Because systolic and diastolic dysfunction frequently coexist, it is hypothesized that a combined measure of left ventricular chamber performance may be more reflective of overall cardiac dysfunction than systolic or diastolic measures alone. METHODS Study patients consisted of 170 subjects: 70 normals, 47 patients with severe dilated cardiomyopathy in NYHA class III-IV awaiting cardiac transplantation and 53 patients with idiopathic dilated cardiomyopathy of intermediate severity [NYHA class II, ejection fractions (EF) 30-50%]. EF, stroke volume and cardiac indexes were measured using conventional echo-Doppler methods. Pre-ejection period/ejection time (PEP/ET), isovolumetric relaxation time (IRT), isovolumetric contraction time/ET (ICT/ET) were also measured. A new derived index of myocardial performance: (ICT+IRT)/ET, was obtained by subtracting ET from the interval between cessation and onset of the mitral inflow velocity to give the sum of ICT and IRT. RESULTS The index was easily measured, reproducible, and had a narrow range in normals. The mean value of the index was significantly different between normal, intermediate and pre-transplant subjects (0.39 +/- 0.05, 0.59 +/- 0.10 and 1.06 +/- 0.24, respectively, p < 0.001 for all comparisons). The degree of inter-group overlap was smaller for the index compared to PEP/ET, ICT/ET and other parameters. Within functional groups, the value of the index did not appear to be related to heart rate, mean arterial pressure and the degree of mitral regurgitation. CONCLUSION (ICT+IRT)/ET is a conceptually new, simple and reproducible Doppler index of combined systolic and diastolic myocardial performance in patients with primary myocardial systolic dysfunction.