Is Current Drug Therapy For Heart Failure Sufficient To Control Heart Rate Of Patients?

Background: Studies have shown that heart failure (HF) patients with heart rate (HR) < 70 bpm have had a better clinical outcome and lower morbidity and mortality compared with those with HR > 70 bpm. However, many HF patients maintain an elevated HR.Objective: To evaluate HR and the prescription of medications known to reduce mortality in HF patients attending an outpatient cardiology clinic.Methods: We consecutively evaluated patients seen in an outpatient cardiology clinic, aged older than 18 years, with diagnosis of HF and left ventricular ejection fraction (LVEF) < 45%. Patients with sinus rhythm were divided into two groups - HR <= 70 bpm (G1) and HR > 70 bpm (G2). The Student's t-test and the chi-square test were used in the statistical analysis, and a p-value < 0.05 was considered statistically significant. The SPSS software was used for the analyses.Results: A total of 212 consecutive patients were studied; 41 (19.3%) had atrial fibrillation or had a pacemaker implanted and were excluded from the analysis, yielding 171 patients. Mean age of patients was 63.80 +/- 11.77 years, 59.6% were men, and mean LVEF 36.64 +/- 7.79%. The most prevalent HF etiology was ischemic (n=102; 59.6%), followed by Chagasic (n=17; 9.9%). One-hundred thirty-one patients (76.6%) were hypertensive and 63 (36.8%) diabetic. Regarding HR, 101 patients had a HR <= 70 bpm (59.1%) and 70 patients (40.93%) had a HR >70 bpm (G2). Mean HR of G1 and G2 was 61.5 +/- 5.3 bpm and 81.8 +/- 9.5 bpm, respectively (p<0.001). Almost all patients (98.8%) were receiving carvedilol, prescribed at a mean dose of 42.1 +/- 18.5 mg/day in G1 and 42.5 +/- 21.1mg/day in G2 (p=0.911). Digoxin was used in 5.9% of patients of G1 and 8.5% of G2 (p=0.510). Mean dose of digoxin in G1 and G2 was 0.19 +/- 0.1 mg/day and 0.19 +/- 0.06 mg/day, respectively (p=0,999). Most patients (87.7%) used angiotensin converting enzyme inhibitors (ACEI) or angiotensin II receptor blockers (ARB), and 56.7% used spironolactone. Mean dose of enalapril was 28.9 +/- 12.7 mg/day and mean dose of ARB was 87.8 +/- 29.8 mg/day. The doses of ACEI and ARB were adequate in most of patients.Conclusion: The study revealed that HR of 40.9% of patients with HF was above 70 bpm, despite treatment with high doses of beta blockers. Further measures should be applied for HR control in HF patients who maintain an elevated rate despite adequate treatment with beta blocker.