INTRODUCTION: Functional mitral regurgitation (FMR) is a common complication in patients with ischaemic (ICM) or idiopathic dilated cardiomyopathy (DCM), as a consequence of left ventricular (LV) remodelling. The aim of this study was to elucidate the differences in FMR between patients with ICM and DCM utilising conventional and tissue Doppler echocardiography.METHODS: We studied 21 patients with ICM and 17 with DCM using conventional and tissue Doppler echocardiography. The severity of FMR was assessed quantitatively and by the PISA method. The 2 groups were similar in terms of NYHA class, LV ejection fraction and pharmacological treatment.RESULTS: Patients with ICM had higher pulmonary artery systolic pressures (48 +/- 16 vs. 38 +/- 10 mmHg, p=0.04), more severe FMR as assessed by colour Doppler (1.9 +/- 0.9 vs. 1.1 +/- 0.5, p=0.006), and a larger effective regurgitant orifice (0.17 +/- 0.07 vs. 0.1 +/- 0.05 cm(2), p=0.003) and tenting area (2.3 +/- 0.8 vs. 1.7 +/- 0.7 cm(2), p=0.02). In addition, ICM subjects had lower mitral annular systolic (Sm 2.3 +/- 0.8 vs. 3.4 +/- 0.9 cm/s, p<0.001) and diastolic (Em 2.5 +/- 1 vs. 3.8 +/- 1.5 cm/s, p=0.005; Am 3.1 +/- 1.4 vs. 4.3 +/- 1.7 cm/s, p=0.02) myocardial velocities, and a higher ratio of early transmitral filling velocity to early mitral annular diastolic velocity (LV E/Em 42 +/- 29 vs. 22.7 +/- 7.6, p=0.008) compared to DCM patients. Systolic and diastolic mitral annular velocities were significantly correlated with effective regurgitant orifice. Tenting area >1.27 cm(2) exhibited the highest sensitivity and regurgitant volume >24 ml the highest specificity for predicting ischaemic aetiology of LV dysfunction. However, only age and Sm were independent predictors of the diagnosis of ICM rather than DCM.CONCLUSIONS: Mitral apparatus deformity, incomplete closure of mitral leaflets and global remodelling are more prominent in patients with ICM and lead to more severe FMR than in patients with DCM.