Page 13 - Simplicity is Key in CRT

Heart Failure
Heart Failure (HF) is a clinical syndrome of signs and symptoms resulting from structural and/or functional cardiac abnormality, leading to reduced output and/or elevated intracardiac filling pressures [1]. HF is a common disease occurring in 1-2% of the adult population, mainly affecting older people. Despite significant advances in HF therapies over the last decades, prognosis of HF remains poor with high annual rates of mortality (7-17%) (due to progressive HF and sudden cardiac death), and hospitalisation (32-44%), and overall poor quality of life [2]. Moreover, HF patients usually have one or more serious comorbidities affecting general well-being and prognosis apart from HF [3]. Therefore HF entails high health care costs, averaging 1.1% of the total health care budget in the Netherlands [4].
Treatment
Current HF treatment has significantly improved prognosis, especially in patients with a reduced left ventricular ejection fraction (LVEF) [5]. The mainstay of HF treatment consists of lifestyle changes and pharmacotherapy to reduce cardiac stress (reducing neurohormonal activation) and filling pressures, and to induce reverse remodelling of structural changes. Implantable cardioverter defibrillators (ICD) are used to prevent sudden cardiac death in patients at increased risk of life threatening arrhythmias. Biventricular pacemakers are used in cardiac resynchronization therapy (CRT) in patients with electrical conduction delay. In case of progressive HF despite optimal medical treatment, interventions like left ventricular assist devices (LVAD) and cardiac transplantation can be considered [1]. Above all, treatment should aim at taking away the cause of the underlying structural and/or functional disease and factors aggravating the disease.
Causes of Heart Failure
Different aetiologies in HF encompass differences in prognosis, particularly because some can be treated and others cannot. Causes of HF are numerous; with ischemic, valvular and hypertensive heart disease as classic aetiologies, while inflammatory, infiltrative, toxic, genetic, tachycardia, irregularity, dyssynchrony and adrenergic stress are increasingly recognized as causes of HF [1]. Moreover, many times these causes interact within one patient, and surface at different moments in the course of the disease. In order to effectively treat HF, the cause and aggravating factors have to recognized and treated.
Cardiac Resynchronization Therapy
CRT aims to correct a dyssynchronous ventricular electrical activation, and hence dyscoordinate ventricular contraction. The dyssynchronous electrical activation amenable to CRT classically entails an early activation and contraction of the septum and delayed activation and contraction of the left ventricular lateral wall. This dyscoordinate contraction leads to a reduction in stroke volume and LVEF, which over time is associated with LV dilatation and increased filling pressures [6, 7].
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