The Use of Single-Beat TE-e' in Evaluation of Left Atrial Pressure in Critically Ill Patients: The TELAP-ICU Trial

Left atrial pressure (LAP) is an important measure in the care of critically ill patients but usually requires an invasive catheter to assess directly. Echocardiography offers a non-invasive alternative. One promising marker, TE-e' (the time difference between the onset of the mitral inflow E wave and the septal e' wave on tissue Doppler imaging), was recently incorporated into the 2025 American Society of Echocardiography (ASE) diastolic function guidelines. The conventional method for calculating TE-e' requires measurements from two separate heartbeats, introducing potential error from beat-to-beat heart rate variability - a common issue in the critically ill patients. This study assesses a novel single-beat method, in which both waveforms are captured on the same Doppler display within one cardiac cycle, eliminating that source of variability. Patients undergoing clinically indicated transthoracic echocardiography (TTE) in the Adult Intensive Care Unit of Queen Mary Hospital, Hong Kong will have TE-e' measured by both methods, along with other echocardiographic parameters associated with LAP, to evaluate correlation between the two methods and their relationship with clinically assessed LAP.

• Echocardiography (Diagnostic test): Full echocardiogram performed on recruited patients.

Primary outcomes

• Correlation between novel (single-beat) and conventional (two-beat) TE-e' values [At the time of index TTE (single time point for each patient) during the course of ICU stay (from day 1 of ICU admission till ICU discharge, up to 1 month)]

Secondary outcomes

• Correlation between novel and conventional methods in obtaining septal e' and s' velocities - At time of index TTE [At the time of index TTE (single time point for each patient) during the course of ICU stay (from day 1 of ICU admission till ICU discharge, up to 1 month)]
• Correlation between clinical evaluation of LAP and TE-e' value [At the time of index TTE (single time point for each patient) during the course of ICU stay (from day 1 of ICU admission till ICU discharge, up to 1 month)]
• Correlation between other echocardiographic parameters of LAP (E/A ratio, LAVi, TR Vmax, lung ultrasound 6-point protocol) and TE-e' value [At the time of index TTE (single time point for each patient) during the course of ICU stay (from day 1 of ICU admission till ICU discharge, up to 1 month)]

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adult patients ≥18 years admitted to the QMH Adult Intensive Care Unit (AICU)
* Requiring a transthoracic echocardiogram (TTE) as part of routine clinical care
* TE-e' obtainable by both the conventional and the novel method

Exclusion Criteria:

* Patients <18 years of age
* Patients in atrial fibrillation
* Patients with a poor TTE acoustic window
* Patients in whom TE-e' is technically difficult to obtain or interpret by either method

• Study Protocol (PDF, 2026-06-24)