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His bundle electrogram in patients with acute myocardial infarction complicated by atrioventricular or
Insights
His bundle electrogram studies in acute myocardial infarction patients revealed that proximal atrioventricular block often resolves, with low mortality and no need for permanent pacing. Bundle-branch block patients showed varied outcomes, with higher mortality in those progressing to severe atrioventricular block.
Area of Science:
- Cardiology
- Electrophysiology
- Internal Medicine
Background:
- Acute myocardial infarction (AMI) can cause conduction abnormalities.
- Atrioventricular (AV) and bundle-branch block (BBB) complicate AMI management.
- His bundle electrogram (HBE) aids in localizing block origins.
Purpose of the Study:
- To investigate the characteristics and outcomes of conduction abnormalities in AMI patients.
- To determine the prognostic significance of block location and severity.
- To evaluate the need for permanent pacing in specific patient groups.
Main Methods:
- Seventy-two AMI patients with AV or BBB underwent HBE.
- Repeat HBE was performed in 19 patients before discharge.
- Block location (proximal vs. distal) and HV interval were assessed.
Main Results:
- 30/32 patients with AV block and narrow QRS had proximal block; 3/11 showed residual dysfunction.
- Low hospital and follow-up mortality in proximal AV block, no pacing benefit.
- BBB patients with normal PR: 9/18 had prolonged HV interval, no mortality difference.
- 22 BBB patients developed AV block; 5 proximal, 14 distal, 3 both.
- Higher mortality in BBB patients progressing to 2nd/3rd-degree AV block vs. 1st-degree.
Conclusions:
- Proximal AV block in AMI often resolves, with favorable outcomes and no indication for permanent pacing.
- HV interval prolongation in BBB without PR changes did not impact mortality.
- Progression to higher-degree AV block in BBB patients signifies increased mortality risk.
Abstract:
Seventy-two patients with acute myocardial infarction complicated by atrioventricular or bundle-branch block or a combination of both had His bundle electrogram studies performed during their stay in the coronary care unit. In 19 of the 72 patients a repeat His bundle electrogram was performed before discharge from hospital. These studies demonstrated that 30 of the 32 patients with atrioventricular block and narrow QRS complexes had a block above the origin othe His spike (proximal block). Eleven patients in this group had repeat His bundle electrograms performed before discharge and in 3 patients there was evidence of residual atrioventricular nodal dysfunction. Both the hospital and follow-up mortality in this group was low and there was no evidence to suggest that permanent pacing would benefit these patients. Of the 18 patients with bundle-branch block and a normal PR interval, 9 had prolongation of the HV interval, but there was no difference in mortality in patients with normal or prolonged HV intervals. Twenty-two patients with bundle-branch block also developed atrioventricular block. In 5 of these patients the site of the AV block was proximal and in 14 it was distal, while 3 patients had both proximal and distal block. The hospital mortality in those patients who progressed to second- or third-degree atrioventricular block was considerably higher than in those patients who remained in first-degree atrioventricular block.