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Electrocardiogram of the failing heart
1Department of Internal Medicine II, Cardiology, University Hospital of Ulm, Germany. vinzenz.hombach@medizin.uni-ulm.de
Insights
Electrocardiogram (ECG) changes, including arrhythmias and heart rate variability, offer prognostic insights in heart failure. Further research is needed to clarify the predictive value of repolarization abnormalities for sudden cardiac death.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- The failing heart exhibits various electrocardiogram (ECG) changes, both specific and unspecific.
- These changes include conduction abnormalities, arrhythmias, and repolarization abnormalities.
- The prognostic significance of these ECG findings in congestive heart failure (CHF) requires further elucidation.
Purpose of the Study:
- To review the prognostic significance of various ECG parameters in patients with congestive heart failure.
- To explore the utility of conventional ECG, Holter monitoring, signal-averaged ECG, and repolarization studies in predicting adverse outcomes.
Main Methods:
- Review of conventional 12-lead ECG for specific and unspecific changes.
- Analysis of 24-hour Holter ECG for atrial and ventricular tachy-arrhythmias.
- Evaluation of signal-averaged ECG for P-wave duration, QRS duration, and ventricular late potentials.
- Assessment of cardiac repolarization abnormalities through QT dispersion, QT/QTc fluctuation, and T-wave alternans studies.
Main Results:
- Specific ECG changes like Q-waves and ST-elevations indicate myocardial infarction and aneurysm.
- Unspecific changes include bundle branch blocks and ST-T alterations.
- Heart rate variability is a significant prognostic marker in CHF.
- Abnormal signal-averaged ECG parameters may predict atrial fibrillation and ventricular arrhythmias.
- The prognostic value of repolarization abnormalities for sudden cardiac death in CHF remains uncertain.
Conclusions:
- ECG parameters provide valuable prognostic information in congestive heart failure.
- Holter monitoring and signal-averaged ECG can identify patients at risk for arrhythmias and sudden death.
- The prognostic role of cardiac repolarization abnormalities in CHF warrants further investigation.
Abstract:
In the failing heart general specific (e.g., Q-waves after acute myocardial infarction, persistent ST-elevations in post-myocardial infarction left ventricular aneurysm) and unspecific ECG changes (e.g., left bundle branch block, right bundle branch block, ST-T-alterations due to digitalis glycosides or antiarrhythmic drugs) may be seen in the conventional 12-lead ECG. In addition, atrial and ventricular tachy-arrhythmias may be detected and quantified by 24-hour-Holter ECG recordings, that may be relevant for a worse prognosis of patients with congestive heart failure. Heart rate variability as the most relevant derived ECG parameter of sympathetic tone fluctuations may be of important prognostic significance in congestive heart failure patients. An abnormal signal averaged P-wave duration may predict the incidence of atrial fibrillation, as may apply to QRS-prolongation and/or ventricular late potentials in the signal averaged ECG for the incidence of serious life-threatening ventricular tachy-arrhythmias or death from pump failure. Last but not least, cardiac repolarization abnormalities may be detected by QT dispersion-, QT-/QTc-fluctuation- or T-wave alternans studies, but the true prognostic significance of these parameters for predicting sudden cardiac death or death from pump failure in patients with congestive heart failure remains unclear.