Rate adaptive pacing in sick sinus syndrome: effects of pacing modes and intrinsic conduction on physiological responses, arrhythmias, symptomatology and quality of life

An atrial-based pacing mode is superior to ventricular constant rate demand pacing (VVI) mode in patients with sick sinus syndrome (SSS) by providing both rate adaptation and atrioventricular (AV) synchrony. The use of a non-atrial sensor to overcome chronotropic incompetence and preserve normal intrinsic AV conduction in pacemaker therapy for SSS was investigated in 15 consecutive patients (mean age 66±2 years). All had intact AV conduction (antegrade conduction capacity >100 beats. min−1 and an atrialpaced to intrinsic R interval of ≤ 220 ms). DDDR pacemakers capable of being programmed into atrial rate adaptive (AAIR), dual chamber rate adaptive (DDDR) and ventricular rate adaptive ( VVIR) modes were used Beginning with an acute study, arterial pressure was invasively assessed in each pacing mode during physiological stresses and low level exercise. In the ambulatory phase, the incidence of ventricular pacing and arrhythmias (Holier recording), diurnal blood pressure changes (ambulatory blood pressure recording), and symptom and quality of life level (questionnaires and interviews) were compared. Despite similar heart rate changes during acute physiological stresses, a higher blood pressure was recorded during AAIR or DDDR pacing compared with VVIR pacing. Systolic blood pressure over 24 h was lower in the VVIR mode (122 ± 5 mmHg) than AAIR/DDDR pacing (129 ± 61128 ± 6 mmHg, P