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Point | Counterpoint – Calcium Channel Blockers First-Line for SVT?

May 13, 2024

Written by Ketan Patel and Jacob Altholz

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Nondihydropyridine calcium channel blockers (CCB) are an efficacious option to treat supraventricular tachycardia (SVT) and do not cause the sense of doom that adenosine imparts. When taking into account CCB contraindications, diltiazem and verapamil could be first-line options for SVT.

Should diltiazem and verapamil spell the impending doom of adenosine in SVT?
Adenosine imparts a “sense of doom” for some patients, which may be distressing. Alternatives agents without this side effect should be considered.

Authors argue that literature suggests equal or even better efficacy with diltiazem/verapamil in certain situations, while mitigating adverse, though short-lived, side effects of adenosine. Of note, there have not been great head-to-head studies comparing the efficacy of each approach, and medications and administration regimens vary.

The authors acknowledge that there are a few situations where CCBs are relatively or absolutely contraindicated, such as heart failure, pregnancy, and atrial fibrillation with pre-excitation. They argue that with a careful history taking and bedside ultrasonography to rule-out heart failure in some patients, CCBs can be used safely, with low risk of causing hypotension.

How will this change my practice?
I will likely continue to utilize adenosine in my practice. With appropriate coaching, the adverse effects can be anticipated and are not insurmountable. This paper gave me insight into another medical approach to SVT and covered some medication interactions I was not aware of with adenosine (e.g. caffeine). However, the screening required to utilize CCBs seems at least on par with the “pitfalls” of adenosine: impending doom and potential need for re-dosing. Make sure to read the companion piece tomorrow that argues adenosine should remain the first-line drug.

Editor’s note added 5/14/24: We have gotten some comments and emails about this post and the companion post on 5/14/24. Remember, adenosine can cause severe bronchospasm. Use caution in patients with severe asthma or COPD. I have seen this go poorly! Also, any AV nodal blocker – including adenosine – is contraindicated in atrial fibrillation with preexcitation (i.e. WPW). Thanks for the comments and clarifying emails! ~Clay Smith

Calcium Channel Blockers Versus Adenosine for Paroxysmal Supraventricular Tachycardia. Annals of Emergency Medicine. 2024;83:394-395. https://doi.org/10.1016/j.annemergmed.2023.09.003