The aim of the study is to find out whether aliskiren reduces atrial fibrillation burden measured with a pacemaker device

The aim of the study is to find out the effect of a direct renin inhibitor, aliskiren, in reduction of AF with patients who have a pacemaker due to sinus node disease and paroxysmal atrial fibrillation.

Hypothesis is that there is a possibility to reduce atrial remodeling due to AF and also to enhance atrial reverse remodeling with aliskiren. The effect of aliskiren to total AF burden will be evaluated from the pacemaker's memory storage.

The main purpose of the study is to find new and safe drug treatments targeting to reduce AF recurrences and related complications in pacemaker patients. Also the aim is to evaluate the feasibility of a modern and highly sophisticated pacemaker system in the evaluation of drug treatment with AF reduction.

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