The Cardiology Report

This edition of The Cardiology Report focuses on the mechanisms of action of warfarin and the newer oral anticoagulants; the pathophysiology and treatment of atrial fibrillation; the evidence supporting the use of oral anticoagulants in patients with atrial fibrillation, as well as deep venous thrombosis and pulmonary embolism; and the issues surrounding their use in clinical practice.

VIEW Report

Dr. CannonThe American Heart Association (AHA)’s Scientific Sessions is one of the largest annual meetings in the United States of scientists, researchers, physicians, nurses, and other healthcare workers involved in studying or treating patients with cardiovascular disease and stroke. Each year, over 17,000 health professionals and 22,000 total attendees receive and share information emerging from basic research, laboratory studies, and clinical trials. Experts speaking at the November 2011 gathering in Orlando, Florida, delivered over 4,000 presentations covering the prevention, diagnosis, and treatment of cardiovascular disease and its sequelae from the perspectives of different researchers and healthcare providers.

This edition of The Cardiology Report focuses on the prevention of stroke and systemic embolism in patients with atrial fibrillation (AF) and management of deep venous thrombosis (DVT) and other thrombotic disorders in patients at risk. The authors of this report—all senior cardiology fellows at leading medical institutions—cover the physiologic phenomena that ultimately lead to stroke and describe current strategies for preventing thrombotic disease in patients with AF via surgical techniques and anticoagulation therapy. Further, they summarize the results of important clinical trials that have contributed immeasurably to our understanding of thrombosis-based disease and its optimal treatment. Finally, these reports offer a glimpse at future therapies and research directions.

Understanding the impact and origins of thrombotic disease provides the background necessary for clinicians to offer their patients the best care possible. Payal Kohli, MD, from Brigham and Women’s Hospital and Harvard Medical School in Boston, provides an overview of the impact of AF in the United States and around the world. This report covers current knowledge about the triggers of AF and the body’s responses to these catalysts. Dr. Kohli shares information on the electrophysiologic mechanisms of AF and the efficacy of ablative techniques in correcting the arrhythmia. In addition, the article describes the advantages and disadvantages of rhythm and rate control in managing AF and the use of anticoagulants as a main strategy to prevent stroke and thromboembolism.

Ravi Marfatia, MD, from the University of Connecticut School of Medicine in Farmington, follows this theme with a summary of presentations devoted to anticoagulation in treating patients with AF. This report begins with currently used risk-stratifying schemes and the considerable differences in management recommendations that physicians find when they weigh therapeutic options.

After discussing factors that discourage warfarin therapy, Dr. Marfatia describes the actions of the direct thrombin inhibitor dabigatran and the factor Xa inhibitors rivaroxaban, apixaban, betrixaban, and edoxaban and discusses the results of clinical studies comparing the safety and efficacy of these drugs with those of warfarin.

A closer look at the newer anticoagulants approved by the US Food and Drug Administration and in late stages of clinical development provides insight into the future of AF therapy. Satyam Sarma, MD, from Northwestern University’s Feinberg School of Medicine in Chicago, reports on the usefulness of direct factor Xa inhibitors in providing oral anticoagulation without the need for frequent and continued blood monitoring. Direct thrombin inhibitors allow convenient oral administration and offer a more predictable dose response than do vitamin K antagonists such as warfarin. Comparisons of direct factor Xa inhibitors with warfarin help differentiate these drugs. Recently published studies provide crucial information on anticoagulants used in patients with AF, DVT, and pulmonary embolism and the advantages and disadvantages of different drug types. In addition, Dr. Sarma summarizes findings from the recently completed Apixaban Dosing to Optimize Protection from Thrombosis (ADOPT) trial, which compared the ability of apixaban with that of enoxaparin in preventing DVT and pulmonary embolism by prolonging prophylaxis of venous thromboembolism in patients at high risk.

These first three articles set the stage for a glimpse into the future of anticoagulation therapy as reported by Suraj Kapa, MD, from the Hospital of the University of Pennsylvania in Philadelphia. Clinicians often are torn between short-and long-term anticoagulation schemes. The need for close monitoring during warfarin therapy, owing to its narrow therapeutic window and multiple food and drug interactions, has resulted in the underutilization of oral anticoagulant therapy and poor patient adherence.

Newer oral anticoagulants are more targeted and cause more predictable responses than warfarin, and clinical trials comparing these drugs to warfarin have produced interesting and promising results. Dr. Kapa reviews the known advantages and disadvantages of these agents, their mechanisms of action, and ongoing research into how their anticoagulant effects can be reversed when needed. In addition, Dr. Kapa recounts how warfarin therapy may become more patient-friendly, what factors must be considered when switching patients from warfarin to a newer anticoagulant, and why these novel drugs may become the standard of care for treating AF and DVT.

Dr. Cannon is a Senior Investigator in the TIMI Study Group, Cardiovascular Division, Brigham and Women’s Hospital, and Professor of Medicine, Harvard Medical School, Boston, Massachusetts.

Bristol-Myers Squibb/Pfizer

This activity is supported by an educational grant from Bristol-Myers Squibb and Pfizer Inc.