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Detecting abnormalities in left ventricular function during exercise before angina and ST-segment depression
Insights
In patients with coronary artery disease, left ventricular dysfunction often occurs before chest pain or ECG changes indicating myocardial ischemia. This study used radionuclide angiocardiography to reveal these early functional abnormalities during exercise.
Area of Science:
- Cardiology
- Physiology
Background:
- Coronary artery disease (CAD) can lead to myocardial ischemia, manifesting as angina and electrocardiographic (ECG) changes.
- The precise timing of left ventricular (LV) functional abnormalities relative to these clinical and ECG signs is not fully understood.
Purpose of the Study:
- To investigate whether abnormalities in LV function precede the onset of angina pectoris and ECG evidence of myocardial ischemia in patients with CAD.
- To assess changes in LV ejection fraction, volumes, cardiac output, and wall motion during exercise in patients with and without CAD.
Main Methods:
- Utilized radionuclide angiocardiography (RNA) to evaluate LV function at rest and during two levels of upright bicycle exercise.
- Studied 25 patients with CAD and 10 normal subjects.
- In CAD patients, RNA was performed before and after the onset of ST-segment depression during exercise.
Main Results:
- Normal subjects exhibited increased ejection fraction and decreased end-systolic volume with exercise.
- In CAD patients, exercise induced LV functional abnormalities (reduced ejection fraction, increased volumes, wall motion deficits) in a significant number of patients *before* chest pain or ST-segment depression.
- All CAD patients showed hemodynamic and wall motion abnormalities when ST-segment depression was present.
Conclusions:
- LV functional abnormalities frequently develop during exercise in patients with CAD *prior* to the manifestation of angina pectoris or ECG evidence of myocardial ischemia.
- Radionuclide angiocardiography is a valuable tool for detecting these subclinical LV functional changes in CAD.
Abstract:
To determine if abnormalities in left ventricular function precede angina pectoris and electrocardiographic evidence of myocardial ischemia, we used radionuclide angiocardiography to measure left ventricular ejection fraction, volumes, cardiac output and wall motion in 10 normal subjects and 25 patients with coronary artery disease at rest and during two levels of upright bicylce exercise. In the patients with coronary artery disease, the first radionuclide study during exercise was performed before and the second after the onset of ST-segment depression. In all normal subjects, the ejection fraction increased more than 5%, the end-diastolic volume increased less than 25% and the end-systolic volume decreased from rest to both levels of exercise. Wall motion was normal at rest and increased with exercise. No patient with coronary artery disease had chest pain or ST-segment depression during the first level of exercise. The ejection fraction either decreased or increased less than 5% in 18 patients, the end-diastolic volume increased more than 25% in nine, the end-systolic volume increased in 19 and a segmental contraction abnormality developed in 14. Hemodynamic and wall motion abnormalities occurred in all patients during the second level of exercise when ST-segment depression was present. During exercise in patients with coronary artery disease, abnormalities in left ventricular function frequently develop before angina pectoris and electrocardiographic evidence of myocardial ischemia.