Changing Metrics, Changing Evidence: Atrial Fibrillation and Risk of Stroke
Posted January 2017
When Dr. Tom Price underwent the confirmation hearings this week as the nominee for Secretary of Health and Human Services, he was asked about the use of quality metrics by the Department of Health and Human Services to drive the quality of care in the US healthcare system. He responded by stating that he would like to focus on those metrics that are actually tied to positive outcomes and jettison those that seem to be simply busy work.
Also, this week, Medscape (Emergency Medicine, Top Journal Articles) ran two fascinating articles (URL’s below). The first is a Danish study that utilized the National Patient Registry to identify the risk of thromboembolic stroke in patients with and without atrial fibrillation relative to age, sex and other known risk factors. The results a bit surprising.
Atrial fibrillation has long been singled out as the primary culprit in thromboembolic strokes. So much so that anticoagulants have generally only been recommended for patients with atrial fibrillation for primary stroke prevention. This study indicated that atrial fibrillation was no more contributory than that hypertension, diabetes, heart failure, increasing age or any of the other risk factors for stroke. (The exception was in octogenarian females). These results challenge our standard approach to therapy and may expose the opportunity to expand the utilization of anticoagulants for stroke prevention.
The second article discusses a fascinating insight on the evolution of our thinking about the relationship between atrial fibrillation and stroke. Our dogmatic adherence to the idea that the arrhythmia itself was the thrombogenic source through local atrial hemodynamic changes that it has potentially influenced out thinking adversely. Many cryptogenic strokes have likely been attributed to an “undiagnosed” atrial fibrillation. Yet, as this article points out, there have been a number of studies that have failed to show justification for that idea in the majority of thromboembolic strokes.
The authors further explore the growing amount of evidence to suggest that atrial pathology, in the form of fibrosis, is quite possibly the culprit. Atrial fibrosis can be identified with advanced MRI technology and correlates with biopsy findings. The finding of atrial fibrosis has been shown to impact atrial dynamics and hemodynamics in the absence of atrial fibrillation. Atrial fibrosis alone appears to have better predictive value in determining who will have a future stroke than the latest screening tool (CHADS2 VASC). The atrial fibrillation may be consequence of the fibrosis in the same way that stroke may be.
In both articles, our paradigm is challenged. They are not only incredibly interesting, but they also help make a large point that ties back to Representative Price’s response. Truly, it is a larger philosophical issue in healthcare in general.
We have tried diligently to focus on “evidence-based” medicine as the standard of care. Pursue the course that has been proven by evidence of scientific investigation and rigor. We put our highest confidence in these treatments and in turn, use these for benchmark for quality care. Yet, we often see the evolution of our understanding challenge what we thought we knew. We have already seen some of the original metrics initiated by HHS fall by the wayside as they were revealed to be ineffectual or harmful.
Certainly, our understanding of complex pathology will continue to change. Our standards will evolve and our evidence continue to grow. It can become increasingly difficult to be confident in any our currently held ideologies. Best wishes to soon-to-be Secretary Price in finding the metrics that genuinely produce the positive outcomes and stand the test time.