Chronic Pacing and Adverse Outcomes After TAVI
Does chronic pacing have adverse effects on outcomes of patients after transcatheter aortic valve implantation (TAVI)?
The PARTNER (Placement of Aortic Transcatheter Valves) trial and associated registries were used to analyze clinical outcomes in patients who underwent TAVI. Clinical outcomes of four groups of patients were compared: those with prior permanent pacemaker (PPM), new PPM, no PPM, and left bundle branch block (LBBB) without a PPM. Mortality and hospitalization risks were assessed using the Cox regression analysis.
There were 586 patients with prior PPM, 173 patients with new PPM, 1,612 patients with no PPM, and 160 patients with LBBB and no PPM. At 1 year, prior PPM, new PPM, and LBBB/no PPM patients had higher all-cause mortality than no PPM patients (27.4%, 26.3%, 27.7%, and 20.0%; p < 0.05), and patients with prior PPM or new PPM had higher re-hospitalization or mortality/re-hospitalization (p < 0.04). By Cox regression analysis, new PPM and prior PPM were independently associated with 1-year mortality (HR, 1.38 and 1.31, respectively). Patients with prior PPM, new PPM, and LBBB/no PPM had lower left ventricular ejection fraction (LVEF) at 1 year compared to patients with no PPM, and patients with prior PPM had worsened recovery of LVEF after TAVI. Paced electrocardiograms displayed a high prevalence of right ventricular (RV) pacing (>88%).
The presence of prior PPM, new PPM, or chronic LBBB was associated with worsened clinical and echocardiographic outcomes, and the presence of a PPM was independently associated with 1-year mortality post-TAVI.
The reported incidence of newly implanted PPM after TAVI ranges from approximately 6% with the balloon-expandable Edwards SAPIEN valve to 25% with the self-expanding Medtronic CoreValve. Some patients undergoing TAVI have pre-existing PPM. The deleterious effects of RV pacing on clinical outcomes have been demonstrated in patients with and without cardiomyopathy. It has also been previously shown that patients who require PPM post-TAVI have worse outcomes, but this study is the first to suggest that even patients with a PPM implanted prior to TAVI (chronically implanted) have worse LV recovery and mortality than patients without a PPM. Ventricular dyssynchrony due to chronic RV pacing is probably responsible for these findings. This and prior studies raise the inevitable question of whether cardiac resynchronization therapy in patients who require pacing after TAVI might benefit from this therapy.
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