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Usefulness of systolic time intervals in coronary artery disease
Insights
Systolic time intervals help assess left ventricular performance in coronary artery disease. Abnormalities indicate poorer prognosis and aid in evaluating therapy effectiveness, especially post-exercise.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Systolic time intervals (STI) offer insights into left ventricular (LV) function.
- Coronary artery disease (CAD) significantly impacts LV performance and adrenergic tone.
Purpose of the Study:
- To review the utility of STI in assessing LV performance in CAD.
- To explore the role of STI in diagnosing and monitoring CAD patients.
Main Methods:
- Analysis of preejection period (PEP) and left ventricular ejection time (LVET) in CAD patients.
- Correlation of STI with LV ejection fraction and adrenergic activity.
- Evaluation of post-exercise LVET in angina pectoris detection.
Main Results:
- Abnormal STI correlate with poorer prognosis, increased heart failure risk, and impaired LV function in CAD.
- STI are useful in chronic CAD, showing correlation with ejection fraction.
- Post-exercise LVET aids in identifying false-negative stress test results.
Conclusions:
- STI are valuable for assessing LV performance and adrenergic hyperactivity in CAD.
- STI can improve diagnostic accuracy of exercise stress tests.
- Repeated STI measurements are beneficial for monitoring therapeutic interventions in CAD.
Abstract:
This review summarizes current knowledge concerning the value of systolic time intervals in coronary artery disease. Although the usual pattern of prolongation of the preejection period (PEP) and shortening of the left ventricular ejection time (LVET) characteristic of left ventricular failure is seen in acute myocardial infarction, the systolic time intervals (as well as all other measures) are profoundly influenced by adrenergic hyperactivity characteristics of this disorder. Adrenergic stimulation normally shortens both the PEP and LVET indexes and decreases the PEP/LVET ratio. The degree of shortening of electromechanical systole (QS2) is directed related to the excessive adrenergic tone. Patients with the greatest systolic time interval abnormalities have a poorer prognosis, a greater incidence of congestive heart failure and more abnormalities of directly measured indexes of left ventricular performance. The systolic time intervals are useful for assessing left ventricular performance in chronic coronary artery disease as well. In chronic coronary artery disease the PEP/LVET ratio and angiographically determined left ventricular ejection fraction are closely correlated ( r = -0.76), but the level of this correlation is less than that in other forms of left ventricular disease. The left ventricular ejection time index is prolonged after exercise in patients with angina pectoris when compared with findings in normal subjects. Failure of the ischemic ventricle to respond to adrenergic stimulation is the most likely mechanism. Addition of the postexercise left ventricular ejection time to standard treadmill stress testing identifies a significant number of patients (23 percent) who would have had false negative results by electrocardiographic criteria alone. In addition, this index provides confirmatory evidence in those with apparently positive electrocardiographic test data. The systolic time intervals have been useful in assessing both medical and surgical therapy in coronary artery disease. The test can be performed repeatedly and provides a measure of both left ventricular performance and extent of adrenergic hyperactivity. Thus, evaluation of therapy represents the most useful future application of systolic time intervals.