Impact of IMR on Prognosis
Similar to the challenges of estimating the true prevalence of IMR, the prognosis of IMR and CAD is also heterogeneous in many studies. It is common in studies that patients with MR and CAD may have been considered as IMR, however, some patients may have MR yet the etiology of MR is not necessarily IMR. Nevertheless, the retrospective analyses of single center studies demonstrate that presence of MR always portends poor prognosis. Hickey et. al used the Duke Clinical Research Institute in 11,748 patients. The investigators demonstrated that that 1-year mortality for severe IMR was 40%, for moderate IMR 17%, for mild IMR 10% and for patients without IMR 6% [12].
A case-controlled study from Mayo Clinic demonstrated that patients with IMR detected in the chronic phase (more than 16 days) after Q-wave myocardial infarction have lower 5-year survival than patients without MR (38.5% vs 61.6%, p < 0.001) [2].
The SAVE (Survival and Ventricular Enlargement) study demonstrated that mild IMR increases the risk of cardiovascular mortality, even in patients without CHF [3]. Patients
with IMR had a higher incidence of cardiovascular mortality (29% vs 12%, p < 0.001) and CHF (24% vs 16%, p < 0.001) than patients without IMR at a mean of 3.5 years after AMI.