HEART FAILURE
Clinical Overview

Epidemiology and Pathophysiology

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There are two major types of heart failure; 1) due to left ventricular systolic dysfunction, or 2) due to left ventricular diastolic dysfunction. Systolic dysfunction is caused by ischemic disease, including myocardial ischemia or infarction, or nonischemic disease. Nonischemic disease includes primary myocardial muscle dysfunction, valvular abnormalities, hypertension, or structural damage and/or damage to myocardial walls. Ultimately, both ischemic and nonischemic disease result in dilated cardiomyopathy, thus causing systolic dysfunction. On the other hand, diastolic dysfunction results from hypertrophic cardiomyopathy or restrictive cardiomyopathy.⁷

The clinical differentiation between diastolic and systolic dysfunction is difficult and in many elderly patients with heart failure, diastolic dysfunction is often unrecognized.¹⁰ This table adapted from Tresch et al, lists the clinical differences between the two etiologies. Often in the elderly population, these etiologies are mixed and clinical assessment alone is inadequate to distinguish systolic from diastolic failure. For these reasons, and because drug therapy between the two is different, an echocardiogram or radionuclide ventriculography to assess left-ventricular (LV) function is necessary to confirm diagnosis.¹⁰

Clinical Differentiation of Systolic vs. Diastolic Dysfunction^10,12
 

Systolic Dysfunction   EF < 35-40% Presentation:  •younger than 65 years •progressive shortness of breath Results from  •decreased contractility •ventricles lose ability to eject blood into a high pressure aorta Contributing factors:  •CAD, MI •HTN •cardiomyopathy •diabetes •chronic valvular insufficiency Physical Exam  •Displaced PMI (point of impact) •S3 gallop Radiographic findings  •Pulmonary congestion •cardiomegaly ECG shows Q waves

Diastolic Dysfunction   EF > 40-45% Presentation:  •65 years or older •acute pulmonary edema Results from  •restriction in ventricular filling •stiffness of ventricle Contributing factors:  •CAD •HTN •renal disease •diabetes •aortic stenosis Physical Exam •Sustained PMI •S4 gallop Radiographic findings  •Pulmonary congestion •normal sized heart ECG shows left ventricular hypertrophy

 

Systolic Dysfunction:
The majority of patients with heart failure have left ventricular systolic dysfunction and ejection fractions less than 35% to 40%. This type of heart failure results from decreased contractility of the cardiac muscle causing the ventricles to lose the ability to eject blood into a high pressure aorta.¹² Primary causes include coronary artery disease, hypertension, and cardiomyopathies. Increases in survival and decreases in morbidity with drug treatment have been demonstrated in clinical trials.¹³

Diastolic Dysfunction:
Diastolic ventricular dysfunction is a significant problem in older people, with at least 40% of older heart failure patients having diastolic dysfunction as the etiology of their heart failure.¹⁰ The primary cause is the result of restriction in ventricular filling, or stiffness of the ventricle. These patients have an ejection fraction (EF) greater than 40% to 45%. Coronary artery disease and hypertension are major factors contributing to diastolic dysfunction by impairing left ventricular diastolic relaxation and increasing cardiac mass in response to chronic pressure overload. Older patients with diastolic dysfunction may have a better prognosis than those with systolic dysfunction, although long-term survival is still poor and morbidity is high.¹⁰

In a study by Aronow and associates, left ventricular ejection fraction was found to be the most important predictor of mortality, specifically in older patients (mean age 82 years) with heart failure and coronary artery disease.¹¹ At 23 month follow-up, 51% of those with normal ejection fraction had cardiac deaths compared to 85% cardiac mortality in patients with decreased ejection fractions.

Reversible causes are not as common but should be looked for during evaluation, because once corrected, heart failure symptoms may subside. It is important to understand the differences in etiology since therapy is based on type, cause, and symptoms of the disease.

Potentially Reversible Causes:4 valvular heart disease can be corrected surgically and could alleviate symptoms which mimic heart failure. hemochromatosis should be considered in patients with a history of liver disease, unexplained hepatomegaly, or bronze discoloration of skin. Evaluate a serum iron level, total iron binding capacity, and ferritin level. thyroid dysfunction sarcoidosis

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