Prevalence and predisposing conditions for atrial fibrillation in hospitalised patients with hypertension.

Background: Hypertension, due to its prevalence, is a common and independent risk factor for atrial fibrillation (AF). High blood pressure causes structural and functional changes in the myocardium, leading to an increased risk of arrhythmia. This risk is higher when hypertension is accompanied by concomitant diseases that contribute to the development of AF.

Aim: To estimate prevalence of AF and predisposing factors for AF in patients with hypertension hospitalised in our cardiology unit.

Methods: This retrospective analysis included 4459 patients hospitalised in the Clinical Department of Cardiology in 2009-2010. Hypertension was identified in 2512 (56.3%) patients. The study group consisted of 685 (27.3%) patients with hypertension and concomitant AF, and the control group included 1827 (63.7%) hypertensive patients without AF. We analysed clinical data including AF type, coexisting diseases and left ventricular ejection fraction evaluated by echocardiography.

Results: Mean patient age in the study group was 74 years compared to 67 years in the control group. Most patients in the study group had either paroxysmal (46%) or permanent AF (45.5%). The following rates of coexisting diseases were found in the study and control groups: heart failure (HF) 54.3% vs. 31.4%, respectively (p < 0.001), ischaemic heart disease (IHD) 44.4% vs. 25.2% (p < 0.001), diabetes 28.3% vs. 24.2% (p = 0.126), hypercholesterolaemia 25.4% vs. 30.4% (p = 0.067), stroke 10% vs. 3% (p = 0.0028), hyperthyroidism 4.7% vs. 1.9% (p = 0.0002), hypothyroidism 5.1% vs. 2.1% (p = 0.0001), and euthyroid goitre 5.3% vs. 2.1% (p < 0.0001). Multivariate logistic regression analysis identified the following factors that significantly affected the occurrence of AF in patients with hypertension: hypothyroidism (hazard ratio [HR] 3.27), IHD (HR 2.75), hyperthyroidism (HR 2.55), euthyroid goitre (HR 2.13), previous myocardial infarction (HR 1.96), and HF (HR 1.66).

Conclusions: Among hospitalised patients with hypertension, AF is present in a significant proportion of patients. Conditions predisposing to this arrhythmia in hypertensives include HF, IHD, thyroid diseases, and previous myocardial infarction. There was no evidence that diabetes, abnormal lipid profile, and impaired kidney function affected AF rate among patients with hypertension.