Causes of death in patients with unipolar single chamber ventricular pacing: prevalence and circumstances in dependence on arrhythmias leading to pacemaker implantation.

Cardiac pacing improves the prognosis of patients with severe impulse formation and conduction disturbance, though sudden death can occur frequently in paced patients. In the present study, we analyzed the causes and the circumstances of 378 deaths in 2,243 paced patients followed over a 5-year period. Sudden cardiac death occurred in 71 of these 378 patients (18.7%), 56 patients died of stroke (15%), heart failure was the cause of death in 91 subjects (24%). We analyzed the causes of death in two groups with respect to the arrhythmia that had led to pacemaker implantation. The prevalence of cardiac sudden death was higher in patients with AV block than in patients with sick sinus syndrome, while stroke was more frequent in patients with sick sinus syndrome, particularly those with both fast and slow components. Atrial fibrillation is common in patients with sick sinus syndrome and is an important well-known risk factor for stroke. Death from heart failure was frequently reported in our population, but in our study group only a few patients had heart failure at the moment of pacemaker implantation. We conclude that sudden death is a common event in paced patients and the disturbance that led the patient to pacemaker implantation was also a factor in the cause of death.