What are the main clinical differences between systolic heart failure, diastolic heart failure, and high-output heart failure?

From the Guidelines

The main clinical difference between systolic failure, diastolic failure, and high output failure lies in their underlying mechanisms and presenting symptoms, with systolic failure characterized by reduced ejection fraction, diastolic failure by impaired relaxation and filling, and high output failure by excessive cardiac output and high metabolic demands. The differences between these types of heart failure are crucial for diagnosis and treatment. Systolic heart failure occurs when the heart cannot contract effectively, resulting in reduced ejection fraction (typically <40%) and forward flow, as noted in the 2016 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 1. Patients often present with fatigue, dyspnea on exertion, and signs of fluid overload like peripheral edema. A classic example is a patient with a history of myocardial infarction who develops progressive shortness of breath and decreased exercise tolerance due to damaged heart muscle that cannot pump efficiently.

Diastolic heart failure, by contrast, involves impaired relaxation and filling of the ventricles despite preserved ejection fraction (typically >50%), as described in the 2008 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 1. These patients experience similar symptoms of congestion but often have more pronounced orthopnea and paroxysmal nocturnal dyspnea. An example would be an elderly hypertensive patient with left ventricular hypertrophy who presents with acute pulmonary edema despite normal contractile function.

High output heart failure represents a fundamentally different scenario where the heart pumps adequately or even excessively, but cannot meet abnormally high metabolic demands, as characterized in the 2005 executive summary of the guidelines on the diagnosis and treatment of acute heart failure 1. These patients typically present with warm extremities, bounding pulses, and wide pulse pressure. A classic example is a patient with severe anemia, hyperthyroidism, or arteriovenous fistulas who develops heart failure symptoms despite hyperdynamic cardiac function. Some key points to consider when differentiating between these types of heart failure include:

• The underlying cause of the heart failure, such as myocardial infarction, hypertension, or anemia
• The presence of symptoms such as fatigue, dyspnea, or orthopnea
• The results of diagnostic tests, such as echocardiography or cardiac catheterization
• The patient's response to treatment, such as medications or lifestyle modifications

Treatment approaches differ significantly:

• Systolic failure requires medications to improve contractility and reduce afterload (ACE inhibitors, beta-blockers, SGLT2 inhibitors)
• Diastolic failure focuses on controlling blood pressure and heart rate (calcium channel blockers, beta-blockers)
• High output failure requires addressing the underlying cause (treating anemia, hyperthyroidism, or closing fistulas). It is essential to note that the 2016 ESC guidelines 1 provide the most recent and comprehensive guidance on the diagnosis and treatment of heart failure, and should be consulted for the most up-to-date information.

From the Research

Clinical Differences Between Systolic Failure, Diastolic Failure, and High Output Failure

• Systolic heart failure (SHF) is characterized by a dilated left ventricle and reduced ejection fraction, whereas diastolic heart failure (DHF) is marked by a non-dilated left ventricle with preserved ejection fraction 2, 3.
• The pathophysiology of DHF involves impaired left ventricular filling during diastole, leading to elevated filling pressures and symptoms of heart failure, despite normal systolic function 3, 4.
• High output failure is not explicitly discussed in the provided studies, but it can be inferred that it refers to a condition where the heart's output is increased, potentially due to conditions such as anemia, thyrotoxicosis, or arteriovenous fistula.
• The management of SHF has seen significant progress, with established treatments such as ACE inhibitors, whereas the management of DHF remains largely empirical due to a lack of understanding of its molecular and biochemical mechanisms 2, 5, 6.
• ACE inhibitors have been shown to be beneficial in patients with systolic dysfunction, but their effectiveness in patients with preserved systolic function (DHF) is less clear, with some studies suggesting potential benefits in preventing myocardial infarction and controlling blood pressure 5, 6.

Key Characteristics of Each Condition

• Systolic Heart Failure (SHF):
  • Dilated left ventricle
  • Reduced ejection fraction
  • Impaired contractility
• Diastolic Heart Failure (DHF):
  • Non-dilated left ventricle
  • Preserved ejection fraction
  • Impaired left ventricular filling during diastole
• High Output Failure:
  • Increased cardiac output
  • Potential causes: anemia, thyrotoxicosis, arteriovenous fistula

Therapeutic Considerations

• Assessing left ventricular systolic function is crucial before initiating therapy in a patient with heart failure, as treatment for systolic dysfunction may be ineffective or even counterproductive if symptoms are due to abnormal diastolic properties with preserved systolic function 4.
• ACE inhibitors are a mainstay of therapy in patients with systolic dysfunction, but their use in patients with preserved systolic function (DHF) requires further study 5, 6.