SPECIAL SECTIONS: LETTERS TO THE EDITOR
Reply
Paul S. Watson, MB, BS, FRACPa,
Gregory M. Scalia, MB, BS, FRACPa,
Andrew Galbraith, MB, BS, FRACPa,
Darryl J. Burstow, MB, BS, FRACPa,
Nicholas Bett, MB, BS, FRACPa and
Constantine N. Aroney, MD, BS, FRACPa
a Department of Cardiology and Heart Failure and Transplant Unit, The Prince Charles Hospital, Brisbane, Australia
We thank Dr. Mortensen for his interest in our study (1). We assure him that the data we reported on patient demographics are correct—that over three-quarters of our patients suffered from dilated cardiomyopathy while the remainder had coronary heart disease. When we stated that we would require 17 patients in order to demonstrate an increase in left ventricular ejection fraction from 25% to 30% with a standard deviation (SD) of 5% using 95% confidence intervals (CI) with a power of 80% (1), we did no more than calculate the probability that our failure to show such as change (a negative study) would reflect a true lack of effort.
The design of the Scandinavian study to which Dr. Mortensen refers (2) was very similar to that of our trial. Despite having nearly three times as many patients, it also failed to show any significant difference (p < 0.05) in this primary end point. The study reported by Permanetter et al. (3) also failed to show any therapeutic effect of coenzyme Q10. Meta-analysis of clinical trials of coenzyme Q10 treatment of congestive heart failure might be seen as encouraging but cannot be taken as any more than an argument for more blinded control studies (4,5).
We agree with Dr. Mortensen that if agents such as coenzyme Q10 are to be helpful, this would more likely be demonstrable early in the course of heart failure. Unfortunately, success in treating chronic failure with angiotensin-converting enzyme inhibitors (6), beta-adrenergic blockers (7), and spironolactone (8) means that it has become increasingly difficult to recruit patients for trials of unproven agents until they have been stabilized on what must now be regarded as standard therapy.
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References
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- Watson PS, Scalia GM, Galbraith A, Burstow DJ, Bett N, Aroney CN. Lack of effect of coenzyme Q on left ventricular function in patients with congestive heart failure. J Am Coll Cardiol. 1999;33:1549–1552[Abstract/Free Full Text]
- Hofman-Bang C, Rehnqvist N, Swedberg K, Wiklund I,
 ström H. Coenzyme Q10 as an adjunctive in the treatment of chronic congestive heart failure. The Q10 Study Group. J Card Fail. 1995;1:101–107[CrossRef][Medline]
- Permanetter B, Rossy W, Klein G, Weingartner F, Seidl KF, Blomer H. Ubiquinone (coenzyme Q10) in the long-term treatment of idiopathic dilated cardiomyopathy. Eur Heart J. 1992;13:1527–1533
- Soja AM, Mortensen SA. Treatment of chronic cardiac insufficiency with coenzyme Q10: results of meta-analysis in controlled clinical trials. Ugeskr Laeger. 1997;159:7302–7308[Medline]
- Overvad K, Diamant B, Holm L, Holmer G, Mortensen SA, Stender S. Coenzyme Q10 in health and disease. Eur J Clin Nutr. 1999;53:764–770[CrossRef][Medline]
- Yusuf S, Garg R, McConachie D. Effect of angiotensin-converting enzyme inhibitors in left ventricular dysfunction: results of the studies of left ventricular dysfunction in the context of other similar trials. J Cardiovasc Pharmacol. 1993;22:S28–S35
- Heidenreich PA, Lee TT, Massie BM. Effect of beta-blockade on mortality in patients with heart failure: a meta-analysis of randomized clinical trials. J Am Coll Cardiol. 1997;30:27–34[Abstract]
- Pitt B, Zannad F, Remme WJ, et al. The effect of spironolactone on morbidity and mortality in patients with severe heart failure. Randomized Aldactone Evaluation Study Investigators. N Engl J Med. 1999;341:709–717[Abstract/Free Full Text]
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