Continuous ST-segment monitoring of patients with left bundle branch block and suspicion of acute myocardial infarction.
OBJECTIVE
Patients with left bundle branch block comprise 5-9% of all patients with acute myocardial infarction. Limited data exist on the usefulness of continuous electrocardiographic monitoring of these patients. We have investigated prospectively the usefulness of real-time continuous vectorcardiography for monitoring patients with left bundle branch block and suspicion of acute myocardial infarction.


METHODS
A prospective multi-centre study.


METHODS
Fourteen Swedish coronary care units.


METHODS
Patients with left bundle branch block and suspicion of acute myocardial infarction with <6-h symptom duration were included.


METHODS
All patients were monitored with continuous vectorcardiography for 12-24 h.


RESULTS
One hundred thirty-three patients were included, 47% had acute myocardial infarction. Patients with acute myocardial infarction showed a marked relative decrease in ST-vector than those without (P = 0.0002). These changes were most marked in the first 90 min. When comparing patients with acute myocardial infarction receiving thrombolytic therapy or not, those treated with thrombolytics showed more marked decline in ST-vector magnitude (P < 0.0001) and in shorter time (P = 0.0017). All patients showed STC-vector magnitude changes that were more marked in patients with acute myocardial infarction (P = 0.0002). An STC-vector magnitude cut-off value of 65 microV after 90 min of monitoring gave 54% sensitivity and 72% specificity for diagnosis of acute myocardial infarction.


CONCLUSIONS
Real-time continuous vectorcardiographic monitoring of patients with left bundle branch and suspicion of acute myocardial infarction shows significant differences between those with and without acute myocardial infarction and could be of use for early diagnosis and subsequent monitoring.
Gunnarsson
G
G
Department of Medicine, Akureyri Regional Hospital, V/Eyrarlandsveg, 600 Akureyri, Iceland. gunnarg@fsa.is
Eriksson
P
P
Dellborg
M
M
D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000150:complications*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D009203:Myocardial Infarction / Q000150:complications* / Q000175:diagnosis*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014672:Vectorcardiography / Q000379:methods