Although previous studies have shown that pacemaker implantation is associated with increased mortality and heart failure hospitalisation, a new study in Circulation has not found an association between permanent pacemaker implantation after transcatheter aortic valve implantation (TAVI) and an increased risk of all-cause mortality or heart failure hospitalisation.
Study authors Marina Urena (Quebec Heart & Lung Institute, Laval University, Quebec City, Canada) and others state that pacemaker implantation after TAVI is a common complication “with an overall incidence of about 15%”. They add: “Strong evidence supports the potential negative impact of right ventricular apical pacing, which has been associated with an increased rate of the combined endpoint of mortality and rehospitalisation due to heart failure.”
However, little evidence exists for the impact of pacemaker implantation after TAVI and the data that are available are from small studies. The authors comment: “While these studies did not find any impact of permanent pacemaker implantation on mortality, concerns that they may have been underpowered as a result of an inadequate sample size have been raised.”
The aims of the new study were, therefore, to review the impact of permanent pacemaker implantation on late outcomes, left ventricular function and functional status changes in a cohort of patients who received either a balloon-expandable valve or a self-expandable valve. The primary endpoint was a composite of all-cause mortality and heart failure hospitalisation. Secondary endpoints included: all-cause mortality, cardiovascular mortality, sudden cardiac death, a composite of sudden cardiac death and unexpected death resulted from unknown cause, and left ventricular ejection fraction changes.
Urena et al reviewed 1,811 consecutive patients who underwent TAVI at eight centres between January 2005 and February 2013. Of these, 239 patients received a permanent pacemaker implantation within 30 days of undergoing TAVI—with significantly more patients in the self-expandable group requiring a pacemaker than in the balloon expandable group (25.5% vs. 7.1%, respectively; p<0.001). The authors report that there were no significant differences between the patients who received a pacemaker and those who did not in the rate of 30-day mortality or major complications after TAVI (p>0.20), adding: “After a mean follow-up of 22±17 months, a total of 525 patients had either died or required a rehospitalisation due to heart failure, with no difference between permanent pacemaker implantation and no permanent pacemaker implantation groups (34.1% vs. 31.8%; p=0.980). “
Speculating as to why these results were not consistent with the studies that showed the need for a paced rhythm increases the risk of late mortality and heart failure, Urena et al state that several TAVI studies have shown that new conduction disturbances following TAVI “may resolve over time in about 50% of patients, especially with the use of balloon expandable valves.” They add that one third of the patients with a pacemaker in their study did not exhibit any pacing activity on the ECG performed at the 6- or 12-month follow-up point.
The authors also note that while an association between poorer mortality and permanent pacemaker implantation has been observed in younger patients, “some studies have shown that permanent pacemaker implantation has no impact on mortality in octogenarians and nonagenarians, who in fact represent the vast majority of patients undergoing TAVI nowadays.”
Another finding in the study was that pacemaker implantation after TAVI was associated with a significant decrease in unexpected death (sudden cardiac and unknown) during the follow-up period, which Urena say “merits further evaluation” as it indirectly raised questions about “the most appropriate management of new conduction disturbances that do not meet the criteria for permanent pacemaker implantation following TAVI”.
However, permanent pacemaker implantation was associated with a negative effect on left ventricular function. The authors conclude: “Further efforts will be important to determine the long-term impact of this decrease in left ventricular ejection fraction and the potential benefits of resynchronisation therapies in some patients.”
Study author Josep Rodés-Cabau (Quebec Heart & Lung Institute, Laval University, Quebec City, Canada) says: “These results confirm that permanent pacemaker implantation following TAVI is less of a concern regarding overall mortality, cardiovascular mortality and heart failure at midterm (two year) follow-up. However, permanent pacemaker implantation was associated with a decrease in left ventricular ejection fraction. The clinical impact of this finding and its most appropriate management should be evaluated in future studies with a longer follow-up.”