Safety and efficacy of prehospital diltiazem

Very few studies exist on the use of diltiazem in the prehospital setting. Some practitioners believe this medication is prone to causing hypotension in this setting. Our goals were to determine whether the prehospital administration of diltiazem induced hypotension and to evaluate the efficacy of the drug.

Our two-tiered system is located in a suburban region of New Jersey with advanced life support (ALS) care provided by fly-car units. The ALS units do not transport patients, and all of them are hospital based. The ALS providers are employed by the hospital system. In New Jersey, all ALS care requires online medical control, including the administration of diltiazem. We retrospectively reviewed patient care records for those who were believed to be in rapid atrial fibrillation and were given diltiazem in a suburban emergeny medical services system over a 22-month period. We examined the differences between heart rate (HR) and blood pressure (BP) on the initial evaluation and on arrival to the emergency department (ED). A hypotensive response was defined as a final systolic BP (SBP) less than 90 mmHg and a drop in SBP of at least 10 mmHg. Diltiazem was considered effective if the ED HR was <100 beats per minute (bpm) or if it decreased ≥20%.

During the study period, 26,979 patients were transported. Of these patients, 2,488 had a documented rhythm of atrial fibrillation or atrial flutter. Of the 320 patients who received diltiazem, 42 patient encounters were excluded for incomplete data, yielding 278 patients for analysis. The average initial SBP was 139 mmHg and the average diastolic BP was 84 mmHg. The average diltiazem dosage was 16.7 mg. Two patients became hypotensive. The average initial HR was 154 bpm. On arrival to the ED, 33% of the patients had an HR < 100 bpm and 69% had a drop in HR ≥ 20%. The overall efficacy of prehospital diltiazem was 73%.

In the prehospital setting, diltiazem is associated with a very low rate of hypotension and appears to be effective in decreasing HR adequately. Prospective studies are needed to confirm these findings.