For TAVR patients, either having a preexisting pacemaker or receiving one postprocedure is associated with worse 1-year outcomes including reduced survival, according to an analysis of PARTNER data published online August 10, 2015, ahead of print in Heart.

José M Dizon, MD, of Columbia University Medical Center (New York, NY), and colleagues looked at 2,531 patients (mean age 84.5 years; 52.3% men) who underwent TAVR with the balloon-expandable Sapien valve (Edwards Lifesciences) in cohorts A and B of the PARTNER randomized trial (n = 519) or in the continued access registries (n = 2,012).

At 30 days, 759 patients (29.7%) had a permanent pacemaker (PPM), with the vast majority of new PPMs (97.1%) implanted during the index hospitalization. Patients were divided into 4 groups based on having:

• Prior PPM (n = 586)
• New PPM within 30 days (n = 173)
• No PPM (n = 1,612)
• Left bundle branch block (LBBB) but no PPM (n = 160)

The most common indications for PPM were high-degree atrioventricular block (79%) or sick sinus syndrome (17.3%). Newly implanted devices were predominantly dual- or single-chamber RV pacemakers.

Overall, the study population had substantial comorbidities and a mean STS score of 11.5. Compared with the other groups, prior PPM patients were more often men and had more CAD, prior CABG, and prior PCI and higher STS scores. The no PPM group had more chronic obstructive pulmonary disease (COPD) compared with the prior PPM and LBBB/no PPM groups.

Worse 1-Year Outcomes With Any Pacing, LBBB

At 1 year, patients with prior PPM, new PPM, and LBBB/no PPM had higher all-cause mortality (primary endpoint) than those with no PPM (27.4%, 26.3%, 27.7%, and 20.0%, respectively; P < .05). Also, those with either type of PPM had higher risks of rehospitalization. The prior PPM and LBBB/no PPM groups had a higher risk of cardiac death than the no PPM group, whereas there was no difference between the new PPM and no PPM patients (table 1).

Propensity matching of prior PPM and no PPM patients did not affect the findings regarding all-cause and cardiac mortality. However, rates of stroke and A-fib were higher in the no PPM than in the prior PPM patients at 1 year. No differences in the prevalence of NYHA class III or IV or incidence of MI were seen between the PPM and no PPM groups. In addition, prior PPM and LBBB/no PPM had similar rates of mortality and rehospitalization.

On Cox regression analysis (excluding patients with LBBB/no PPM), new (HR 1.38; 95% CI 1.00-1.89) and prior PPM (HR 1.31; 95% CI 1.08-1.60) were both predictors of 1-year mortality and, as were liver disease, A-fib, anemia, renal disease, male sex, COPD, and STS score. When LBBB patients were added to the no PPM group, new PPM was no longer associated with mortality.

Patients without any PPM had the lowest LVEF at baseline. At 1 year, prior PPM patients had lower LVEF and decreased recovery of LVEF, with the poorest recovery seen in those with baseline LV systolic dysfunction. In addition, new PPM and LBBB patients with normal baseline LVEF had lower LVEF at 1 year than patients without any pacing, while LBBB/no PPM patients with LVEF < 35% had worse recovery of LVEF.

Is Chronic Pacing the Culprit?

In contrast to prior studies that focused on new conduction abnormalities or pacemaker implantation after TAVR, the current analysis includes a large group with prior PPM, on the premise that acquired conduction abnormalities may be more common in patients with chronic pacing, the authors say. And indeed this group experienced increased mortality and diminished LVEF recovery at 1 year.

“Given the similarity in the conduction abnormalities and outcomes between chronic RV pacing and LBBB, we hypothesize an adverse effect of RV pacing post-TAVI,” Dr. Dizon and colleagues say, noting that detrimental effects have been observed previously in patients with an LVEF below 40% and implantable defibrillators.

“The worsened recovery of LVEF after TAVI at all baseline levels also argues for a mechanistic effect of pacing,” the investigators say. The fact that the chronic PPM group had nearly twice the cardiac mortality of the new pacemaker group “supports the possibility that the mortality associated with pacing was due to the duration of pacing and its long-term consequences rather than the need for pacing itself.”

Confounding a Possibility

But in a telephone interview with TCTMD, Ted Feldman, MD, of NorthShore University HealthSystem (Evanston, Illinois), favored an alternate explanation. He noted that a link between pacing and increased mortality has not been found consistently even in analyses of PARTNER data and has been absent in several CoreValve (Medtronic) reports.

Dr. Feldman suggested that the discrepancy is more likely due to confounding. For example, patients with chronic pacing had more CAD than the other groups, and “CAD burden is a powerful predictor of late mortality,” he said.

Overall, PARTNER patients are the sickest group in the entire TAVR database, Dr. Feldman observed. The worst of the worst—the 7% who for whatever reason ended up with a new PPM—may be very different, he said, from the quarter of patients with new pacemakers in the CoreValve population with much lower surgical risk scores.

Still, “the bottom line is that whatever identifies the patient who needs a pacemaker either before or after TAVR is one more factor that has a negative prognostic implication,” Dr. Feldman said. “We also have to learn more about the longer-term effects of chronic RV pacing in lower-risk patients, because that’s where the real problem is.”

Meanwhile, cardiac resynchronization may be considered for patients who need permanent pacing after TAVR, the authors suggest, although they note that the cost-effectiveness of such a strategy in elderly patients remains unknown.

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

 

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Source: 
Dizon JM, Nazif TM, Hess PL, et al. Chronic pacing and adverse outcomes after transcatheter aortic valve implantation. Heart. 2015;Epub ahead of print.

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