Systolic time-interval evaluation by thermistor plethysmography during uninterrupted dynamic stress test in normals and in patients with coronary artery disease.

18 patients with coronary artery disease (CAD) and 21 normal subjects underwent a triangular bicycle exercise test. Systolic time intervals (STI) were calculated at rest and every 2 min during exercise. Under resting conditions, STI were similar in the two groups. During exercise, the ejection time index (ETI), i.e. left ventricular ejection time (LVET) corrected for HR, rose significantly more in CAD patients, as compared to normals. Pre-ejection period (PEP) was also differently affected by exercise in CAD patients, who showed a more shortened PEP (p less than 0.001) in the early stage of dynamic stress. PEP/LVET ratio, which in the control group decreased continuously, in CAD patients fell during exercise at lower work loads (p less than 0.001), whilst rose during strenuous exercise. Finally, significant differences (p less than 0.001) were found in the percent change (% delta) PEP/LVET ratio between the two groups during the early phase of exercise, in which no superimposition of single values was present. Therefore, this last parameter seems the most reliable to differentiate clearly CAD patients from normal subjects, but its use must be limited at early exercise.