The purpose of this study is to determine which of 4 lead positions is most effective for pacemaker patients with Sick Sinus Syndrome in order to avoid development of atrial fibrillation.

The incidence of Atrial Fibrillation (AF) in Sick Sinus Syndrome patients treated with pacing is quite high. As AF can cause dizziness, fatigue, thromboembolism and ischemic stroke it is clinically relevant. Due to earlier publications pacing modes and lead placement seem to influence the incidence of AF. In this study the incidence of AF will be compared between 4 different atrial lead positions:

1. Free atrial wall
2. right atrial appendage
3. coronary sinus-os
4. Dual site right atrial pacing: b) plus c).

The following primary parameters will be evaluated during the study period of 2 years after implantation:

1. Amounts of AF episodes with a duration of > 48 hours
2. Amounts of AF episodes with a duration of > 30 minutes
3. Consultations of physicians due to AF Secondarily, AF burden, Incidence of AF in total, Quality of Life, implant duration and complications will be evaluated.

Inclusion Criteria:

• Sick Sinus Syndrome
• Symptomatic sinus bradycardia
• Symptomatic SA block
• Bradycardia-Tachycardia-Syndrom
• Binodal diseases, Sinus Node Syndrome and high degree AV-Block
• In case of antiarrhythmic drug therapy: patient must be on a stable dose for at least 3 months before enrollment

Exclusion Criteria:

• Permanent atrial tachycardia that cannot be transferred into sinus rhythm by drugs or electric cardioversion
• Decompensated heart failure
• Dilatative cardiomyopathy with an ejection fraction < 35%
• Hypertrophic obstructive cardiomyopathy
• Symptomatic hypo- or hyperthyreosis
• Myocardial infarction less than 6 months ago
• Planned cardiac surgery intervention
• Pregnant woman
• Patients under 18 years of age
• Patients involved in other studies
• Patients, already implanted with other (cardiac) leads
• Patients with reduced expectancy of life due to other diseases
• Patients who are not able to agree in participation of the study
• Patients, who cannot attend follow-up visits due to their place of residence