PARTNER Analysis Looks at Predictors, Clinical Impact of Pacemaker Implantation

About 1 in every 12 patients who undergo TAVR with a balloon-expandable prosthesis have conduction abnormalities that lead to permanent pacemaker implantation within 30 days, according to an observational study published in the January 2015 issue of JACC: Cardiovascular Interventions. Moreover, pacemakers—the need for which is predicted by certain baseline ECG or echo parameters—are linked to longer and more hospitalizations but not increased mortality or heart failure at 1 year. Take Home: PARTNER Analysis Looks at Predictors, Clinical Impact of Pacemaker Implantation

A team led by Susheel K. Kodali, MD, of Columbia University Medical Center (New York, NY), analyzed data from 1,973 inoperable or high-risk patients (mean age ~84 years) who underwent TAVR with the balloon-expandable Sapien valve (Edwards Lifesciences) in the PARTNER randomized trial (n = 409) or continued access registry (n = 1,564) and did not have a preexisting pacemaker. A transfemoral approach was used in a little over half of patients and transapical was utilized in the rest.

Permanent pacemakers were required in 8.8%, typically during the index hospitalization. Only 1.9% received a pacemaker more than 30 days after TAVR.

The most common indications for pacemaker were high-degree or complete atrioventricular (AV) block (79%) and sick sinus syndrome (17.3%). Nearly all of the devices were either dual-chamber (75.7%) or single-chamber (19.7%) right ventricular pacemakers.

Patients with and without new pacemakers had similar baseline clinical characteristics with the exception of more prior chest wall radiation in the pacemaker group. Compared with those who did not receive a new pacemaker, the pacemaker group had a smaller LV end-diastolic diameter (4.32 vs 4.47 cm; P = .02) and left ventricular outflow tract (LVOT) diameter (1.98 vs 2.01 cm; P = .02) and a larger ratio of annulus diameter to LVOT diameter (1.09 vs 1.07; P = .004).

Procedurally, there were trends toward higher use of 26-mm (vs 23-mm) valves and transapical (vs transfemoral) access in the pacemaker group. No differences were seen in use of balloon valvuloplasty, postdilation, or postdilation balloon size, although pacemaker patients were about twice as likely to require intraaortic balloon pump support (7.0% vs 3.2%; P = .01). They also had a higher ratio of prosthesis diameter to LVOT diameter (1.23 vs 1.21; P = .001) and a longer post-TAVR hospital stay (7.3 vs 6.2 days; P < .001).

On multivariable analysis, predictors of permanent pacemaker implantation within 30 days were right bundle branch block (RBBB), LV end-diastolic diameter, prosthesis diameter/LVOT diameter ratio, and treatment in the continued access registry (table 1).

 Table 1. Multivariable Predictors of Permanent Pacemaker After TAVR

At 30 days, having a new permanent pacemaker was associated with higher rates of repeat hospitalization and renal failure requiring dialysis but not mortality. At 1 year, permanent pacemakers were linked to a higher incidence of the composite of mortality or repeat hospitalization as well as trends toward its individual endpoints (table 2).

Table 2. Outcomes at 1 Year

No differences between groups were seen in heart failure symptoms and functional status as assessed by NYHA class and 6-minute walk time. LVEF and LV dimensions also were similar between the groups at 1 year.

Cardiac Close Quarters

The crux of the pacemaker problem is anatomic, point out Marina Urena, MD, and Josep Rodés-Cabau, MD, of the Quebec Heart and Lung Institute (Quebec City, Canada), in an accompanying editorial. “The spatial proximity between the aortic valve and the conduction system… explains the risk of [AV block] when the stent frame of the transcatheter valve prosthesis mechanically interacts with the ventricular septum.”

While several studies have failed to show an adverse clinical impact of pacemakers, there is solid evidence that cardiac pacing can induce heart disease, the editorialists say, offering some possible explanations for the discrepancy:

 

  • The clinical effect of right ventricular pacing manifests first in patients with LV dysfunction (whereas two-thirds of TAVR patients have normal LV function) and after longstanding ventricular pacing (existing studies have provided less than 2 years of follow-up)
  • Cumulative pacing time is the strongest predictor of heart failure, and more than half of TAVR patients with pacemakers are no longer dependent at 1 year

 

Identifying who is at risk for permanent pacemaker is unlikely to affect decisions about whether or even how to perform TAVR, study coauthor Howard C. Herrmann, MD, of the Hospital of the University of Pennsylvania (Philadelphia, PA), told TCTMD in a telephone interview. Nonetheless, such predictors can help inform patients of the possibility of prolonged hospitalization and may steer physicians toward using a kind of temporary pacemaker that avoids patients needing to be managed in the ICU.

Permanent Pacemaker Dilemma

Decisions on whether a pacemaker is required are based on the presence of any preexisting conduction disease and the severity of the post-TAVR conduction problem, Dr. Herrmann observed. But it is tricky because on one hand, “you can’t leave a temporary pacemaker in for weeks while you wait to see if a patient might recover,” he said. On the other hand, if a permanent pacemaker is implanted, there is a good chance that in 30 days or so it will no longer be needed, he continued.

While the finding that pacemakers do not worsen mortality or LV function at 1 year is welcome, Dr. Herrmann said, most previous data on the adverse effects of pacemakers have emerged at a later period. “In a short-term study with patients who mostly have good LV function, we may not see some of those adverse effects,” he observed. In addition, the odds are diminished in the study’s “pacemaker group” because only half were actually paced over the entire study period.

Given the underlying pathophysiology of the problem, Dr. Herrmann did not seem optimistic that improvements in technique or technology would substantially lower the incidence of pacemaker implantation. Furthermore, there appears to be a trade-off between efforts to reduce paravalvular leakage and to lower pacemaker rates, he said, noting that in early studies of newer valves that curb regurgitation, pacemaker rates have risen.

In addition, he pointed out that the current study involves only 23-mm and 26-mm valves. With the introduction of the Sapien XT, 29-mm devices are now part of the mix—a fact that could increase pacemaker use.

Before TAVR is offered to younger, lower-risk patients, Dr. Hermann said, it will be essential to pin down whether new pacemakers increase mortality and heart failure over the long term. Another goal is to identify which patients at high risk of postprocedural conduction problems will recover enough that they can forgo permanent implantation.

Note: Dr. Kodali and several coauthors are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 


Sources:
1. Nazif TM, Dizon JM, Hahn RT, et al. Predictors and clinical outcomes of permanent pacemaker implantation after transcatheter aortic valve replacement: the PARTNER (Placement of AoRtic TraNscathetER Valves) trial and registry. J Am Coll Cardiol Intv. 2015;8:60-69.
2. Urena M, Rodés-Cabau J. Permanent pacemaker implantation following transcatheter aortic valve replacement: still a concern [editorial]? J Am Coll Cardiol Intv. 2015;8:70-73.

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PARTNER Analysis Looks at Predictors, Clinical Impact of Pacemaker Implantation

About 1 in every 12 patients who undergo TAVR with a balloon-expandable prosthesis have conduction abnormalities that lead to permanent pacemaker implantation within 30 days, according to an observational study published in the January 2015 issue of JACC: Cardiovascular Interventions. Moreover, pacemakers—the need for which is predicted by certain baseline ECG or echo parameters
Disclosures
  • Dr. Kodali reports receiving research and grant support from Edwards Lifesciences and serving as a consultant to Meril, on the scientific advisory board of and holding equity in Thubrikar Aortic Valve, and as principal investigator for and receiving research support from Claret Medical.
  • Dr. Rodés-Cabau reports serving as a consultant to Edwards Lifesciences and St. Jude Medical.
  • Dr. Urena reports no relevant conflicts of interest.
  • Dr. Herrmann reports receiving grant support from Abbott Vascular, Boston Scientific, Edwards Lifesciences, Medtronic, Siemens, St. Jude Medical, and WL Gore and serving as a consultant to Edwards Lifesciences, Siemens, and St. Jude Medical.

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