Preventing Stroke in Atrial Fibrillation

In this issue of Cardiovascular Consults, we continue to explore stroke prevention for patients with atrial fibrillation. This topic has been receiving a good deal of attention lately, especially with the presentation and publication of the results of two large randomized clinical trials of new anticoagulants for this indication.

As Michael D. Ezekowitz, MD, points out in his insightful interview, clinicians are being presented with multiple therapeutic alternatives for atrial fibrillation. In the absence of head-to-head trials, physicians will need to make their best judgment about the relative value of each component of therapy for individual patients.

The process should begin, as Deepak L. Bhatt, MD, tells us, with the most fundamental decisions regarding rate versus rhythm control. As he explains, overextrapolation of the results of the many strategy trials carried out over the last decade have led some to eschew rhythm control in favor of the much simpler and cheaper approach of rate control. However, Dr. Bhatt correctly opines that neither strategy should be chosen based on the issue of anticoagulation alone, for it has become clear that the risk of stroke in patients with atrial fibrillation is independent of rhythm status, at least as it is currently assessed, but is a function of vascular risk.

As several of the contributors to this issue posit, our tools for assessing vascular risk need to be refined in order to provide maximum benefit without exposing patients to an undue risk of bleeding, highlighted so well in the case study from Evan Adelstein, MD. As Dr. Adelstein further points out in his essay, we also need better methods to assess the risk of bleeding, especially in our high-risk elderly patients, so as to accurately quantify benefit and risk in these susceptible individuals.

In addition to risk stratification, we also wish for better noninvasive tools to understand the underlying disease process. The ability to image the heart and its contents will necessarily lead to focused therapies. Itzhak Kronzon, MD, points out that the amazing success of transesophageal echocardiography, which has permitted prompt and safe cardioversion of atrial fibrillation, serves as a shining example of how low-risk procedures can optimize management of this complex disease.

As Dr. Ezekowitz states in his interview, we should expect a marked improvement in our ability to prevent strokes in our atrial fibrillation patients. However, we cannot be complacent. A number of questions remain. How should these new drugs be used in patients who require cardioversion or after open heart surgery? Though monitoring is not a requirement with the new agents, how will we assess the intensity of anticoagulation or drug adherence when we really need to know? What can be done to reverse anticoagulant effect in an emergency situation? When can we appropriately assume that we know everything there is to know about the new drugs such that unexpected side effects are not an issue? How do we justify the increased costs of the drugs, and how can we make them available to all of our patients, regardless of their means?

The future of AF therapeutics is bright, but with innovation comes consternation. Our success will be predicated on an aggressive approach to educate our colleagues, professional staffs, trainees and patients. We are off to a good start, but we have miles to go.