Comparison of prehospital monomorphic and polymorphic ventricular tachycardia: prevalence, response to therapy, and outcome.

OBJECTIVE

Monomorphic ventricular tachycardia (MVT) is the most common form of prehospital ventricular tachycardia (VT). Recent literature suggests that polymorphic ventricular tachycardia (PVT) is more common during cardiopulmonary arrest than previously thought but responds poorly to advanced cardiac life support (ACLS) therapy. We undertook this study to determine the prevalence, response to therapy, and outcome of both MVT and PVT in the prehospital sudden cardiac death victim.

DESIGN

Retrospective prehospital chart review from 1987 to 1991.

SETTING

Municipal, fire department-based, multitiered emergency medical system serving a population of approximately one million.

PARTICIPANTS

Adult patients older than 18 years experiencing prehospital, nontraumatic cardiopulmonary arrest with VT occurring at any time during the resuscitation. VT was defined as PVT if the QRS-complex configuration was not stable when viewed in a single electrocardiographic lead (ie, episodic changing of the QRS-complex electrical axis, amplitude, or both or the presence of more than two QRS-complex morphologies). Outcome was defined in terms of both the presence or absence of spontaneous circulation at the end of the prehospital phase of care and ultimate outcome (survival to hospital discharge or death). Four hundred seventy-six patients met entry criteria; 37 patients were excluded because of incomplete medical records, and 439 patients were used for data analysis.

INTERVENTIONS

ACLS therapy based on the 1987 American Heart Association guidelines.

RESULTS

MVT occurred in 323 patients (73.6%), with 119 (36.8%) showing return of spontaneous circulation (ROSC) in the prehospital setting; 35 MVT patients (10.8%) survived to hospital discharge. PVT occurred in 116 patients (26.4%), with 48 (41.4%) showing ROSC in the prehospital setting; 15 PVT patients (12.9%) survived to hospital discharge. The use of ACLS therapy (defibrillation, endotracheal intubation, medication usage) between the two rhythm groups was not statistically different. The P values for ROSC, ultimate outcome, and use of ACLS therapy were all not significant.

CONCLUSION

We conclude that PVT is a common rhythm occurring in prehospital cardiopulmonary arrest that responds as well as MVT to ACLS therapy. Until prospective data are available, standard ACLS therapy should be used in all forms of prehospital VT occurring during cardiopulmonary arrest.