Calcium Channel Blockers Versus Adenosine for Paroxysmal Supraventricular Tachycardia

Authors: Megan A. Rech, PharmD, MS; Michael Gottlieb, MD; Marc McDowell, PharmD; Neal Lyons, PharmD

Journal: Annals of Emergency Medicine

Year: 2024

Volume: 83

Issue: 4

Type of Study: Clinical Controversy/Opinion Piece

DOI: 10.1016/j.annemergmed.2023.09.003

Quick Reference Summary

• Calcium channel blockers demonstrate a significantly higher conversion rate to normal sinus rhythm (98%) compared to adenosine (86.5%) in hemodynamically stable patients with paroxysmal supraventricular tachycardia (PSVT).
• The relative risk favoring calcium channel blockers is 1.13 (95% CI: 1.04 to 1.23), with a number needed to treat of 9 (95% CI: 8 to 10).

Core Clinical Question

In hemodynamically stable patients with paroxysmal supraventricular tachycardia (PSVT), do calcium channel blockers compare to adenosine in achieving conversion to normal sinus rhythm?

Background

Disease Overview:

• Supraventricular tachycardia is a common arrhythmia treated in the emergency department, characterized by a regular, narrow QRS complex tachycardia.
• PSVT can be abruptly terminated with pharmacologic interventions, particularly adenosine or calcium channel blockers (CCBs) like verapamil and diltiazem.

Prior Data:

• A 2017 Cochrane review encompassing 7 trials with 622 patients found similar reversion rates between adenosine (89.7%) and calcium channel blockers (92.9%; OR 1.51, 95% CI: 0.85 to 2.68).
• A 2011 meta-analysis reported high efficacy rates for both adenosine (90.8%) and verapamil (89.9%; OR 1.27, 95% CI: 0.63 to 2.57).

Current Standard of Care:

• American Heart Association (2016) and European Society of Cardiology (2019) guidelines recommend adenosine as a first-line pharmacotherapy for hemodynamically stable SVT.

Knowledge Gaps Addressed by Study:

• Comparative efficacy and safety of calcium channel blockers versus adenosine in PSVT management.
• Addressing adverse effect profiles and patient comfort between the two treatment options.

Study Rationale:

• To evaluate whether calcium channel blockers should be considered first-line agents over adenosine in the treatment of stable PSVT, given their similar efficacy and potentially better patient tolerance.

Methods Summary

• Study Design: Comparative analysis/opinion based on existing trials and meta-analyses.
• Setting and Time Period: Not explicitly stated; references studies from 1993 to 2022.
• Population Characteristics: Hemodynamically stable patients presenting with paroxysmal supraventricular tachycardia.
• Inclusion/Exclusion Criteria: Not explicitly detailed; focuses on patients without systolic heart failure and excludes those with pre-excitation syndromes.
• Intervention Details:
  • Adenosine: Initial 6 mg dose, followed by 12 mg if necessary.
  • Calcium Channel Blockers: Continuous infusion of up to 50 mg diltiazem (2.5 mg/min) or up to 20 mg verapamil (1 mg/min).
• Control/Comparison Group Details: Comparison between adenosine administration and calcium channel blocker infusion.
• Primary and Secondary Outcomes:
  • Primary Outcome: Conversion to normal sinus rhythm.
  • Secondary Outcomes: Adverse effects, hypotension incidence, and patient distress.
• Statistical Analysis Approach: Analysis of conversion rates, relative risk, confidence intervals, and number needed to treat.
• Sample Size Calculations: Derived from referenced studies; specific calculations not provided.
• Ethics and Funding Information: Not explicitly mentioned; references existing studies and guidelines.

Detailed Results

• Participant Flow and Demographics: Not detailed; synthesis based on multiple studies.
• Primary Outcome Results:
  • Higher conversion rates with calcium channel blockers (98%) compared to adenosine (86.5%).
  • Relative Risk: 1.13 (95% CI: 1.04 to 1.23).
  • Number Needed to Treat: 9 (95% CI: 8 to 10).
• Secondary Outcome Results:
  • Calcium channel blockers associated with fewer adverse effects and less patient discomfort.
  • Adenosine linked to transient adverse effects such as "sense of impending doom," chest tightness, and shortness of breath.
• Subgroup Analyses: Not explicitly discussed.
• Adverse Events/Safety Data:
  • Hypotension was rare, with only one case in the verapamil group.
  • Adenosine’s transient adverse effects may cause significant distress despite their transient nature.

Authors' Conclusions

• Primary Conclusions:
  • Calcium channel blockers are efficacious and may offer higher conversion rates to normal sinus rhythm compared to adenosine in the treatment of PSVT.
• Authors' Interpretation of Results:
  • Calcium channel blockers spare patients from the distressing and transient adverse effects associated with adenosine.
• Clinical Implications Stated by Authors:
  • Emergency clinicians should consider calcium channel blockers as first-line agents over adenosine in hemodYNAMically stable patients with PSVT.
• Future Research Recommendations:
  • Reconsideration of current practices favoring adenosine as the first-line treatment.
  • Further studies to solidify the preference for calcium channel blockers in PSVT management.

Critical Analysis

A. Strengths:

• Comprehensive Review: Synthesizes data from multiple studies and meta-analyses to compare calcium channel blockers and adenosine.
• Clinical Relevance: Addresses a common clinical scenario in emergency medicine, aiding in informed decision-making.
• Emphasis on Patient Comfort: Highlights the importance of patient-centered outcomes, such as reduced distress from adverse effects.

B. Limitations:

• Study Design Variability: Relies on data from various studies with differing methodologies, which may introduce heterogeneity.
• Potential Biases: As an opinion piece, it may reflect the authors' interpretations and biases towards calcium channel blockers.
• Generalizability Issues: Limited information on specific patient populations, settings, and exclusion criteria across referenced studies.
• Statistical Limitations: Lack of detailed statistical analysis within the article itself; relies on secondary data.
• Missing Data Handling: Not explicitly addressed due to the nature of the article being a commentary/review.

C. Literature Context

A. Previous Studies and Meta-Analyses:

1. Cochrane Review (2017):
   • Findings: Similar reversion rates between adenosine and calcium channel blockers.
   • Citation: Cochrane Database Syst Rev. 2017;10:CD005154.
2. Meta-Analysis (2011):
   • Findings: High efficacy rates for both adenosine and verapamil with no significant difference.
   • Citation: Eur J Emerg Med. 2011;18:148-152.
3. American College of Cardiology/American Heart Association (2016) Guidelines:
   • Findings: Recommend adenosine as first-line treatment for PSVT.
   • Citation: J Am Coll Cardiol. 2016;67:e27-e115.
4. European Society of Cardiology (2019) Guidelines:
   • Findings: Recommend adenosine as first-line pharmacotherapy in stable SVT.
   • Citation: European Heart Journal. 2020;41:655-720.
5. Additional Studies:
   • Research on drug interactions and safety profiles of calcium channel blockers vs. adenosine.
   • Citations: Various, including Resuscitation. 2009;80:523-528 and Ann Emerg Med. 2024;83:395-397.

B. Contrasting Methodological Quality:

• Referenced Trials: Vary in design, sample size, and intervention protocols, affecting the consistency of outcomes.
• Impact on Outcomes: Differences in administration methods (e.g., continuous infusion vs. bolus) may influence efficacy and safety results.
• Citation Example: Resuscitation. 2009;80:523-528.

C. Comparisons with Guidelines:

• American Heart Association (2016):
  • Recommendation: Adenosine as first-line treatment for PSVT.
  • Citation: J Am Coll Cardiol. 2016;67:e27-e115.
• European Society of Cardiology (2019):
  • Recommendation: Adenosine as first-line pharmacotherapy in stable SVT.
  • Citation: European Heart Journal. 2020;41:655-720.

D. This Trial's Contribution:

• Adds Evidence: Supports the efficacy and safety of calcium channel blockers as a potentially superior first-line treatment compared to adenosine.
• Contradicts Current Guidelines: Suggests reevaluation of adenosine's primacy in treatment protocols.
• Citation References: Ann Emerg Med. 2024;83:395-397.

Clinical Application

• Findings suggest that calcium channel blockers should be considered as the first-line treatment for hemodynamically stable PSVT due to higher efficacy and better patient tolerance compared to adenosine.
• Most applicable to stable PSVT patients in emergency settings where rapid conversion and patient comfort are priorities.
• Implementation should consider availability of calcium channel blockers, staff training on administration protocols, and patient-specific factors such as contraindications to calcium channel blockers.

How To Use This Info In Practice

Practitioners should consider adopting calcium channel blockers as the initial pharmacologic intervention for stable PSVT, aligning treatment protocols with evidence favoring higher efficacy and improved patient comfort.

Notes for Clarity

• Statistical Significance: Conversion rates and relative risks are bolded to highlight significance.
• Confidence Intervals: Included where available to convey precision of estimates.
• Adverse Effects: Highlighted differences in patient discomfort and transient side effects.
• Conflicts of Interest: Not explicitly stated; assume neutrality unless specified.
• Funding Sources: Not detailed; consider reviewing original studies for disclosures.
• Areas of Uncertainty: Variability in study designs and potential biases noted in limitations.
• Number Needed to Treat: Provided to contextualize the clinical impact of findings.

This structured summary synthesizes the key points from the article, emphasizing the comparative efficacy and safety of calcium channel blockers versus adenosine in the management of PSVT, and provides a critical appraisal to aid in clinical decision-making.