Coronary artery bypass grafting (CABG) plus mitral valve repair resulted in similar changes in left ventricular reverse modeling and rate of death in patients with multivessel coronary disease and moderate ischemic mitral regurgitation (MR) but was associated with higher rates of serious adverse events (SAEs) when compared to CABG alone. Robert E. Michler, MD, Montefiore-Einstein Heart Center, New York, New York, USA, presented data from the Surgical Interventions for Moderate Ischemic Mitral Regurgitation study [Smith PK et al. N Engl J Med. 2014].

About 50% of MR cases are associated with ischemia, 10% of which are moderate in severity. Importantly, ischemic MR is associated with an increased risk of morbidity and mortality [Go AS et al. Circulation. 2014]. Surgical treatment options for MR include CABG, with or without mitral valve replacement. The purpose of this study was to determine whether valve repair for moderate ischemic MR at the time of CABG was superior to CABG alone.

In this phase 2 trial, 301 patients with moderate ischemic MR were randomly assigned to undergo CABG alone or CABG plus mitral valve repair with an undersized ring and were followed for 12 months. At baseline, 68% of patients were men; 47% had diabetes mellitus; and the mean age was 64.5 years. The primary end point was the degree of reverse modeling in the left ventricle according to changes in left ventricular end systolic volume index. Secondary end points included major adverse cardiac and cerebrovascular events (MACCEs), mortality, residual MR, hospitalization, quality of life, and other SAEs.

There was no significant difference in change in left ventricular end systolic volume index in patients who underwent CABG alone or CABG with mitral valve repair at 12 months (P = .61). In addition, the mortality rate was similar between arms, with 30-day mortality occurring in 2.7% and 1.3% of patients who underwent CABG or CABG plus valve repair, respectively (P = .68), and with 12-month mortality occurring in 7.3% and 6.7%, respectively (P = .81). Similarly, the rate of MACCEs was similar between arms at 12 months. Patients who had CABG plus valve repair experienced a greater reduction in severity of MR when compared with patients who had CABG alone.

However, patients who underwent CABG plus valve repair required greater rates of aortic cross clamp, cardiopulmonary bypass, and intensive care unit stay time versus those who underwent CABG only. In addition, postoperative low-output syndrome occurred more frequently in patients who received mitral valve repair. Other SAEs that occurred more frequently in patients who underwent CABG plus valve repair included neurologic events and supraventricular arrhythmia (P = .03 for both). At the end of the study, quality of life, NYHA functional class, and rate of death were similar between arms.

In conclusion, Dr Michler stated that data from this trial suggest no clinical advantage to performing a mitral valve repair in patients with moderate ischemic MR who are undergoing CABG. However, long-term follow-up is ongoing. In addition, Dr Michler commented that a limitation of this study was that the primary end point was not a clinical end point. However, the more appropriate end point of mortality would require a much larger study population and a longer follow-up time, he stated.