THE THROMBOEMBOLIC RISK IN PAROXYSMAL VS. PERMANENT ATRIAL FIBRILLATION
Received for publication: 15th of May, 2013
Revised: 1st of June, 2013
SUMMARY: (Hide the summary)
Evaluarea fibrilației atriale este un subiect de real interes datorita creșterii vârstei populației, a mortalității pacienților cu fibrilație atrială cauzata, mai ales, de complicațiile tromboembolice. Scopul acestui studiu a fost evidențierea celor mai frecvenți factori de risc tromboembolici la pacienții cu fibrilație atrială paroxistica si permanenta. Rezultatele au arătat că hipertensiunea arteriala si insuficienta cardiaca au fost factorii de risc predominanți in ambele tipuri de fibrilație atrială. Similar unor studii anterioare, s-a remarcat faptul ca riscul de accident vascular cerebral este aproximativ egal la pacienții diagnosticați cu fibrilație atrială paroxistica si permanenta. Conform scorului CHA2DS2-VASc, majoritatea pacienților au avut un scor de cel putin 2, indiferent de tipul fibrilației.
stroke, atrial fibrillation, risk factors, hypertension
Atrial fibrillation (AF) is the most common sustained cardiac arrhytmia affecting about 1-2% of the general population. The incidence of atrial fibrillation increases with age, occuring in 10% of the population aged over 80 . The prevalence of AF increases with the severity of congestive heart failure or valvular disease. Regarding gender, men are more often affected than women. The lifetime risk of developing AF is about 25% in patients over the age of 40 .
Atrial fibrillation is associated with increased rates of stroke and other thromboembolic events (4% per year in nonvalvular AF). The risk of stroke seems to be highest during the first period after the initial diagnosis of AF or immediately after a transition from paroxysmal to persistent/permanent AF. Studies have shown that there is essentially no difference in incidence of stroke between paroxysmal and permanent AF. This happens due to the fact that patients with paroxysmal atrial fibrillation receive anticoagulant treatment less often than patients with permanent atrial fibrillation. However, patients with paroxysmal AF are younger and healthier than ones with permanent AF and they are expected to have fewer thromboembolic events.
The annual stroke rate, in patients with AF, is between 3% and 8% per year, in the presence of risk factors. Prior stroke/TIA and age over 75 are the most important risk factors. Besides prior thromboembolism, independent risk factors for stroke in nonvalvular AF include chronic heart failure (CHF), hypertension, and diabetes mellitus.
Moreover, female sex and LV dysfunction have been associated with stroke .
Fig. 1. Gender distribution in atrial fibrillation.
Fig. 2. Risk factors in paroxysmal AF.
Fig. 3. Risk factors in permanent AF.
METHODOLOGY AND RESULTS
The aim of this study was to find the correlation between the thromboembolic risk in patients with paroxsysmal and permanent atrial fibrillation. The analysis included a pool of 420 patients diagnosed with AF over a one year period (2011). To gather information we made use of anamnesis, history, ankle-brachial index and ecocardiography.
Out of the total pool of patients, 122 were diagnosed with paroxysmal AF, 238 with permanent AF and 60 with persistent AF. While women are more likely to have parosysmal AF (ratio of 76 women to 46 men), the risk of having permanent AF is similar for both genders (114 women to 124 men). All above mentioned values (Fig. 1) are statistically significant (p = 0.009).
In decreasing order of their magnitude, the highest risk factors in paroxysmal AF are: hypertension, congestive heart failure and the feminine gender (Fig. 2). For permanent AF the highest risk factors are congestive heart failure, hypertension and the age over 75 (Fig. 3).
Fig. 4. CHA2DS2-VASc distribution in paroxysmal AF.
Fig. 5.CHA2DS2-VASc distribution in permanent AF.
Although hypertension is more likely to occur in patients with paroxysmal AF, the percentage was not statistically significant. The frequency in which congestive heart failure was found in patients with permanent AF was much higher than in paroxysmal AF. These values were statistically significant. A quarter of the patients with paroxysmal AF were over the age of 75, but this risk factor was found in half of the patients with permanent AF as well. Diabetes and vascular heart disease were not very common in either type of AF.
An interesting observation is that prior stroke/TIA was present equally in patients with both types of AF; these values were, however, not statistically significant (p = 0.31). With regards to the CHA2DS2-VASc scheme, the majority of patients from the sampled pool had a score of at least 2 (Fig. 4, Fig. 5).
The current study has found that permanent atrial fibrillation was approximately two times more common than paroxysmal atrial fibrillation among patients. Women were more prevalent in the population diagnosed with paroxysmal AF, but men exceeded their percentage in the group with permanent AF.
The most frequent risk factors found in patients with paroxysmal AF were: hypertension, congestive heart failure and feminine gender. On the other hand, in the permanent AF group congestive heart failure was by far the most considerable risk factor, followed by hypertension and age over 75. Patients with paroxysmal AF were younger than the ones having permanent AF.
With regards to other risk factors there were no statistically significant findings. Stroke, as a risk factor, appears to be equally common in patients with paroxsymal and permanent atrial fibrillation.
According to CHA2DS2-VASc score, patients without any risk factor have all been diagnosed with paroxysmal AF. These patients are clearly at very low risk of developing stroke. A score of 1 was found in the same percentage in both types of atrial fibrillation. Furthermore, two thirds of all patients had a score of 2, regardless of the type of atrial fibrillation. These patients have a high risk of stroke and they certainly need anticoagulant treatment.
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