AF is a known complication in 4% to 10% of patients with pneumonia. Stroke risk may exceed that of the general population with AF, but clear guidelines are lacking for anticoagulant treatment decisions in these patients. “Until recently, a prevailing thought has been that AF triggered by acute infection is a transient and self-terminating condition that reverses with resolution of infection,” explains Mette Søgaard, DVM, PhD, lead author of a Danish population cohort study that aimed to examine the thromboembolic risk in patients with new-onset AF following infection with pneumonia. The study included 274,196 adult patients who were hospitalized with community acquired pneumonia (CAP), with enrollment over a 10- year period. Within this group, 6,553 patients (52.0%) had new-onset AF. In patients not receiving anticoagulation, the 1-year thromboembolism risk was 2.1% in patients with AF—which “exceeds the general threshold for a net clinical benefit of anticoagulation therapy,” notes Dr. Søgaard—compared with 1.8% in those without AF (95% CI, 1.8% to 2.5%). At 3 years, the all-cause mortality rate was 49.8% in patients with CAP and new-onset AF (95% CI, 48.6% to 51.1%), compared with 25.7% (95% CI, 25.6% to 25.9%) in patients with pneumonia without AF. These findings suggest that AF and thromboembolic risk following acute infection may not be a transien phenomenon, and further risk-benefit analysis of therapeutic anticoagulation may be warranted. “Our study relates to patients hospitalized with pneumonia who develop new-onset AF in relation to this pneumonia hospitalization,” notes Dr. Søgaard. “Our findings do not necessarily relate to all patients with AF.”

In-Depth [Prospective cohort study]

The source population was drawn from three Danish linked registries. Patients with prior diagnoses of AF and treatment wit anticoagulation within 180 days were excluded, as were patients who initiated treatment or died during the landmark period of 30 days. Follow-up continued from a 30-day landmark period to a maximum of 3 years. Primary outcomes included proportions of arterial thromboembolic events that led to hospital admission (either stroke or systemic arterial embolism). Secondary outcomes were recurrent hospital or outpatient clinic contacts with AF, oral anticoagulant therapy initiation, and all-cause mortality at 1 and 3 years of follow-up. Each patient’s stroke risk was determined using the CHA2DS2- VASc score. It was found that most patients with new-onset AF had an intermediate or high CHA2DS2-VASc score (94%). Furthermore, stroke risks in patients with intermediate or high risk were 1.4% (95% CI, 1.0% to 2.0%) and 2.8% (95% CI, 2.3% to 3.4%), respectively. At 3 years, 32.9% of patients had AF at new hospitalizations (95% CI, 31.8% to 34.1%) and 14.0% had begun anticoagulation therapy (95% CI, 13.2% to 14.9%). Stroke risk at 3-year follow up was 3.5% (95% CI, 2.8% to 4.3%) in patients with intermediate risk, and 5.3% (95% CI, 4.4% to 6.5%) in those with high stroke risk, respectively. “As highlighted above, our findings suggest that new-onset AF during pneumonia is a marker of future AF,” explains Dr. Søgaard. “This implies that vigilance for recurrent AF may be warranted and that attention should be given to each episode of infection-related AF, regardless of its duration, to tailor surveillance in patients developing this complication. Second, our findings suggest that new-onset AF occurring with pneumonia is associated with a risk for thromboembolism that reaches a level at which oral anticoagulation is considered beneficial. A previous study showed that patients with resolved AF remain at higher risk for stroke than patients without AF, and the updated European guidelines (ESC 2020) state that the clinical pattern of AF (ie, first detected, paroxysmal, persistent, long-standing persistent, permanent) should not condition the indication to thrombopro phylaxis. Taken together, physicians caring for patients with pneumonia who develop AF should give attention to the AF episode and consider anticoagulation therapy based on the patient’s perceived stroke risk. At the same time, it is important to stress that the decision to initiate anticoagulation in the setting of severe infections is complex. High bleeding risk due to systemic activation of the inflammatory response and depletion of coagulation factors and platelets may outweigh the benefits of anticoagulation, making it a challenging decision that lacks high-quality evidence.”

Originally Published By 2 Minute Medicine®. Reused in Physician’s Weekly with permission. ©2022 2 Minute Medicine, Inc. All rights reserved. No works may be reproduced without expressed written consent from 2 Minute Medicine, Inc. No article should be construed as medical advice and is not intended as such by the authors or by 2 Minute Medicine, Inc.