Calcium channel blockers as first line treatment for broad complex tachycardia with right bundle branch block: ingenuity or folly?

OBJECTIVE

To study the response of regular broad-complex tachycardia (BCT) demonstrating right bundle branch block (RBBB) to treatment in the Emergency department (ED).

METHODS

Retrospective chart review of management of patients with BCT, RBBB without a history of ischaemic heart disease. A diagnosis of ventricular tachycardia (VT) was made if the ECG showed features such as atrioventricular dissociation, capture or fusion beats or if VT was demonstrated during electrophysiological studies (EPS).

RESULTS

A total of 25 patients were eligible. Nineteen patients were given intravenous (IV) calcium channel blockers (either verapamil or diltiazem), as first line treatment. Of these, 18 converted to sinus rhythm and the other one patient subsequently converted with amiodarone. The remaining six patients were given IV adenosine (n=3), lignocaine (n=2) or amiodarone (n=1) as first line treatment but none of them were converted. Of these, four of them converted with IV calcium channel blockers eventually. Of the other two patients, who were both given lignocaine initially, one deteriorated haemodynamically with the use of verapamil and required synchronised cardioversion to convert. The other patient did not respond to amiodarone and synchronised cardioversion but was subsequently converted with verapamil. The difference between the success rate of calcium channel blockers and other anti-arrhythmics is statistically significant (P<0.01 by Fischer's exact method). Fourteen cases had diagnoses of VT, including the two patients given lignocaine. Five cases were found to have supraventricular tachycardia with aberrant conduction. Six cases did not have confirmed diagnoses.

CONCLUSION

In patients presenting with BCT and RBBB but without underlying ischaemic heart disease, there is evidence to suggest that calcium channel blockers could effectively be used as the treatment of choice.