Non-invasive estimation of left ventricular systolic peak-pressure: a prerequisite to calculate of myocardial work in hypertrophic obstructive cardiomyopathy

Abstract

Abstract Introduction Myocardial work (MW) is an echocardiographic parameter to estimate global and regional myocardial performance. This method utilizes pressure strain loops derived from global longitudinal strain (GLS) and left ventricular systolic pressure (LVSP) estimated by brachial blood pressure (BP). Purpose Since LVSP cannot be equated with BP in pts with HOCM, we investigated whether the LVSP can be calculated non-invasively by combining Doppler echo parameters and the BP. This estimation is mandatory to make MW applicable for HOCM-pts. Methods We studied 20 consecutive pts (8 women, 12 men; mean age 57.0±13.9 years; NYHA class 2.1±0.8) with indication for first alcohol septal ablation. 6 pts had hypertension and 2 pts unexplained syncope. 18 (90%) pts were in sinus rhythm. NTproBNP was 1431 pg/ml (1912 IQR). Echo baseline measurements showed subaortic septal (IVS) thickness of 21.0±5.0 mm and maximal IVS thickness of 24.7±6.3 mm. Pts showed high-normal left ventricular ejection fraction (70.4±10.1%). Left atrial (LA) volume was 101.2±26 ml. All measurements of pressures and gradients were performed in the catheterization laboratory after placement of a 5F Judkins JR4 in the ascending aorta and a 5.2F special pigtail catheter in the apex of LV beyond the obstruction. Simultaneous measurements of BP at left upper arm, echo intraventricular gradients (instantaneous and mean) with CW Doppler (GE Vivid E70), and invasive pressures and gradients (peak-to-peak and mean) of the LV and ascending aorta were performed. Echo and invasive gradients were averaged over 3 cardiac cycles. Finally, we tried to identify an estimation of invasively measured LV systolic pressure by combining systolic BP and echo measured gradients. Results Systolic BP was 143±21 mmHg. Max. CW Doppler gradient was 65±29 mmHg and mean gradient was 31±14 mmHg. Invasive simultaneous measurements at rest showed peak-to-peak gradient of 55±24 mmHg and mean gradient of 34±13 mmHg between apical LV and ascending aorta. Mean LVSP was 190±40 mmHg. Systolic pressure of the ascending aorta was 134±28 mmHg. Adding systolic peripheral BP and maximal echo-gradient mean value was 208±38 mmHg. Adding systolic peripheral BP and echo-mean gradient mean value was 174±26 mmHg. Correlating these values with the invasively measured systolic LV pressure we found a slightly higher correlation of the sum of systolic BP and mean-echo gradient (Pearson correlation coefficient: 0.867 p<0.001) compared with the sum of systolic BP and maximal echo-gradient (Pearson correlation coefficient: 0.851; p<0.001). Bland–Altman plots demonstrated good levels of agreements between invasively measured LVSP and both non-invasively estimated LVSP. Conclusions Non-invasive estimation of LVSP is feasible by combining conventional BP and CW Doppler measured mean LV outflow tract gradient in HOCM. Hereby estimation of MW in pts with HOCM is applicable.