Precipitating Factors

A number of precipitating factors (see Table 12.6) may worsen cardiac function and volume status, resulting in an episode of ADHF. Proper detection and treatment of precipitating factors is an important part of the management of ADHF and a key to preventing recurrent episodes.

Process of Care and Adherence Issues. A number of factors not directly related to the circulatory pathophysiology of HF often contribute in a substantial way to hospitalization for ADHF. These precipitating factors are the target of disease management programs which are a critical factor in limiting recurrent admission for HF in many patients.

Dietary Indiscretion. Excessive sodium intake is a well recognized precipitating factor for admission for ADHF. Less well understood is the role of excessive water intake. A careful review of the patient's dietary history is a critical part of the assessment of patients admitted with ADHF.

Medication Nonadherence. Lack of access to medication for financial reasons or from access to care problems is a major cause of nonadherence which may be addressed during hospital admission.

Latrogenic Volume Overload. ADHF may be precipitated by inappropriate administration of fluid related to surgical or other procedures. Volume status may be difficult to assess in certain clinical conditions (eg, pulmonary infection) and inaccurate assessment of volume status may yield to unwarranted volume replacement. Patients with chronic HF and symptomatic hypotension do not require fluid resuscitation, and those with mild orthostatic hypotension may improve with liberalization of oral fluid intake.

Progressive Cardiac Dysfunction. Progression of underlying cardiac dysfunction with ventricular remodeling is an important cause of ADHF and if present will necessitate changes in chronic therapy. Progressive cardiac dysfunction is not always a consequence of worsening underlying disease, but may reflect adverse concomitant problems, such as pneumonia, uncontrolled diabetes, alcohol withdrawal, or cocaine use.

Atrial Fibrillation. The onset of atrial fibrillation is accompanied by the loss of coordinated atrial contraction, which may have detrimental hemodynamic effects. Uncontrolled atrial fibrillation with rapid heart rate is particularly troublesome to patients with HF. Ventricular filling may be compromised further, myocardial oxygenation adversely affected and myocardial contractility diminished. Atrial flutter or tachycardia with a 2:1 AV block may masquerade as or be mistaken for sinus tachycardia.

Uncontrolled Hypertension. Uncontrolled hypertension is a very common finding in patients admitted with ADHF. Data from the ADHERE registry indicate that approximately 50% of patients admitted with this syndrome have blood pressure >140/90 mm Hg.2 Hospitalization for ADHF provides another opportunity to add medication aimed at improving long-term control of hypertension. However, excessive dosing of antihypertensive medication during concomitant diuresis may result in symptomatic orthostasis.

Myocardial Ischemia/Infarction. The occurrence of myocardial ischemia and infarction are significant, potentially treatable precipitants of acute exacerbation of HF. Use of coronary angiography and noninvasive imaging to determine the presence and extent of myocardial ischemia is important in the evaluation of patients with acute as well as chronic HF. Patients with HF complicating acute coronary syndrome often require rapid coronary angiography and intervention in the catheterization laboratory. Considerations that determine the diagnostic approach toward ischemic heart disease are often similar in patients with acute and chronic HF (see Section 13).

Other Precipitants of Acute HF. A number of other factors, many of which are preventable or avoidable, may be primary or secondary causes of hospital admission for HF.

Right Ventricular (RV) Pacing. If the underlying heart rate slows over time in response to beta blockers or for other reasons, patients with RV pacemakers may pace more frequently. In some patients, the increase in RV pacing may lead to myocardial dysfunction, presumably from the dyssynchrony produced by the pacing.144

Pulmonary Disease. Even minor congestion may be poorly tolerated in the presence of chronic obstructive pulmonary disease (COPD) because volume expansion easily impairs the already limited pulmonary function in these patients. Both HF and COPD increase the risk of pulmonary infections, which can cause ADHF. Sleep disordered breathing may exacerbate HF through adverse hemodynamic changes, hypoxia and fluid retention.

Anemia. The presence of anemia has been associated with increased risk of admission for ADHF. The reduction in hemoglobin may be profound in cases where bleeding, especially gastrointestinal, is a cause, or end-stage renal disease is the principal mechanism.

Thyroid Diseases. Hypo- or hyperthyroidism may exacerbate the signs and symptoms of HF. Up to 20% of patients hospitalized for ADHF are already being treated for thyroid disease. Therefore, evaluation of patients' thyroid therapy is recommended. For patients taking amiodarone, worsening HF with emergence of tachyarrhythmias may be due to amiodarone-induced thyrotoxicosis.

Noncardiac Medications. A number of medications, both cardiac and noncardiac, can precipitate or contribute to an episode of worsening HF. Medications for diabetes, including pioglitazone or rosiglitazone, may lead to peripheral edema, which can be associated with adverse clinical and hemodynamic effects. Similar effects are seen with pregabalin, which is frequently used to treat diabetic neuropathy.146 Nonsteroidal anti-inflammatory drugs and COX-2 inhibitors can promote sodium and fluid retention, interfere with the pharmacologic mechanism of ACE inhibitors, worsen renal function, and decrease the effectiveness of loop diuretics. Tricyclic antidepressants, whether used to treat depression or neuropathy, may cause cardiac conduction delays and increase the risk for ventricular arrhythmia. Theophylline and beta agonist bronchodilators may exacerbate HF by inducing tachyarrhythmias, including atrial fibrillation and flutter and ventricular arrhythmias. Over-the-counter drugs containing pseudoephedrine can aggravate hypertension, worsen HF by enhancing the activation of the sympathetic nervous system, and predispose to arrhythmias. Certain calcium antagonists and anti-arrhythmics may impair cardiac function and result in worsening HF.

Hospital admission provides the opportunity to educate patients concerning their HF and to reinforce both pharmacologic and non-pharmacologic approaches to management. Education in the hospital should be focused, because retention may be limited. Particular attention should be paid to the basic facts of HF, monitoring of fluid status, and medications. Identifying patients with limited social and family support before discharge may promote the development of a support system. Establishing support systems for patients with financial constraints is critical to their ability to obtain prescribed medications and access follow-up care. In a randomized, controlled trial of 233 hospitalized HF patients, a 1-hour pre-discharge teaching session directed by a nurse educator improved clinical outcomes and reduced cost of care.64