Functional capacity impairment in patients with coronary artery disease: prevalence, risk factors and prognosis

BACKGROUND: Some patients developing heart failure and functional capacity impairment have no history of myocardial infarction (MI), and stable angina pectoris is their principal clinical manifestation of coronary artery disease (CAD). The present study was aimed to evaluate the outcome of CAD-related functional capacity impairment in patients with and without a history of MI over a 7.7-year follow-up. METHODS: The study sample comprised 14,283 coronary patients aged 45-74 years, screened for participation in the Bezafibrate Infarction Prevention study. The presence of NYHA functional class II was defined as mild functional capacity impairment and the presence of NYHA functional class III-IV was defined as advanced functional capacity impairment. RESULTS: The patients were divided in two groups: (1) those with a history of MI, 10,307 patients, who formed three subgroups: NYHA I 7,551 patients (73.3%); NYHA II 2,176 patients (21.1%); NYHA III + IV 580 patients (5.6%), and (2) those without a history of MI, 3,976 patients, who also formed three subgroups: NYHA I 2,744 patients (69.0%); NYHA 981 patients (24.7%); NYHA III + IV 251 patients (6.3%). Multivariate analysis identified a history of MI as a consistent predictor of increased all-cause and cardiac mortality for patients with NYHA I, II and III + IV subgroups with escalating significance for patients with advanced functional capacity impairment: hazard ratios of 1.55 (95% CI 1.36-1.75), 1.56 (95% CI 1.30-1.86) and 1.72 (95% CI 1.24-2.40) for all-cause and 1.93 (95% CI 1.60-2.33), 1.73 (95% 1.35-2.20) and 3.22 (95% CI 1.87-5.54) for cardiac mortality, respectively. CONCLUSIONS: The prevalence of low functional capacity is similar among coronary patients with and without a history of MI, but their long-term survival differs substantially in favor of the latter. Therefore, two different types of CAD-related advanced functional capacity impairments (post-MI and non-post-MI) can be distinguished.