Evaluation of Patients at Risk

Identification of Risk Factors. Identification of risk factors, predisposing conditions, and markers that confer increased risk for developing HF is an important part of the routine medical evaluation.1 A number of conditions predispose to the development of HF,2-12 and persuasive evidence exists that treatment of these risk factors decreases the likelihood of subsequent HF (see Guideline Section 3 for more details on risk factor modification and HF prevention). Although risk factors vary in the degree to which they are modifiable, detection of any risk factor identifies a patient in whom aggressive risk factor modification and more careful follow-up are warranted.

Method of Evaluation. Patients at risk for developing cardiac dysfunction should undergo careful history and physical examination to detect evidence of clinical HF and to uncover other conditions that predispose to HF. Appropriate therapies should be introduced to reduce the likelihood that left ventricular (LV) dysfunction will develop. Selected groups of high-risk patients and patients with signs and symptoms of HF should undergo echocardiographic examination to assess cardiac structure and function.13 This initial examination may identify patients with cardiac dysfunction with or without symptomatic HF. These patients should undergo evaluation and treatment as defined in this guideline.

Echocardiography. The presence of certain risk factors makes the likelihood of underlying ventricular remodeling and dysfunction sufficiently likely to warrant diagnostic echocardiography (Table 4.2).

Characterization of cardiac structure and function is critical for proper diagnosis, estimation of prognosis, and therapeutic decision-making. Contributions of cardiac dysfunction to the HF syndrome extend beyond the traditional view of simply quantifying LV systolic function (or left ventricular ejection fraction, LVEF), since the capacity and the efficiency of the LV also dictates the adequacy of stroke volume. This may explain why approximately 50% of patients with symptoms and signs of HF have a preserved LVEF.14-17 Therefore, echocardiographic and Doppler assessment should include analysis of chamber sizes, valve function, LV mass and wall thickness, parameters of LV systolic and diastolic function, right ventricular (RV) systolic function, the presence of pulmonary hypertension, and the presence of pericardial disease. In patients whose echocardiographic imaging is unsatisfactory or when the degree of LVEF influences therapeutic decision making, other techniques such as radionuclide ventriculography, cardiac magnetic resonance imaging, or computed tomography may be used.

Interest is high in developing markers of cardiac dysfunction that can be used to screen patients at risk for HF. Although initial data suggest that determination of BNP or NT-proBNP levels may be useful in this regard, data are insufficient to make a specific recommendation concerning their use for screening in a routine manner. The positive predictive value for these tests in a low-prevalence and asymptomatic population for the purpose of detecting cardiac dysfunction varies among studies, and the possibility of false positive results has significant cost-effectiveness implications.18-23

BNP is released by the heart in response to increased ventricular filling pressures, but may also be increased in the plasma as a result of ongoing myocardial dysfunction or hypertrophy. A low plasma BNP or NT-proBNP concentration has a high negative predictive value for cardiac dysfunction in patients presenting to the emergency room with dyspnea, and it may therefore be used to exclude HF as a cause of dyspnea with a relatively high degree of certainty.24,25