Chronic fatigue syndrome and abnormal heart function.

An August 2003 study, performed by Arnold Peckerman, PhD, and colleagues, found a correlation between poor cardiac function and symptom severity in people with chronic fatigue syndrome (CFS). In this study, the authors explain that previous research had identified circulatory-related problems in CFS patients such as autonomic dysfunction, lower plasma volume and/or red cell mass, neurohormonal abnormalities that affect circulation, post-exercise reduction in brain blood flow (using nuclear imaging), and reduced blood flow in exercising muscles (using magnetic resonance spectroscopy). This information caused Dr. Peckerman and colleagues to hypothesize that people with CFS have reduced cardiac output. They collected symptom data and measured cardiac output using impedance cardiography in 38 people with CFS and 27 matched, sedentary controls.

In Peckerman's study, heart stroke volume and cardiac output were significantly lower in 18 of 38 CFS patients. These patients also reported the most severe symptoms (ratings [greater than or equal to] three on a scale of zero to five). They had a higher percentage of severe ratings for post-exertional fatigue, joint pain, headache, swollen lymph nodes, fever-chills, and sore throat, compared to the remaining CFS patients and controls. The study's authors report that "post-exertional fatigue and flu-like symptoms ... were predictive of lowered cardiac output (p<0.0002) .... neuropsychiatric symptoms showed no specific association with cardiac output." Heart rate and mean arterial blood pressure were similar in the three groups.

In an interview conducted by Mark Giuliucci, Dr. Peckerman explains that CFS patients do not show the clinical signs of hypoperfusion, in which cardiac output cannot meet metabolic demand. Nonetheless, he believes that the reduced blood flow found in CFS patients may have clinical significance. Dr. Peckerman took part in another study that used cardiac stress testing. Preliminary evidence from that test indicates that some CFS patients have heart failure.

Why do some people with CFS develop heart failure? Dr. A. Martin Lerner believes that chronic mononucleosis infection in the heart leads to left-ventricular dysfunction in a large subset of CFS patients. Dr. Lerner owns "U.S. patents for the diagnosis of ME/CFS in the chronic mononucleosis subset of this disease using 24-hour Holter monitoring," according to Myalgic Encephalomyelitis Society of America. Paul Cheney, MD, PhD, hypothesizes that mitochondrial dysfunction and low ATP energy in the heart, not chronic infection in itself, lead to diastolic cardiomyopathy. "Many of the symptoms of CFS could be explained by heart failure ...," Dr. Sarah Myhill writes in her explanation of Dr. Cheney's mitochondrial hypothesis. "Cardiologists and other doctors are used to dealing with heart failure due to poor blood supply to the heart itself. In CFS, the heart failure is caused by poor muscle function...." Mitochondria, including those in the heart's cells, are simply not producing enough energy (ATP).

Denoon D. Abnormal heart pumping after exercise linked to chronic fatigue syndrome. WebMD Medical News. April 14, 2003. Available at: www.webmd.com/news20030414/trickly-heart-may-cause-chronic-fatigue. Accessed November 21, 2007.

Giuliucci M. Cardiac output linked to severe CFS cases. Available at: www.cfids.org/archives/2003rr/2003-rr2-article01.asp. Accessed November 26, 2007.

Myalgic Encephalomyelitis Society of America. Cardiac insufficiency hypothesis. Available at: www.cfids-cab.org/MESA/Lerner.html. Accessed November 21, 2007.

Myhill S. CFS is heart failure secondary to mitochondrial malfunction. Available at: www.drmyhill.co.uk/article.cfm?id=373. Accessed November 21, 2007.

Peckerman A, Lamanca JJ, Dahl KA, et al. Abnormal impedance cardiography predicts symptoms severity in chronic fatigue syndrome. The American Journal of the Medical Sciences. August 2003: 326(2):55-60. Available at www.cfidscab.org/MESA/Peckerman.pdf. Accessed November 26, 2007.