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The electrocardiographic diagnosis of acute myocardial infarction in patients with ventricular paced rhythms
F H Kozlowski1, W J Brady, T P Aufderheide
1Department of Internal Medicine, University of Virginia School of Medicine, Charlottesville, VA, USA. wb4z@avery.med.virginia.edu
Insights
Interpreting electrocardiograms (ECGs) for ischemic heart disease is challenging with ventricular paced rhythms (VPRs). Recognizing expected ST-segment and T-wave discordance in VPRs is key for accurate diagnosis.
Area of Science:
- Cardiology
- Medical Diagnostics
Background:
- Electrocardiogram (ECG) interpretation for ischemic heart disease is complicated by ventricular paced rhythms (VPRs).
- Ventricular pacing alters intraventricular conduction, affecting ST-segment and T-wave morphology.
Observation:
- The typical ECG pattern in VPRs involves QRS-complex, ST-segment, and T-wave discordance.
- Physicians can utilize several strategies for ECG interpretation in patients with permanent pacemakers.
Findings:
- Awareness of anticipated ST-segment/T-wave changes in VPRs is the most crucial diagnostic aid.
- This awareness aids in recognizing acute ischemic morphologies without additional tests or records.
- Two cases illustrate successful acute myocardial infarction diagnosis using ECG analysis in VPRs.
Implications:
- Accurate ECG interpretation in VPRs is vital for timely diagnosis of acute myocardial infarction.
- Understanding VPR-specific ECG changes improves diagnostic confidence and patient care.
- This knowledge empowers clinicians to identify critical cardiac events even with pacing interference.
Abstract:
Use of the ECG for diagnosis of ischemic heart disease is more difficult in the setting of ventricular paced rhythms (VPRs). ST-segment/T-wave configuration are changed by the altered intraventricular conduction associated with ventricular pacing. The anticipated, or expected, morphology in patients with VPRs is one of QRS-complex-ST-segment to T-wave discordance. Several strategies are available to the physician to assist in the correct interpretation of the 12-lead ECG in patients with permanent ventricular pacemakers, including: a knowledge of the anticipated ST-segment-T-wave changes of VPRs and consequently the ability to recognize acute, ischemic morphologies; the performance of serial ECGs or ST-segment trend monitoring demonstrating dynamic changes encountered in acutely ischemic patients; a comparison with previous ECGs; and, if appropriate, an analysis of the native, underlying rhythm. The first strategy, an awareness of the anticipated ST-segment morphologies of VPRs, is the most important and not dependent on additional diagnostic testing, past medical records, or additional expertise in pacemaker function. Two cases are reported in which an analysis of the ECG in the setting of VPR assisted the treating physicians in establishing the correct diagnosis of acute myocardial infarction.