Whats The Take Home?: Worsening Fatigue and Dyspnea in a New Mother

A 22-year-old woman presents with progressive fatigue and dyspnea on exertion that develops after she walks about 30 feet. She also reports orthopnea, lower extremity swelling, weight gain, dry cough, and paroxysmal nocturnal dyspnea. She delivered her first child 1 month earlier, and she says that these symptoms began toward the end of her pregnancy and have progressively worsened since delivery.

HISTORY

Her pregnancy was complicated by gestationa1 hypertension and preeclampsia. She denies any recent viral illness, chest pain, and alcohol or drug use. There is no family history of heart failure or coronary heart disease.

PHYSICAL EXAMINATION

The patient is in respiratory distress; she is short of breath at rest. Temperature is 37.2ºC (98.9ºF); heart rate, 118 beats per minute; respiration rate, 24 breaths per minute; and blood pressure, 112/90 mm Hg. Jugular venous pressure is elevated (12 cm). A 3/6 systolic blowing murmur is audible at the apex and left sternal border, radiating to the axilla. Both lungs are clear to auscultation. She has 3+ pitting edema from her ankles to her knees bilaterally.

LABORATORY AND IMAGING RESULTS

Results of a complete blood cell count and comprehensive metabolic panel are normal. An ECG shows sinus tachycardia, evidence of left atrial enlargement, and diffuse nonspecific ST-T-wave flattening. Her thyroid-stimulating hormone level is normal (4.49 µIU/mL). An echocardiogram reveals an ejection fraction of 10% to 15%, moderate dilatation of all 4 heart chambers, severe mitral and tricuspid regurgitation, and mild aortic insufficiency. The ECG and echocardiogram findings are interpreted as consistent with cardiomyopathy.

CORRECT ANSWER: C

Peripartum cardiomyopathy is congestive heart failure that develops in the last month of pregnancy or within 5 months of delivery. It is one of a number of medical complications of pregnancy that can develop after delivery. This relatively rare form of dilated cardiomyopathy occurs in 1 of every 3000 to 4000 births in the United States and is diagnosed when other causes of heart failure are absent. Risk factors for peripartum cardiomyopathy include older age, African American race, multiple gestations, preeclampsia, and gestational hypertension. However, every woman of childbearing age in whom new-onset heart failure develops should be asked about pregnancies and any history of peripartum cardiomyopathy.

Pathogenesis. Although multiple mechanisms have been proposed, the cause of peripartum cardiomyopathy remains unclear. One proposal is that the cardiomyopathy is an exaggerated version of the normal hyperdynamic response to the stress of pregnancy. (A 45% increase in cardiac output is seen in normal pregnancies; this usually results in transient hypertrophy and a mild reversible decrease in left ventricular function.) Other experts suggest that fetal cells lodge in maternal cardiac tissue and trigger an abnormal immune response. Yet another proposal is that an immune-mediated myocarditis causes the cardiomyopathy.

Finally, a few cases of familial peripartum cardiomyopathy have been reported, suggesting a hereditary component. However, this patient does not have a family history of heart disease. Moreover, no specific, detectable genes are associated with peripartum cardiomyopathy. Thus, choice D is incorrect.

Treatment. The treatment of peripartum cardiomyopathy is similar to that of any other type of congestive heart failure. Not all antihypertensive agents are contraindicated for nursing mothers (choice A). Although any of these medications can be transmitted to an infant via breast milk, some are transmitted more readily than others. For example, atenolol, metoprolol, and nadolol occur in high concentrations in breast milk and are best avoided. Labetalol and propranolol occur in low concentrations in breast milk and are thus the preferred b-blockers in this setting.

Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor antagonists should not be used during gestation and delivery because of their effect on neonatal renal function; nitrates and hydralazine are recommended instead. After delivery, aggressive management is needed to prevent the cardiomyopathy from worsening. At this point, the risk-benefit ratio usually favors initiation of ACE inhibitor therapy at the expense of breast-feeding, and mothers may be counseled to avoid breast-feeding to optimize management of heart failure.

Prognosis. In women in whom peripartum cardiomyopathy develops, the prognosis depends on whether there is full recovery of left ventricular function within 6 months of initiation of treatment. Function normalizes in about 50% of affected women, while persistent dysfunction or further deterioration and increased mortality are seen in the other 50%. Patients with less severe heart failure and smaller chambers are more likely to experience resolution. Consider heart transplantation for women whose condition does not improve with maximal therapy.

Future pregnancies and risk of recurrence. Patients who have had peripartum cardiomyopathy are at increased risk for its recurrence. Most literature distinguishes between patients who recovered cardiac function after the first occurrence and those who did not. Patients in whom left ventricular dysfunction continues should avoid subsequent pregnancies because of the risk of worsening heart failure and death. Patients who have recovered left ventricular function are at lower risk (choice B) but still need to understand that subsequent pregnancies may precipitate heart failure through reactivation of the idiopathic process that led to its initial development. Advise such women that recovery from a second episode cannot be assured.

In a survey of 44 women who had had peripartum cardiomyopathy in a previous pregnancy, 60 subsequent pregnancies were reported.¹ Twenty-eight of first subsequent pregnancies occurred in women who had normal left ventricular function after their initial episode of peripartum cardiomyopathy, and 16 occurred in women who had residual ventricular dysfunction. Heart failure symptoms occurred in 21% of the women who began their first subsequent pregnancy with normal cardiac function and in 44% of those who began a first subsequent pregnancy with residual heart failure. None of the patients who began a first subsequent pregnancy with normal ventricular function died, but 19% of those who began with ventricular dysfunction did.

Outcome of this case. A diuretic, a b-blocker, and an ACE inhibitor were prescribed for this patient. Her symptoms improved dramatically, and she was able to resume all her routine activities within weeks. At a follow-up visit, she was counseled about the risks of future pregnancy and an echocardiogram was ordered to determine her prognosis.