Role of ALiskiren, a Direct Renin Inhibitor, in Preventing Atrial Fibrillation in Patients With a Pacemaker; RALF.

Inclusion Criteria: * age between 18 and 85 years * sinus node disease and paroxysmal AF * provided signed informed consent according to the Declaration of Helsinki for study participation * a previously implanted St. Jude Medical Identity / Victory / Zephyr ADX or any newer model of SJM DDDR pacemaker with ability to record high atrial rates Exclusion Criteria: * contraindication for the use of aliskiren * severe impairment of renal function (serum creatinine \> 160 µmol/L) or patient with solitary kidney or renal transplant or renal artery stenosis * significant known aortic or mitral valve stenosis or obstructive hypertrophic cardiomyopathy * hypersensitivity to aliskiren or to any of the excipients * concomitant treatment with cyclosporine * patients with uncontrolled hypertension requiring treatment for hypertension * systolic blood pressure measured in two separate occasions ≥ 160 mmHg * diastolic blood pressure in two separate occasions ≥ 100 mmHg * absolute indication for the use of an RAAS blocker * chronic, persisting AF (persisting AF at screening with ≥ 4 cardioversions performed beforehand) * sitting systolic arterial blood pressure of less than 100 mm Hg at the time of randomisation * need for ventricular pacing more than 30% at the enrolment * pregnancy and/or lactation * women of childbearing potential (only postmenopausal women or women after tubal ligation will be allowed) * other serious disease expected to cause substantial deterioration of patient's health during the next two years * past or present alcohol or drug abuse * participation in other clinical trials during the last three months * suspicion of poor study compliance