Permanent pacemaker implantation after concomitant mitral and tricuspid valve surgery

Mitral (MV) and tricuspid valve (TV) procedures are associated with a relatively increased risk of permanent pacemaker implantation (PPI) due to the proximity of these two valves to the electrical conduction system of the heart. The atrioventricular node, which lies at the apex of the triangle of Koch (bordered by the septal leaflet of the TV, the tendon of Todaro and the orifice of the coronary sinus) is particularly prone to injury during TV surgery. As a result of the placement of the atrioventricular node close to the posteromedial commissure and the annulus of the anterior MV leaflet, MV surgery can also lead to PPI. The sinus node artery originates from the right coronary artery and crosses the superior posterior border of the interatrial septum in most patients [1]. Intraoperative damage to the sinus node artery and the internodal conduction pathways, and electrical isolation of the sinus node may occur in cases of extended superior transseptal approach to the MV, which may lead to conduction disturbances and PPI [2, 3].

Even though most published studies find at least a tendency for higher PPI rate after concomitant MV and TV surgery, the reported PPI rates vary widely. The recent Cardiothoracic Surgical Trials Network randomized trial, comparing isolated MV surgery with concomitant MV surgery and TV annuloplasty in 401 patients, has found a clinically and statistically significantly higher PPI rate with concomitant MV and TV surgery (14.1% vs 2.5%; rate ratio, 5.75; 95% confidence intervals 2.27–14.60) [4]. Another study of the data of state-mandated hospital discharge databases of New York and California including 32 736 patients undergoing isolated MV repair (n = 28 003) or MV repair and TV annuloplasty (n = 4733) has shown a clinically and statistically significantly higher PPI rate for combined surgery (14.0% vs 7.7%; P < 0.001) [5]. Conversely, a systematic review and meta-analysis based on a pooled analysis of 6 studies, including 1027 MV and TV vs 795 MV-only patients, found a not statistically significantly higher PPI rate in the combined group (7.6% vs 5.3%; P = 0.23) [6].

Several confounders may influence PPI rates after MV and/or TV surgery. Atrial fibrillation is a common finding in patients undergoing either MV or TV surgery and is treated with concomitant surgical ablation, with the lesion set ranging from pulmonary vein isolation to biatrial complete lesion Maze procedure, which is associated with an increased risk for PPI [7]. MV replacement is associated with higher PPI rates than MV repair [8]. The timing of PPI is another factor influencing PPI rate. The waiting time for PPI varies widely in clinical practice, and there is currently no universally accepted optimal timing. In a systematic review of studies examining conduction disturbances and pacing after cardiac surgery, the suggested timing for PPI ranged between 5 and 30 days [9]. However, further analysis of the included observational studies revealed that the used receiver operating characteristic methodology to determine the optimal PPI timepoint is strongly biased to indicate a value near the median PPI time as optimal, so that the use of observational data for answering the question of optimal PPI timepoint are intrinsically problematic, and clinical judgement with an individualized approach should be used to guide PPI timing. Furthermore, the authors found that only pacing dependence at PPI and time from surgery to PPI were associated with 30-day pacing dependence, with the only predictor of regression of pacing dependence being time from surgery to PPI, which supports the hypothesis that longer waiting might reduce PPI. Finding the optimal timepoint for PPI as well as avoiding futile waiting could be further assisted through the study of conduction recovery after different cardiac surgical procedures.

In their manuscript ‘Permanent pacemaker implantation after combined MV and TV surgery—a nationwide multicentre study’, Olsthoorn et al. [10] cross-linked the Cardiothoracic and Pacemaker/ICD registry of the Netherlands Heart Registration and analysed the data of patients undergoing primary MV and TV surgery (with or without concomitant atrial septal defect closure, rhythm surgery and coronary artery bypass grafting) between 1 January 2021 and 31 December 2021. The study included a total of 1060 patients (n = 833 MV, n = 227 MV + TV) and found no statistically significant difference in PPI between MV and MV + TV surgery (3.7% vs 6.6%, P = 0.06), even though it should be noted that the difference could be considered clinically relevant (1.78-fold—almost 2-fold—PPI rate with concomitant TV) and with a P-value almost reaching the level of statistical significance α = 0.05. The authors performed further analyses in subgroups of MV surgery and MV repair without concomitant procedures, which confirmed these findings. The median waiting duration for PPI was 11 days, one factor that might have contributed to the relatively low observed PPI rates as compared to previous studies. Even though based on registry data with no information about pre-existing conduction disturbances, atrial fibrillation ablation set, and MV and TV access approach (left atrial/transseptal), and possibly underpowered to detect a statistically significant difference in PPI between the 2 groups, this analysis provides further real-world data about PPI after concomitant MV and TV surgery, with PPI rates which lie on the lower end of the published incidence ranges.

Conflict of interest: none declared.

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