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Ischemic blocks during early phase of anterior myocardial infarction: correlation with ST-segment shift
S Sclarovsky1, A Sagie, B Strasberg
1Israel and Ione Massada Center for Heart Diseases, Beilinson Medical Center, Petah Tikva, Israel.
Insights
Acute myocardial infarction (AMI) with bundle-branch block (BBB) during ST-segment elevation has a higher incidence of right BBB and left anterior hemiblock. ST-segment depression during AMI with BBB is associated with left BBB and higher mortality.
Area of Science:
- Cardiology
- Electrocardiography
- Myocardial Infarction
Background:
- Anterior acute myocardial infarction (AMI) can present with various conduction abnormalities.
- Bundle-branch block (BBB) during the hyperacute ECG stage of AMI indicates significant cardiac events.
Purpose of the Study:
- To investigate the characteristics and outcomes of acute BBB in anterior AMI based on ST-segment changes.
- To differentiate BBB patterns and mortality associated with ST-segment elevation versus ST-segment depression in anterior AMI.
Main Methods:
- Retrospective analysis of 760 anterior AMI cases, identifying 55 with acute BBB, fascicular block, or high-degree AV block.
- Patients were categorized into Group A (ST-segment elevation) and Group B (ST-segment depression) based on initial ECG findings.
- Comparison of BBB types, transient block duration, AV block progression, and mortality rates between the two groups.
Main Results:
- Group A (ST elevation) showed higher rates of right BBB and left anterior hemiblock (p<0.005).
- Group B (ST depression) exhibited higher rates of left BBB and left posterior hemiblock (p<0.001).
- Mortality was high in both groups, significantly higher in Group B (74%) especially with LBBB (85%), with death often occurring on the day of BBB onset.
Conclusions:
- ST-segment behavior during anterior AMI with BBB predicts specific conduction abnormalities and clinical outcomes.
- Left BBB in the context of ST-segment depression during anterior AMI is associated with particularly poor prognosis and high mortality.
- Cardiogenic shock and/or electromechanical dissociation were the primary causes of death in these high-risk patients.
Abstract:
Of 760 consecutive cases with anterior acute myocardial infarction (AMI), 55 developed acute bundle-branch block (BBB), fascicular block, or high-degree atrioventricular block during the hyperacute ECG stage of AMI. According to the direction of the ST segment during the acute ischemic episode, patients were divided into two groups. Group A consisted of 32 patients who developed BBB during ST-segment elevation, positive T wave, and absent or minimal Q wave. Group B consisted of 23 patients who developed BBB during ST-segment depression and evolved into anterior AMI. Group A was characterized by a higher incidence of right BBB and left anterior hemiblock [91% vs. 26% and 56% vs. 13%, respectively (p less than 0.005)]. Group B was characterized by a higher incidence of left BBB and left posterior hemiblock [57% vs. 9% and 26% vs. 12%, respectively (p less than 0.001)]. The BBB was transient (disappearing within hours to one day) in 14 patients in Group A and in 5 patients in Group B. The incidence of progression to high-degree atrioventricular block was almost equal in the two groups (25% and 26%). The mortality rate was very high in both groups, but higher in Group B [74% vs. 59% (p = NS)] especially in those with LBBB (85%). Most patients died on the day of occurrence of BBB [Group A, 50% vs. Group B, 70% (p = NS)]. The causes of death in both groups were cardiogenic shock and/or electromechanical dissociation.(ABSTRACT TRUNCATED AT 250 WORDS)