Editor's Corner | Atrial Fibrillation: What's Next?
For many years, we’ve lived with the concept that untreated atrial fibrillation (AFib) will ultimately result in multiple strokes or heart failure due to a tachycardia-induced cardiomyopathy. Neither would be an acceptable outcome for a patient under our care. The recent literature is replete with clinical trials and other studies on AFib. Yet it’s taken nearly 200 years, and the invention of electrocardiography by Einthoven, to gain a full understanding of this arrhythmia and how to treat it.
When warfarin was developed as an anticoagulant, around 1950, an organized method for anticoagulation and its reversal with vitamin K was established. It became the norm for AFib therapy for the next 55 years until the novel oral anticoagulants were developed. However, there’s wide variation in the use of anticoagulation. The IMPACT-HF trial showed only about 50 percent of patients with AFib are treated with anticoagulation, most still use warfarin and antiplatelet agents are most common in those not taking warfarin. This has been observed in other studies over many years and points to the need for better education and other strategies to improve adherence to established treatment protocols for anticoagulation.
Most patients with AFib worldwide use warfarin. It’s incumbent on us to maintain appropriate therapeutic protocols for warfarin management. Recent data indicate therapeutic efficacy can be increased by careful attention to INR surveillance, methods to increase motivation to follow physician instructions on use of warfarin and timely follow-up of INR measurements. With careful follow-up and education, adherence rates for anticoagulation can be increased from about 60 percent to nearly 80 percent. This can translate into a significant reduction in strokes in these patients.
The direct-acting oral anticoagulants (DOACs) have been available for about six years. The clinical trials comparing DOAC therapy with warfarin have provided firm data indicating that bleeding rates are lower with DOACs than with aspirin, and stroke rates are either lower or unchanged in the face of a lower rate of bleeding. Because there are no generic versions of a DOAC, the drugs are significantly more expensive than warfarin. However, some studies have compared the cost of a DOAC with the full cost of warfarin use, including the cost of periodic INR measures and the economic burden on the patient for lost work days for testing and travel for monthly blood draws. The funding for these various components of warfarin therapy comes from different sources, making it difficult to fully assess its total cost. But it’s likely not much different than the cost of a daily DOAC. Since most insurance plans offset some of the DOAC cost, the out-of-pocket cost is acceptable to many patients as a tradeoff for abandoning the monthly blood draws, the lack of dietary restriction and the equivalent or better clinical performance of the new drugs. We’re seeing a continuous drift toward greater use of DOACs as initial therapy for AFib.
Some uncertainty remains regarding cessation of DOAC therapy for planned surgical procedures. Patients need to discuss stopping a DOAC with their physician before doing so. Most of us are now comfortable with using a DOAC for our patients with AFib. Aspirin has fallen out of favor due to its well-documented bleeding risk compared with a DOAC and lack of a substantial gain in stroke prevention compared with a DOAC.
Where do we go next? Several technical advances designed to improve detection and follow-up of AFib are emerging. Smartphone rhythm monitoring is readily available and we’re seeing wrist watches that measure heart rate and rhythm as well as blood pressure.
With the advent of DOAC therapy, it seemed reasonable to consider patients to be on lifetime therapy in a chronic state of AFib. Some clinical trials have demonstrated similar outcomes for chronic AFib compared with therapy aimed at maintaining sinus rhythm. More recent studies examining the use of left atrial ablation suggest that long-term sinus rhythm is in fact feasible after left atrial ablation. Most studies recommend continuous anticoagulation therapy even with sinus rhythm, and there’s still some uncertainty about stopping anticoagulation after some period of sinus rhythm.
Concern has arisen from long-term monitoring studies that demonstrate continued evidence of intermittent AFib that is often undetected, but still increases risk for a stroke. Ablation for AFib is a useful option that is beginning to show favorable long-term outcomes compared with persistent AFib for patients who are younger, symptomatic from the irregular rhythm or who have a persistent tachycardia on medications.
For patients who cannot take an anticoagulant, we now have the option of occluding the left atrial appendage with an implanted device that excludes the left atrial appendage from the body of the left atrium. While this procedure does not eliminate the AFib, thrombus originating in the left atrial appendage is prevented from entering the circulation. This procedure has been shown to reduce the risk of stroke in patients who cannot be anticoagulated.
We can also restore or maintain sinus rhythm in patients undergoing cardiac surgery with the Maze procedure. This procedure is often an add-on for many cardiac surgeons who are willing to spend a few minutes at the completion of a valvular or coronary procedure to disrupt the conduction pathways in the left atrium to prevent the reentrant rhythms that cause AFib. Some early studies suggest this could be an initial therapy for many patients whose AFib is difficult to manage or who are intolerant to anticoagulation.
Unlike the 1950s when our only option for oral anticoagulation was warfarin, we now have a menu of therapeutic options for patients with AFib that can be tailored to individual patient needs, which in many cases will leave the patient in sinus rhythm. This should be our goal.
Alfred A. Bove, MD, PhD, MACC, is professor emeritus of medicine at Temple University School of Medicine in Philadelphia, and a former president of the ACC.
Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Anticoagulation Management and Atrial Fibrillation, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure
Keywords: ACC Publications, Cardiology Magazine, ACC18, ACC Annual Scientific Session, Warfarin, Anticoagulants, Vitamin K, Platelet Aggregation Inhibitors, Atrial Fibrillation, Aspirin, Atrial Appendage, Wrist, Blood Pressure, Uncertainty, Motivation, Inventions, Follow-Up Studies, Goals, Health Expenditures, Heart Rate, International Normalized Ratio, Thrombosis, Stroke, Heart Atria, Electrocardiography, Tachycardia, Heart Failure, Clinical Protocols, Cardiomyopathies, Surgeons, Longitudinal Studies
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