Recurrent dilated cardiomyopathy reversed with conversion of atrial fibrillation

Tachycardia-Induced Cardiomyopathy in a Young Adult: The Significance of Early Diagnosis and Treatment

Tachycardia-induced cardiomyopathy (TIC) is gradually gaining the attention it deserves as one of the most common causes of reversible cardiomyopathy. Although TIC appears common, there has been limited data, especially among young adults. Patients with tachycardia and left ventricular dysfunction should be suspected of having TIC, with or without established etiology of heart failure, because TIC can develop by itself or contribute to cardiac dysfunction. We present a case of a previously healthy 31-year-old woman with persistent nausea and vomiting, poor oral intake, fatigue, and persistent palpitations. Vital signs at presentation were significant for tachycardia of 124 beats per minute, which she reported was similar to her baseline heart rate of 120s per minute. There were no apparent signs of volume overload at the presentation. Labs were significant for microcytic anemia with hemoglobin/hematocrit of 10.1/34.4 g/dL, and mean corpuscular volume was low at 69.4 fL; other labs were unremarkable. Transthoracic echocardiography obtained at admission was significant for mild global left ventricular hypokinesis, systolic dysfunction with an estimated left ventricular ejection fraction of 45-50%, and mild tricuspid regurgitation. Persistent tachycardia was suggested as the primary cause of cardiac dysfunction. The patient was subsequently started on guideline-directed medical therapy, including beta blockers, angiotensin-converting enzyme inhibitors, and spironolactone, with eventual normalization of the heart rate. Anemia too was also treated. Follow-up transthoracic echocardiography done four weeks after was notable for significant interval improvement in left ventricular ejection fraction of 55-60%, with a heart rate of 82 beats per minute. The case illustrates the need for early identification of TIC regardless of the patient's age. It is essential that physicians consider it in the differential diagnosis of new-onset heart failure because prompt treatment leads to the resolution of symptoms and improvement of ventricular function.

Tachycardia-induced Cardiomyopathy (Tachycardiomyopathy)

The term tachycardia-induced cardio-myopathy or tachycardiomyopathy refers to impairment in left ventricular function secondary to chronic tachycardia, which is partially or completely reversible once the tachyarrhythmia is controlled. Tachycardia-induced cardiomyopathy has been shown to occur both in experimental models and in patients with incessant tachyarrhythmia. Data from several studies and from case reports have shown that rate control by means of cardioversion, negative chronotropic agents, and surgical or catheter-based atrio-ventricular node ablation, resulted in significant improvement of systolic function. The diagnosis of tachycardia-induced cardiomyopathy is usually made following observation of marked improvement in systolic function after normalization of heart rate. Clinicians should be aware that patients with unexplained systolic dysfunction may have tachycardia-induced cardiomyo-pathy, and that controlling the arrhythmia may result in improvement of systolic function.

Left Ventricular Dysfunction in Atrial Fibrillation: Restoration of Sinus Rhythm by the Cox-Maze Procedure Significantly Improves Systolic Function and Functional Status

BACKGROUND

Atrial flutter or fibrillation with rapid, uncontrolled ventricular response may lead to left ventricular dysfunction, and conversion to sinus rhythm with control of heart rate can improve left ventricular ejection fraction. Little is known about the effects of the Cox-maze procedure on this form of tachycardia-induced cardiomyopathy.

METHODS

Four hundred forty-three patients underwent the Cox-maze procedure from 1993 to 2002. Ninety-nine had atrial flutter or fibrillation without associated valvular or congenital heart disease, and 37 (37%) had decreased left ventricular function (ejection fraction < 0.35 in 11 [severe], ejection fraction 0.36 to 0.45 in 8 [moderate], and ejection fraction 0.46 to 0.55 in 18 [mild]). Ages of these 37 patients (34 male) ranged from 35 to 74 years (median, 55 years).

RESULTS

Atrial flutter or fibrillation was present for 3 months to 19 years (median, 48 months) preoperatively, and 24 patients (65%) exhibited symptoms of heart failure. Preoperative ejection fraction ranged from 0.25 to 0.55 (median, 0.45). At last follow-up (median, 63 months), the Cox-maze procedure eliminated atrial flutter or fibrillation in all but 1 patient, and the greatest improvement was observed in patients with severe preoperative impairment (0.31 to 0.53; p = 0.01, preoperative versus follow-up), and patients with preoperative chronic atrial flutter or fibrillation (0.43 to 0.55; p < 0.05 preoperative versus follow-up). This improvement was observed immediately postoperatively and was sustained at last follow-up. Further, improvement in left ventricular function correlated with enhancement of functional status.

CONCLUSIONS

In some patients, atrial flutter or fibrillation may be the cause rather than the consequence of left ventricular dysfunction. Importantly, systolic function and functional status can be significantly improved with the restoration of sinus rhythm by the Cox-maze procedure.

Usefulness of low-dose dobutamine stress echocardiography in predicting recovery of poor left ventricular function in atrial fibrillation dilated cardiomyopathy

Assessment of contractile reserve was performed in 16 patients with dilated cardiomyopathy and chronic atrial fibrillation. In this prospective study, low-dose dobutamine echocardiography could predict recovery of left ventricular dysfunction and could identify tachycardiomyopathy before restoration of sinus rhythm.