Idiopathic atrial fibrillation as a risk factor for mortality. The Paris Prospective Study I

Aims: Idiopathic atrial fibrillation describes atrial fibrillation of unknown origin occurring without heart disease. Mortality is considered unaffected by idiopathic atrial fibrillation. We used the long follow-up period (23 years on average) of the Paris Prospective Study I to assess the mortality of idiopathic atrial fibrillation subjects in middle-aged men.

Methods: 7746 working Frenchmen, aged 43-52 in 1967-72, underwent a physical examination plus ECG, answered questionnaires, and provided blood samples. Strict exclusion criteria were used to select idiopathic atrial fibrillation only, and men with known cardiac disease were further excluded from analysis. At 1 January 1994, vital status was unknown for 4.6% of the subjects. The analysis was conducted on the 6722 remaining subjects.

Results: Twenty-five subjects had idiopathic atrial fibrillation at inclusion. The relative risk (and 95% confidence interval) associated with idiopathic atrial fibrillation was 4.22 [2.10-8.47] for cardiovascular mortality (P=0.0001) and 1. 97 [1.14-3.40] for total mortality (P=0.01). When age, systolic blood pressure, cholesterol, body mass index and tobacco consumption were entered into a Cox model, idiopathic atrial fibrillation remained an independent risk factor for cardiovascular (P=0.0008) and total death (P=0.04).

Conclusion: With a long follow-up period, idiopathic atrial fibrillation was associated with higher mortality in middle aged Frenchmen.