Adenosine versus intravenous calcium channel antagonists for the treatment of supraventricular tachycardia in adults.
BACKGROUND
Patients with paroxysmal supraventricular tachycardia frequently present to the Emergency Department. Where vagal manoeuvres fail, the two most commonly used drugs are adenosine and calcium channel antagonists. Both are known to be effective but both have a significant side-effect profile.


OBJECTIVE
To examine the relative effects of adenosine and calcium channel antagonists and, if possible, to determine which is most appropriate for the management of supraventricular tachycardia.


METHODS
Studies were identified from The Cochrane Central Register of Controlled Trials (CENTRAL), Issue 3 2006, MEDLINE (1966 to June 2006), Pre-MEDLINE and EMBASE (1980 to June 2006). Bibliographies of identified studies were also examined. No language restrictions were applied.


METHODS



METHODS
randomised trials comparing adenosine and a calcium channel antagonist in patients of any age with supraventricular tachycardia, where one of the defined outcomes was reported. Outcomes of interest were: reversion rate, mortality, time to reversion, rate of relapse, minor adverse events, major adverse events, length of hospital stay and patient satisfaction. Major adverse events were defined as cardiac arrest, prolonged hypotension, symptomatic bradycardia requiring treatment and acute cardiac failure. Minor adverse events were any other reported event.


METHODS
Two reviewers independently checked the results of searches to identify relevant studies. Dichotomous outcomes were reported as Peto Odds ratios and continuous outcomes as weighted mean differences.


RESULTS
Eight trials were identified. In the pooled analysis there was no significant difference in reversion rate or relapse rate between the two drugs. Time to reversion was slower for verapamil than adenosine in all studies that reported this outcome, but the data were not suitable for combining. Minor adverse events such as nausea, chest tightness, shortness of breath and headache were reported much more frequently in patients treated with adenosine with 10.8 % of patients reporting at least one of these events, compared with 0.6% of those treated with verapamil (OR 0.15, 95% CI 0.09 to 0.26, P<0.001). There was no significant difference in the rate of major adverse events between the two groups, although hypotension was reported exclusively in the verapamil treatment group (3/166 patients treated with verapamil, 0/171 treated with adenosine).


CONCLUSIONS
Adenosine and verapamil are both effective treatments for supraventricular tachycardia in the majority of patients. However, given the high incidence of minor but unpleasant side effects in patients treated with adenosine and the potential for hypotension with verapamil, patients should be fully informed of these risks prior to treatment.
Holdgate
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Liverpool Hospital, Emergency Medicine Research Unit, Sydney South West Area Health Service, Liverpool, NSW, Australia. Anna.holdgate@sswahs.nsw.gov.au
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D000241:Adenosine / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D002121:Calcium Channel Blockers / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D016032:Randomized Controlled Trials as Topic; D013617:Tachycardia, Supraventricular / Q000188:drug therapy*; D014700:Verapamil / Q000009:adverse effects / Q000627:therapeutic use
D002121:Calcium Channel Blockers; D014700:Verapamil; D000241:Adenosine