RESEARCH • Feasibility and Discriminatory Value of Tissue Motion Annular Displacement in Sepsis-Induced Cardiomyopathy: A Single-Center Retrospective Observational Study

BACKGROUND

Sepsis-induced cardiomyopathy (SICM), which was initially described in the 1980s, is usually defined as an acute and reversible cardiac dysfunction that involves decreased left and/or right ventricular systolic and/or diastolic function, left ventricular dilatation, and absence of acute coronary syndrome.

There is no formalized or consensus definition of SICM, yet frequently left ventricular ejection fraction (LVEF) of less than 50% in septic patients is often considered as indicative of SICM. The mortality among septic patients with SICM is 2 ~ 3 times higher than those without SICM.

Echocardiography is considered the most important method for the diagnosis of SICM. In addition to LVEF, mitral annular plane systolic excursion (MAPSE) is another simple method which is obtained by M-mode echocardiography and commonly used to detect LV dysfunction.

Speckle tracking echocardiography (STE) is a relatively new technology for LV strain measurement, which is characterized by angle-independence and semi-automatization. STE assesses the cardiac function by tracking the displacement of groups of acoustic greyscale “speckles” frame by frame through the whole myocardium. According to its working principle, STE directly measures the myocardium deformation; therefore, it is less affected by the LV loading conditions and myocardial compliance. Global longitudinal strain (GLS) has demonstrated to be a more sensitive indicator of LV dysfunction in sepsis.

Tissue motion annular displacement (TMAD) is a novel speckle tracking indicator that quickly assesses the LV longitudinal systolic function and tracks the displacement of the mitral annulus and the apex of the left ventricle instead of the whole LV endocardium. While TMAD may be a valuable tool to evaluate cardiovascular diseases, it application in SICM is rarely reported.

The authors hypothesized that TMAD plays an important role in evaluating LV longitudinal systolic function and discriminating SICM in septic patients. They setup this study to assess the feasibility and the discriminatory value of TMAD for predicting SICM defined as LVEF < 50%, as well as the prognostic value of TMAD in septic patients.

METHODS

Study Population

This was a single-center retrospective observational study. Patients who were admitted to the surgical intensive care unit (SICU) from March 2019 to July 2021 and met the following criteria were enrolled as study subjects:

1. Age ≥ 18 years
2. Diagnosis of sepsis or septic shock
3. Underwent echocardiography examination within the first 24 h after admission to SICU

Exclusion criteria included:

1. Poor echocardiographic image quality or incomplete echocardiographic data
2. Incomplete clinical data
3. History of valvular heart disease
4. Chronic heart failure (CHF) with the history of coronary artery disease (CAD), hypertrophic cardiomyopathy (HCM) or other ischemic heart diseases
5. Presence of cardiac implanted device
6. Atrial fibrillation
7. Refusal to participate in the study
8. Loss to follow-up and fail to get consent

Conventional echocardiographic data

The recorded parameters included: left atrial dimension, LV end-systolic and end-diastolic volume (LVESV/LVEDV), LVEF, velocitytime integral of LV outflow tract (LVOT VTI), cardiac output (CO), early (E) and late (A) diastolic trans-mitral inflow velocity, early (e′) and late (a′) lateral diastolic mitral annular tissue velocity, maximal lateral systolic mitral annular tissue velocity (MA Smax), mitral annular plane systolic excursion (MAPSE), tricuspid annular plane systolic excursion (TAPSE), pulmonary arterial systolic pressure (PASP).

Speckle tracking echocardiographic data

STE analysis was performed offline and averaged by two independent investigators who were trained by an echocardiography software engineer. During the echocardiographic analysis, the investigators were blinded to the patients’ clinical conditions.

GLS

The opening and closing times of the mitral and aortic valves were derived from the electrocardiograph and were used to distinguish the different phases of the cardiac cycle. The semi-automated CMQ package of the QLAB software was used along the apical longitudinal axis of the left ventricle in four-, two-, and three chamber views were used for GLS evaluation.

TMAD

TMAD was measured offline in the apical four-chamber views using the TMAD package of the QLAB software. To assess TMAD, three regions of interest (ROIs) were selected: the septal (TMAD1) and lateral (TMAD2) areas of the mitral annulus, as well as the apex of the LV.

The midpoint (TMADMid) between the two annuli ROIs was automatically detected after setting these three ROIs. Then, tracking was automatically performed frame by frame and the average of the base-to-apical displacement of the two mitral annulus ROIs was calculated in millimeters. TMADMid was also calculated in millimeters, and a percentage value of the midpoint displacement in relation to the total length of the left ventricle was calculated (%TMAD).

Study outcomes

All patients were followed for 28 days after ICU admission or discharge, whichever occurred later. The primary outcomes of the study were the feasibility and discriminatory value of TMAD for SICM defined as LVEF < 50%. The secondary outcomes of the study were the feasibility and discriminatory value of MAPSE and GLS for SICM.

RESULTS

Out of 4865 critically ill adult patients who were consecutively admitted to SICU during the study period, 656 were diagnosed with sepsis. Among these patients, 143 patients met all inclusion criteria and were included in the study.

Of all participants, 94 patients (65.7%) were male, mean age was 69 years old, BMI was 22.9 ± 3.2, APACHE II score was 17.1 ± 6.2, and SOFA score was 6.8 ± 2.7. all patients enrolled were divided into the SICM (n = 26, 18.2%) or the non SICM (n = 117, 81.8%) group. No significant difference was found in age, gender, BMI, comorbidity, medication history and sepsis source between the SICM and non-SICM group. However, the APACHE II score and SOFA score of the SICM group were significantly higher than that of the non-SICM group (19.9 ± 6.9 vs 16.4 ± 5.8, p = 0.008; 8.3 ± 3.1 vs 6.4 ± 2.5, p = 0.007).

Intra‑ and inter‑observer variabilities and time‑consuming for measurement

Intra- and inter-observer variabilities for LVEF, MAPSE, GLS and TMAD were assessed – TMAD had the highest ICC value when compared to LVEF, MAPSE or GLS. The time consumed for TMAD measurement was similar to MAPSE (41 s ± 9 s vs. 36 s ± 8 s, p = 0.216), but significantly shorter than that for LVEF or GLS (41 s ± 9 s vs. 83 s ± 15 s, p < 0.001; 41 s ± 9 s vs. 70 s ± 11 s, p = 0.006, respectively).

Echocardiographic data of SICM and non‑SICM patients

LVEF, MAPSE, MA Smax, LVOT VTI, CO, TAPSE, TMAD 1, TMAD 2, TMADMid and %TMAD were significantly lower in the SICM group than in the non-SICM group. ween TMAD, GLS, MAPSE and LVEF were analyzed. Positive correlations were detected between TMADMid, %TMAD, MAPSE and LVEF, respectively, while a negative correlation between GLS and LVEF was confirmed.

Discriminatory value of different echocardiographic parameters for SICM

The results showed that the 28d and in-hospital mortality were significantly higher in patients with

• TMADMid: 75
• %TMAD: 11.55
• GLS: − 12.5
• MAPSE: 11.65

CONCLUSION

The authors concluded that SICM is a common disease among septic patients with significantly high mortality. They think that STE-based TMAD is a novel and feasible technique for discriminating SICM defined as LVEF < 50% in patients with sepsis.