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Sinus arrest caused by atenolol-verapamil combination
Clinical Cardiology
|June 1, 1987
Summary
Concomitant atenolol-verapamil therapy can cause dangerous heart rhythm problems like sinus arrest and bradycardia, even at low doses. This suggests pharmacodynamic interactions, not just pharmacokinetics, are key to adverse reactions.
Area of Science:
- Cardiology
- Clinical Pharmacology
Background:
- Hypertension and angina pectoris are commonly treated with beta-blockers and calcium channel blockers.
- Concomitant use of atenolol (a beta-blocker) and verapamil (a non-dihydropyridine calcium channel blocker) is a recognized therapeutic strategy.
Observation:
- A case of sinus arrest and life-threatening bradycardia developed in a patient receiving low-dose concomitant atenolol-verapamil therapy.
- The patient had a normal electrophysiologic status of the heart prior to the event.
Findings:
- The adverse cardiac event occurred despite low dosages of both atenolol and verapamil.
- Pharmacodynamic synergism between atenolol and verapamil is proposed as the primary mechanism for the observed adverse reaction.
- Pharmacokinetic interactions are considered less likely to be the main cause of this specific adverse event.
Implications:
- Clinicians should be aware of the potential for severe bradycardia and sinus arrest with combined beta-blocker and verapamil therapy.
- This case highlights the critical role of pharmacodynamic interactions in drug-induced adverse events.
- Careful patient monitoring is essential when initiating or adjusting concomitant beta-blocker and verapamil regimens, particularly in patients with cardiovascular conditions.