Clinical variables associated with mortality in out-of-hospital patients with hemodynamically significant bradycardia.

OBJECTIVES: To estimate mortality rates and identify clinical variables associated with mortality among patients with hemodynamically unstable bradycardia in an urban emergency medical services (EMS) system.

METHODS: This was a retrospective study conducted in a large, urban EMS system. Adult non-cardiac arrest patients transported by advanced life support paramedics from March 1996 to February 1997 with a heart rate < or =60 beats/min and systolic blood pressure < or =90 mm Hg were included. Transcutaneous pacing was not available. Patients under age 18 years, pregnant, or presenting with vital signs absent were excluded from the study population. Multivariate analysis of the association of patient characteristics with 30-day mortality was conducted by using a Cox proportional hazards model.

RESULTS: Of the 247 patients studied, 133 (53.9%) received a fluid bolus, 37 (15.0%) were treated with atropine, and 17 (6.9%) received dopamine. Fifty-one (20.7%) died in the 19-month follow-up period (15.6 per 100 person-years); 10.5% died on the same day, 15.8% within 30 days, and 17.8% within one year. Variables associated with 30-day mortality included wide QRS complex (adjusted risk ratio [RR] 2.6 [95% confidence interval (95% CI) = 1.3 to 5.2]), use of heart rate-lowering calcium channel blockers (adjusted RR 2.1 [95% CI = 1.0 to 4.7]), and paramedic assessment of lack of patient improvement over the course of the call (adjusted RR 0.2 [95% CI = 0.1 to 0.6]).

CONCLUSIONS: Out-of-hospital patients with hemodynamically unstable bradycardia have a high mortality rate. A wide QRS complex and use of heart rate-lowering calcium channel blockers were associated with 30-day mortality.