Safety and Efficacy of a Cardiac Conduction System-Sparing Modified Aortic Valve Replacement

Introduction 

Surgical aortic valve replacement (SAVR) and transcatheter aortic valve replacement (TAVR) are associated with postoperative conduction abnormalities necessitating permanent pacemaker implantation (PPMI). Stress on the conduction system seems to be a major cause of this complication (1, 2). Modified aortic valve replacement (MAVR) aims to lessen the trauma on the conduction system by applying the pledgets of the sutures between the non-coronary and right coronary sinuses above the annulus (Figure 1). The aim here is to evaluate the safety and efficacy of MAVR in reducing the need for permanent pacemaker implantation. 

Material and Methods 

The authors tested the safety and efficacy of the modified aortic valve replacement technique in reducing the need for pacemaker implantation.  

Study Design and Population 

Following institutional review board (IRB) approval and oral consent (minimal-risk research; confidentiality fully respected), patients underwent modified bioprosthetic aortic valve replacement (AVR) by a single operator at Saint George Hospital University Medical Center, Beirut, Lebanon, from January 1, 2018, to December 31, 2023. The cohort consisted of a total of 179 consecutive patients (68.4± 10.4 yrs, 54 percent male) (Table 1). The study consisted of two phases. Phase I aimed at assessing the safety of the modified AVR technique and included the first 53 patients in whom transesophageal echocardiography (TEE) was performed during bypass and immediately after going off bypass. Patients were followed for two years to evaluate valve function. Phase II consisted of 126 patients who underwent modified AVR and were followed for a minimum of two years for permanent pacemaker implant. 

Statistical Analysis 

The authors analyzed data using SPSS 24.0. Descriptive analysis was performed using counts and percentages to summarize categorical variables and means and standard deviation to summarize continuous variables. 

Results 

Among the 53 patients in Phase I, all had normal valve function, and none had a perivalvular leak (PVL) in the immediate postoperative course. Over the next two years, all patients continued to have normal bioprosthetic valve function. Eleven patients (20 percent) developed trace PVL, one patient (1.8 percent) had mild to moderate PVL, and three patients (5 percent) had mild central aortic regurgitation. None of these were clinically significant or required intervention. Among the entire cohort of 179 patients undergoing modified AVR, 18 patients (10.1 percent) had preoperative first-degree atrioventricular block, 24 patients (13.4 percent) had preoperative atrial fibrillation or flutter, 22 patients (12.3 percent) had pre-existing right bundle branch block, eight patients (4.5 percent) had pre-existing left bundle branch block, and nine percent had an ejection fraction of less than 30 percent. Only one patient (0.5 percent) developed postoperative complete heart block necessitating the implantation of a dual-chamber permanent pacemaker. This patient had a preoperative low ejection fraction (30 percent) and first-degree atrioventricular (AV) block (PR: 250ms). No other patient required pacemaker implantation over the course of a minimum two-year follow-up. 

Discussion 

SAVR and TAVR are both associated with postoperative conduction abnormalities necessitating the implantation of a permanent pacemaker (PPM). Many papers have reported that 2 to 7 percent of patients require permanent pacing after SAVR, while a larger percentage (6 to 34 percent) of patients need a PPMI following TAVR (1, 2, 3).  
Numerous factors have been incriminated in increasing the incidence of complete AV block, such as age, preoperative rhythm abnormalities, myocardial infarction, use of beta blockers, calcium channel blockers, perioperative electrolytes imbalance, surgery for aortic insufficiency, and long bypass (2, 3, 4).  

Dizone et al. reported that the rate of PPMI during a period of 10 days post-surgery was 6.1 percent following SAVR vs 9.3 percent following TAVR. The two-year prevalence was 11 percent after SAVR vs 13 percent post-TAVR. The most important risk factor for PPMI was preoperative bundle branch block, either right or left. Atrial fibrillation and enlarged left ventricular end-diastolic (LVED) dimension were among the risk factors for PPM in the constant hazard phase (5). 

This article evaluates the efficacy and safety of a MAVR. It analyzes, in its first phase, the safety of MAVR by evaluating its impact on the incidence and severity of valvular leak post-replacement, since this adverse event has been a major concern following SAVR and TAVR despite the implementation of new modalities. 

The clinical importance of aortic PVL arises from the fact that it may have a deleterious effect on ventricular function and increase morbidity and mortality (7). None of the 53 patients in Phase I had a perivalvular leak in the immediate postoperative period.  

In the next two years, all continued to have normal valve function; however, 1.8 percent had mild to moderate PVL and 5 percent had mild central aortic regurgitation. None of these cases were clinically significant or required intervention. The efficacy of MAVR in decreasing PPMI was also evaluated among the entire cohort of 179 patients who underwent this surgical technique. Only one patient (0.5 percent) developed postoperative complete heart block necessitating implantation of a dual-chamber permanent pacemaker. This patient had a preoperative low ejection fraction (30 percent) and first-degree AV block (PR: 250ms). No other patient required pacemaker implantation over the course of a minimum two-year follow-up.  

The low incidence of PPMI following MAVR was reported previously by Kawkabani et al. They found that the MAVR surgical technique was a very strong predictor of PPMI, while other known risk factors, such as preoperative conduction abnormalities and atrial fibrillation, did not seem to affect the incidence of PPMI (6). The very low incidence of pacemaker implantation following MAVR (0.5 percent) observed here may be attributed mainly to the significant decrease of trauma to the conduction system while implanting the valve . 

Conclusion 
 
The modified AVR is a simple, safe, and effective technique that spares the cardiac conduction system, thereby markedly reducing the incidence of postoperative heart block and the need for PPMI. This significantly low incidence (0.5 percent) should be considered as the new benchmark for all candidates undergoing SAVR. Furthermore, it should be taken into account whenever TAVR is offered as a therapeutic option. However, larger and multicenter studies are mandatory to confirm these findings. 
 
Figure and Table Legends 

Figure 1: Modified AVR technique: 3-4 pledgeted sutures are applied at the commissure  between the right and non-coronary sinuses above the annulus. 

Table 1: Patients data collection.  

References

1. KlapkowskiA,PawlaczyKR,KempaM,et al.Complete atriovascular block after isolated valve replacement.Kardiol Pol 2026;74:985-993
2. ErdoganH,KayalarN,ArdalH,et al.Risk factors for requirement of permanent pace maker implantation after aortic valve replacement.J card Surg.2006;21:211-215
3. NazifT,DizonJ,HahnK,et al.Predictors and clinical outcomes of permanent pace maker implantation after transcatheter aortic valve replacement.JACC 2005;8:60-69
4. BagurR,ManazzaniJ,DumontE,et al.Permanent pace maker implantation following isolated aortic valve replacement in a large cohort of elderly patients with severe aortic stenosis.Heart 2011;97:1687-1694
5. DizonJ,NazifT,BivianoA et al.New pace maker implantation after surgical aortic valve replacement in the partners trials:Rates,risk factors and clinical outcomes.JACC 2018 ;71:308
6. Two-year incidence of permanent pace maker implantation post modified SAVR.KawkabaniN,BoustrosO,FarahR et al.Cardiol Vasc Res 2022;6(3):1-4.
7. FreixaX,GabaniR,Cepas-GuillenP,Flores-UmanzorE et al.Paravalvular leakages after surgical aortic valve replacement and after transcatheter aortic valve implantation:Strategies to increase the success rate of percutaneous closure.J.Clin.Med.2022;11:2989.

Disclaimer

The information and views presented on CTSNet.org represent the views of the authors and contributors of the material and not of CTSNet. Please review our full disclaimer page here.