Diagnosis and Management of Diastolic Heart Failure
Diego H. Delgado, MD, Division of Cardiology and Transplant, Toronto General Hospital, Toronto, ON.
The incidence of heart failure is rising rapidly, and it is currently the most common cardiovascular disease. Approximately 20–40% of patients with heart failure have preserved left ventricular systolic function, and an impairment of ventricular relaxation is considered the primary cause. There is controversy surrounding the definition of diastolic dysfunction and the diagnostic criteria for diastolic heart failure. Moreover, there are few studies on therapy for diastolic heart failure, which makes the management of these patients a real challenge.
Key words: heart failure, treatment, diagnosis, diastolic dysfunction.
Introduction
The incidence of heart failure is rising rapidly, and it is currently the most common cardiovascular disease. More than 400,000 Canadians are afflicted with this condition, and more than 50,000 new cases are diagnosed per year.1 Moreover, the average period of hospitalization due to heart failure is eight days, and more than one billion Canadian dollars are spent each year on inpatients. However, approximately 20–40% of patients with heart failure have preserved left ventricular systolic function, and an impairment of ventricular relaxation is thought to be the primary mechanism leading to symptoms. The prevalence of diastolic heart failure increases with age, approaching 50% in patients over 70 years.2 The annual mortality rate for patients with diastolic heart failure is 5–8% versus 10–15% for patients with systolic heart failure.
There is controversy surrounding the definition of diastolic dysfunction and the diagnostic criteria for diastolic heart failure. In addition, there are few studies on therapy for diastolic heart failure, which makes the management of these patients a real challenge.
This review examines the current evidence for the diagnosis and treatment of this unique clinical entity and emphasizes particular features of this condition in older patients.
Definitions
It is important to differentiate diastolic heart failure from diastolic dysfunction.
Diastolic heart failure is a clinical syndrome characterized by symptoms and signs of heart failure, a preserved ejection fraction, and abnormal diastolic function.3 Diastolic heart failure is the consequence of a decrease in ventricular relaxation and/or an increase in ventricular stiffness. Patients may present with clinical signs and symptoms of congestive heart failure, such as dyspnea, orthopnea, and pulmonary rales.
Diastolic dysfunction refers to a condition in which abnormalities in mechanical function are present during diastole. Diastolic dysfunction can occur in the presence or absence of a clinical syndrome of heart failure and with or without normal systolic function. Therefore, whereas diastolic dysfunction describes an abnormal mechanical property, diastolic heart failure describes a clinical syndrome.
Pathophysiology
The underlying pathophysiology of diastolic dysfunction is impaired relaxation of the left ventricle (LV), resulting in reduced left ventricular compliance and therefore inadequate filling of the LV at normal diastolic pressures.4
Diastolic dysfunction is primarily a disease of older people. This observation may be related to the fact that aging has a greater impact on diastolic than systolic function. There is a progressive loss of myocytes and hypertrophy of the remaining myocytes with aging.5 Other physiologic changes occur with aging: systemic vascular resistance is increased, LV stiffness is increased, LV compliance is decreased, systolic blood pressure is increased, early LV diastolic filling is decreased, and LV relaxation is impaired.6 Increased LV stiffness occurs with aging because of increased interstitial fibrosis and cross-linking of collagen in the heart. Older patients are also more likely to have hypertension, myocardial ischemia due to coronary disease, and LV hypertrophy caused by hypertension or aortic stenosis. These deleterious effects on diastolic function are exacerbated by a decrease in beta-adrenergic receptor density