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[Detection and prognostic value of silent myocardial ischemia]
Insights
Silent myocardial ischemia (SMI) significantly increases cardiac event risk, even without symptoms. Detecting SMI is crucial for managing coronary artery disease and improving patient outcomes.
Area of Science:
- Cardiology
- Ischemic Heart Disease
- Diagnostic Imaging
Context:
- Silent myocardial ischemia (SMI) is a prevalent manifestation of coronary artery disease (CAD).
- A significant majority (75%) of ischemic episodes occur asymptomatically.
- SMI carries similar adverse effects on myocardial perfusion and ventricular function as symptomatic ischemia.
Purpose:
- To review the detection methods for SMI, including electrocardiographic monitoring and stress testing with imaging.
- To evaluate the prognostic significance of SMI in various CAD patient populations.
- To highlight the increased risk of cardiac events and mortality associated with SMI.
Summary:
- SMI is detected using continuous electrocardiographic monitoring, exercise stress tests (with or without imaging), and pharmacological stress tests.
- Prevalence of SMI is high in patients with angina (50%) and post-myocardial infarction (25%).
- SMI is linked to a 2-3 times greater risk of cardiac events in asymptomatic CAD patients, and even higher risks in angina and post-MI patients.
Impact:
- SMI detection and management are critical for risk stratification in coronary artery disease.
- Identifying asymptomatic ischemia can lead to timely interventions, potentially reducing adverse cardiac events.
- Further research is needed to confirm prognostic observations across all patient reports.
Abstract:
Silent myocardial ischaemia (SMI) is a common manifestation of coronary artery disease. Continuous electrocardiographic recordings have shown that 75% of ischemic episodes are asymptomatic. In addition, SMI has the same consequences as symptomatic ischaemia on myocardial perfusion and ventricular function. There are many means of detecting SMI, continuous electrocardiographic monitoring, exercise stress testing with or without methods of analysis of myocardial perfusion or wall motion using radioactive tracers or echocardiography. The latter techniques seem to improve the sensitivity of exercise stress testing. More recently, pharmacological stress testing coupled with myocardial scintigraphy or echocardiography has been introduced. In coronary patients, the prevalence of SMI on Holter monitoring is about 50% in angina and 25% after myocardial infarction. The prognostic value of SMI has been the object of much research. In asymptomatic patients with documented coronary artery disease, SMI is associated with a relative risk of a cardiac event 2 to 3 times greater than that of subjects without ischaemia. In angina pectoris, the relative risk of future cardiac events is 5.3 times greater, and that of death is 2.3 times greater. These results reported with the Holter method have been confirmed by those of exercise stress testing with and without coupled imaging techniques. In unstable angina, the results are the same: the relative risk of cardiac events in patients with SMI on Holter monitoring is increased by a factor of 4.5, and that of death by a factor of 4. This increased risk is also observed after myocardial infarction whether SMI is recorded by Holter monitoring or exercise stress testing. However, these observations are not confirmed in all reports.(ABSTRACT TRUNCATED AT 250 WORDS)