Second cross-clamping after mitral valve repair for degenerative disease in contemporary practice

Scanty data are available on 'second cross-clamping' following mitral valve repair in contemporary practice. The aim of this study was to evaluate the incidence, causes and outcomes of this event in patients referred for mitral repair for severe degenerative mitral regurgitation (MR).

The study population included 2318 patients with severe degenerative MR referred for mitral repair. A second cross-clamping was performed in 94 (4%) patients. Causes of the second cross-clamping, revising repair procedures, immediate echocardiographic outcomes and postoperative course were assessed and compared with the 'single cross-clamping cases' (2224 patients used as control). Clinical and echocardiographic follow-up information was available for 91 of the 94 second cross-clamping patients (97% complete) (median time 6 years, interquartile range 3-11).

The most frequent causes of the second cross-clamping were residual MR >1+/4+ and systolic anterior motion. A residual prolapse was identified in 41 (43.5%) patients, systolic anterior motion in 22 (23.5%), untreated clefts in 14 (15%) and other mechanisms in 17 (18%). Second cardiopulmonary bypass and aortic cross-clamping times were 36 (range 28-50) and 23 (range 17-34) min, respectively. Hospital mortality was 0% in the second cross-clamping and 0.3% in the control group (P = 0.2). Postoperative complications and length of hospital stay were similar. At discharge, residual MR ≥2+/4+ was 2.1% in the second cross-clamping and 2.7% in the control group (P = 0.99). In the second cross-clamping, at 12 years, the cumulative incidence function of reoperation, recurrent MR ≥3+ and MR ≥2+ with death as competing risk were 5.7 ± 2.5% (95% confidence interval 2-12), 10.3 ± 4.3% (95% confidence interval 3.8-20) and 17 ± 5.2% (95% confidence interval 8-29), respectively.

In a large volume centre for mitral repair, a second cross-clamping is still performed in 3-5% of the patients. Because suboptimal immediate results are associated with impaired late outcomes of mitral reconstruction, a low threshold for a second cross-clamping seems to be justified. If the second repair is carried out with a relatively shorter additional cross-clamping time, mortality and morbidity are not increased and immediate and long-term results are very satisfactory.