A standardized definition of ischemic cardiomyopathy for use in clinical research

OBJECTIVES: We sought to evaluate the association between the extent of coronary artery disease (CAD) and survival in patients with symptomatic heart failure (HF) and to create the most prognostically powerful clinical definition of ischemic cardiomyopathy. BACKGROUND: An ischemic etiology of HF is known to be a predictor of adverse outcome; however, there is no uniform definition for ischemic cardiomyopathy. METHODS: We assessed the clinical history and coronary anatomy of patients with symptomatic HF and ejection fraction < or = 40% undergoing diagnostic coronary angiography between 1986 and 1999 (n = 1,921). Five classification schemes were tested to identify the most prognostically powerful method for defining the extent of CAD and to develop the best definition of ischemic cardiomyopathy for prognostic purposes. RESULTS: A more extensive CAD was independently associated with shorter survival. When the various classification schemes were compared, a modified number-of-diseased-vessels classification, in which patients with single-vessel disease and no prior history of revascularization or myocardial infarction (MI) were classified as nonischemic, provided the most prognostic power. A definition of ischemic cardiomyopathy that incorporated this definition had more prognostic power than the traditional definition. CONCLUSIONS: Angiographically diagnosed ischemic HF is associated with shorter survival than nonischemic HF. A more extensive CAD is independently associated with shorter survival, and patients with single-vessel disease and no history of MI or revascularization should be classified as nonischemic for prognostic purposes. Standardization of the definition of ischemic cardiomyopathy will be useful in the conduct and interpretation of clinical research in HF.