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Atrial fibrillation – Prognosis in heart failure and risk during interruption of anticoagulant treatment

Jakob Raunsø

Summary

More than 50,000 persons in Denmark have atrial fibrillation mak-ing it the most common arrhythmia requiring treatment. Atrial fibrillation is associated with an increase in mortality, primarily due to an increased risk of thromboembolic complications but also attributable to a possible impact of atrial fibrillation on other con-ditions such as heart failure.  Thromboprophylaxis with anticoagulant treatment is a corner-stone in the treatment of atrial fibrillation while risk stratification and prognosis assessment are other important aspects of a com-plete treatment plan for the patients.  

Atrial fibrillation and heart failure are two disease entities with a complex interplay and it is controversial in the literature whether atrial fibrillation has a direct prognostic impact in heart failure patients. Specifically, the relationship between prognostic impact of atrial fibrillation and the aetiology of heart failure has not been established. Echocardiography is an essential tool for prognosis assessment in a heart failure population and particularly evaluation of diastolic dysfunction has received attention in the recent years.  Shortened mitral deceleration time (restrictive filling pattern) is a prognostic marker in patients with heart failure, however, its use has been limited to patients with sinus rhythm due to concerns about the varying R-R interval and, hence, the varying filling pat-tern of the left ventricle in patients with atrial fibrillation. It is unknown if the measurement of mitral deceleration time is of prognostic value in an atrial fibrillation population.

 Anticoagulant treatment is indicated in all patients with atrial fibrillation at increased risk of thomboembolic events. However, this is counterbalanced by the increased risk of bleeding when treated with anticoagulants. Many patients interrupt anticoagulant treatment for shorter or longer durations due to the bleeding risk. Interruption of treatment can be detrimental as there is biochemi-cal evidence of a hypercoagulable state shortly after interruption of anticoagulant treatment but it is not clear if this translates into clinical thromboembolic events.

The purpose of this PhD-thesis was 1) to determine if an echo-cardiographic assessment of mitral deceleration time can be used as a prognostic marker in patients with atrial fibrillation; 2) to clarify the prognostic impact of atrial fibrillation in a heart failure population in relation to the aetiology of heart failure; and 3) to investigate the frequency of thromboembolisms or deaths in atrial fibrillation patients interrupting anticoagulant treatment.

 The findings of this thesis were that mitral deceleration time has the same prognostic value in heart failure patients regardless of the underlying heart rhythm (atrial fibrillation or sinus rhythm). In the same cohort of 3,000 heart failure patients chronic atrial fibrillation had a detrimental prognostic impact but only in a sub-group of patients with ischemic heart disease, underlining the importance of heart failure aetiology. Finally, in a nation-wide study of patients with atrial fibrillation on warfarin treatment it was shown that 2 out of 3 patients have at least one treatment interruption during ten years of follow-up and that the first 90 days of treatment interruption were associated with a tripled risk of thromboembolism or death.