• 
• 

Three Part Question

In [adults with supraventricular tachycardia] is [adenosine or verapamil] more effective at [restoring sinus rhythm]?

Clinical Scenario

A 55 year old women presents to A & E with palpitations and shortness of breath. The physician on-call performs an ECG revealing a regular rhythm, with a p-wave distorting the start of the QRS complexes. The patient is diagnosed with atriventricular nodal re-entry tachycardia. Induction of AV block is attempted using both the carotid sinus massage and the valsava manoeuvre unsucessfully. The clinical team considers using either verapamil or adenosine as the next step in the managing this patient's arrhythmia.

Search Strategy

MedLine using the OVID interface-1966 to June Week 3 2005.
EMBASE using the OVID interface-1980 to 2005 Week 26
CINAHL using the OVID interface-1982 to June Week 3 2005
[(exp Supraventricular Tachycardia) OR (exp Tachycardia, Atrioventricular Nodal Reentry) OR (supraventricular tachycardia.mp) OR (narrow complex tachycardia OR narrow-complex tachycardia OR junctional tachycardia.mp.)] AND [(exp Verapamil/) OR (verapamil.mp.)] AND [(exp Adenosine) OR (adenosine.mp.) OR (adenocor.mp.)] limit to (humans and english language)

Search Outcome

79 papers were found of which 4 were clinically relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Garrat C. et al 1989 UK	20 patients with a history of documented, recurrent, sustained paroxysmal junctional tachycardia referred for electrophysiologic study. All drugs stopped >72 hours before admission, amiodarone stopped >3 months	non-randomized, unblinded crossover clinical trial	sucessful termination of arrhythmia	100% vs 95% (adenosine vs verapamil); p<0.05	treatments were not randomly allocated small numbers criteria for exclusion not explained statistical methods not explained possibility for selection bias
			presence of significant arrhythmias afterconversion	ocurred in 35% with verapamil vs 0% with adenosine; p<0.05
			unmasking of latent or intermittent preexcitation	0.5% revealed with verapamil vs 100% with adenosine; p<0.05
Rankin AC et al february 1990 UK	43 patients who presented with spontaneous episodes of paroxysmal tachycardia treated with either adenosine or verapamil	retrospective review	restoring sinus rhythm (verapamil vs adenosine)	81% vs 96% (p<0.05)	treatments not randomly allocated outcomes not assessed blind sample size not justified patient bias
Di Marco JP et al 1990 USA	359 with a tachycardia electrocardiographically consistent with paroxysmal ventricular tachycardia	two prospective,multicentre, double-blind, randomized, placebo controlled, single crossover clinical trials	cumulative efficacy of adenosine vs placebo in conversion to sinus rhythm	91.4% vs 16.1% (p<0.001)	patient bias exclusion of patients to avoid verapamil side-effects randomisation not explained no confidence interval given
			cumulative efficacy of adenosine vs verapamil in conversion to sinus rhythm	93.4% vs 90.6% (p=NS)
Hood MA et al 1992 New Zealand	25 patients with narrow complex tachycardia presenting to the emergency room and those whom tachycardia was induced in the electrophysiologic laboratory	Randomized, unblinded, double cross-over trial	termination of PSVT by adenosine vs verapamil	100% vs 73%, p=0.07	outcomes not assessed blind size of sample not justified no placebo control patient numbers small
			conversion arrhythmias post administration of adenosine vs verapamil	57% vs 50%, p=NS

Comment(s)

Adenosine in doses up to 20 mg is a rapid, safe and effective means in terminating paroxysmal supraventricular tachycardias in patients whose arrhythmia did not responde to vagal manoeuvres. Side-effects are common but generally well tolerated and transient. It should be the treatment of choice in those patients in whom verapamil is known to have adverse effects, including those with hypotension, cardiac failure or who are taking beta-blocker drugs and in those in whom the diagnosis is in doubt (e.g. if the QRS complexes are broad). Verapamil is reserved in those in which adenosine produces severe symptoms, in those where arrhythmias recur or for patients with poor venous acess, patients with bronchospasm or those taking agents that interfere with adenosine action or metabolism like methylxanthines and dypiridamole.

Clinical Bottom Line

Adenosine is the initial drug in the acute management of paroxysmal supraventricular tachycardia after the failure of vagal manoeuvres.

References

1. Garrat C. Linker N. Griffith M Ward D. Camm J. Comparison of Adenosine and Verapamil for termination of paroxysmal junctional Tachycardia The American Journal of Cardiology 1989;64:1310-1316
2. Rankin AC. Rae AP Oldroyd KG Cobbe SM Verapamil or Adenosine for the Immediate Treatment of Supraventricular Tachycardia Quarterly Journal of Medicine February 1990; no 274,203-208
3. Di Marco JP, Miles W, Akhtar M, Milstein S, Sharma A, Platia E, McGovern B, Sheinman M, Govier W Adenosine for Paroxysmal Supraventricular Tachycardia: Dose ranging and Comparison with Verapamil Annals of Internal Medicine 1990; 113:104-110
4. Hood MA, Smith WM Adenosine versus Verapamil in the treatment of supraventricular tachycardia: a randomized control trial American Heart Journal 1992; 123: 1543