This study aims to establish the normal reference values for left ventricular myocardial work in healthy Chinese adults and the influencing factors. Non-invasive myocardial work serves as a new parameter for identifying CRT responders and provides a scoring system for predicting the efficacy of CRT in clinical practice. CRT can improve cardiac function and quality of life, and reduce mortality and hospitalization rates due to heart failure (HF). Currently, the number of CRT treatments is increasing year by year, but even when strictly following the indications, approximately 30% of patients do not respond. Therefore, precise prediction of CRT efficacy is of great clinical significance for improving prognosis. Currently, the indications for CRT mainly rely on clinical, electrocardiogram (CLBBB), and LVEF. By correcting ventricular contraction asynchrony to improve systolic function, however, CLBBB indicates electrical asynchrony, and LVEF improvement depends on mechanical synchrony. If the mechanical asynchrony of the ventricles can be evaluated directly before surgery, it will help predict the efficacy of CRT. Myocardial work is a recently developed non-invasive method that combines LV afterload with the overall longitudinal strain (GLS) analysis of echocardiography. Myocardial work reflects the contraction ability of the heart, stroke work, residual myocardial contraction ability, myocardial oxygen consumption, useless work, useful work, etc., and is represented by the pressure-volume loop analysis, thus having the potential to predict the efficacy of CRT. Therefore, this study intends to adopt the left ventricular myocardial work technique, combined with the current indication criteria, to predict the long-term efficacy of patients with heart failure who are scheduled for CRT treatment, thereby increasing the response rate of CRT and improving the prognosis of patients. Currently, there are no normal reference values for left ventricular myocardial work in healthy Chinese adults. Therefore, our center has initiated this multicenter clinical research project, collaborating with multiple ultrasound centers across the country, aiming to establish the normal ultrasound values for left ventricular myocardial work in healthy Chinese adults, providing new quantitative reference basis for the diagnosis of myocardial function, assessment of the severity of myocardial lesions, and efficacy observation.

Healthy Adults Group

Inclusion Criteria:

• Participants must meet all of the following criteria to be enrolled:

  1. Of Han Chinese ethnicity
  2. Aged 18-79 years
  3. Normal blood pressure (< 140/90 mmHg)
  4. Normal fasting blood glucose
  5. Normal blood lipid levels (triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein)
  6. Normal complete blood count results (hemoglobin concentration, white blood cell count, red blood cell count, platelet count)
  7. Normal liver and renal function (alanine transaminase < 2× upper limit of normal; normal creatinine and blood urea nitrogen)
  8. Normal electrocardiogram results (occasional atrial premature beats may be enrolled at the investigator's discretion)
  9. No structural heart disease and normal cardiac function confirmed by echocardiography

Exclusion Criteria:

Participants will be excluded if they meet any of the following criteria:

1. Clinically significant cardiac valve regurgitation (≥ mild severity)
2. Respiratory diseases: acute or chronic respiratory disorders
3. Endocrine diseases: thyroid disease, diabetes mellitus, hyperaldosteronism, pheochromocytoma, etc.
4. Abnormal liver function (alanine transaminase > 2× upper limit of normal), abnormal renal function (elevated creatinine beyond normal range), or dyslipidemia (elevated triglycerides, total cholesterol, low-density lipoprotein, or high-density lipoprotein)
5. Other systemic diseases: anemia, malignancy, connective tissue disease, large artery/peripheral vascular diseases (aortic dilation, aortic dissection, coarctation of the aorta, Takayasu arteritis, atherosclerosis), etc.
6. Pregnant or lactating women
7. Professional athletes
8. Poor-quality ultrasound images that cannot support parameter measurement and analysis

Heart failure patients with LBBB who are scheduled for CRT treatment Group

Inclusion criteria:

1. LVEF ≤ 35%
2. QRS ≥ 150ms; LBBB
3. At least 3 months of optimal drug therapy before implantation

Exclusion Criteria:

1. Suffering from connective tissue diseases such as systemic lupus erythematosus, polymyositis, and rheumatoid arthritis;
2. Having a history of blood diseases and severe systemic diseases such as infections;
3. Those who cannot cooperate with the examinations.

Patients with LBBB who have preserved LVEF Group

Inclusion criteria:

1. LVEF≥53%
2. LBBB

Exclusion Criteria:

1. Suffering from connective tissue diseases such as systemic lupus erythematosus, polymyositis, and rheumatoid arthritis;
2. Having a history of blood diseases and severe systemic diseases such as infections;
3. Those who cannot cooperate with the examinations.

Patients with reduced LVEF but without LBBB Group

Inclusion criteria:

1. LVEF ≤ 35%
2. non-LBBB

Exclusion Criteria:

1. Suffering from connective tissue diseases such as systemic lupus erythematosus, polymyositis, and rheumatoid arthritis;
2. Having a history of blood diseases and severe systemic diseases such as infections;
3. Those who cannot cooperate with the examinations.

This study enrolls 4 groups (18-79 years) from clinics/community:

Healthy Adults: Han Chinese with normal cardiovascular function (vitals, labs, ECG, echo; no structural heart disease/systemic diseases/poor ultrasound).

Heart failure patients with LBBB who are scheduled for CRT treatment： LVEF ≤ 35%,QRS ≥ 150ms; LBBB.At least 3 months of optimal drug therapy before implantation.

Patients with LBBB who have preserved LVEF :LVEF≥53%, LBBB. Patients with reduced LVEF but without LBBB :LVEF ≤ 35%,non-LBBB.