A new approach to the measurement of heart rate in patients with chronic heart failure-Heart rate performance index: an observational study

Abstract

Objective: In order to evaluate the utility of the heart rate performance index (HRPI), which is obtained by dividing HR mean by the difference of HR max and HR min in the context of Holter monitoring, we sought to determine whether there was any correlation or relationship between the HRPI and LVEF values as determined by echocardiography and to compare the HRPI between the study and control groups. Methods: This study is a cross-sectional, controlled observational study. Thirty-two patients with symptomatic or asymptomatic left ventricular systolic dysfunction (LVEF <45%) were included as study group and 32 subjects without chronic heart failure (CHF) were included as a control group. In the study group, 10 patients were in NYHA class I (31.2%), 12 - were in NYHA class II (37.6%) and 10 - were in NYHA class III (31.2%). Heart rate analysis was measured using 24-hour Holter ambulatory electrocardiography. To determine the HRPI, the difference between maximum (HR max) and minimum heart rate (HR min) was divided by mean heart rate (HR mean) (beats/minute): HRPI=(HR max-HR min) / HR mean. Statistical analysis was performed using t-test for independent samples, Mann-Whitney U test, Chi-square test, Kruskal-Wallis test, Pearson's correlation and linear regression analyses. Results: The HRPI index value was markedly decreased [0.83 (0.58-1.1) and 1.10 (0.74-1.3), p<0.001] in the study group as compared to the control group. The data collected for the study group and the control group (n=64) demonstrated a positive correlation between the HRPI and LVEF (r=0.62, p<0.001) as well as a negative correlation between the HR mean and LVEF (r=-0.39, p<0.003). The HR mean was higher (80.2 +/- 11.3 and 75.2 +/- 6.7, p<0.007) and HR max-HR min (67.9 +/- 11.6 and 83.3 +/- 14.3, p<0.001) were lower in the study group as compared to the control group. Linear regression analysis demonstrated no significant relationship between LVEF and HRPI and other heart rate derivatives (unstandardized beta=42.43 95% CI: 21.98-50.51, p=0.231). Conclusion: According to our findings, patients with CHF exhibited higher HR mean values, reduced HR max-min values and significantly decreased HRPI values. There is a positive correlation between HRPI and LVEF, a decreased HRPI is associated with a decreased LVEF, but there is no relationship between these two variables. Therefore HRPI values may represent a viable option for assessing daily exercise activity and potentially sympathetic activation in patients with CHF. The assessment of HRPI may be helpful the evaluation of CHF patients, as well as resting HR.