NSTEMI and severe MI: mitral repair reduces valvular regurgitation at one year

Surgical arbitration in NSTEMI: CABG alone or associated mitral valve repair?

When faced with a non-ST-segment elevation myocardial infarction (NSTEMI) complicated by severe ischemic mitral regurgitation (IMR), the cardiac surgeon is confronted with a complex technical trade-off: can revascularization alone correct the valvular leak, or is it imperative to combine it with a repair procedure? This issue is at the heart of this retrospective study conducted at the Hanoi Heart Hospital, including 39 patients operated on between January 2020 and December 2022.

The specific objective of this study was to compare the clinical characteristics as well as the short-term and 12-month operative outcomes of two strategies: isolated coronary artery bypass grafting (CABG) (n=13) versus CABG combined with concomitant mitral valve repair (n=26). The study evaluates whether the addition of the valvular procedure provides a lasting structural benefit without compromising immediate postoperative safety.

The authors test the hypothesis that concomitant mitral repair more significantly reduces the degree of regurgitation at one year compared to CABG alone, despite a predictable increase in aortic cross-clamp time. This 12-month follow-up allows for the comparison of the functional revascularization theory with the reality of mechanical annular correction in these fragile patients.

Methodology: a monocentric retrospective analysis

This retrospective study was conducted at Hanoi Heart Hospital over a two-year period, from January 2020 to December 2022. It focuses on a population of 39 patients diagnosed with non-ST-segment elevation myocardial infarction (NSTEMI) associated with severe ischemic mitral regurgitation (IMR).

Patients were divided into two distinct groups according to the surgical strategy adopted:

• Isolated Bypass Group (n = 13): patients who underwent coronary artery bypass grafting (CABG) only.
• Mitral Repair Group (n = 26): patients who underwent CABG associated with concomitant mitral valve repair.

The protocol included the collection and comparative analysis of preoperative, intraoperative, immediate postoperative, and long-term data (12-month follow-up). The primary evaluation criteria were based on the severity of mitral regurgitation (graded on a clinical scale), left ventricular function, early complications, and overall mortality. Statistical analysis notably compared aortic cross-clamp times and the evolution of regurgitation grades between the two arms, with a significance threshold set at p < 0.05.

Study results: Impact of concomitant mitral repair

The retrospective analysis conducted on 39 patients (13 isolated coronary artery bypass grafts [CABG] and 26 CABG with mitral repair) reveals significant differences in both anatomical terms and the operative procedure. Initially, the group that underwent repair presented a more marked preoperative mitral regurgitation (MR) severity (2.9 ± 0.2 versus 2.6 ± 0.2; p=0.006).

Evolution of mitral regurgitation and ventricular function

Although mitral regurgitation improved in both groups in the immediate postoperative period, a significant divergence appears during medium-term follow-up. At 12 months, the group that underwent concomitant mitral repair shows a statistically superior reduction in MR compared to the CABG-only group (p=0.041).

Parameters evaluated	Isolated PAC (n=13)	PAC + Repair (n=26)	p-value
Preoperative MI severity	2.6 ± 0.2	2.9 ± 0.2	0.006
MI severity at 12 months	-	Significantly lower	0.041
Aortic clamping time	Shorter	Longer	0.002

Safety and operative complications

The addition of the mitral procedure directly impacts the complexity of the intervention. The authors report a significantly longer aortic cross-clamp time in the repair group (p=0.002). Clinically, the following observations were noted:

• Early complications: A trend towards an increase in early complications was observed in the repair group, without however reaching a statistically significant difference compared to CABG alone.
• Mortality: No significant difference was found between the two groups regarding postoperative mortality or mortality at 12 months.
• LV function: The results show no significant disparity between the groups regarding the evolution of left ventricular function at 12 months.

In summary, while concomitant mitral repair with CABG in NSTEMI patients ensures better valvular competence at one year, it imposes a longer duration of intraoperative myocardial ischemia.

Analysis of these data suggests that, for the clinician, the choice of concomitant mitral valve repair during CABG is based on a trade-off between surgical complexity and functional stability. The anatomical benefit is concrete: MR reduction is more sustainable at 12 months in the group surgically treated for their valve, despite greater initial severity. However, this study highlights a significant technical cost, illustrated by longer cross-clamp times and a trend towards more early complications. Compared to classic debates in the literature, these results confirm that while revascularization alone can attenuate MR by improving myocardial perfusion, it appears less effective than direct valvular intervention in ensuring valve competence in the medium term. The limitations of this work lie primarily in its retrospective design and the modest sample size (n=39), which does not allow for conclusions regarding an overall survival benefit.

Study summary

This retrospective study conducted on 39 NSTEMI patients demonstrates that adding mitral valve repair to coronary artery bypass grafting (CABG) significantly reduces residual mitral regurgitation at 12 months (p=0.041) compared to isolated CABG, despite a more pronounced initial severity in the combined surgery group (2.9 ± 0.2). While this strategy requires a longer aortic cross-clamp time (p=0.002), it does not alter mortality or left ventricular function at one year.

In concrete terms, for the practitioner:

• Target the valve in cases of severe IMR: Revascularization alone is not sufficient to stabilize valve function in the long term; combined annuloplasty is therefore preferred to ensure a lasting result.
• Anticipate operative time: Accept prolonged aortic clamping, as the study shows it does not negatively impact survival or myocardial recovery at 12 months.
• Interpret with perspective: Although the results are clinically significant regarding valve stability, the modest sample size (n=39) requires particular vigilance concerning the generalisation of the absence of increased mortality.

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