Implantable Atrial Defibrillator: Why not a Patient-Activated Drug Delivery System?

Abstract

Atrial fibrillation is a very frequent and potentially dangerous cardiac arrhythmia, increasing in prevalence with advancing years (from < 0.3% between 25 and 35 years of age to > 5% between 62 and 90 years of age) [1]. The arrhythmia is a source of substantial morbidity and mortality and is associated with increased medical care costs. The risk of systemic embolism and stroke is approximately 3- to 5-fold enhanced in patients with atrial fibrillation and full anticoagulation is frequently recommended in these patients [2]. The loss of atrial contraction and the irregularity of RR intervals reduce cardiac performance and may precipitate heart failure in patients with organic heart disease. It is also possible that a tachycardia-induced cardiomyopathy develops as consequence of a persistently high ventricular rate during atrial fibrillation [3]. Quality of life is frequently compromised by the occurrence of atrial fibrillation and patients often complain of disabling symptoms such as palpitations, fatigue, dyspnea and angina [4]. Finally, the risk of dying is 1.5- to 1.9-fold increased in patients with atrial fibrillation, even after adjustment for other variables [5]. Atrial fibrillation is also the most common cardiac rhythm disorder associated with hospitalization, being responsible for 0.5% of all hospital admissions and for one-third of all arrhythmia principal diagnoses [6]. It has been estimated that hospital costs are 12% to 24% higher in patients with atrial fibrillation compared with those without atrial fibrillation [7].