Laurie Thomas
2015 Feb 24 11:58 a.m. (7 days ago)
Clinical studies of chronic fatigue syndrome are plagued by serious problems in the inclusion/exclusion criteria. These problems stem from the fact that the syndrome consists of nonspecific symptoms that are "medically unexplained." However, there is a major difference between medically
unexplained and medically
inexplicable. The symptoms of chronic fatigue syndrome can result from a serious circulatory problem that is easily overlooked. In 2003, Peckerman and coworkers showed that low cardiac output, as measured by impedance cardiography, predicts the severity of symptoms in CFS patients.[1] Miwa and Fujita found a small left ventricular size leading to low cardiac output in CFS patients with orthostatic intolerance.[2] Porter and coworkers reported that a case of femoral arteriovenous fistula causing high-output cardiac failure was originally misdiagnosed as chronic fatigue syndrome.[3]
The studies of graded exercise for management of CFS are based on the presumption that CFS is the result of laziness and deconditioning and that the solution to the problem is to persuade the patient to exercise. Yet in many reported cases, the real problem was unrecognized cardiac decompensation. This state of cardiac decompensation could account for the push-crash phenomenon (serious, prolonged adverse events from overexertion) among people with CFS. Thus, a graded exercise program that might be beneficial for the large number of people who are tired and achy because of major depressive disorder could be catastrophic for the relatively small number of people whose problem is due to cardiac decompensation. Unfortunately, the existing studies of exercise for management of CFS do not shed light on this problem. The patients whose exercise intolerance is too severe to allow them to participate in the exercise program might refuse to enroll or might be dismissed as noncompliant if they try but fail to exercise. Yet as a result of the positive results of graded exercise for subjects whose real problem is major depressive disorder, patients with unrecognized cardiac decompensation are being scolded for failing to exercise.
For ethical and scientific reasons, the protocol for a clinical study of subjects with CFS should be based on the best possible model for clinical management of CFS patients. It would begin with a careful assessment of the subject's circulatory status. This assessment should include a tilt-table test, or at least a measurement of supine, sitting, and standing pulse and blood pressure. Any circulatory problem should be addressed appropriately. (Note that once the patient's condition is found to be due to a circulatory problem, the patient no longer fits the inclusion criteria of "medically unexplained" symptoms.)
As improper diet is the most prevalent cause of chronic ill-health, the cardiology assessment should be followed by a run-in period of at least a week of optimal dietary management. Subjects should be fed a low-fat (<10% of calories), purely plant-based diet that excludes the most common causes of food allergies or intolerance syndromes (i.e., wheat, rye, barley, corn, soy, strawberries, and citrus fruits). To ensure adherence, the diet should be administered in a residential setting. This kind of low-fat, plant-based diet can bring about a significant drop in blood pressure in hypertensive patients within 7 days, even if the patients stop taking blood pressure medication at baseline.[4] This correction of hypertension results from the decrease in systemic resistance. Thus, this diet could lead to a significant improvement in circulation, which would be beneficial to patients whose symptoms are due to poor circulation, even if they are not hypertensive. Note also that the elimination of poorly tolerated foods is the only reliable way to establish that the patient's problem is due to a food intolerance. Of course, once the subject's problem has been shown to be dietary in origin, the subject no longer has "medically unexplained" symptoms and thus no longer fits the inclusion criteria for a study of CFS.
Many patients with a diagnosis of CFS are inactive, but they may be inactive because they are sick, rather than being sick because they are inactive. Thus, any study of exercise and CFS should be structured to establish the direction of causality. If a study of subjects with a diagnosis of CFS involves exercise, the outcome variables must involve some measurement of the subjects' overall activity levels, not just to assess compliance with the exercise program but to assess whether the subjects are merely wasting their energy on the exercises and thus become less able to perform activities of daily living. In that situation, the exercise program could actually decrease the subject's quality of life.
[1] Peckerman A, LaManca JJ, Dahl KA, Chemitiganti R, Qureishi B, Natelson BH. Abnormal impedance cardiography predicts symptom severity in chronic fatigue syndrome. Am J Med Sci. 2003 Aug;326(2):55-60.
[2] Miwa K1, Fujita M. Small heart with low cardiac output for orthostatic intolerance in patients with chronic fatigue syndrome.Clin Cardiol. 2011 Dec;34(12):782-6. doi: 10.1002/clc.20962. Epub 2011 Nov 28.
[3] Porter J1, Al-Jarrah Q1, Richardson S. A case of femoral arteriovenous fistula causing high-output cardiac failure, originally misdiagnosed as chronic fatigue syndrome. Case Rep Vasc Med. 2014;2014:510429. doi: 10.1155/2014/510429. Epub 2014 May 20.
[4] McDougall J1, Thomas LE, McDougall C, Moloney G, Saul B, Finnell JS, Richardson K, Petersen KM.Effects of 7 days on an ad libitum low-fat vegan diet: the McDougall Program cohort. Nutr J. 2014 Oct 14;13:99. doi: 10.1186/1475-2891-13-99.
