Severe MR: Should mitral valve replacement be preferred over repair?

Mitral valve repair vs replacement in ischemic settings: addressing the clinical dilemma

Severe ischemic mitral regurgitation (MR), a frequent complication following myocardial infarction, is associated with high mortality and often requires surgical intervention concomitant with coronary artery bypass grafting (CABG). Although valve repair is classically preferred to preserve the subvalvular apparatus and avoid complications related to prostheses, the optimal therapeutic choice in the presence of impaired left ventricular function remains a subject of clinical debate, particularly regarding short-term outcomes, neurological recovery, and postoperative survival.

This prospective study, conducted between March 2023 and June 2024 at Kasr Al-Ainy Hospital, compared early surgical outcomes of mitral repair (group A, n=50) versus mitral replacement (group B, n=50) in patients presenting with severe ischemic MR requiring concomitant CABG. The objective was to evaluate the respective impact of these two techniques on morbidity, neurological status, and hospital survival.

The central hypothesis of this study is to determine whether mitral valve replacement, despite involving the removal of the native valve, offers superior clinical advantages over repair in terms of preventing residual leaks and ensuring the stability of postoperative results, while analyzing whether the repair technique constitutes an independent predictive factor for recurrence of mitral regurgitation after coronary artery bypass grafting. Clinical and echocardiographic data were rigorously examined to identify determinants of short-term survival and perioperative morbidity.

Methodology and study framework

This prospective study, conducted between March 2023 and June 2024 at Kasr Al-Ainy Hospital and its affiliated institutions, evaluated the postoperative outcomes of 100 patients (77% men, 23% women) presenting with severe ischemic mitral regurgitation (MR) requiring surgery combined with coronary artery bypass grafting (CABG).

Participants were divided into two distinct groups according to the surgical technique performed on the mitral valve:

• Group A (Repair): 50 patients (mean age 59.74 ± 11.04 years; 74% men, 26% women).
• Group B (Replacement): 50 patients (mean age 56.88 ± 9.84 years; 80% men, 20% women).

The protocol integrated a rigorous evaluation of clinical and imaging data. The analysis focused on postoperative morbidity, neurological recovery, measured by the Glasgow Coma Scale (GCS), as well as short-term survival. Intraoperative transoesophageal echocardiography (TEE) was used to assess valve competence immediately after the procedure. Variables were processed via multivariate analyses to identify independent predictive factors for residual MR, with particular attention paid to initial valve morphology and surgical technique. Statistical significance thresholds were set to compare complications such as postoperative atrial fibrillation and hospital mortality between the two strategies.

Clinical results: Repair versus Replacement

This prospective study, conducted at Kasr Al-Ainy Hospital and its affiliated centers between March 2023 and June 2024, compared 100 patients suffering from severe ischemic mitral regurgitation (MR) associated with coronary artery bypass grafting (CABG). Patients were divided into two groups: 50 in group A (repair) and 50 in group B (replacement).

The primary endpoint, recurrence of postoperative MR, was significantly more frequent in group A (34%) than in group B (8%; P=0.001). Multivariate analysis confirms that the repair technique is an independent predictive factor for this recurrence (P=0.001), as is the presence of preoperative valvular morphological abnormalities (P=0.015). Intraoperative transoesophageal echocardiography (TEE) confirmed this disparity, showing more marked residual MR in the repair group (P=0.027).

Regarding complications, valve replacement (group B) was associated with a higher rate of postoperative atrial fibrillation (P=0.001) and increased in-hospital mortality (P=0.046). It is, however, noteworthy that preservation of the subvalvular apparatus showed no statistical influence on these results (P=1). Finally, despite the differences observed in residual MR, no significant impact was noted on ejection fraction, renal function, or neurological scores (GCS 13.68 ± 2.09 vs 13.50 ± 2.64; P>0.05).

While valve replacement presents a higher initial mortality risk, it stands as a robust option to limit reinterventions, whereas repair exposes to a higher risk of MR recurrence.

Repair or replace: the dilemma of ischemic mitral regurgitation

This prospective study conducted between March 2023 and June 2024 on 100 patients undergoing coronary artery bypass grafting (CABG) combined with mitral surgery challenges the supremacy of valve repair. With a rate of postoperative residual mitral regurgitation (MR) reaching 34% in the "repair" group compared to only 8% in the "replacement" group (p=0.001), the data suggest that the repair technique itself constitutes a predictive factor for residual MR.

Clinically, while residual MR did not significantly impact renal parameters, neurological parameters, or ejection fraction, valve replacement was distinguished by a reduction in reinterventions. However, this benefit must be balanced: replacement is associated with an increased incidence of postoperative atrial fibrillation (p=0.001) and higher in-hospital mortality (p=0.046). Multivariate analysis highlights that preoperative morphological valve abnormalities are, along with technical choice, major determinants of surgical success.

This study, although limited by a small sample size, nuances the recommendations systematically favoring repair. It aligns with certain previous works pointing out the limitations of annuloplasty in the face of severe ventricular remodeling, while providing a precise measure of the immediate mortality risk associated with replacement. The absence of a significant difference in medium-term survival remains, however, a point of uncertainty.

Summary of clinical results

This prospective study conducted on 100 patients (March 2023–June 2024) compares repair (Group A) to valve replacement (Group B) combined with coronary artery bypass grafting. The repair technique proves to be an independent predictor of postoperative residual mitral regurgitation (MR) (34% versus 8% in the replacement group, p=0.001). While preservation of the subvalvular apparatus does not influence the results, valve replacement is associated with a higher rate of atrial fibrillation (p=0.001) and increased in-hospital mortality (p=0.046).

Concretely, for the practitioner:

• Mitral repair carries a significant risk of immediate residual MR; accurately assess preoperative valve morphology, a determining factor for this failure.
• Valve replacement represents a robust therapeutic option to ensure the absence of reintervention, despite a perioperative risk profile including higher in-hospital mortality and incidence of atrial fibrillation.
• In cases of left ventricular dysfunction and chronic ischemic mitral regurgitation, replacement should be considered a valid strategy over repair, in order to minimize the risk of valve recurrence.

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