Calcium Channel Blockers Contraindicated in Brugada Syndrome
Non-dihydropyridine calcium channel blockers (verapamil and diltiazem) are contraindicated in Brugada syndrome as they can aggravate Brugada-type ECG abnormalities and potentially trigger ventricular fibrillation. 1
Mechanism and Risk
The contraindication of certain calcium channel blockers in Brugada syndrome is based on their potential to:
- Increase ST-segment elevation in the right precordial leads
- Worsen the characteristic Brugada ECG pattern
- Potentially trigger life-threatening arrhythmias including ventricular fibrillation
- Increase the voltage gradient through the right ventricle 2
- Slow intraventricular conduction at very fast heart rates 2
Specific Calcium Channel Blockers to Avoid
Non-dihydropyridine CCBs:
- Verapamil - Has been specifically documented to increase ST-segment elevation and shorten ventricular fibrillatory intervals in Brugada syndrome 2
- Diltiazem - Similar mechanism of action to verapamil with potential for harm
Dihydropyridine CCBs:
- While less evidence exists specifically for dihydropyridines in Brugada syndrome, caution is warranted with all calcium channel blockers according to comprehensive guidelines 1
Clinical Evidence
Case reports have documented adverse events when calcium channel blockers were administered to patients with Brugada syndrome:
- A case report showed verapamil administration led to increased ST-segment elevation and induced ventricular fibrillation with shorter F-F intervals that was more difficult to terminate with defibrillation 2
- Another case documented ventricular fibrillation attacks occurring after calcium channel blocker treatment in a patient with coexisting Brugada syndrome and vasospastic angina 3
Management Considerations
For patients with Brugada syndrome requiring treatment for conditions typically managed with calcium channel blockers:
- For coronary vasospasm/angina: Consider alternative therapies such as long-acting nitrates
- For supraventricular arrhythmias: Quinidine should be considered as it has additional Ito blocking properties that may be beneficial in Brugada syndrome 1
- For electrical storms: Isoproterenol is recommended rather than calcium channel blockers 1
Important Precautions
All patients with Brugada syndrome should:
- Check medication safety on www.brugadadrugs.org before taking any new drugs
- Be educated about avoiding all contraindicated medications
- Promptly treat fever with antipyretic medications
- Avoid excessive alcohol intake and large meals
- Receive an ICD if they have survived cardiac arrest or have documented spontaneous VT
Conflicting Evidence
While most evidence suggests avoiding calcium channel blockers in Brugada syndrome, one study reported that long-term use of calcium antagonists within normal dosage ranges was not associated with ECG parameter aggravation in some patients 4. However, this finding should be interpreted with extreme caution given the more substantial evidence supporting contraindication and the potentially fatal consequences of triggering ventricular arrhythmias.
Given the risk of life-threatening arrhythmias, the safest approach is to avoid all calcium channel blockers in patients with Brugada syndrome and use alternative treatments when indicated.