P2504Chronotropic incompetence and exercise capacity in patients treated with beta-blockers
Abstract Background Chronotropic incompetence (CI) in patients treated with beta-blockers correlates with worse prognosis but influence of CI on exercise capacity (EC) is unclear. Aim To assess relationship between CI and EC in patients treated with beta-blockers. Methods We have analysed retrospectively data from consecutive cardiopulmonary exercise tests performed between 2008 and 2016 in our department. The inclusion criteria were: treatment with beta-blockers started at least 4 weeks before and continued on the day of the test, sinus rhythm during the test, respiratory exchange ratio ≥1.05 at peak exercise, absence of haemodynamically important valve dysfunction, pulmonary hypertension, exercise induced ischemia, pulmonary or peripheral limitations of exercise. CI was defined as chronotropic index ≤62%. Beta-blocker dose was calculated as bisoprolol equivalent dose. Included patients were divided, according to CI, in two groups: with CI and without CI. EC was assessed as percent of maximal predicted oxygen uptake achieved at peak exercise (%peakVO2). Results One hundred forty two patients (age 61±10 years, 73% males, hypertension 63%, ischemic heart disease 79%, chronic heart failure 12%, diabetes mellitus 20%, paroxysmal atrial fibrillation 10%) fulfilled the inclusion criteria. The group with CI comprised 115 and the group without CI 27 patients. Diabetes mellitus was more frequent and beta-blockers daily dose was higher in the CI group. There were no differences in other clinical parameters between groups. The group with CI had worse EC than the group without CI (69±18% vs 89±18%, p=0.ehz748.083301). In multivariate regression analysis, chronotropic index was independently related to EC (Table). Table 1. Relationship of variables to exercise capacity in multivariate regression analysis Variable Coefficient β 95% Confidence interval p Age (years) 0.242 −0.049 to 0.533 NS Sex (male vs female) 5.260 −1.344 to 11.865 NS Body mass index (kg/m2) −0.786 −1.476 to −0.095 0.05 Left ventricular ejection fraction (%) 0.353 0.116 to 0.590 0.01 Beta-blocker daily dose (mg) 0.150 −0.962 to 1.262 NS Diabetes mellitus 0.070 −7.103 to 7.243 NS Heart rate at rest (bpm) −0.238 −0.440 to −0.035 0.05 Chronotropic index 0.496 0.327 to 0.665 0.ehz748.083301 Conclusions In patients treated with beta-blockers CI was revealed as an independent factor related to worse EC.