at Stanford University, and colleagues found that all measures of lean body mass independently predicted AF onset. These included:
- total lean body mass (HR = 1.24 per 5 kg increase; 95% CI, 1.14-1.34);
- central lean body mass (HR = 1.51 per 5 kg increase; 95% CI, 1.31-1.74); and
- peripheral lean body mass (HR = 1.39 per 5 kg increase; 95% CI, 1.19-1.63).
When Azarbal and colleagues adjusted for total fat mass, total lean body mass remained an independent predictor of AF (HR = 1.22 per 5 kg increase; 95% CI, 1.13-1.31).
Compared with those in the lowest tertile of total lean body mass, those in the highest tertile were more likely to be younger and black (P < .001 for both), according to the researchers. They also found that those in the highest tertile were more likely than those in the lowest tertile to have AF risk factors such as hypertension (P < .001), diabetes (P < .001), CAD (P = .029), HF (P = .007), peripheral artery disease (P = .036) and smoking (P < .001).
“Greater [lean body mass] may predict changes in the size and structure of cardiac chambers implicated in AF pathophysiology,” Azarbal and colleagues wrote, noting that other possible explanations include the association between increased body size and left atrial enlargement, skeletal muscle secretion of myokines promoting atrial arrthythmogenesis and left body mass being a mediator of the association between height and left atrial size. – by Erik Swain
Disclosure: The researchers report no relevant financial disclosures.