Silent myocardial ischemia in patients with coronary artery disease. Possible links with diastolic left ventricular dysfunction.
Silent myocardial ischemia is now recognized as a common manifestation within the clinical spectrum of coronary artery disease and has important physiological, hemodynamic, and prognostic implications. Asymptomatic ST segment shifts during ambulatory 24-hour electrocardiographic monitoring and exercise treadmill testing are far more frequent than symptomatic ST shifts and are associated with abnormal myocardial perfusion as assessed by radionuclide scintigraphy. Seemingly healthy asymptomatic patients and patients with stable coronary artery disease, unstable angina, or recent myocardial infarction are all at higher risk of subsequent cardiovascular morbidity if there is evidence of silent ischemia. Hemodynamic studies have clearly documented the adverse effects of ischemia on left ventricular systolic function. Furthermore, diastolic relaxation and filling appear to be altered by both symptomatic and asymptomatic ischemia during atrial pacing and dynamic exercise independent of changes in systolic function. The majority of patients with coronary artery disease have abnormal diastolic parameters at rest, regardless of anginal symptoms, which are partially reversible after coronary revascularization procedures such as angioplasty and bypass surgery. Regional diastolic dysfunction from scar or ischemia can lead to asynchronous myocardial relaxation and thus affect global diastolic function, depending on the extent and severity of the regional abnormalities. Diastolic function seems more susceptible to ischemia than systolic function and can take longer to recover.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Internal Medicine, Baylor College of Medicine, Houston, Texas.
J J
JJ
Mahmarian
C M
CM
Pratt
D003327:Coronary Disease / Q000453:epidemiology* / Q000503:physiopathology; D015716:Electrocardiography, Ambulatory; D006801:Humans; D008137:Longitudinal Studies; D009200:Myocardial Contraction / Q000502:physiology*; D011379:Prognosis; D011446:Prospective Studies