The effect of left ventricular systolic function on maximal aerobic exercise capacity in asymptomatic patients with coronary artery disease.

Abstract

The purpose of this study was to examine the relationship between maximal 02 uptake (VO2max) and left ventricular systolic function in patients with coronary artery disease. We studied 27 patients, age 50 10 years (mean + SD), who were asymptomatic and able to attain true VO2max. VO2max was defined by the leveling-off criterion and/or a respiratory exchange ratio of 1.15 or greater. Left ventricular ejection fraction was determined, by gated cardiac blood pool imaging. In patients whose ejection fraction decreased with exercise, VO2max was 21 + 4 vs 27 + 4 ml/kg/min in those whose ejection fraction increased (p < .001). Systolic blood pressure/end-systolic volume relation was shifted upward and to the right in the former group in response to peak exercise. In contrast, the pressure-volume relation was shifted upward and to the left in patients whose ejection fraction increased with exercise. Ejection fraction at rest did not correlate with VO2max. There was a significant but weak correlation between peak exercise ejection fraction and VO2max (r .43, p < .025). Left ventricular exercise reserve, i.e., the change in ejection fraction from rest to exercise, correlated with VO2max (r .77, p < .0002), maximal 02 pulse (r = .50, p < .005), and maximal heart rate during treadmill exercise (r = .61, p < .001). Maximal heart rate during treadmill exercise correlated with VO2max (r = .70, p < .0002). These data suggest that impaired left ventricular function can limit VO2max and that maximal heart rate and left ventricular exercise reserve are among the variables affecting VO2max in patients with coronary artery disease who are not limited by angina. Circulation 70, No. 4, 552-560, 1984. MAXIMAL 02 uptake capacity (VO2max), the best available objective measure of aerobic exercise capacity, 1 is generally lower in patients with coronary artery disease than in age-matched healthy subjects.

Impaired Left Ventricular Function during Exercise in Coronary Artery Disease and Exertional Hypotension

“…Spatial calibration of the X and Y axes of the digital images were determined with the use of a phantom as previously described [12]. Values for LVEDV corre lated well with those measured by contrast ventriculo graphy (r = 0.97) over a wide range of volumes.…”

“…Radionuclide ventriculography with gated cardiac blood pool imaging was performed at rest and during supine exercise as described previously [ 12]. Erythro cyte labeling was accomplished in vivo after an intra venous injection of 7.7 mg of stannous pyrophosphate followed in 20 min with an intravenous injection of 25 mCi 99mTc.…”

“…Processing was performed with a DEL PDP 11-34 minicomputer and a Lexidata display unit. This method requires minimal operator training, and provides reproducible results with good correlation between radionuclide and contrast angiography ejec tion fraction [12]. Ejection fraction (EF) was defined as: EF = (EDC-ESC) X 100/EDC, where EDC and ESC are end-diastolic and end-systolic counts, respec tively, corrected for background activity.…”

“…Left ventricular end-diastolic volume (LVEDV) was measured by one investigator blinded to the patient's category, using the area-length method of Dodge et al [12]: V = 8A2/3 n 1 where V is volume, A is the area, and 1 is the long axis of the left ventricle. Spatial calibration of the X and Y axes of the digital images were determined with the use of a phantom as previously described [12].…”

Effects of long-term enalapril therapy on cardiopulmonary exercise performance after myocardial infarction.

“…13 Assessment of cardiac reserve in patients with mild left ventricular dysfunction may be accomplished by evaluating performance during peak exercise.14 '15 Cardiopulmonary exercise testing permits objective determination of peak oxygen consumption (Vo2) 16,17 and the Vo2 at the anaerobic threshold.18 This technique provides a sensitive tool for evaluating the effect of therapeutic intervention. '9 Therapy with inotropes,20 vasodilators,21 and exercise training pro-grams22 have demonstrated improvement in peak and submaximal exercise parameters in patients with symptomatic heart failure.…”