Diagnosis and outcome in a prehospital cohort of patients with bundle branch block and suspected acute myocardial infarction.
BACKGROUND
Immediate revascularization is beneficial in patients with presumed new-onset bundle branch block myocardial infarction (BBBMI). In the prehospital setting, it is a challenge to diagnose new-onset BBBMI and triage accordingly.


METHODS
ECG, final diagnosis, and mortality were assessed in a prehospital cohort of 4905 consecutive patients with suspected acute myocardial infarction (AMI). Bundle branch block (BBB) was defined as QRS duration ≥120 ms caused by delayed intraventricular conduction. Mortality and angiography data were obtained from the Central Office of Civil Registration and the Western Denmark Heart Registry. Definite diagnosis of AMI and the onset of BBB were determined by expert consensus. Patients were divided into four groups: with or without AMI and with or without BBB. Mortality was evaluated by Kaplan-Meier plots and compared using log-rank statistics.


RESULTS
AMI was diagnosed in 954 patients, of whom 118 had BBB. In 3951 patients without AMI, 436 had BBB. Patients with BBBMI were less often revascularized than patients with AMI without BBB (24 vs. 54%, p<0.001). BBBMI was categorized as new onset in 43 patients of whom two were triaged for acute angioplasty. One-year mortality was 47.2, 17.5, 20.8, and 8.6% (log-rank <0.001) in patients with BBBMI, patients with AMI without BBB, patients with BBB without AMI, and patients without AMI or BBB, respectively.


CONCLUSIONS
Patients with BBBMI have a high mortality. Less than 25% undergo revascularization and only very few patients with new-onset BBBMI are transferred for urgent revascularization. Focus on improving triage and prehospital identification of high-risk patients with BBB and chest pain could improve outcome.
Aarhus University Hospital, Department of Cardiology, Aarhus, Denmark.
Jacob Thorsted
JT
Sørensen
Carsten
C
Stengaard
Christina Ankjær
CA
Sørensen
Kristian
K
Thygesen
Hans Erik
HE
Bøtker
Leif
L
Thuesen
Christian Juhl
CJ
Terkelsen
D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D003718:Denmark; D004562:Electrocardiography / Q000379:methods / Q000401:mortality; D004632:Emergency Medical Services / Q000379:methods; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000401:mortality; D011379:Prognosis; D017216:Telemedicine / Q000379:methods
Acute myocardial infarction; bundle branch block; prehospital diagnosis; primary percutaneous coronary intervention