Prevalence and Risk Factors
The true prevalence of IMR is unknown due to a number of factors. The heterogeneity of MR patients presented in different studies makes the assessment of the prevalence more challenging. In addition, the impact of the imaging modality used to identify MR or timing of imaging at the time of the diagnosis make the accurate assessment of MR less desirable [11]. As note earlier, IMR occurs in 25% of patients presenting with AMI without CHF and in 50% of patients with post-infarct CHF [1–4]. It is estimated that up to 20% of patients undergoing cardiac catheterization for symptomatic CAD [12] and nearly up to 28% of patients undergoing coronary artery bypass graft (CABG) [13] may have IMR.
The risk factors for developing IMR are; inferior AMI (38%) versus anterior AMI (10%) at echocardiographic follow-up after 2 years [14, 15], advanced age, female gender, prior acute MI, large infarct size, recurrent myocardial ischemia, multi-vessel CAD and CHF on admission [16].