Comparison of efficacy of intravenous diltiazem and esmolol in terminating supraventricular tachycardia.

OBJECTIVE: Paroxysmal supraventricular tachycardia (PSVT) can be effectively terminated by the intravenous administration of adenosine or verapamil. However adenosine is expensive and injectable verapamil currently is scarcely available. While intravenous diltiazem has been shown to be useful for terminating PSVT, the efficacy of esmolol in this regard has not been evaluated previously. Hence these latter two drugs were studied for their efficacy in terminating PSVT.

METHODS: A prospective, randomised, crossover study was undertaken in patients presenting with hemodynamically tolerated PSVT to the ICCU. While 50 patients had been planned for the trial, the study had to be prematurely terminated after 32 patients had been enrolled due to the marked superiority of diltiazem. Two sequential doses with a 5 minute interval of either drug were administered before crossover. Diltiazem was given in a dose of 0.25 mg/kg while the esmolol dose was 0.5 mg/kg.

RESULTS: Diltiazem terminated PSVT in all the 16 patients in whom it was given as the first drug. The 12 patients who did not respond to esmolol were also effectively treated with diltiazem. Thus totally 28/28 patients responded to diltiazem while only 4/16 patients responded to esmolol (p < 0.001). Of the 28 patients who responded to diltiazem, in 13 patients the second bolus of diltiazem worked after the first one had failed. No significant adverse effects were seen.

CONCLUSION: Intravenous diltiazem is highly effective and safe for terminating PSVT. When the first bolus is ineffective, the second bolus given after 5 minutes usually succeeds. Esmolol in the dose of 0.5 mg/kg has poor efficacy for terminating PSVT, even when 2 boluses are administered.