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Prediction of maximal cardiac output in preoperative patients with coronary artery disease
Insights
Coronary patients exhibit reduced maximal cardiac output (CO) and oxygen consumption (VO2max) due to impaired heart rate and peripheral extraction. VO2max, stenosis severity, ST depression, and sex significantly predict CO.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Coronary artery disease (CAD) significantly impacts cardiovascular function.
- Preoperative assessment of aerobic and hemodynamic profiles is crucial for surgical risk stratification.
Purpose of the Study:
- To evaluate the aerobic and hemodynamic responses to exercise in patients with coronary artery disease.
- To identify factors influencing maximal cardiac output (CO) and maximal oxygen consumption (VO2max) in this population.
Main Methods:
- 100 patients (89 men, 11 women) underwent preoperative assessment.
- Direct Fick principle used to measure maximal cardiac output during upright treadmill exercise.
- Maximal oxygen consumption (VO2max) and other hemodynamic variables were recorded.
Main Results:
- Mean maximal CO was 57% of normal, primarily limited by reduced maximal heart rate.
- Mean VO2max was 48% of normal, with greater reduction than CO attributed to lower peripheral extraction.
- Univariate analysis showed correlations between maximal CO and angina severity, VO2max, heart rate, left ventricular dysfunction, blood pressure, and stenosis severity.
- Multivariate analysis identified VO2max, stenosis severity, ST depression, and sex as significant predictors of maximal CO (r=0.77).
Conclusions:
- Coronary patients have significantly impaired exercise capacity.
- Maximal oxygen consumption is a key determinant of cardiac output in these patients.
- Preoperative assessment of VO2max, coronary anatomy, and ECG changes can predict exercise hemodynamics.
Abstract:
Of 100 patients (89 men, 11 women) studied preoperatively to determine their aerobic and hemodynamic profiles at rest and during upright treadmill exercise. The mean maximal cardiac output (CO), measured using the direct Fick principle, was 57 +/- 14% of average normal values. The reduction in maximal heart rate (63 +/- 13% of normal) was a greater factor in the reduction in CO than stroke volume (88 +/- 16% of normal). Maximal oxygen consumption (VO2max) was 48 +/- 15% of normal and the greater reduction in VO2max compared with CO was due to lower peripheral extraction in the coronary patients. Variables that correlated with maximal CO in a univariate analysis included angina severity (r = -0.45), VO2max (r = 0.67), maximal heart rate (r = -0.31), left ventricular dysfunction (r = -0.45), maximal systolic blood pressure (r = -0.31) and number of vessels with greater than or equal to 50% diameter reduction (r = -0.3). Resting ejection fraction did not correlate with maximal CO. In a multivariate analysis, 4 variables correlated significantly (r = 0.77) with maximal CO: in order, VO2max, number of vessels with greater than or equal to 50% stenosis, magnitude of ST depression and sex.