Book Review

Oral Anticoagulants

N Engl J Med 1997; 337:432-433August 7, 1997

Article

Oral Anticoagulants
Edited by Leon Poller and Jack Hirsh. 280 pp., illustrated. London, Arnold, 1996. (Distributed by Oxford University Press, New York.) $125. ISBN: 0-340-55266-2

Venous thromboembolism and arterial thromboembolism are leading causes of morbidity and mortality in the developed countries. During the past two decades, there has been substantial progress in understanding the mechanisms of thromboembolism, in clinical management, and in prophylaxis. Oral anticoagulants have been used for more than 50 years, but their role in treating and preventing thromboembolism has recently been greatly expanded. There are two reasons for this: excellent randomized clinical trials that have shown the efficacy of these drugs in, for example, reducing the risk of stroke in patients with atrial fibrillation, and the development of standardized methods to measure prothrombin time and set safe therapeutic ranges. The editors of this book, experts in oral anticoagulation, state in the preface that a comprehensive book on the subject is very timely. I agree. The authors of the various chapters have made salient contributions to our understanding. The first eight chapters give basic information on the discovery, mechanism of action, pharmacology, and monitoring of oral anticoagulant treatment. The chapter on the fascinating history of the field nicely describes the days of discovery in the 1930s and the key actors. The chapter on mechanisms provides a well-illustrated discussion of the hemostatic system, the vitamin K–dependent factors, and the impairment of blood coagulation caused by oral anticoagulants. The table appended to it showing the vitamin K content of foods is, however, disproportionately exhaustive (nine pages). The informative chapters on pharmacokinetics and drug interactions provide key references. Unfortunately, neither the chapter on monitoring nor any other chapter reviews the simple devices to monitor prothrombin time that are now used in outpatient clinics and by patients at home.

The remaining 14 chapters thoroughly review the benefits and risks of oral anticoagulants in a wide spectrum of clinical circumstances. The chapter on prophylaxis and treatment of venous thromboembolism provides not only an in-depth review but also information on important practical matters. The chapter on the prevention of stroke contains a superb review of vasculopathies that result in stroke and is well illustrated. In the other chapters in this part of the book, the reader will find updated information about the use of oral anticoagulants in patients with atrial fibrillation, valvular dysfunction, myocardial infarction, and cardiomyopathy, and there are good answers to questions about the use of anticoagulants during pregnancy, in childhood, and in the elderly. The weakness of this section is the redundancy stemming from the editors' choice of overlapping topics. For instance, the use of oral anticoagulants in atrial fibrillation is reviewed in chapters 10, 13, 14, 15, and 20. And hemorrhagic complications are specifically reviewed in chapter 15, but also in chapters 10, 13, and 19. The combined use of oral anticoagulants and antiplatelet therapy is covered in detail in chapter 20 and in a more restricted manner in chapters 12, 14, and 15. In two instances the redundancy has resulted in different approaches to controversial issues or, in my view, a mistake. Chapter 3 states that exposure to warfarin at any time during pregnancy is associated with central nervous system abnormalities, but chapter 16 advises that treatment should be avoided only between weeks 6 and 12 and after the 36th week of gestation. Chapter 14 correctly states that to reverse the effect of oral anticoagulants, doses of 5 mg or more of vitamin K may render the patient resistant to warfarin for up to one week, but chapter 15 advises that a 5-mg dose of vitamin K allows anticoagulant therapy to be continued.

Despite these minor weaknesses, the book is a notable compilation of information, approaches, guidelines, and references. It will be much appreciated by physicians in almost all disciplines, by interested scientists, and by professionals in laboratory medicine.

Uri Seligsohn, M.D.
Sheba Medical Center, Tel Hashomer 52621, Israel