Exercise Echocardiography of Left Ventricular Diastolic Function in Healthy Subjects: Insights From the RIGHT-NET

Exercise transthoracic Doppler echocardiography (TTE) is considered suggestive of left ventricular (LV) diastolic dysfunction when the ratio of mitral Doppler E to tissue Doppler e' waves is >15 with or without a peak tricuspid regurgitation velocity (TRV) >3.4 m/s. However, these measurements may be affected by exercise intensity. The aim of the study was to define the normal limits of LV diastolic function indices during exercise TTE.

One hundred ninety-two healthy adults (47% females, aged 16-76 years) underwent resting and exercise TTE on a semirecumbent cycle ergometer. LV diastolic measurements were acquired at baseline and midlevel exercise (heart rate ≤110 bpm) fusion of E and A waves. TRV was acquired at rest and at peak exercise. The E/e' ratio was calculated with e' as the average of septal and lateral measurements.

At midlevel exercise, E/e' increased modestly from 6.3 ± 1.9 to 7.3 ± 2.3 (P < 0.001) as a function of workload and cardiac output (CO), independently of sex and age. The 95th percentile of exercise E/e' was 11.8. The slope of E/e'/CO was 0.4 ± 1.2/L/min. The slope of TRV/CO was 10.8 ± 11.5 cm/s/L/min. The upper 95% confidence interval of the E/e'/CO and TRV/CO slopes were 0.6/L/min and 13.1 cm/s/L/min, corresponding to an E/e' of 13.2 and a TRV of 3.4 m/s at a CO of 15 L/min.

In healthy adult subjects, E/e' slightly increased during midlevel exercise. Both E/e' and TRV are exercise intensity-dependent and would therefore be better expressed as a function of CO for the diagnosis of normal vs abnormal LV diastolic response to exercise.