Idiopathic atrial fibrillation (AF) may be an expression of as yet undetected underlying heart disease. We found it useful for clinical practice to study the long-term development of cardiovascular disease (CVD) in patients diagnosed with idiopathic AF. Methods and results Forty-one consecutive idiopathic AF patients (56 + 10 years, 66% male) were compared with 45 healthy control patients in permanent sinus rhythm. Patients were free of hypertension, antihypertensive and antiarrhythmic drugs,

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... abetes, congestive heart failure, coronary artery or peripheral vascular disease, previous stroke, thyroid, pulmonary and renal disease, and structural abnormalities on echocardiography. Baseline characteristics and echocardiographic parameters were equal in AF cases and controls. During a mean follow-up of 66 + 11 months, CVD occurred significantly more often in idiopathic AF patients compared with controls (49 vs. 20%, P ¼ 0.006). Patients with idiopathic AF were significantly younger at the time of their first CV event compared with controls (59 + 9 vs. 64 + 5 years, P ¼ 0.027), and had more severe disease. Multivariable Cox regression analysis revealed that age, a history of AF, and echocardiographic left ventricular wall width were significant predictors of CVD development. Conclusion Patients originally diagnosed with idiopathic AF develop CVD more often, at younger age, and with a more severe disease profile compared with healthy sinus rhythm control patients. The detection and treatment of CVD in an early stage could improve the prognosis of these patients. At present it seems prudent to regularly check idiopathic AF patients for the insidious development of CVD.