Evaluation of aggressive heart rate reduction in patients with stable angina

There is a strong correlation between heart rate and myocardial ischemia, cardiovascular diseases, and life expectancy in general; however, heart rate has been neglected as an important risk factor as well as a therapeutic opportunity.

To investigate the effect of aggressive heart rate reduction (50 ⩽ HR ⩽ 60 bpm) on anti-ischemic and anti-anginal efficacy, left ventricular function, exercise tolerance and quality of life in patients with stable coronary artery disease with or without left ventricular dysfunction during 4 months.

A total of 159 patients presented with stable CAD without clinical heart failure symptoms were included in a open-label, non-comparative, prospective clinical study between June 2009 to February 2010 in King Abdul Aziz Specialist Hospital, Taif, KSA, Al Hayah National Hospital, Khamis Mushyt, KSA and Critical care department, Cairo University, Egypt. All included patients were, in addition to the ant ischemic treatment, subjected to aggressive heart rate control starting by beta blocker titrated to the maximum dose as tolerated, then Ivabradine added if the target heart rate is not achieved or rate control started by Ivabradine if beta blockers are contraindicated. Exercise treadmill test (ETT) to assess exercise capacity using time to 1 mm ST-segment depression in milliseconds, ejection fraction (EF) assessed by transthoracic echocardiography and frequency of angina attacks and the use of sublingual nitroglycerin per week during the last week were evaluated during a follow-up for 4 months. The patients were divided into two groups, group-I (patients achieved a resting heart rate between 50 and 60 bpm with heart rate reduction treatment) and group-II (patients with resting HR >60 bpm in spite of maximum treatment for heart rate reduction).

The resting heart rate was significantly reduced from 77.98 ± 8.7 at baseline to 60.68 ± 4.34 bpm after 4 months of treatment, P < 0.001. The frequency of angina pectoris attacks had been significantly reduced from 2.14 ± 1.27 to 0.48 ± 0.58 attacks per week, P < 0.001 and the highest significant reduction was observed with group-I. Also, the frequency of use sublingual nitrate therapy was significantly reduced from 1.38 ± 1.1 tablet per week at the last week before the study to 0.12 ± 0.33 tablet per week during the last week after 4 months of treatment, P < 0.001 and the reduction was more significantly with group-I. Exercise treadmill test demonstrated statistically significant increase in the time to 1 mm ST-segment depression from 357.36 ± 66.73 at baseline to 387.96 ± 65.19 ms. after 4 months with P < 0.001. The degree of improvement was significantly higher for group-I (from 358.06 ± 68.81 at baseline to 391.71 ± 69.01 after 4 months with P < 0.001) than that of group-II (from 356.11 ± 64.8 at baseline to 381.27 ± 59.08 after 4 months with P < 0.001). Ejection fraction showed a statistically significant increase from 59.76 ± 6.86 at baseline to 61.04 ± 5.35 after 4 months with P < 0.001.

This study indicates that heart rate reduction has been associated with an improvement in quality of life in patients with stable coronary artery disease, presenting new opportunities for treatment.