Orthostatic hypotension and long-term incidence of atrial fibrillation: the malmo preventive project

Fedorowski A, Hedblad B, Engstrom G, Gustav Smith J, Melander O (Department of Clinical Sciences, Lund University, Malmo; and Skane University Hospital, Malmo, Sweden). Orthostatic hypotension and long-term incidence of atrial fibrillation: the Malmo Preventive Project. J Intern Med 2010; 268: 383-389. Objectives. Orthostatic hypotension (OH), a common manifestation of autonomic dysfunction, has been identified as an independent risk factor for all-cause mortality and incident cardiovascular disease. However, the role of OH in the development of atrial fibrillation has not been studied. Design. We investigated the incidence of atrial fibrillation in relation to baseline presence of OH according to international consensus criteria in the Swedish population-based prospective cohort of the Malmo Preventive Project. The study sample consisted of 33 346 individuals (67.3% men; mean age, 45.6 +/- 7.4 years; range, 26-61 years). The association between OH and incidence of atrial fibrillation during follow-up was assessed using the Kaplan-Meier method and multivariable Cox proportional hazard models, taking into account conventional risk factors for atrial fibrillation. Results. At baseline, 1987 participants (6.1%) met the diagnostic criteria for OH. Over a follow-up period of approximately 24 years, 2312 individuals (3.0 events/1000 person-years) were diagnosed with new-onset atrial fibrillation. Of these, 196 had OH at baseline (4.6 events/1000 person-years amongst all OH-positive individuals). In a multivariable Cox regression analysis, OH predicted incidence of atrial fibrillation independently of other risk factors (hazard ratio [HR]: 1.30; 95% confidence interval [CI]: 1.05-1.61; P = 0.016), and this association was significant in hypertensive (HR: 1.44; 95%CI: 1.10-1.88; P = 0.008), but not in normotensive participants (HR: 1.10; 95%CI: 0.77-1.58; P = 0.60). Conclusions. The presence of OH predicts the incidence of atrial fibrillation in middle-aged hypertensive individuals, independently of conventional risk factors. Further studies of the association of autonomic dysfunction and OH with atrial fibrillation are needed.