From the Guidelines
Nondihydropyridine calcium channel blockers are recommended over dihydropyridine calcium channel blockers for supraventricular tachycardia (SVT) because they effectively terminate reentry SVTs and control ventricular response rates. The primary reason for this recommendation is that nondihydropyridine calcium channel blockers, such as verapamil and diltiazem, act primarily on nodal tissue to terminate reentry SVTs or slow the ventricular response to other SVTs by blocking conduction through the atrioventricular (AV) node 1. Some key points to consider when using these medications include:
- Verapamil can be given as a 2.5 mg to 5 mg IV bolus over 2 minutes, with repeated doses of 5 mg to 10 mg every 15 to 30 minutes to a total dose of 20 mg, if necessary 1.
- Diltiazem can be given as a 15 mg to 20 mg (0.25 mg/kg) IV dose over 2 minutes, with an additional 20 mg to 25 mg (0.35 mg/kg) dose in 15 minutes, if needed, and a maintenance infusion dose of 5 mg/hour to 15 mg/hour, titrated to heart rate 1.
- Nondihydropyridine calcium channel blockers should be used with caution in patients with impaired ventricular function or heart failure, and should not be given to patients with wide-complex tachycardias or pre-excited atrial fibrillation or flutter that conducts to the ventricles via both the AV node and an accessory pathway 1. It is essential to carefully evaluate the patient's condition and medical history before administering these medications to ensure safe and effective treatment.
From the Research
Nondihydropyridine Calcium Channel Blockers vs Dihydropyridine Calcium Channel Blockers
- Nondihydropyridine calcium channel blockers are recommended over dihydropyridine calcium channel blockers for certain conditions due to their distinct pharmacological properties 2.
- The main difference between these two types of calcium channel blockers lies in their binding sites on the calcium channel and their effects on the heart and blood vessels 2.
- Nondihydropyridine calcium channel blockers, such as diltiazem and verapamil, are more myocardial selective and tend to reduce heart rate, whereas dihydropyridine calcium channel blockers are more vascular selective 2.
Clinical Implications
- In the context of atrial fibrillation, nondihydropyridine calcium channel blockers may be preferred for rate control due to their ability to reduce heart rate without causing significant hypotension 3.
- A study comparing the effects of nondihydropyridine calcium channel blockers and beta-blockers on heart rate in patients with non-permanent atrial fibrillation found that both types of medications were effective in achieving a resting heart rate <110 beats per minute during atrial fibrillation, but nondihydropyridine calcium channel blockers were associated with less bradycardia during sinus rhythm 3.
- However, the use of nondihydropyridine calcium channel blockers in patients with heart failure with reduced ejection fraction is still a topic of debate, and more research is needed to fully understand their safety and efficacy in this population 4, 5.
Safety and Efficacy
- The safety and efficacy of nondihydropyridine calcium channel blockers versus dihydropyridine calcium channel blockers have been compared in several studies, with mixed results 5, 6.
- One study found that the use of nondihydropyridine calcium channel blockers was associated with a lower risk of heart failure hospitalization compared to beta-blockers, but a higher risk of all-cause mortality 5.
- Another study found that the use of nondihydropyridine calcium channel blockers was not associated with a significant change in the safety or efficacy of rivaroxaban compared to warfarin in patients with atrial fibrillation 6.