Rhythm Control Versus Rate Control: Unresolved Riddle in Daily Clinical Practice
Atrial fibrillation (AF) is the most common supraventricular arrhythmia: the prevalence is 1% over the age of 60 years and above 5% over the age of 70 . In the past 10 years various studies have suggested a worse outcome in patients affected by AF. From the analysis of the Framingham study population, AF seems related to excessive mortality, irrespective of underlying structural heart disease, age, diabetes, smoking, hypertension, or stroke, with an odds ratio of 1.5 in men and of 1.9 in women . Other studies have shown an increased risk of death in patients with AF, between 1.3 and 2.6 with respect to those in sinus rhythm [3,4]. In patients with dilated cardiomyopathy AF has been shown as an independent predictor of sudden death when the ejection fraction is less than 50% . AF is thought to increase the risk of death mainly through thromboembolic complications and their hemodynamic consequences. The risk of cerebral thromboembolism in patients with nonvalvular AF is increased by a factor of 5-7, with a probability of ischemic stroke of 5% per year; the risk increases in presence of hypertension, diabetes, previous ischemic events, recent heart failure, and age over 65 years (in the 50% of cases cerebral events occur in patients older than 75 years). Even in patients with lone AF the risk of stroke is increased four times compared to age-matched controls in sinus rhythm ; counting transient ischemic attacks and asymptomatic stroke, the incidence rises to 7% per year [7,8]. The hemodynamic consequences of AF are related to the rapid and irregular ventricular response and to the lack of atrial contribution to ventricular filling. They are more evident in patients with reduced left ventricular function, and the loss of atrial kick may reduce cardiac output by up to 20% in patients with impaired diastolic function . The persistence of a rapid ventricular rate for more than 6 months may induce the development of a reversible form of tachy-cardiomyopathy . However, the real impact of AF on prognosis has been questioned more recently, and critical attention must be paid to the actual role of AF in Divisione di Cardiologia, Ospedale Mauriziano Umberto I, Turin, Italy the clinical outcome of affected patients. Its hemodynamic and thromboembolic consequences can be limited by the use of anticoagulant therapy and drugs that slow the heart rate. Does the prognostic value of AF go beyond that? Even in patients at high risk, such as those with heart failure, the proposition that AF has independent prognostic significance is controversial, following from some studies but not from others.
KeywordsAtrial Fibrillation Sinus Rhythm Structural Heart Disease Recurrent Atrial Fibrillation Rhythm Control
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