Author + information
- aSection of Interventional Cardiology, Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic Foundation, Cleveland, Ohio
- bOutpatient Electrophysiology Section, Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic Foundation, Cleveland, Ohio
- ↵∗Address for correspondence:
Dr. Samir R. Kapadia, Sones Cardiac Catheterization Laboratories, Department of Cardiovascular Medicine, J2-3, Heart and Vascular Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, Ohio 44195.
- transcatheter aortic valve implantation
- transcatheter aortic valve replacement (TAVR)
Transcatheter aortic valve replacement (TAVR) has become an established treatment option for patients with aortic stenosis who are inoperable or who are at high or intermediate risk for surgical aortic valve replacement (1). As we apply TAVR to lower-risk patients, it is imperative that the risks of TAVR are commensurate with those of surgical aortic valve replacement. One of these risks is the need for a permanent pacemaker (PPM), which may be different depending on the device used for TAVR. Although balloon-expandable valves have traditionally demonstrated lower rates of PPM implantation than self-expanding valves, the rates remain generally higher than after surgical aortic valve replacement (2). It appears that among balloon-expandable valves, the latest-generation SAPIEN 3 (third generation balloon expandable valve) (Edwards Lifesciences, Irvine, California) has a higher 30-day PPM rate (10.2% in S3i study) compared with the original SAPIEN (first generation balloon expandable valve) (3.8% in PARTNER 1A [Placement of Aortic Transcatheter Valves]) and SAPIEN XT (second generation balloon expandable valve) (8.5% in PARTNER 2A) valves (1,3,4). Conversely, the newer-generation second-generation self-expanding (CoreValve Evolut-R [Medtronic, Minneapolis, Minnesota]) valves have reported lower PPM rates (11.7%) compared with their first-generation (CoreValve Classic [Medtronic]) counterparts (19.8%) (5,6). The newest second-generation repositionable valves have 30-day new PPM rates ranging from 28.6% for the Boston Scientific (Natick, Massachusetts) Lotus valve to 9.8% for the St. Jude (St. Paul, Minnesota) Portico valve (7).
There are several questions with regard to the need for PPM in patients undergoing TAVR. What are the indications for new PPM implantation? What predicts the need for a new PPM? Does a new PPM increase the risk of death or functional deterioration on follow-up?
In this issue of iJACC, Maeno et al. (8) attempt to identify predictors for PPM implantation after third generation balloon expandable valve implantation. Of 240 patients undergoing TAVR with the third generation balloon expandable valve, 35 required PPM (14.6%), mostly because of complete heart block (CHB) (n = 25) or left bundle branch block (LBBB) progressing to CHB (n = 3). These investigators determined that pre-TAVR right bundle branch block (RBBB), calcification volume at the noncoronary cusp device-landing zone, and height of membranous septum (MS) were all independent predictors of PPM implantation.
Current Practice of Permanent Pacemaker Implantation After TAVR
There are no clear guidelines for PPM implantation after TAVR. Persistent CHB is a common indication; however, the duration necessary to monitor before designating a patient with “persistent CHB” remains variable. More difficult situations arise when new LBBB, LBBB with first-degree atrioventricular block, LBBB and atrial fibrillation, or alternating LBBB and RBBB are encountered after TAVR. Lack of consensus in these situations has resulted in tremendous variability for PPM use after TAVR (9). Further, many studies report a “new” PPM rate with an entire patient population as a denominator. Because 20% to 30% of patients already have a PPM, the reported numbers underestimate the “real” need for PPM.
What Predicts the Need for a Permanent Pacemaker?
The risk factors for PPM implantation identified by Maeno et al. (8) can be explained by anatomy of the conduction system (10). The His bundle bifurcates into the right and left bundles at the inferior border of the MS, with the latter emerging beneath the noncoronary cusp. Therefore, valve implantation that overlaps the distal MS may affect both the right and left bundles and lead to CHB. Similarly, substantial calcification at the noncoronary cusp device-landing zone is likely to exert uneven pressure either at the level of the MS or at the left bundle that runs on the left ventricular (LV) side of the muscular septum.
How do the data from the current analysis dovetail with those of previous studies? In an analysis from the PARTNER 1 trial, there was significant early hazard for PPM, with 86% of devices implanted within 1 week of TAVR, mostly as a result of high-grade atrioventricular block (11). Importantly, there was a continued risk of PPM among patients with new-onset LBBB, up to 10% at 30 days and 12.9% at 12 months (12). Further, 58% of new LBBB cases were noted at 1-year follow-up. Interestingly, among patients with new LBBB, almost one-half received a PPM for sick sinus syndrome, which is unrelated to TAVR procedures. Demonstrating the importance of understanding pre-TAVR conduction, Holter monitoring prior to TAVR among 435 patients revealed that 16% of all patients and 31% of patients eventually receiving a PPM displayed some evidence of previously unknown conduction disease (13).
It is evident that although an understanding of a patient’s potential predisposing factors for PPM is important, these features are uncontrollable. However, the presence of these factors may inform the need for continued observation for conduction deficit (Table 1). Ultimately, the only variable that can be controlled at the time of the procedure is the depth of implantation, and the current analysis demonstrates that MS height helps to define the degree of “freedom” for this depth.
New Permanent Pacemakers and the Risk of Mortality or Morbidity
The impact of PPM implantation on mortality and morbidity after TAVR remains controversial. In the general population, patients with a high burden of right ventricular pacing demonstrate an increased risk of LV dysfunction development and also of worse survival, perhaps resulting from the abnormal electrical and mechanical activation pattern (14). Among TAVR-treated patients, however, the impact on survival of PPM implantation is controversial, although the development of LV dysfunction has been demonstrated (12,15,16). Similarly, patients with LBBB after balloon-expandable TAVR demonstrate a higher risk of PPM implantation and failure of improvement in LV ejection fraction after TAVR. Whether all patients with LBBB and/or a need for long-term pacing after TAVR should automatically receive a biventricular pacemaker remains unknown.
The need for PPM implantation after TAVR is a complication that may result in new-onset or worsening LV dysfunction and may be associated with overall worse survival. These implications may be especially germane as TAVR is offered to lower-risk patients. Studies such as the one by Maeno et al. (8) are important in furthering our understanding of pre-procedural and procedural factors that may allow us to provide TAVR to our patients even more safely.
↵∗ Editorials published in JACC: Cardiovascular Imaging reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Imaging or the American College of Cardiology.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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