Author + information
- Svend Aage Mortensen, MD, DSc, FESCa
Lack of effect from treatment with coenzyme Q10 in congestive heart failure is not an objective title or conclusion for the study by Watson et al. (1) in which the main limitation obviously is their sample size and its lack of study patients. Even so, the investigators state in their introduction that previous studies with coenzyme Q10 “lack credibility because of small sample sizes, lack of controls, etc.”
The majority of the 27 study patients, who were not classified according to the New York Heart Association (NYHA), were seemingly at late-stage disease (mean length of symptoms 3.4 years). Mean patient age was 55 years, which is compatible with predominantly ischemic origin. This was also recently confirmed at an International Conference in Sydney, Australia—“Oxidative Pathways in Health and Disease”—in a lecture by one of the co-authors, Nicholas Bett (2). However, according to the Watson et al. (1) study, in the Patients’ Demographics in Table 1, 77% of the patients were listed as having dilated cardiomyopathy. This is a patient clientele that is, at least partially, prone to respond either spontaneously or to medical intervention with subsequent improvement of myocardial function.
Conversely, it is well-known that changes—and not least improvements—in echocardiographic parameters of left ventricular (LV) function are minimal in late-stage disease, especially in heart failure due to ischemic heart disease. This is why the calculated number of patients necessary (n = 17) in this cross-over trial seems highly underestimated.
In a nearly threefold larger trial of 79 patients from Scandinavia, the same double-blind, cross-over design was used over two periods of three months on coenzyme Q10 100 mg/day or placebo. The beneficial results of this study were presented initially at The American College of Cardiology Meeting in 1992 (JACC 1992;19:216A, abstract 774–6) and later published in the Journal of Cardiac Failure(3). Watson et al. (1) have not included this trial in their reference list.
In the Scandinavian Multicenter Study, a balanced randomization was used with respect to the diagnosis of ischemic versus nonischemic disease and the treatment with or without an angiotensin-converting enzyme inhibitor. There was a slight improvement on LV ejection fraction at volume load based on the results from the MUGA scans (p = 0.025). Maximal exercise capacity increased slightly but significantly (p = 0.016) and coenzyme Q10 mediated a significant decrease in the scoring for dyspnea (p = 0.007) and leg fatigue (p = 0.04) at end-exercise (using the Borg-scale). According to the scoring from the Quality of Life Questionnaire, the total score (p = 0.016), the physical activity level (p = 0.048) and the life satisfaction (p = 0.016) increased significantly during the coenzyme Q10 period.
During the last 15 years, only 2 of 12 double-blind heart-failure trials have been “neutral” (i.e., without positive effect or side effects), whereas the remaining 10 studies have been positive and statistically significant with respect to improvement in clinical and or hemodynamic parameters (4). In Watson and colleagues’ “neutral study,” adequate methods to assess myocardial function were used, but obviously the trial was insufficiently powerful to confirm or reject the hypothesized increase in LV function.
- American College of Cardiology
- Watson P.S.,
- Scalia G.M.,
- Galbraith A.,
- Burstow D.J.,
- Bett N.,
- Aroney C.N.
- ↵Waston PS, Scalia GM, Galbraith A, Burstow DJ, Bett N, Aroney CN. Lack of effect of coenzyme Q10 on left ventricular function in patients with congestive heart failure. Proceedings from an International Symposium: Oxidative Pathways in Health and Disease, University of Sydney, Australia, December 1–4, 1999.
- ↵Hofman-Bang C, Rehnquist N, Swedberg K, Wiklund I, Åström H, for the Q10 Study Group. Coenzyme Q10 as an adjunctive in the treatment of chronic congestive heart failure. J Card Fail 1995;1:101–7.