Arterial thromboembolism in patients with sick sinus syndrome: prediction from pacing mode, atrial fibrillation, and echocardiographic findings

Objective-To evaluate whether thromboembolism in sick sinus syndrome can be predicted by pacing mode, atrial fibrillation, or echocardiographic findin gs. Methods-Patients were randomised to single chamber atrial (n = 110) or vent ricular (n = 115) pacing. They were divided into subgroups with and without brady-tachy syndrome at time of randomisation. The occurrence of atrial fi brillation and thromboembolism during follow up were investigated and compa red with echocardiographic findings. Results-The annual risk of thromboembolism was 5.8% in patients with bradyt achy syndrome randomised to ventricular pacing, 3.2% in patients without br ady-tachy syndrome randomised to ventricular pacing, 3% in patients with br ady-tachy syndrome randomised to atrial pacing, and 1.5% in patients withou t brady-tachy syndrome randomised to atrial pacing. In atrial paced patient s without brady-tachy syndrome at randomisation and without atrial fibrilla tion during follow up, the annual risk of thromboembolism was 1.4%. Left at rial size measured by M mode echocardiography was of no value in predicting thromboembolism. Conclusions-Arterial thromboembolism in patients with sick sinus syndrome i s very common and is associated primarily with brady-tachy syndrome at rand omisation and with ventricular pacing. The risk of thromboembolism is small in atrial paced patients in whom atrial fibrillation has never been docume nted.