Sustained hemoconcentration in patients with chronic atrial fibrillation, a potential risk for stroke and thromboembolic complications. A retrospective study

Incidence and predictors of ischemic stroke during hospitalization for congestive heart failure

Heart failure (HF) increases the risk of ischemic stroke. Data regarding the incidence and predictors of ischemic stroke during hospitalization for HF are limited. The study population of this retrospective cohort study consisted of patients with congestive HF, consecutively admitted to our center from October 2010 to April 2014. We excluded patients complicated with acute myocardial infarction, infective endocarditis, and takotsubo cardiomyopathy. We also excluded those with dialysis or mechanical circulatory support. We investigated the incidence of ischemic stroke during hospitalization for HF. Thereafter, we divided the patients without oral anticoagulants at admission into two groups: patients with ischemic stroke and those without it, and explored the predictors of ischemic stroke. A total of 558 patients (287 without atrial fibrillation (AF), 271 with AF) were enrolled. The mean age was 76.8 ± 12.3 years, and 244 patients (44 %) were female. The mean left-ventricular ejection fraction was 47.4 %. Oral anticoagulants were prescribed in 147 patients (8 without AF, 139 with AF). During hospitalization (median length 18 days), symptomatic ischemic stroke (excluding catheter-related) occurred in 15 patients (2.7 % of the total, 8 without AF, 7 with AF). Predictors significantly associated with increased risk of ischemic stroke in patients without oral anticoagulants were as follows; short-term increases in blood urea nitrogen after admission (at day 3; odds ratio (per 1 md/dl): 1.06, 95 % confidence interval (CI) 1.01-1.11, p = 0.02, and at day 7; odds ratio: 1.03, 95 % CI 1.00-1.07, p = 0.03, respectively), and previous stroke (odds ratio; 3.33, 95 % CI 1.01-11.00, p = 0.04). The incidence of ischemic stroke during hospitalization for HF was high, even in patients without AF. Previous stroke and short-term increases in blood urea nitrogen was significantly associated with the incidence of ischemic stroke.

Cardioembolic stroke in atrial fibrillation-rationale for preventive closure of the left atrial appendage

Atrial fibrillation is the most common cardiac arrhythmias, and a major cause of morbidity and mortality due to cardioembolic stroke. The left atrial appendage is the major site of thrombus formation in non-valvular atrial fibrillation. Loss of atrial systole in atrial fibrillation and increased relative risk of associated stroke point strongly toward a role for stasis of blood in left atrial thrombosis, although thrombus formation is multifactorial, and much more than blood flow irregularities are implicated. Oral anticoagulation with vitamin-K-antagonists is currently the most effective prophylaxis for stroke in atrial fibrillation. Unfortunately, this treatment is often contraindicated, particularly in the elderly, in whom risk of stroke is high. Moreover, given the risk of major bleeding, there is reason to be skeptical of the net benefit when warfarin is used in those patients. This work reviews the pathophysiology of cardioembolic stroke and critically spotlights the current status of preventive anticoagulation therapy. Various techniques to exclude the left atrial appendage from circulation were discussed as a considerable alternative for stroke prophylaxis.

Distinct increase in hematocrit associated with paroxysm of atrial fibrillation

In a previous study we found that hemoconcentration, which was identified by an increase in hematocrit, occured during a paroxysm of atrial fibrillation. In the present study we investigated the changes in hematocrit from sinus rhythm to paroxysm in 10 patients who had multiple paroxysms of atrial fibrillation in order to assess the ranges of the changes in hematocrit among the paroxysms. In these patients hematocrit was measured simultaneously with electrocardiographic recording during 3 or more paroxysms and sinus rhythm just before each paroxysm. The changes in hematocrit varied among the paroxysms. The maximum increase in hematocrit in each patient ranged from 3.5 to 8.0 points with an average of 5.1 points. Such a distinct increase in hematocrit which abruptly develops with a paroxysm of atrial fibrillation may be a potential risk for thrombus formation.