Evaluation and management of bradyarrhythmias in the emergency department

A randomized controlled feasibility trial comparing safety and effectiveness of prehospital pacing versus conventional treatment: 'PrePACE'

OBJECTIVE

To evaluate the feasibility of a prehospital randomized controlled trial comparing transcutaneous pacing (TCP) with dopamine for unstable bradycardia.

METHODS

Unstable bradycardic patients who failed to respond to a fluid bolus and up to 3mg atropine were enrolled. The intervention was dopamine or TCP with crossover to dopamine if TCP failed. The primary outcome was survival to discharge or 30 days. Randomization compliance, safety, follow-up rates, primary outcome, and sample size requirements were assessed.

RESULTS

Of 383 patients with unstable bradycardia, 151 (39%) failed to respond to atropine or fluid and were eligible for enrollment and 82 (55%) were correctly enrolled. Fifty-five (36%) of eligible patients could not be enrolled for practical reasons; 3 had advance directives, 32 met inclusion criteria on arrival at hospital and in 20 cases, paramedics chose not to enroll based on the circumstances of the case. The remaining 13 were missed cases; 8 were missing randomization envelopes and in 5, the paramedic forgot. Randomization compliance was 95% (78/82). Forty-two (51%) patients were randomized to TCP and seven of these crossed over to dopamine. Two cases were randomized but did not receive the intervention; either due to lack of time or loss of IV access. Three adverse events occurred in each group. Survival to discharge or 30 days in hospital was 70% (28/40) and 69% (29/42) in the dopamine and TCP groups, respectively with 100% follow up. To detect a 10% relative difference in 30 days survival between treatment arms, a sample size of 690 per group would be required.

CONCLUSIONS

It is feasible to conduct a prehospital randomized controlled trial of TCP for unstable bradycardia and a definitive trial would require a multi-centre study.

Compromising bradycardia: management in the emergency department

AIM OF THE STUDY

Bradycardia may represent a serious emergency. The need for temporary and permanent pacing is unknown.

METHODS

We analysed a registry for the incidence, symptoms, presenting rhythm, underlying mechanism, management and outcome of patients presenting with compromising bradycardia to the emergency department of a university hospital retrospectively during a 10-year period.

RESULTS

We identified 277 patients, 173 male (62%), median age 68 (IQR 58-78), median ventricular rate 33 min(-1) (IQR 30-40). The leading symptoms were syncope [94 (33%)], dizziness [61 (22%)], collapse [46 (17%)], angina [46 (17%)] and dyspnoea/heart failure [30 (11%)]. The initial ECG showed high grade AV block [134 (48%)], sinus bradycardia/AV block [46 (17%)], sinuatrial arrest [42 (15%)], bradycardic atrial fibrillation [39 (14%)] and pacemaker-failure [16 (6%)]. The underlying mechanisms were primary disturbance of cardiac automaticity and/or conduction [135 (49%)], adverse drug effect [58 (21%)], acute myocardial infarction [40 (14%)], pacemaker failure [16 (6%)], intoxication [16 (6%)] and electrolyte disorder [12 patients (4%)]. In 107 (39%) patients bed rest resolved the symptoms. Intravenous drugs to increase ventricular rate were given to 170 (61%) patients, 54 (20%) required additional temporary transvenous/transcutaneous pacing. Two severely intoxicated patients could be stabilised only by cardiopulmonary bypass. A permanent pacemaker was implanted in 137 patients (50%). Mortality was 5% at 30 days.

CONCLUSION

In our cohort, about 20% of the patients presenting with compromising bradycardia required temporary emergency pacing for initial stabilisation, in 50% permanent pacing had to be established.

Temporary Pacemakers in Critically Ill Patients

Temporary cardiac pacing provides electrical stimulation to a heart compromised by disturbances in the conduction system causing hemodynamic instability. The use of a temporary pacemaker to treat a bradydysrhythmia or in some cases, a tachydysryhthmia, is undertaken when the condition is temporary and a permanent pacemaker is not necessary or available in a timely fashion. Temporary cardiac pacing is utilized in acute situations and for critically ill patient populations requiring immediate therapy. This article discusses the various indications and contraindications to temporary cardiac pacing therapy, reviews the different modalities of temporary pacemakers, and outlines critical considerations in the management of patients being treated with a temporary pacemaker.

THERAPEUTIC PROCEDURES IN THE EMERGENCY DEPARTMENT PATIENT WITH ACUTE MYOCARDIAL INFARCTION

Life-threatening cardiac arrhythmias and other peri-infarct complications are often unexpected and commonly present with little warning. The therapeutic procedures reviewed often require immediate implementation and should be second nature to any physician involved in the management of patients with an AMI.