Heart Rate Control in an Unselected Consecutive Population of Outpatients With Stable Coronary Artery Disease: Analysis of the CARDIf Study Cohort

Abstract

Background: Despite increasing pharmacological and mechanical treatment options, coronary artery disease (CAD) continues to be associated with considerable mortality and morbidity. The detrimental effects of elevated heart rate (HR) on cardiac morbidity and mortality are well established. Although β-blockers represent the mainstay of treatment of patients with CAD and heart failure (HF), according to current guidelines, these drugs are most often undertitrated for various reasons despite the lack of real contraindications. This observational, cross-sectional, multicenter survey was designed to assess which clinical variables influence HR and whether HR is adequately controlled; and the rate of administration of β-blockers in patients with chronic CAD attending outpatient clinics. Methods: Over 6 months 2226 (of 2362 screened) outpatients with stable CAD and resting HR > 60 beats/min (bpm) were enrolled. Left ventricular systolic function was not a criterion of inclusion. Each patient had a full clinical examination and the past medical history, angina, or HF-related symptoms were evaluated. In each patient, the demographics and cardiovascular risk factors were assessed; weight, height, and body mass index (BMI) was calculated; sitting blood pressure and a HR by a 12-lead electrocardiogram was obtained. Results: Overall, 45.4% of patients with CAD were not under β-blocker therapy. Male patients featured a significantly lower HR than females, corrected from β-blockers use. In multiple regression analysis, which also included the use/nonuse of β-blockers as independent variable, not using β-blockers, female sex (OR 2.55), New York Heart Association (NYHA) classes I and II (OR 1.62 vs classes III-IV), smoking (OR 0.89), and increased BMI (OR 0.14) were all independent determinants of resting HR, with the lack of β-blockade therapy (OR 3.35) being the main determinant of the magnitude of HR increase. Heart rate in patients under β-blocker therapy was significantly less than in untreated patients (73.6 10.0 vs 77.1 10.4, P < .0001), although it often did not reach target values of <70 bpm. Among patients with HF symptoms, 56.6% were under β-blocker therapy. In patients free of symptoms of HF, HR was significantly less in those receiving a β-blocker (72.3 10 vs 76.7 11 bpm, P < .0001). Conclusion: This survey demonstrates that HR is poorly controlled in a broadly representative cohort of outpatients with CAD, even in those on β-blocker therapy, mainly because of undertitration of therapy—almost half of the patients with CAD and elevated resting HR are not on β-blockers. This might be related to absolute or relative controindications and to haemodynamic and chronotropic intolerance to beta-blockers.