A Young Woman With Recurrent Atrial Fibrillation

An 18-year-old woman was referred to our adult congenital heart disease center for investigation of chest pain and atrial fibrillation (AF). She had reported intermittent chest pain without precipitating factors since the age of 8 years. This had been evaluated by a pediatric cardiologist and was felt to be noncardiac in nature. Persistence of pain and associated distress eventually prompted referral to adolescent psychiatry. At age 17 years she experienced 3 episodes of AF, each treated with direct-current cardioversion. An electrophysiologist commenced treatment with flecainide and warfarin. Warfarin was stopped after 6 months arrhythmia-free. At our clinic, she reported intermittent, nonexertional, atypical chest pain and exertional dyspnea with a gradual decline in exercise capacity, confirmed by cardiopulmonary exercise test (oxygen consumption peak 65% predicted). Electrocardiogram demonstrated sinus rhythm, a prominent biphasic p-wave, and occasionally prolonged interval between the beginning of the electrocardiographic wave representing ventricular depolarization and the end of the T-wave (QT, QTc up to 594 milliseconds) (Figure 1A). Transthoracic echocardiogram revealed normal ventricular dimensions and systolic function with biatrial dilatation (left > right) (Figure 1B), dilated pulmonary veins, and abnormal diastolic filling. Cardiac magnetic resonance imaging with gadolinium confirmed dilatation of the atria, pulmonary veins, and inferior vena cava with normal ventricular size, mass, and ejection fraction without enhancement suggestive of infarction, inflammation, or fibrosis. Pericardium was of normal thickness.

Box Section Ref ID

Idiopathic restrictive cardiomyopathy (iRCM)

B. Start diuretic, implant cardioverter defibrillator, and evaluate for cardiac transplantation

The key to this diagnosis was recognizing the pattern of progressive, nonspecific cardiac symptoms, abnormal electrocardiogram, and echocardiographic hallmarks of restrictive ventricular filling with normal systolic function. Cardiac catheterization confirmed left ventricular end diastolic pressure of greater than 20 mm Hg (Figure 2) and cardiac output of 1.5 L/min/m². Atrial fibrillation is very unusual in children and young adults and always warrants investigation for underlying pathology. This rare form of cardiomyopathy usually presents in childhood and has poor prognosis.^1,2 Without heart transplantation, few patients survive into adult life. Deaths result from heart failure, thromboembolic events, and arrhythmia.^1,2

In 2013, the World Heart Federation endorsed the new MOGES classification system: Morpho-functional, Organ involvement, Genetic/familial inheritance, Etiology, and heart failure Stage.³ By this nomenclature, our patient would be: M_R, O_H, G_N, E_G-Neg, and S_D-3. Readers are likely more familiar with phenotypical classification, where RCM is characterized by normal or decreased volume of both ventricles associated with biatrial enlargement, normal left ventricular wall thickness, impaired ventricular filling with restrictive physiology, and normal (or near normal) systolic function. Dyspnea, exercise intolerance, fatigue, palpitations, and syncope are frequent presenting features. Physical examination is often normal. Echocardiography often demonstrates marked biatrial enlargement with normal ventricular dimensions and systolic function. Cardiac catheterization typically reveals elevated left ventricular end diastolic pressure, capillary wedge, and atrial pressures along with reduced cardiac output.¹ Cardiac biopsy is considered unnecessary for diagnosis. Genetic pleiotropy, where 1 gene influences 2 or more phenotypically different traits, is common in patients with RCM and patients may develop hypertrophy with time.⁴ Transplant-free survival is usually limited to a few years.⁵ However, most series include outliers (such as our patient) and those with an overlapping RCM/hypertrophic cardiomyopathy phenotype may do somewhat better than those with pure RCM.² Elevated pulmonary artery pressures and pulmonary vascular resistance are frequent, and assessment for transplantation should be initiated prior to hemodynamic deterioration.⁵

The patient obtained limited benefit from diuretics. Owing to the risk of thromboembolism, her estrogen-containing contraceptive was switched to a progesterone-only formulation and warfarin recommenced. An implant cardioverter defibrillator was implanted to mitigate the risk of sudden cardiac death. Genetic screening for cardiomyopathy and long QT were negative. Over the following year, the patient reported progressive decline in exercise tolerance, confirmed by further reduction in peak oxygen consumption and a fall of blood pressure on exertion. Pulmonary artery pressures remained stable on serial hemodynamic assessment. Seventeen months after initial presentation, she underwent successful cardiac transplant. As expected, examination of the explanted heart demonstrated biatrial dilatation, variable degree of myocyte hypertrophy, interstitial fibrosis, and myofibril disarray. After cardiac transplant, her exercise capacity improved and she recommenced university to complete her studies. We present an interesting and unusual case of iRCM recognized in young adulthood. Despite its rarity, it is imperative adult cardiologists are aware of this condition because it is associated with a grave prognosis and rapid decline, with early referral for transplant the only viable treatment option.

Corresponding Author: S. Lucy Roche, MB, ChB, MRCPCH, MD-Research, Toronto Congenital Cardiac Centre for Adults, Peter Munk Cardiac Center, Toronto General Hospital, 585 University Ave, Toronto, ON M5G 2N2, Canada (lucy.roche@uhn.ca).

Published Online: June 22, 2016. doi:10.1001/jamacardio.2016.0725.

Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Additional Contributions: We thank the patient for granting permission to publish this information.