Lung function and dyspnea in patients with permanent atrial fibrillation

Reduced forced expiratory volume in one second (FEV(1)) has been associated with new-onset atrial fibrillation (AF), and AF patients often complain of dyspnea. We hypothesized that patients with permanent AF had reduced lung function compared to subjects in sinus rhythm.

The participants were 75year-olds from the general population. FEV(1), forced vital capacity (FVC), maximal voluntary ventilation (MVV), total lung capacity by single breath (TLC(SB)), single-breath diffusing capacity of the lung for carbon monoxide (DLCO(SB)) and exercise testing with peak oxygen uptake (VO(2) peak) were assessed. The slope of minute ventilation over carbon dioxide output defined ventilatory efficiency. The Symptom Checklist-frequency and severity questionnaire assessed dyspnea.

AF patients had significantly higher number (%) of subjects below the 5th percentile of predicted FEV(1) (7 (27) versus 3 (4), p=0.005), FVC (6 (23) versus 2 (3), p=0.006) and TLC(SB) (11 (42) versus 12 (18), p=0.014) compared to control subjects, also after adjustment for smoking and obesity, or if disregarding subjects with chronic heart failure. The dyspnea frequency and severity scores correlated with VO(2) peak (r=-0.6, p<0.01) in AF patients, and in control subjects with % predicted FEV(1), MVV and TLC(SB) (r=-0.3, p<0.05).

More patients with permanent AF had lung function below normal range than control subjects in sinus rhythm, irrespective of smoking, obesity or chronic heart failure. Dyspnea, however, was related to exercise capacity rather than to lung function in AF patients.