What Is Systolic Heart Failure

Introduction

Heart failure (HF) is a term familiar to many, but what exactly is it, and what do people with this disease actually experience? HF is a multifactorial syndrome arising from an abnormal heart morphology (shape) and/or an impaired heart function. It is characterised by specific symptoms, including shortness of breath, ankle swelling and fatigue, combining further clinical signs such as elevated jugular venous pressure, pulmonary crackles, and peripheral oedema. Identifying the precise aetiology of the heart dysfunction is essential for accurate HF diagnosis and implementation of an effective treatment plan.¹

There is a clinical distinction between specific types of HF, which is obtained by measuring the left ventricular ejection fraction (EF), denoting the percentage of blood pumped from the left ventricle of the heart to the body per heartbeat.² Normal EF ranges between 52-72% for individuals assigned male at birth and 54-74% for individuals assigned female at birth.³ Systolic HF is defined as heart failure with reduced EF (HFrEF) at or below 40%.² This indicates an abnormal left ventricular systolic function, meaning that the left ventricle pumps inadequate blood to the body.

In this article, we will go through the anatomy of the heart and further explore the symptoms and treatment methods of systolic HF. The objective is to provide more in-depth knowledge to you, with the goal of raising awareness and reducing mortality rates for this incapacitating disease.

Anatomy and physiology of the heart

The human heart, known as the cardiac muscle, comprises four chambers: the two upper chambers, the right and left atria, and the two lower chambers, the right and left ventricles. It is the primary organ involved in the circulatory system, responsible for pumping blood throughout the body. Specifically, the:⁴

• Right atrium: Receives deoxygenated blood from the systemic circulation via the vena cavae. This oxygen-poor blood then flows into the right ventricle through a designated valve.
• Right ventricle: Pumps the oxygen-poor blood through the pulmonic valve into the pulmonary artery, which transports it to the lungs for oxygenation. The oxygenated blood then returns through the pulmonary veins to reach the left atrium.
• Left atrium: This upper chamber subsequently pumps the blood into the lower left ventricle.
• Left ventricle: Pumps the oxygen-rich blood into systemic circulation through the aortic valve.

This cardiac cycle repeats with each heartbeat. An electrical conduction system regulates the heart's pumping action, which acts by sending electrical signals facilitating the coordinated contraction (systole) to pump blood into the circulation and relaxation (diastole) to fill the chambers.⁴

Evidently, a complex network of regulatory anatomical components ensures the body receives sufficient blood, maintaining normal blood flow and pressure. Defects within this system can lead to cardiovascular conditions that may be life-threatening.

Systolic heart failure: an overview

As previously mentioned, different clinical phenotypes have been identified representing distinct types of HF and are classified based on the EF:⁵

• Systolic HF: This is defined as HFrEF with an EF of ≤40%, where the left ventricle of the heart is unable to contract properly, resulting in inefficient blood pumping throughout the body.
• Diastolic HF: Designated as heart failure with preserved ejection fraction >50% (HFpEF). Even with EF within the normal range, specific signs and symptoms, including evidence for structural or functional heart aberrations and/or elevated natriuretic peptides (NP) are indicative of diastolic HF. In this scenario, the left ventricle of the heart fails to relax properly and subsequently cannot be sufficiently filled with blood.
• Mildly reduced ejection fraction (HFmrEF) of 41-49% is registered as a diverse type of HF.

Risk factors and causes

Certain lifestyle choices and underlying health conditions play a pivotal role in the development of HFrEF. Particularly, conditions associated with systolic HF include:⁶

• Coronary artery disease
• Hypertension
• Previous myocardial infarction (heart attack): A heart attack signifies inadequate blood supply to the heart, contrasting the inadequate blood pumped from the heart in HF.
• Valvular heart disease
• Diabetes Mellitus
• Smoking habits
• Dilated cardiomyopathy
• Left ventricular hypertrophy

Some of these previous events can result in impaired pumping of the left ventricle, ultimately reducing the cardiac output (the volume of blood pumped by the heart per minute), and potentially causing systolic HF.

Symptoms

A variety of signs and clinical symptoms have been observed in HF patients, some of which are outlined below:⁷

• Shortness of breath (dyspnea) is noticeable even when lying flat (orthopnea) or while bending over (bradypnea)
• Swelling (oedema) in the lower extremities or the abdominal region
• Fatigue, weakness, dizziness, and fainting (syncope)
• Loss of appetite (anorexia)
• Persistent coughing and wheezing
• Palpitations

These symptoms are generally exacerbated with exercise and can be due to fluid accumulation and a decrease in cardiac output. Clinical symptoms in more advanced stages of the disease include:⁷

• Sinus tachycardia (persistent rapid heart rhythm)
• Excessive sweating (diaphoresis)
• Narrow pulse pressure
• Peripheral oedema (swelling in the ankles or presence of ascites)
• Elevated jugular venous pressure
• Pulmonary congestion

Diagnostic methods

Patients with suspected HF undergo a thorough history and physical evaluation to confirm the diagnosis and detect the specific HF type. The clinical examination process includes the following steps:⁵

• Electrocardiogram (ECG): Irregularities in the ECG are common in patients with HF.
• B-type NP (BNP) measurement: Elevated concentrations of BNP are associated with HF.
• Blood test: Full blood count, creatinine measurement, serum urea, and electrolyte levels are all crucial for the accurate HF diagnosis and treatment scheme.
• Echocardiogram: Vital for assessing abnormal heart function and structure.
• Chest X-ray: Useful in confirming HF presence, especially in patients with pulmonary symptoms.

Following confirmation of HF, additional tests measuring the EF are conducted to determine the HF type. An EF of ≤40% signifies the presence of HFrEF or systolic HF. Symptoms can be indistinguishable regardless of the EF, and in general, HFrEF is relatively less challenging to diagnose compared to HFpEF. Some of these tests are:⁸

• Cardiovascular magnetic resonance (CMR) scan
• Nuclear stress test - Although rarely used

Further evaluation is crucial to determine the underlying condition that requires management, thus enabling the adoption of an appropriate treatment plan.

Treatment

The European Cardiological Society has outlined specific guidelines for the management and treatment of systolic HF. The first target of these therapies is to reduce mortality and hospitalisation rates in patients. These practices include various approaches, including pharmacological, surgical and lifestyle modifications:

Medications

A recommended pharmacological regimen for patients with HFrEF involves a combination of drugs from different classes, namely:⁵

1. Angiotensin-converting enzyme inhibitors (ACE-Is)
2. Angiotensin receptor-neprilysin inhibitors (ARNIs)
3. beta-blockers
4. Mineralocorticoid receptor antagonists (MRAs)
5. Sodium-glucose co-transporter 2 inhibitors (SGLT2 inhibitors)
6. Diuretics
7. Angiotensin II type 1 receptor blockers (ARBs)

The initial pharmacologic approach typically involves a combination of drugs from the first four classes, with alternative options considered in case of intolerance or contraindications.⁵

Surgical interventions

Procedures impacting cardiac rhythm can be considered and include specific implantable devices such as an implantable cardioverter-defibrillator (ICD) and cardiac resynchronisation therapy (CRT)⁵:

• Particularly, ICD has shown effectiveness in reducing sudden deaths linked to ventricular arrhythmias in patients with HF.
• CRT may also reduce morbidity and mortality by improving heart function and the overall quality of life of patients.
• Left ventricular assist devices may be considered to enhance organ function and prepare patients for potential heart transplantation.

Lifestyle modifications

Healthcare professionals emphasise several lifestyle adjustments for HF patients, including:⁹

• Dietary modifications incorporating plant-based, antioxidant-rich, low-sodium and high-potassium foodsCertain dietary supplements such as coenzyme Q10, L-carnitine, taurine, and vitamins. The aim of dietary changes is to address underlying conditions in HF patients, regulating factors such as blood pressure, lipid concentrations, body weight rehabilitation and exercise therapy, quitting smoking, and reducing alcohol intake. 

Prognosis

The outlook for HFrEF patients strongly depends on the severity and stage of HF. Generally, HFrEF exhibits a poorer prognosis in terms of combined risk of hospitalisation and all-cause mortality when compared to HFmrEF and HFpEF. Additionally, the prognosis is significantly influenced by factors such as blood pressure, BNP and EF levels.⁷

Treatment strategies have greatly improved the effectiveness of managing  HFrEF, thereby reducing the associated morbidity and mortality risks. However, prevalent comorbidities such as coronary artery disease or ischemic HF still pose challenges. Mortality related to cardiovascular disorders, particularly sudden cardiac death, remains higher in this type of HF, accentuating the importance of early diagnosis, treatment, and management of underlying conditions.¹⁰

Prevention

Adopting a shift in daily life choices could be crucial in reducing HF risk. Embracing a nutritious diet comprising high-quality and appropriately portioned ingredients, incorporating a well-balanced schedule of physical activity and rest, limiting alcohol consumption and smoking habits, and exploring effective stress relief techniques are all essential practices. These measures not only minimise the likelihood of HF but also contribute to an enhanced quality of life for individuals.

Summary 

HF is a chronic and debilitating condition associated with high morbidity and mortality rates. It can often limit the functional capacity and decrease the quality of life of affected individuals.

The British Society for Heart Failure offers a wealth of information online, aiming to educate the public about this disease. Exploring the plethora of causes and treatment options and providing detailed insights into diagnostic methods are practices to improve prognosis in patients.

Talk to your healthcare provider if you are experiencing symptoms of systolic HF. A healthier lifestyle and seeking early intervention are essential tools in effectively combating this disease.