The impact of right ventricular free wall strain on current international echocardiography guidelines for the assessment of pulmonary hypertension

Current guidelines define pulmonary hypertension (PH) as a mean pulmonary artery pressure (mPAP) >20mmHg at right heart catheterisation (RHC). International transthoracic echocardiography (TTE) PH guidelines recommend a multi-parameter assessment to estimate PH probability. Effectiveness of the inclusion of right ventricular free wall strain (RVFWS) has not been established using real world data.

To determine the accuracy of current European and American TTE PH guidance in detecting PH in patients attending a UK PH centre. The impact of addition of RVFWS to the efficacy of the European and American guidance was also evaluated.

TTE with subsequent RHC (within 1.4 months) were undertaken in patients with suspicion of PH, referred for first time investigations. Echocardiographic variables were assessed in accordance with current European and American TTE guidance.

Of 549 patients assessed, 431 (79%) had RHC confirmed PH (average mPAP = 41mmHg). Sensitivity / specificity for detecting PH was calculated for the European Society of Cardiology (ESC) TTE PH recommendations (83% / 65% respectively); ESC + RVFWS (92% / 62% respectively); American Society of Echocardiography (ASE) TTE PH recommendations (89% / 49% respectively); ASE + RVFWS (96% / 36% respectively); TTE PASP > 35mmHg alone (75% / 73% respectively); TTE TRV > 2.8 m/s alone (77% / 78% respectively). Of those with RHC PH 3 (1%) subjects with a TRV > 2.8 m/s and 7 (3%) with a PASP > 35mmHg had no supporting signs of PH. Using TTE PASP > 35mmHg or TRV >2.8m/s with at least 2 abnormal TTE parameters (including RVFWS) gave similar sensitivity / specificity (74% / 79% vs 73% / 87% respectively). In those with RHC PH and TTE PASP >35mmHg or TRV >2.8m/s the significant majority had at least 2 TTE PH markers (99% & 97%). Whilst TTE PASP and RHC PASP correlation was good (r = 0.745), accuracy was poor with limits of agreements as high as 44mmHg (range = -29 to 44mmHg). In those with no measurable tricuspid regurgitation, 64% (n = 49) had RHC PH (11% of whole cohort); in those where TTE PASP <35mmHg 23% (n = 70) had RHC PH. In those felt to have an ESC PH low TTE probability 44% (n = 60) had RHC PH (14% of whole cohort). Incorporating RVFWS improved detection in those with a ESC low TTE PH probability, reducing false negatives by 43%.

Current TTE PH algorithms lack sensitivity to detect patients with milder haemodynamic forms of PH. This can be improved with the addition of RVFWS.