Beyond endocarditis, other causes can lead to severe damage to the mitral-aortic junction, making conventional prosthesis implantation techniques unsuitable. Among the most frequent causes, besides endocarditis, are severe anterior annulus calcification or its destruction during repeat cardiac surgeries. The Commando procedure, which includes reconstruction of the mitral-aortic junction/curtain, was introduced over three decades ago and is primarily used in cases of severe mitral-aortic curtain destruction due to endocarditis, allowing double-valve replacement (DVR). Over the years and with accumulated experience, the indications for this procedure have broadened. This study examines these indications and patient follow-up through Cleveland Clinic’s results for patients with mitral-aortic junction destruction, excluding endocarditis cases. 

From January 2011 to January 2022, 129 Commando procedures and 1,191 mitral and aortic DVRs were performed, excluding endocarditis cases. The primary reasons for the Commando procedure were severe calcification (67 patients with prior radiation exposure and 43 patients without prior radiation) and other causes in 19 patients. Commando procedures were compared to a balanced subset of DVRs using score-matching (109 pairs). 

Between balanced groups, Commando versus DVR procedures showed higher total calcium scores (median 6140 vs 2680 HU; p = .03). Hospital outcomes were similar, including operative mortality (12/11% vs 8/7.3%; p = .35) and reoperation for bleeding (9/8.3% vs 5/4.6%; p = .28). Five-year survival and freedom from reoperation rates were 54% vs 67% (p = .33) and 87% vs 100% (p = .04), respectively. Higher calcium scores were associated with lower survival after DVR but not after Commando. The Commando procedure showed lower mean aortic valve gradients at 4 years (9.4 vs 11 mm Hg; p = .04). For Commando procedures due to calcification, five-year survival was 60% and 59% with and without prior radiation exposure, respectively (p = .47). 

The authors concluded that the Commando procedure, with mitral-aortic reconstruction due to mitral annular calcification, radiation, or prior surgery, shows acceptable outcomes similar to standard DVR. 

COMMENTARY:

A preliminary reflection on the study by Kakavand et al. is that for patients with similar risk profiles and no endocarditis, performing a Commando procedure with DVR poses a comparable risk to conventional DVR. In other words, the Commando procedure, in the absence of endocarditis and with a similar predicted risk, generally in non-emergency settings, does not pose greater risk than conventional DVR. This notion is plausible but needs further refinement for more precise interpretation. 

Conventional aortic and mitral DVR has historically been associated with in-hospital mortality rates of 5–15%. Calcification of the anterior and posterior mitral annulus presents a significant challenge, particularly when paired with a small mitral annulus and mitral-aortic curtain involvement. The Commando procedure circumvents the need for suturing through the calcium-laden anterior annulus and mitral-aortic curtain, additionally facilitating the implantation of a larger prosthesis. Indeed, this is the only procedure that enables, through complete debridement and patch enlargement of the mitral annulus, the implantation of a larger mitral prosthesis. Initially, this procedure was deemed complex, especially given the extensive reconstruction with patching, posing a considerable geometric challenge and with early series reporting operative mortality of 7–28%. However, it remains uncertain whether this high mortality rate was largely due to procedural factors or to complications such as endocarditis. 

This series can only be compared to the largest series published to date by Tirone David (reviewed on our blog in 2022), involving 182 Commando procedures over 35 years at Toronto Hospital (only 13% involved endocarditis). Their operative mortality was 13%, with one-, five-, and ten-year survival rates of 82%, 69%, and 51%, respectively. In the present study, operative mortality was 11%, similar to David’s, and five-year survival was 53%, an improvement over David’s series. 

In this study, there were no significant differences in ischemic and extracorporeal circulation times or in postoperative complications between the Commando and conventional DVR procedures. However, a higher reoperation rate was noted at five years in the Commando group, suggesting increased bioprosthetic dysfunction among these patients. In Toronto’s study by Tirone David, mitral-aortic curtain reconstruction was performed in two-thirds of cases with bovine pericardium and in one-third with a shaped Dacron conduit. Late calcification was associated with bovine pericardium use, being a cause of late paravalvular leakage. Therefore, in the last decade, the trend has been to use Dacron patches instead of pericardium for this technique. The study by Kakavand et al. under review here does not provide information on this, so we cannot ascertain if the higher reoperation rate in the Commando group is partially due to pericardium patch use. 

The association between annular calcification and valvular dysfunction is increasingly recognized in industrialized countries, along with its relation to poorer prognosis. Quantification and grading of this calcification by echocardiography and CT are essential. Detailed calcium assessment is crucial for surgical risk evaluation in mitral surgery, guiding eligibility and surgical choice. However, in this study, severe mitral annular calcification did not negatively impact survival after Commando surgery; conversely, in conventional DVR patients, higher calcium scores in the mitral-aortic curtain correlated with poorer outcomes. Based on this reasoning, the Commando procedure appears optimal for treating severe mitral-aortic curtain calcification, offering superior exposure for calcium debridement. 

In this study, indications for the Commando procedure, excluding endocarditis cases, were severe mitral-aortic curtain calcification and/or its destruction following debridement, as well as in repeat mitral or DVR surgeries. For certain patients considered inoperable, the Commando procedure provided a new option. Moreover, for patients with extremely fragile tissues, such as those with previous radiation exposure or small hearts, this intervention reduced the likelihood of periprosthetic leakage. Lastly, this technique affords better exposure during DVR, which may explain the slight difference in surgical times compared to conventional surgery. In patients with small mitral annuli, the Commando technique allows for the implantation of an appropriately sized prosthesis, although in this study, there were no significant differences in mitral prosthesis size between the Commando and conventional DVR groups. Notably, we lack data on preoperative annulus sizes, which are challenging to measure with extensive calcifications. 

REFERENCE:

Kakavand M, Stembal F, Chen L, Mahboubi R, Layoun H, et al. Contemporary experience with the Commando procedure for anterior mitral anular calcification. JTCVS Open. 2024 April 30;18:12-30. doi: 10.1016/j.xjon.2023.10.038.