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[Risk stratification after myocardial infarct]
V Hombach1, H H Osterhues, M Höher
1Abteilung Innere Medizin II, Universitäts- und Poliklinik Ulm.
Insights
Sudden cardiac death risk stratification after myocardial infarction is crucial. Combining non-invasive tests with programmed ventricular stimulation improves accuracy in identifying high-risk patients for sudden cardiac death.
Area of Science:
- Cardiology
- Clinical Electrophysiology
Background:
- Sudden cardiac death (SCD) remains a significant concern in industrialized nations, often linked to coronary artery disease.
- Patients post-myocardial infarction (MI) face elevated risks of arrhythmogenic death within two years, necessitating robust risk stratification.
Purpose of the Study:
- To evaluate the efficacy of various non-invasive and invasive techniques for risk stratification in post-MI patients.
- To determine optimal strategies for identifying individuals at high risk of sudden cardiac death.
Main Methods:
- Review of non-invasive methods: clinical profile, LV ejection fraction, ECG stress tests, ambulatory ECG, T wave alternans, heart rate variability, baroreflex sensitivity.
- Inclusion of invasive programmed ventricular stimulation (PVS) for arrhythmogenic substrate detection.
- Analysis of prognostic power and limitations of individual and combined testing strategies.
Main Results:
- Non-invasive tests show high negative predictive value but limited positive predictive value for SCD risk.
- Combining multiple non-invasive tests improves positive predictive value but reduces sensitivity.
- Programmed ventricular stimulation effectively identifies high-risk patients with arrhythmogenic substrates.
Conclusions:
- A combined approach using non-invasive tests to exclude low-risk patients and PVS to identify high-risk patients is a reasonable strategy.
- This integrated method enhances the accuracy of risk stratification post-MI, guiding therapeutic decisions.
Abstract:
In industrialized countries the rate of sudden cardiac death remains unchanged. The most frequently encountered structural heart disease in these patients is coronary artery disease. Despite the era of thrombolytic therapy of acute myocardial infarction patients carry an increased risk of sudden cardiac arrhythmogenic death within a time period of one to two years following the acute event. Therefore, risk stratification post-MI before patient discharge is furthermore mandatory. The spectrum of non-invasive techniques for risk stratification includes the clinical risk profile, measurement of left ventricular global function (LV ejection fraction), the resting ECG (QT dispersion), an ECG stress test (detection and severity of myocardial ischemia), ambulatory ECG monitoring (number and type of ventricular arrhythmias), surface high resolution ECG (detection of ventricular late potentials), measurement of T wave alternans (TWA, alternans ratio), and measurements of the activity and balance of the autonomous nervous system (heart rate variability, baroreflex sensitivity = BRS). Programmed ventricular stimulation (PVS) serves as an invasive risk stratification technique (detection of an arrhythmogenic substrate). The prognostic power of the non-invasive techniques is limited; in general, the prognostic value of a negative test is reasonably high (90 to 100% depending on the test used), whereas the prognostic value of a positive test is rather low (4 to 42% depending on the test used). Combining several non-invasive tests may significantly improve the positive predictive value above 50%, but this goes along with a significant decreases of sensitivity below 50%. Therefore, a combination of several non-invasive tests (detection and exclusion of a large number of low-risk individuals) with the invasive method of PVS (detection of an arrhythmogenic substrate, i.e. a high-risk patient) seems reasonable, as has been convincingly shown by several smaller prognostic studies.