Patients with prolonged ischemic chest pain and presumed-new left bundle branch block have heterogeneous outcomes depending on the presence of ST-segment changes.
OBJECTIVE
The purpose of this research was to examine the prognostic value of ST-segment changes (concordant ST-segment elevation and/or precordial V1 to V3 ST-segment depression) during presumed-new left bundle branch block (LBBB) in patients receiving fibrinolytic therapy.


BACKGROUND
These patients are often considered high-risk, but their outcome is not well-defined.


METHODS
The Hirulog and Early Reperfusion or Occlusion (HERO)-2 trial compared bivalirudin with heparin in patients receiving streptokinase for ST-segment elevation or presumed-new LBBB. Each patient with LBBB was matched with a control (with normal intraventricular conduction) for age, gender, pulse rate, systolic blood pressure, Killip class, and region.


RESULTS
A total of 300 patients had LBBB (92 with and 208 without ST-segment changes) and 15,340 had normal conduction. Acute myocardial infarction (AMI) occurred in 80.7% of LBBB patients and 88.7% of controls (p = 0.006). ST-segment changes were specific (96.6%) but not sensitive (37.8%) for enzymatic diagnosis of AMI. Mortality at 30 days was similar in LBBB patients with ST-segment changes (21.7%) and controls (25.0%, p = 0.563), but lower in LBBB patients without ST-segment changes than in controls (13.5% vs. 21.6%, p = 0.022). In the whole HERO-2 cohort, the LBBB patients with ST-segment changes had higher mortality than patients with normal conduction (odds ratio [OR] 1.37, 95% confidence interval [CI] 0.78 to 2.42). The LBBB patients without ST-segment changes had lower mortality than patients with normal conduction (OR 0.52, 95% CI 0.33 to 0.80).


CONCLUSIONS
ST-segment changes during LBBB are specific for the diagnosis of AMI and predict 30-day mortality; LBBB patients without ST-segment changes have lower adjusted 30-day mortality than those with normal conduction. Trials are required to determine the best treatment for high-risk and low-risk patients with LBBB.
Cardiovascular Research Unit, Green Lane Hospital, Auckland, New Zealand.
Cheuk-Kit
CK
Wong
John K
JK
French
Philip E G
PE
Aylward
Ralph A H
RA
Stewart
Wanzhen
W
Gao
Paul W
PW
Armstrong
Frans J J
FJ
Van De Werf
R John
RJ
Simes
O Christopher
OC
Raffel
Christopher B
CB
Granger
Robert M
RM
Califf
Harvey D
HD
White
D000368:Aged; D000787:Angina Pectoris / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D000925:Anticoagulants / Q000627:therapeutic use; D002037:Bundle-Branch Block / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D005343:Fibrinolytic Agents / Q000627:therapeutic use; D006493:Heparin / Q000627:therapeutic use; D006629:Hirudins; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality; D010446:Peptide Fragments / Q000627:therapeutic use; D011237:Predictive Value of Tests; D011994:Recombinant Proteins / Q000627:therapeutic use; D013300:Streptokinase / Q000627:therapeutic use; D015996:Survival Rate; D013997:Time Factors
D000925:Anticoagulants; D005343:Fibrinolytic Agents; D006629:Hirudins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D006493:Heparin; D013300:Streptokinase; C074619:bivalirudin