Restrictive organic mitral regurgitation associated with benfluorex therapy

To investigate the association between benfluorex use and organic restrictive mitral regurgitation (MR) in patients admitted to hospital for diagnostic work-up of MR of unclear aetiology. Among patients referred between 2003 and 2008 to our tertiary centre for diagnostic work-up of MR, we retrospectively identified 22 consecutive patients (65 +/- 12 years, 64% women) with restrictive organic MR of unclear aetiology. Using propensity scores, 22 out of 156 patients who underwent surgery for dystrophic MR due to flail leaflets during the same time period were matched for age, sex, height, body weight, and diabetes with the study population. Eight of the 22 patients with restrictive organic MR of unclear aetiology (36.4%) had a history of benfluorex use, and in one patient (4.5%) we identified previous exposure to both benfluorex and fenfluramine. The frequency of benfluorex treatment in patients with restrictive organic MR of unclear aetiology was significantly higher compared with that observed in the dystrophic MR group (36.4 vs. 4.5%; P-value 0.039). Patients with restrictive MR treated with benfluorex (body mass index 31 +/- 6 kg/m(2)) were all dyslipidaemic and 67% had diabetes. Echocardiography identified moderate or severe restrictive organic MR in all cases. Median total duration of benfluorex therapy was 63(12-175) months, at a daily dose of 450 (300-450) mg, leading to a cumulative dose of 850 (108-2363) g. Although it cannot affirm a definitive causal relationship, the present study strongly suggests that patients treated with benfluorex might incur a risk of restrictive organic valvular heart disease. Therefore, echocardiography should be performed in patients exposed to benfluorex in case of occurrence of symptoms or signs of valvular disease. Further data are needed to confirm these findings.