Acute decompensated heart failure is a leading cause of hospitalization and is associated with high morbidity and mortality. Early risk stratification in this population is crucial for guiding treatment strategies and predicting short- and long-term clinical outcomes. Transthoracic echocardiography is routinely performed in patients hospitalized with acute decompensated heart failure and provides comprehensive information regarding cardiac structure and function. However, the prognostic value of detailed echocardiographic parameters obtained before the initiation of intravenous diuretic therapy has not been fully clarified.

The objective of this prospective study is to evaluate the prognostic significance of transthoracic echocardiographic findings obtained at hospital admission, prior to intravenous diuretic therapy, in patients hospitalized with acute decompensated heart failure. The study will assess key echocardiographic parameters reflecting left and right heart structure and function, including left ventricular ejection fraction, left ventricular dimensions and geometry, left atrial size and volume, indices of right ventricular systolic function (such as TAPSE, tissue Doppler-derived S' velocity, and fractional area change), pulmonary artery systolic pressure, right ventricular-pulmonary artery coupling assessed by the TAPSE/PASP ratio, and right ventricular outflow tract acceleration time.

Primary outcome measures include in-hospital mortality, post-discharge mortality, myocardial infarction, ischemic stroke, and heart failure-related rehospitalization. Secondary outcomes include the need for non-invasive or invasive mechanical ventilation during hospitalization, requirement for inotropic support, changes in B-type natriuretic peptide levels, development of acute kidney injury, and occurrence of new-onset cardiac arrhythmias.

By prospectively evaluating echocardiographic parameters and their associations with clinical outcomes, this study aims to clarify the prognostic role of early echocardiographic assessment in acute decompensated heart failure and to contribute to improved risk stratification and clinical decision-making in this high-risk population.

This study will be designed as a prospective, single-center, observational investigation conducted at Istanbul University-Cerrahpaşa Cardiology Institute between December 2024 and December 2025. Based on an a priori power analysis performed using G*Power software for linear regression modeling, assuming a two-sided alpha error of 0.05 and 80% statistical power, a minimum of 76 patients will be required for adequate statistical validity.

Study Population

Consecutive adult patients presenting to the emergency department or outpatient cardiology clinic and hospitalized for acute decompensated heart failure following independent cardiologist evaluation and indication for intravenous diuretic therapy will be enrolled. Patients will be evaluated by the study investigator after admission and prior to the first intravenous diuretic administration.

Demographic variables (age, sex), anthropometric measurements (height, weight), body mass index calculated using the Quetelet formula (kg/m²), and body surface area calculated using the Mosteller formula (m²) will be recorded. Vital signs including systolic and diastolic blood pressure (mmHg), peripheral oxygen saturation (%), and heart rate (beats per minute) will be documented.

Comorbidities including hypertension, diabetes mellitus, atrial fibrillation, ischemic heart disease, chronic obstructive pulmonary disease, chronic kidney disease, hypothyroidism, ischemic cerebrovascular disease, peripheral arterial disease, and smoking status will be recorded.

Functional capacity will be evaluated according to the New York Heart Association (NYHA) classification.

Electrocardiographic Evaluation

Standard 12-lead electrocardiography will be obtained in the supine resting position at 25 mm/s speed and 10 mm/mV calibration. Rhythm will be categorized as sinus rhythm or atrial fibrillation. QRS duration will be measured from the onset of the Q wave to the end of the S wave in the lead demonstrating the widest morphology and recorded both as a continuous variable (ms) and categorized using a 120 ms threshold.

Heart Failure Classification and Medical Therapy

Heart failure etiology will be classified as ischemic or non-ischemic in previously diagnosed patients. In newly diagnosed cases, presumed etiology will be recorded at baseline and updated when definitive diagnosis is established.

Patients will be categorized according to ESC and ACC/AHA guideline-recommended left ventricular ejection fraction classifications:

HFrEF (EF <40%)

HFmrEF (EF 40-49%)

HFpEF (EF ≥50%)

Baseline medical therapy will be recorded, including the number and type of guideline-directed medical therapy (GDMT) agents. High-dose diuretic therapy will be defined as ≥80 mg/day for furosemide or ≥20 mg/day for torasemide. Combination diuretic therapy (loop plus thiazide or thiazide-like diuretic) will be documented. Presence of implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D) will be recorded.

Precipitating Factors

Potential precipitating factors for decompensation including atrial fibrillation with rapid ventricular response (defined as AF with resting ventricular rate ≥110 bpm), infection (defined by elevated CRP, leukocytosis, procalcitonin elevation, and compatible clinical findings), and acute kidney injury (defined according to KDIGO criteria) will be documented.

Laboratory Assessment

Admission laboratory parameters obtained without intervention will be extracted from the hospital information system and will include BUN, creatinine, estimated glomerular filtration rate (eGFR), sodium, potassium, AST, ALT, hemoglobin, hematocrit, white blood cell count, platelet count, HbA1c, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, CRP, and B-type natriuretic peptide (BNP).

Patients with severe anemia (hemoglobin <7 g/dL) or receiving chronic dialysis therapy will be excluded.

Transthoracic Echocardiography

Comprehensive transthoracic echocardiography will be performed prior to intravenous diuretic therapy using a Philips EPIQ 7C ultrasound system equipped with an S5-1 phased-array transducer.

Patients will be examined in the left lateral decubitus position with ECG synchronization. In sinus rhythm, three consecutive cardiac cycles will be averaged; in atrial fibrillation, five consecutive cycles will be averaged.

Parasternal long-axis (PLAX), parasternal short-axis (PSAX), apical four-chamber (A4C), apical five-chamber (A5C), and apical two-chamber (A2C) views will be obtained.

Left ventricular ejection fraction will be calculated primarily using the biplane Simpson method. Left ventricular mass will be calculated using the Devereux formula and indexed to body surface area. Relative wall thickness and left ventricular eccentricity index (D2/D1 ratio) will be calculated.

Right ventricular systolic function will be assessed using:

Tricuspid annular plane systolic excursion (TAPSE)

Tissue Doppler-derived tricuspid annular systolic velocity (S')

Right ventricular fractional area change (FAC)

Right atrial area will be measured planimetrically. Tricuspid regurgitation velocity will be obtained using continuous-wave Doppler. Inferior vena cava diameter and inspiratory collapse will be assessed to estimate right atrial pressure according to guideline recommendations. Pulmonary artery systolic pressure will be calculated using the modified Bernoulli equation (4×TRV² + RAP). In the absence of right ventricular outflow tract obstruction, PASP will be accepted as equivalent to right ventricular systolic pressure.

Right ventricular-pulmonary artery coupling will be calculated using:

TAPSE/PASP

Tricuspid S'/PASP

FAC/PASP ratios

Patients with advanced primary valvular disease (moderate/severe mitral stenosis, severe primary mitral regurgitation defined by vena contracta ≥7 mm or EROA ≥40 mm², significant aortic stenosis defined by AVA ≤1.5 cm² or mean gradient ≥20 mmHg, or significant aortic regurgitation defined by vena contracta ≥6 mm or PHT <200 ms) will be excluded. Patients with primary right heart disease or suboptimal imaging quality will also be excluded.

In-Hospital Evaluation

Initial intravenous diuretic dose will be recorded. Patients will be classified according to whether the administered intravenous dose is at least twice the pre-admission oral diuretic dose.

In-hospital clinical events including mechanical ventilation requirement, vasopressor or inotropic support, development of acute kidney injury, and in-hospital mortality will be prospectively recorded. Length of stay will be defined as the interval between admission and discharge.

BNP levels at admission and discharge will be recorded, and percentage change will be calculated. Patients will be categorized according to >30% reduction, no significant reduction, or increase in BNP levels.

Follow-Up

The discharge date will be defined as Day 0 for follow-up. Patients will be prospectively followed for up to 15 months using hospital electronic records. Event time will be calculated from discharge to cardiovascular death or heart failure-related rehospitalization.

Statistical Analysis

Statistical analyses will be performed using SPSS version 25. Normality will be assessed using Kolmogorov-Smirnov and Shapiro-Wilk tests. Continuous variables will be expressed as mean ± SD or median (min-max) as appropriate. Categorical variables will be expressed as n (%).

Group comparisons will be performed using chi-square tests, Mann-Whitney U tests, Pearson or Spearman correlation analyses as appropriate. Time-to-event outcomes will be analyzed using Kaplan-Meier survival curves and compared using log-rank tests. Independent predictors will be identified using univariable and multivariable Cox proportional hazards regression models. In-hospital binary outcomes will be evaluated using logistic regression analysis. Receiver operating characteristic curve analysis will be used to determine optimal prognostic cut-off values. A two-sided p-value <0.05 will be considered statistically significant.

The study will be conducted in accordance with the Declaration of Helsinki and has been approved by the Istanbul University-Cerrahpaşa Non-Interventional Clinical Research Ethics Committee (Approval No: 2024/251). Written informed consent will be obtained from all participants.

Inclusion Criteria:

• Adults aged ≥18 years.
• Hospitalization due to acute decompensated heart failure.
• Intravenous diuretic therapy deemed necessary by the treating cardiologist.
• Predominant left-sided heart failure.
• Provision of written informed consent prior to participation.

Exclusion Criteria:

• Severe anemia (hemoglobin <7 g/dL).
• Requirement for renal replacement therapy, including hemodialysis or peritoneal dialysis, or being listed for kidney transplantation.
• Severe primary mitral regurgitation.
• Severe aortic stenosis.
• Severe aortic regurgitation.
• Severe primary tricuspid regurgitation.
• Primary right heart failure.
• Heart failure secondary to congenital heart disease.
• History of mitral valve replacement.
• History of aortic valve replacement.
• History of bioprosthetic valve replacement.
• History of transcatheter aortic valve implantation.
• Presence of active malignancy.
• Failure to provide written informed consent.
• Inability to perform transthoracic echocardiography prior to intravenous diuretic therapy for any reason.

The study population will consist of adult patients hospitalized for acute decompensated heart failure at Istanbul University-Cerrahpaşa Cardiology Institute Hospital. Participants will be selected from patients presenting to the emergency department or cardiology outpatient clinics who require inpatient management for heart failure decompensation.