The index of myocardial performance and aortic regurgitation: the influence of a volume overload lesion.

Objective: The index of myocardial performance (IMP) is a global cardiac function index with prognostic utility in patients with myocardial infarction and dilated cardiomyopathy but is preload dependent. We hypothesized that a volume overload lesion prolonging LV ejection time (LVET) may reduce IMP despite LV dysfunction (LVD).

Methods: The study groups consisted of 35 normals, 26 with LV dysfunction, and 60 with aortic regurgitation (AR): 40 with ejection fraction (EF) >50% (AR+Normal EF) and 20 with ejection fraction > or = 50% (AR+Reduced EF). We evaluated consecutive patients in each group with technically adequate 2D and Doppler echocardiography.

Results: When compared to normal subjects (0.357+/-0.122), IMP was increased with LVD (0.604+/-0.278 p<0.001) but was similar in AR+Normal EF patients due to isovolumic relaxation time (IRT) and LVET prolongation. The IMP was lower in AR+Reduced EF group (0.346+/-0.172, p<0.001) as compared to the LVD group due to a prolonged LVET and a reduced IRT and isovolumic contraction time (ICT).

Conclusions: The IMP in AR+Normal EF patients was similar to normals due to IRT and LVET prolongation. The IMP was reduced in AR+Reduced EF patients compared to LVD patients due to IRT and ICT shortening and LVET prolongation. The index of myocardial performance in AR patients should be applied with caution.