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Ventricular rate control and exercise performance in chronic atrial fibrillation: effects of diltiazem and verapamil
1Department of Cardiology, Central Hospital, Skövde, Sweden.
Insights
Diltiazem and verapamil, calcium channel blockers, modestly improved exercise tolerance in patients with chronic atrial fibrillation. Both drugs similarly reduced heart rate and enhanced physical performance, offering comparable benefits.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Chronic atrial fibrillation (AF) is a common arrhythmia impacting quality of life.
- Controlling ventricular rate in AF is crucial for managing symptoms and improving exercise capacity.
Purpose of the Study:
- To evaluate the efficacy of diltiazem and verapamil in improving exercise tolerance in patients with chronic AF.
- To compare the effects of these calcium channel blockers on heart rate and physical performance.
Main Methods:
- A randomized controlled trial involving 18 patients with chronic AF.
- 24-hour Holter monitoring to assess mean ventricular rate.
- Symptom-limited exercise testing to measure exercise tolerance and anaerobic threshold.
Main Results:
- Both diltiazem and verapamil significantly reduced mean ventricular rate and heart rate during maximal exercise compared to placebo.
- Maximal symptom-limited exercise tolerance and anaerobic threshold were significantly increased with both drugs.
- Diltiazem and verapamil demonstrated similar efficacy in improving dromotropic responses and physical performance.
Conclusions:
- Calcium channel blockade therapy with diltiazem or verapamil offers modest improvements in exercise tolerance for patients with chronic AF.
- The observed benefits on heart rate control and exercise performance are comparable between diltiazem and verapamil.
Abstract:
The effects of two calcium channel blockers, diltiazem (270 mg/day) and verapamil (240 mg/day), were studied in 18 patients with chronic atrial fibrillation. During 24 h Holter electrocardiographic monitoring, mean ventricular rate (beats/min) decreased from 88 +/- 14 with placebo to 76 +/- 13 (p less than 0.001) with diltiazem and 80 +/- 11 (p less than 0.01) with verapamil. Maximal symptom-limited exercise tolerance (W) increased from 127 +/- 39 during the placebo period to 136 +/- 42 (p less than 0.01) with diltiazem and 137 +/- 39 (p less than 0.01) with verapamil. Ventricular rate and rate-pressure product were lower at rest and during exercise with diltiazem and verapamil than with placebo (p less than 0.001), with the drugs being similarly effective. Ventricular rate at maximal exercise (beats/min) was 179 +/- 13 with placebo compared with 159 +/- 21 with diltiazem and 158 +/- 23 with verapamil. Maximal oxygen uptake (ml/kg per min) was 22.3 +/- 4.5 with placebo, 23.7 +/- 4.9 (p less than 0.05) with diltiazem and 22.9 +/- 4.5 with verapamil (p = NS). Respiratory gas exchange anaerobic threshold was reached at a work load (W) of 76 +/- 21 with placebo, 84 +/- 27 (p less than 0.05) with diltiazem and 85 +/- 23 (p less than 0.01) with verapamil. In conclusion, patients with chronic atrial fibrillation have modestly improved exercise tolerance with calcium channel blockade therapy. The dromotropic responses and the effects on physical performance are of similar magnitude for diltiazem and verapamil.