Medium-term outcomes from mitral valve surgery for rheumatic heart disease in young adults in Aotearoa New Zealand: a cohort study

Background Rheumatic heart disease (RHD) remains an important cause of morbidity and mortality in New Zealand. Factors associated with the choice of surgical treatment for advanced RHD in young adults are poorly understood. We sought to review our local experience with the surgical management of young adults with rheumatic mitral valvular disease. Methods From 2003 to 2016, all patients aged 15-24 years undergoing mitral valve surgery for rheumatic disease at Auckland City Hospital, New Zealand were retrospectively reviewed. Results During the 13-year study period, 73 young adults underwent mitral surgery; 85% were Maori or Pacific Islanders. Mitral repair was performed in 32 patients and replacement in 41 patients. Isolated mitral valve surgery was performed in 36%, double valve procedures in 47%, and triple valve procedures in 17% of patients. The 30-day mortality rate and stroke rate were 1.4% and 2.7% respectively. The medium-term mortality rate was 11.9% across a mean follow-up of 6 years (6.9% in the repair group, 15.8% in the replacement group, p = 0.25). There were increased bleeding complications (p = 0.04) in patients with mechanical mitral valve replacement. For patients on warfarin, across medium-term follow-up, the INR was in the therapeutic range only 23% of the time. Conclusion Most young adults in New Zealand with severe RHD requiring surgery are of indigenous Maori or Pacific Island ethnicity. There is a trend towards improved survival with mitral repair. There is a significant tendency towards increased bleeding complications in patients on warfarin for mechanical mitral replacement. Warfarin compliance is poor.