Advances in anticoagulation in patients with atrial fibrillation

Atrial fibrillation (A-fib) is one of the main risk factors for stroke. For a long time, vitamin K antagonists (VKA) such as warfarin were the drugs of choice in anticoagulation therapy for A-fib. Today, however, the ESC guideline recommends new oral anticoagulants (NOAC) for patients with A-fib in the majority of cases.

Real-World data not yet informative enough

Atrial fibrillation (A-fib) is one of the main risk factors for stroke. For a long time, vitamin K antagonists (VKA) such as warfarin were the drugs of choice in anticoagulation therapy for A-fib. Today, however, the ESC guideline recommends new oral anticoagulants (NOAC) for patients with A-fib in the majority of cases.

Warfarin reduces the risk of stroke by up to 64%, but often severe side effects, such as bleeding, occur during this treatment. All the greater is the progress that the so-called new oral anticoagulants (NOAC) are now bringing.

Studies show that NOAC reduces a patient's risk of stroke by a further 19% compared to warfarin. In addition, NOAC reduces bleeding and the overall side effect profile appears to be more favorable than warfarin. For these reasons, NOAC is now preferred to warfarin in order to reduce the risk of stroke in A-fib patients.

A-fib: a disease with many unknowns

However, A-fib patients suffer more frequently from a variety of comorbidities, which are nevertheless only inadequately reflected in the current study landscape. Examples include A-fib + ACS (acute coronary syndrome), subclinical forms of A-fib and patients with A-fib and simultaneous renal disease.

Patients with chronic kidney failure and A-fib generally have a higher, simultaneous risk of bleeding and stroke. So how do these patients anticoagulate? In addition, there are currently no approaches as to how dialysis patients could be treated with A-fib.

In the case of subclinical A-fib, it should first be borne in mind that the more efforts are made by doctors to find subclinical A-fib patients, the more cases can automatically be detected. Nevertheless, it is therapeutically relevant whether the A-fib episode was shorter or longer than 24 hours. Caution: Anticoagulation is recommended only for patients whose subclinical A-fib has lasted longer than 24 hours.

Real-world data: Where RCT studies are missing

In order to be able to better answer such questions in therapy, where RCT is missing, clinical real-world data must be used. But beware: Real-World data is always based on selected data sets and methods and therefore usually does not allow general conclusions to be drawn about the underlying correlations.

Current real-world data, for example, show that the use of NOAC depends on patient characteristics, among other things: For example, a trend has emerged that Apixaban is used more in older patients, in patients with chronic kidney failure or with a history of repeated severe bleeding events.

In addition, real-world observations also partly coincide with the findings of the large RCTs. In practice, Apixaban vs. VKA showed similar positive effects on risk reduction for stroke and severe bleeding as in the ARISTOTLE study.

Conclusion

The introduction of NOAC in A-fib therapy has further improved patient outcomes in stroke prevention and reduction of bleeding events. Therefore, NOAC is now also the preferred therapy for these patients according to the current ESC guideline.

Nevertheless, there are still a number of A-fib patients who are not or only insufficiently mapped in the available RCTs. Here it is currently necessary to use real-world data which, however, for the NOAC group in particular, often produce results that are surprisingly close to the RCT. However, these data should always be interpreted with the necessary caution, as Real World data are always subject to bias due to the pre-selection of specific patient groups or treatment methods.

Source:
"Advances in anticoagulation to improve patient care in atrial fibrillation" (Organizer: Bristol-Myers Squibb and Pfizer Alliance), 26.08.2018, ESC 2018, Munich.