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Factors influencing exercise performance in patients with left ventricular dysfunction. SOLVD Investigators. Studies
M W Kronenberg1, M A Konstam, T R Edens
1Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
Journal of Cardiac Failure
|October 1, 1998
Summary
Exercise capacity in patients with left ventricular (LV) dysfunction depends on the heart's ability to increase function during exertion. Reserve capacities for heart rate, blood pressure, and ejection fractions are key to better exercise performance.
Area of Science:
- Cardiology
- Exercise Physiology
Background:
- Exercise performance determinants are unclear in left ventricular (LV) dysfunction, especially in asymptomatic patients.
- Limited data exists on hemodynamics and neurohormonal factors affecting exercise in LV dysfunction.
Purpose of the Study:
- To assess hemodynamics and neurohormonal factors influencing exercise performance in patients with LV ejection fractions > or =0.35.
- To compare symptomatic and asymptomatic patients with LV dysfunction.
Main Methods:
- Studied 103 patients with LV dysfunction (38 symptomatic, 65 asymptomatic).
- Utilized rest-exercise radionuclide ventriculography and blood pressure measurements.
- Assessed heart rate, ventricular volumes and ejection fractions, peripheral resistance, contractility index, and plasma renin/norepinephrine.
- Evaluated changes from rest to exercise as cardiovascular reserve indices.
Main Results:
- Asymptomatic patients had higher resting LV ejection fraction (0.30 vs 0.25) and greater increases in heart rate, systolic blood pressure, LV ejection fraction, and cardiac output during exercise.
- Strongest correlates of exercise workload were increased heart rate (r=0.70), pressure/volume ratio (r=0.63), increased systolic blood pressure (r=0.55), and decreased peripheral resistance (r=-0.47).
- Multivariate analysis showed workload best modeled by changes in heart rate, systolic blood pressure, and LV/RV ejection fractions (R2=0.54).
Conclusions:
- Exercise performance and hemodynamics differ between symptomatic and asymptomatic patients with LV dysfunction.
- Cardiovascular reserve, specifically the capacity to increase heart rate, systolic blood pressure, and ejection fractions, predominantly determines exercise capacity.
- Resting parameters are less critical than dynamic functional reserve for exercise performance in LV dysfunction.