Left atrial appendage function in patients with different pacing modes

Many studies suggest that patients who receive a ventricular pacemaker have a higher incidence of systemic thromboembolism compared to patients receiving a physiological pacemaker. However, the exact mechanism regarding the etiology of thromboembolism remains unclear. We evaluated the left atrial appendage (LAA) functions, using multiplane transesophageal echocardiography (TEE), in patients with different pacing modes. In order to evaluate the ejection fraction (EF), peak emptying (V E) and filling (V F) flow velocities of the LAA by TEE, we studied 31 patients (mean age 63±18.5 years) who had been paced for 5.0±2.9 years. Patients with atrial fibrillation, left ventricular dysfunction and mitral valve disease were excluded. The pacing indications were complete atrioventricular block (AVB) in 19 patients (9 VVI, 10 VDD or DDD) and sick sinus syndrome (SSS) in 12 patients (5 VVI, 7 DDD). Mean EF, V E and V F of the LAA were significantly lower in all patients with ventricular pacing (25.5±15.6%, 30.4±15.6 cm/s and 29.1±19.2 cm/s, respectively) compared to those with physiologic pacing (48.5±16.9%, 59.6±16.3 cm/s, 57.9±18.5 cm/s, respectively) ( P