European Society Of Hypertension Scientific Newsletter: Update On Hypertension Management 2009; 10: No.42 Hypertension And Atrial Fibrillation With Emphasis On Prevention

Why discuss atrial fibrillation in hypertension? Atrial fibrillation (AF) is the most frequently occurring sustained cardiac arrhythmia and is related to many cardiac diseases. Its prevalence doubles with each decade after 50 years and approaches 10% in those more than 80 years of age [1]. In men and women, respectively, hypertensive patients have a 1.4and 1.5-fold risk of developing AF [1], and patients with AF have increased cardiovascular morbidity and mortality. Due to the high prevalence of hypertension, it accounts for more cases of AF than any other risk factor [1]. Hypertension is associated with left ventricular hypertrophy, impaired ventricular filling, slowing of atrial conduction velocity, structural changes, and enlargement of the left atria. All these changes in cardiac structure and physiology favour development of AF, and increase the risk of thromboembolic complications. In the following, we will review possible mechanisms for increased risk of AF in hypertensives and look into the effect of different antihypertensive treatments. Hypertension is a prevalent, independent, and potentially modifiable risk factor for AF development [1]. The relative risk (RR) of developing AF in patients with hypertension has been calculated at 1.4–2.1, which is modest compared to e.g. heart failure and valvular disease, which have relative risks of AF development of 6.1– –17.5 and 2.2–8.3, respectively [2]. However, due to the high prevalence of hypertension, it is the most important risk factor. Increased pulse pressure has recently been recognized as a possible, even more important, risk factor. In the Framingham database, increased systolic pressure was associated with AF, but the association was even stronger when low diastolic pressure with a higher pulse pressure effect was added into the statistical model [3]. Other known risk factors for AF are left ventricular hypertrophy, left atrial size, heart failure, valvular (in particular mitral valve) and ischaemic heart disease, heart rate, gender, diabetes mellitus, hyperthyroidism, severe infection, pulmonary pathology, stroke, obesity, alcohol abuse, and smoking [4]. Recently new risk factors for AF, such as sleep apnoea, inflammation, and genetic influence, have also been recognized [5]. Lone AF is defined as AF in individuals younger than 60 years without clinical or echocardiographic evidence of cardiopulmonary disease, including hypertension [6]. These patients have a favourable prognosis with respect to thromboembolism and mortality [6]. However, underlying hypertension often may not be recognized in these patients diagnosed with lone AF due to inadequate diagnostic investigations (e.g. no 24-hour ambulatory blood pressure measurement) or treatment with beta-blockers or calcium channel blockers for AF, which also have antihypertensive effects [5]. Atrial fibrillation itself produces electrical and structural remodelling of the heart, and may be important for the recurrence or the maintenance of the AF. Angiotensin II has been suggested as one important mechanism for the atrial remodelling, and blockers of RAS, such as angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II-receptor blockers (ARBs), have shown promising results in reducing the incidence of AF in heart failure and hypertension trials [7].