Reducing risk after cardiac surgery
by Amanda Chase, PhD
March 24, 2020
Atrial fibrillation (AF) is an irregular heartbeat that can lead to an increase in the risk for strokes, heart failure, and/or other heart-related complications. AF that develops after cardiac surgery (post-operative atrial fibrillation, POAF) is the most common complication for these patients. The overall rates of POAF have persisted over the last decade despite significant attempts to develop an intervention. A team at Stanford University, let by first author Terrence Pong, MD, PhD, and senior author Anson Lee, MD, Assistant Professor of Cardiothoracic Surgery, recently carried out a clinical trial addressing the need for interventions. The results were published in the Journal of the American College of Cardiology.
The irregular heartbeat of AF is a result of the atria and ventricles (heart chambers) contracting out of sync, rather than at the same time. This disrupts normal blood flow, leading to the increased risk for stroke, blood clot, or heart failure. Patients with POAF are at an increased risk of morbidity, mortality, length of hospital stay, and corresponding health care costs. Decreasing incidence of POAF will be imperative to improving patient quality of life following cardiac surgery.
The team from Stanford proposed to combine a test to determine those at risk for POAF with treatment targeted towards those higher-risk patients. They were able to recruit 115 patients who were undergoing cardiac surgery for the first time and had no history of AF. As part of the surgery, the surgeon stimulated the right atrium of the heart with a pacemaker to determine how sensitive the heart was to developing AF. Those patients who did not have inducible AF were treated with standard care. For those patients who were more susceptible to AF, half were randomize to standard care and the other half to an FDA-approved drug proposed to decrease POAF (amiodarone). Based on the results from the clinical trial, the Stanford team was able to conclude that surgeons were able to predict patients at highest risk for POAF using the test during the surgery. They were also able to show that the amiodarone therapy significantly decreased the rate of POAF in the patients identified to be at a higher risk. The ability to identify patients who get the most benefit from amiodarone will likely decrease the rate of hospital readmissions for those patients, while providing a prevention strategy to help lessen the incidence of POAF.
Other authors include Kevin Cyr; John Niesen, RN; Joy Aparicio-Valenzuela; Cody Carlton; Michael Fischbein, MD, PhD; Joseph Woo, MD; and Jack Boyd, MD, all affiliated with Stanford School of Medicine. Funding was provided, in part, by the Stanford Cardiovascular Institute.