Echo metrics flag risk even in mild pulmonary hypertension, UK study finds

Echocardiographic measures routinely used to assess pulmonary hypertension perform well at identifying patients with clearly elevated pulmonary artery pressures but lose accuracy when the elevation is mild, according to an analysis of 1,991 individuals from the EVIDENCE-PAH UK database published in Echo Research & Practice. The study also found that mild pulmonary hypertension itself is associated with increased mortality, and that within this group two echocardiographic markers, tricuspid regurgitation velocity above 3.4 metres per second and a TAPSE/systolic pulmonary artery pressure ratio below 0.31 mm/mmHg, identified patients at highest risk of death.

The 2022 ESC/ERS guidelines lowered the haemodynamic threshold for diagnosing pulmonary hypertension from a mean pulmonary artery pressure of at least 25 mmHg to a value above 20 mmHg. This change introduced a new population of patients with mean pressures of 21 to 24 mmHg, a group the guidelines describe as having mild elevation of pulmonary artery pressure. Echocardiography remains the first-line investigation that raises suspicion of the disease and guides referral for right heart catheterisation, the gold standard for diagnosis, yet the few studies that have evaluated echocardiographic performance using the new thresholds combined the newly included patients as a relatively modest subgroup within their overall analysis, skewing results towards more severe haemodynamics.

EVIDENCE-PAH UK is a national haemodynamic study drawing on the UK National Pulmonary Hypertension Audit, with data collected prospectively at all UK tertiary pulmonary hypertension centres between 2009 and 2017. Because the dataset is enriched with patients whose pressures fall in the 21 to 24 mmHg range, the researchers were able to examine this understudied group in detail. From a total population of 2,929 individuals, the analysis included the 1,991 records with a recorded tricuspid regurgitation velocity, representing 68.0 percent of the database. The median interval between echocardiography and right heart catheterisation was 40 days, with a first-to-third quartile range of 6 to 106 days.

Within the sample, 1,414 individuals, or 71.0 percent, had confirmed pulmonary hypertension under the ESC/ERS 2022 criteria. Of these, 577 individuals, 29.0 percent, had a mean pulmonary artery pressure below 21 mmHg, 472 individuals, 23.7 percent, fell in the 21 to 24 mmHg range, and 942 individuals, 47.3 percent, had pressures of at least 25 mmHg. Median age rose across the three groups from 63 years to 66 years and then 68 years, and women formed the majority in every group, accounting for 71.4 percent, 67.6 percent and 65.3 percent respectively. The analysis excluded records lacking a tricuspid regurgitation velocity, a parameter chosen because it is reliably available and recommended for stratifying the probability of pulmonary hypertension in both previous and redefined ESC/ERS guidelines.

The echocardiographic metrics tracked haemodynamic severity. Median tricuspid regurgitation velocity, the speed of blood leaking backwards across the tricuspid valve, rose from 2.67 m/s in the group without pulmonary hypertension to 2.95 m/s in the mild group and 3.54 m/s in the severe group, with statistically significant differences between every pair of groups. Median estimated systolic pulmonary artery pressure climbed from 32 mmHg to 40 mmHg and 59 mmHg, and median right atrial pressure rose from 4.5 mmHg to 6.0 mmHg and 10.0 mmHg. The TAPSE/systolic pulmonary artery pressure ratio, proposed as a surrogate for right ventricle–pulmonary artery coupling, fell from 0.65 mm/mmHg to 0.51 mm/mmHg and 0.29 mm/mmHg across the same groups, again differing significantly between each pair.

Not every metric moved in step with pressure. Median tricuspid annular plane systolic excursion, a measure of right ventricular contraction, was 21 mm in both the no-pulmonary-hypertension and mild groups and 17 mm in the severe group, and statistical testing found no significant difference in TAPSE between the two lower-pressure groups. TAPSE was available for only a subset of patients, 254 individuals in the lowest-pressure group, 216 in the mild group and 489 in the severe group. This pattern, the authors note, likely explains why the combined ratio loses diagnostic power in mild disease, since the right ventricle does not begin to fail until pressures are more substantially elevated.

Receiver operating characteristic analysis quantified how well the metrics distinguished haemodynamic categories. For predicting a mean pulmonary artery pressure of at least 25 mmHg, tricuspid regurgitation velocity, systolic pressure and the TAPSE ratio achieved area-under-curve values of 0.811, 0.827 and 0.830 respectively, indicating good discrimination. Performance weakened when the threshold was lowered to above 20 mmHg, with area-under-curve values of 0.785, 0.804 and 0.794. When the analysis focused specifically on the mild 21 to 24 mmHg range, excluding patients with pressures of at least 25 mmHg, the values dropped further to 0.663, 0.686 and 0.656, and TAPSE alone showed no utility in this group with an area under the curve of 0.502, equivalent to chance. DeLong’s testing showed systolic pressure outperformed tricuspid regurgitation velocity at the two higher thresholds, though the two methods did not differ significantly in the mild group.

The clinical implications of this diagnostic gap are substantial. Among patients in the mild haemodynamic group, 46.8 percent would have been categorised as low probability of pulmonary hypertension by tricuspid regurgitation velocity alone, using the guideline threshold of 2.8 m/s or below, meaning nearly half of individuals with genuinely abnormal pressures would be missed if echocardiography were relied upon in isolation. Conversely, 29.1 percent of patients without pulmonary hypertension met the diagnostic TAPSE ratio threshold of 0.55 mm/mmHg, a relatively high false-positive rate. The authors conclude that in milder forms of the disease, both single and combined echocardiographic metrics are weaker predictors of diagnosis, underscoring the need to integrate clinical assessment and multiple investigations, and that right heart catheterisation should still be considered when clinical suspicion or risk factors for certain pulmonary hypertension groups exist even in the absence of supportive echo findings.

Prognostic value proved more robust than diagnostic accuracy. In Cox regression models adjusted for age and sex, tricuspid regurgitation velocity carried a hazard ratio of 1.646 for mortality, systolic pressure a hazard ratio of 1.017 per unit, TAPSE a hazard ratio of 0.941, and the TAPSE ratio a hazard ratio of 0.192, all statistically significant. In the mild 21 to 24 mmHg subgroup specifically, patients with a TAPSE ratio below 0.31 mm/mmHg had a median survival of 5.5 years compared with 10.5 years for those above the threshold, a significant difference. Tricuspid regurgitation velocity above 3.4 m/s in this same mild group was associated with a median survival of 5.5 years, compared with 10.0 years in the 2.5 to 2.8 m/s group and more than half of the below-2.5 m/s group surviving the full follow-up period. Five-year survival in the mild group ranged from 78.8 percent at the lowest velocity band to 55.3 percent at the highest.

The study has limitations the authors acknowledge. Echocardiographic parameters were supplementary to a haemodynamic database, measurements were taken from clinical reports rather than re-analysis of raw images, and the dataset contains missing data, including the absence of a measurable tricuspid regurgitation jet in some patients with pulmonary hypertension. Echocardiography and catheterisation were not performed simultaneously, with echo studies accepted up to one year before or three months after catheterisation, and all patients had been deemed to carry enough clinical suspicion of pulmonary hypertension to undergo catheterisation, biasing the cohort towards higher pre-test suspicion. Guidelines also changed over the study period, requiring retrospective application of current standards to older data. Even so, the authors state this represents the largest cohort with echo metrics within the newly defined mild haemodynamic thresholds in a real-life referral population, and the findings support the prognostic utility of tricuspid regurgitation velocity and the TAPSE ratio even in early haemodynamic disease.

Subject of Research: Echocardiographic assessment of mild haemodynamic pulmonary hypertension using tricuspid regurgitation velocity and TAPSE/systolic pulmonary artery pressure ratio in the EVIDENCE-PAH UK cohort

Article Title: Significance of echocardiographic metrics including TRV and TAPSE/SPAP in mild haemodynamic pulmonary hypertension – data from EVIDENCE-PAH UK

Article References: Karia, N., Murphy, D., Howard, L., Johnson, M., Kiely, D. G., Lordan, J., McCabe, C., Pepke-Zaba, J., Knight, D., Muthurangu, V., & Coghlan, J. G. (2026). Significance of echocardiographic metrics including TRV and TAPSE/SPAP in mild haemodynamic pulmonary hypertension – data from EVIDENCE-PAH UK. Echo Research & Practice, 13(1), Article 20. https://doi.org/10.1186/s44156-026-00119-1

Image Credits: AI Generated

DOI: 10.1186/s44156-026-00119-1

Keywords: pulmonary hypertension, echocardiography, tricuspid regurgitation velocity, TAPSE/SPAP, right heart catheterisation, ESC/ERS 2022 guidelines, EVIDENCE-PAH UK, mild haemodynamic PH, survival analysis, right ventricular function, ROC analysis, prognosis