Treatment of out-of-hospital supraventricular tachycardia: adenosine vs verapamil.
OBJECTIVE
To compare the use of adenosine and the use of verapamil as out-of-hospital therapy for supraventricular tachycardia (SVT).


METHODS
A period of prospective adenosine use (March 1993 to February 1994) was compared with a historical control period of verapamil use (March 1990 to February 1991) for SVT. Data were obtained for SVT patients treated in a metropolitan, fire-department-based paramedic system serving a population of approximately 1 million persons. Standard drug protocols were used and patient outcomes (i.e., conversion rates, complications, and recurrences) were monitored.


RESULTS
During the adenosine treatment period, 105 patients had SVT; 87 (83%) received adenosine, of whom 60 (69%) converted to a sinus rhythm (SR). Vagal maneuvers (VM) resulted in restoration of SR in 8 patients (7.6%). Some patients received adenosine for non-SVT rhythms: 7 sinus tachycardia, 18 atrial fibrilation, 7 wide-complex tachycardia (WCT), and 2 ventricular tachycardia; no non-SVT rhythm converted to SR and none of these patients experienced an adverse effect. Twenty-five patients were hemodynamically unstable (systolic blood pressure < 90 mm Hg), with 20 receiving drug and 13 converting to SR; 8 patients required electrical cardioversion. Four patients experienced adverse effects related to adenosine (chest pain dyspnea, prolonged bradycardia, and ventricular tachycardia). In the verapamil period, 106 patients had SVT: 52 (49%) received verapamil (p < 0.001, compared with the adenosine period), of whom 43 (88%) converted to SR (p = 0.11). Two patients received verapamil for WCT; neither converted to SR and both experienced cardiovascular collapse. VM resulted in restoration of SR in 12 patients (11.0%) (p = 0.52). Sixteen patients were hemodynamically unstable, with 5 receiving drug (p = 0.005) and 5 converting to SR; 9 patients required electrical cardioversion (p = 0.48). Four patients experienced adverse effects related to verapamil (hypotension ventricular tachycardia, ventricular fibrillation). Recurrence of SVT was noted in 2 adenosine patients and 2 verapamil patients in the out-of-hospital setting and in 23 adenosine patients and 15 verapamil patients after ED arrival, necessitating additional therapy (p = 0.48 and 0.88, for recurrence rates and types of additional therapies, respectively). Hospital diagnoses, outcomes, and ED dispositions were similar for the 2 groups.


CONCLUSIONS
Adenosine and verapamil were equally successful in converting out-of-hospital SVT in patients with similar etiologies responsible for the SVT. Recurrence of SVT occurred at similar rates for the 2 medications. Rhythm misidentification remains a common issue in out-of-hospital cardiac care in this emergency medical services system.
Brady
W J
WJ
University of Virginia School of Medicine, Department of Emergency Medicine, Charlottesville, USA. wb4z@galen.med.virginia.edu
DeBehnke
D J
DJ
Wickman
L L
LL
Lindbeck
G
G
D000241:Adenosine / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D000368:Aged; D000488:Allied Health Personnel; D000553:Ambulatory Care; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004554:Electric Countershock; D015716:Electrocardiography, Ambulatory / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012008:Recurrence; D013617:Tachycardia, Supraventricular / Q000188:drug therapy*; D014700:Verapamil / Q000009:adverse effects / Q000627:therapeutic use*
D000889:Anti-Arrhythmia Agents; D014700:Verapamil; D000241:Adenosine