Radionuclide assessment of a normal left ventricular response to exercise in patients without evidence of heart disease

The aim of this study was to define normal left ventricularperformance at rest and during supine bicycle exercise withequilibrium radionuclide ventriculography in a normal populationother than young healthy volunteers. Thirty-one patients (meanage 45 years ± 9 SD) with chest pain of varying originandno evidence of heart disease proven by means of noninvasiveand invasive techniques were studied. Left ventricular ejectionfraction (LVEF) at rest averaged 0.64 ± 007 SD and increasedwith peak exercise to 0.73 ± 008 SD (P<0.005). Changein LVEF from rest to maximum exercise ranged within 0–0.19.Six patients (19%) failed to augment LVEF with exercise to morethan 0.05; none of the patients dropped LVEF during exercise.Multivariate analysis revealed no significant predictors ofLVEF response to exercise. However, there was a tendency thatresting LVEF and enddiastolic volume index with exercise mightinfluence LVEF response to exercise. Peak left ventricular ejectionrate (LVER) at rest averaged 3.3s^–1 ± 0.6 SD andincreased to 51 s^–1 ± 11 SD (P<0.005) with exercise.Peak left ventricular early filling rate (LVFR) was 2.8s^–1± 0.6 SD at rest and was measured 5.5 s^–1 ±l.3 SD at maximum exercise (P<0.005). Left ventricular enddiastolicvolume (EDV) did not change significantly from rest to maximumexercise, whereas left ventricular endsystolic volume (ESV)decreased to 79% ± 19 SD (P<0.01) of the value atrest. In conclusion, in a normal population other than healthy youngvolunteers LVEF does not necessarily have to increase with exercise.Moreover, besides an augmentation of heart rate a normal leftventricular response to supine exercise is associated with anincrease of LVER and LVFR, a decrease in ESV and no significantchange in EDV, suggesting augmented contractility and a virtuallynegligible role of the Frank-Starling mechanism during exercise.