Background: "Small heart syndrome", previously referred to as so-called "neurocirculatory asthenia" associated with a small heart shadow on the chest roentgenogram, is characterized by weakness or fatigue even after mild exertion, palpitation, dyspnea, and fainting, many of which resemble symptoms in patients with chronic fatigue syndrome (CFS).
Methods and results: The study population comprised 42 patients with CFS younger than 40 years of age. Cardiothoracic ratio was determined on the chest roentgenogram and echocardiographic examination was performed to evaluate both the cardiac chamber size and function. "Small heart" (cardiothoracic ratio < or = 42%) on the chest X-ray photograph was noted in 26 (62%) of the study CFS patients. Echocardiographic examination demonstrated significantly smaller mean values of both the left ventricular (LV) end-diastolic and end-systolic dimensions, stroke volume indexes and cardiac indexes in CFS patients with "small heart" than in those without it and also in 20 control subjects. Thus, CFS patients with "small heart" had an actually small LV chamber and poor cardiac performance. During a long follow-up period of 10 CFS patients with "small heart", all echocardiographic parameters mentioned above improved and cardiothoracic ratios increased significantly during the remission phase as compared with exacerbation phase.
Conclusions: "Small heart" on the chest X-ray photograph was prevalently noted in CFS patients. Echocardiographic examination revealed that CFS patients with "small heart" had an actually small LV chamber and poor cardiac performance. Cardiac functional changes evaluated by repeated examinations appeared to be directly associated with the severity of their symptoms. Small heart syndrome with impaired cardiac function may contribute to the development of CFS through low cardiac output as a constitutional factor.