Pacing for atrioventricular block.

to the editor: The report by Toff and colleagues on the United Kingdom Pacing and Cardiovascular Events (UKPACE) trial (July 14 issue), 1 evaluating cardiovascular end points in elderly patients with atrioventricular block, showed that the use of dual-chamber pacing to maintain atrioventricular synchrony conferred no survival advantage over the use of single-chamber pacing. These results may be considered along with those of recent trials involving patients with atrial fibrillation that showed a lack of mortality benefit associated with a strategy that maintains atrioventricular synchrony by restoring sinus rhythm. 2 Perhaps the consequences of atrioventricular synchrony deserve closer inspection. As Ellenbogen and Wood mention in the accompanying editorial, 3 atrioventricular pacing increases stroke volume and systolic blood pressure, as compared with ventricular pacing. These effects are probably more pronounced in elderly persons because of reduced aortic compliance and an increased incidence of diastolic dysfunction. Did the different pacing strategies lead to a meaningful difference in blood-pressure control or medication requirements? The harmful effects of higher blood pressure in the dual-chamber group may have offset any benefit from this pacing mode. In addition, how was baseline hypertension ascertained? A prevalence of 33 percent is about half what one would expect for an elderly population.