13.2 EPIDEMIOLOGY

Diastolic heart failure currently accounts for nearly half of all patients with heart failure. In comparison to systolic heart failure, patients with diastolic heart failure are older, more commonly female, more likely to have hypertension and atrial fibrillation, and less likely to have previously diagnosed coronary artery disease. The prevalence of diastolic heart failure increases with age and accounts for more than 50% of the prevalence of heart failure in patients over the age of 70. The mode of death in patients with diastolic heart failure is due to cardiovascular causes in 60% (with sudden death and death from heart failure being the most common), noncardiovascular causes in 30%, and is unknown in the remaining 10%.

13.3 PATHOPHYSIOLOGY

Diastole is composed of four major phases:

Diastolic function is determined by two major factors: the active process of myocardial relaxation and the passive process of left ventricular elasticity or distensibility. Impairment of either LV diastolic relaxation or distensibility leads to increased pulmonary venous, left atrial, and left ventricular diastolic pressures. This results in a shift in LV filling from early to late diastole with subsequent greater reliance on atrial contraction. Recent studies indicate that “diastolic” heart failure is a heterogeneous condition with multiple additional pathophysiologic mechanisms (e.g. vascular dysfunction, subtle systolic dysfunction, chronotropic incompetence, etc.).

13.4 ETIOLOGIES

Numerous cardiac disorders can result in the development of diastolic dysfunction. The most common underlying etiology of diastolic heart failure is systemic hypertension with associated comorbidities such as diabetes mellitus, chronic kidney disease, coronary artery disease, and atrial arrhythmias likely contributing in many cases. Less common etiologies include hypertrophic cardiomyopathy, infiltrative cardiomyopathy, and restrictive cardiomyopathy. These rarer causes should be considered particularly in patients who do not fit the typical epidemiologic profile, i.e. a younger patient without hypertension. It is important to recognize that patients with normal left ventricular ejection fraction can still have heart failure even without definitive evidence of diastolic dysfunction (Table 13.1). Both clinical history and subsequent diagnostic studies as discussed below are essential for the evaluation of potential etiologies for a patient’s diastolic heart failure.

Table 13.1 Etiologies of Heart Failure with Normal Ejection Fraction.

13.5 CLINICAL PRESENTATION

The majority of patients with ventricular diastolic dysfunction are asymptomatic and thus, by definition, do not have diastolic heart failure. Several factors, both cardiovascular and noncardiovascular, can potentiate onset of symptoms and subsequently lead to decompensated diastolic heart failure. Such triggers are similar to those for systolic heart failure and include increased salt and water intake, medication noncompliance, tachyarrhythmias, uncontrolled hypertension, acute or chronic renal disease, arrhythmia, and myocardial ischemia. The resulting symptoms of heart failure are similar to those in patients with systolic dysfunction and include dyspnea on exertion, fatigue, and evidence of volume overload such as lower extremity edema and abdominal distention. It is important to recognize that not all patients who are hospitalized with heart failure in the setting of a normal left ventricular ejection fraction necessarily have diastolic heart failure, as these symptoms may instead be caused by valvular heart disease, pericardial disease, congenital heart disease, or intracardiac masses (Table 13.1).

13.6 EVALUATION AND DIAGNOSTIC STUDIES

The diagnosis of diastolic heart failure requires that three conditions are met: (1) signs and/or symptoms of heart failure; (2) preserved left ventricular ejection fraction, usually defined as greater than 50%; and (3) lack of obvious other structural cause (i.e. valvular, congenital, pericardial heart disease). The diagnosis may be obtained by a complete history and physical exam along with a diagnostic evaluation of cardiac structure and function, typically with an echocardiogram. The evaluation of ventricular diastolic function is complex and typically involves special echocardiographic techniques and, rarely, invasive measurements. Currently, there is much controversy about whether definitive evidence of diastolic dysfunction is necessary to make the diagnosis of “diastolic” heart failure.

As mentioned above, the initial step to evaluating diastolic heart failure is performing a complete history and physical exam. This is necessary both to evaluate for signs and symptoms of heart failure along with determining potential etiologies for the patient’s heart failure. A history of prior hospitalizations for heart failure exacerbation also provides significant prognostic information for both re-hospitalization and death.

Routine laboratory work-up should be performed. Cardiac enzymes can be clinically relevant if the patient presents with signs and symptoms of myocardial ischemia such as angina or rapid onset of heart failure without a clear underlying etiology. The plasma level of B-type natriuretic peptide (BNP) is typically elevated in patients with diastolic heart failure and provides prognostic information. However, a normal BNP level does not rule out diastolic heart failure, and BNP levels cannot be used to differentiate between systolic or diastolic heart failure.

An electrocardiogram should be performed in all patients with diastolic heart failure, and can provide evidence of left ventricular hypertrophy, myocardial ischemia or infarction, and/or arrhythmia to suggest potential etiologies. A chest X-ray can reveal evidence of pulmonary edema or primary pulmonary causes of dyspnea.

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