The Impact of Cardiac Resynchronization Therapy in the Treatment of Heart Failure

Abstract

The number of patients who sufer from heart failure is rapidly increasing. In about onethird of heart failure patients, conduction delays cause dyssynchronous left ventricular contractions, which leads to reduction in left ventricular function, adverse cardiac remodelling and inally increased mortality. Cardiac resynchronization involves simultaneous pacing of both ventricles, and improves left ventricular contractile function. Although resynchronization does not restore myocardial function, multiple studies have shown that cardiac resynchronization therapy improves quality of life, exercise capacity, symptoms of heart failure, left ventricular ejection fraction, morbidity and mortality. The use of cardiac resynchronization therapy has increased signiicantly, since its initial approval in 2001, in patients with advanced heart failure.Keywords: heart failure, cardiac resynchronization therapy, electrophysiologist, left bundle branch block, left ventricular function IntroductionThe number of patients who sufer from chronic heart failure is rapidly growing. According to the 2016 update on heart disease and stroke statistics reported by the American Heart Association, an estimated 5.7 million Americans ≥20 years of age have a diagnosis of heart failure and projections show that the prevalence of heart failure will increase 46% from 2012 to 2030, resulting in >8 million people ≥18 years of age with heart failure [1]. In the year of 2013, heart failure was the underlying cause in >65,000 deaths and contributed to the death of >300,000 people [1]. In the same report, there is an estimate that a total cost of over $30 billion was used for the treatment of heart failure in 2012 [1]. Direct medical costs atributed to 68% of this total amount. The lifetime risk of developing heart failure is 20% for adults at the © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.age of 40 years and goes up with age. Acute heart failure consists of one of the most common reasons for hospitalization, atributing to over 1 million discharges annually and high 30-day readmission rates (up to 25%) and 1 year (up to 60%) [1]. The prognosis for heart failure is poor, with an estimated mortality rate of 50% within 5 years of diagnosis. Cardiac resynchronization therapy (CRT) Advent of CRTAn intraventricular conduction delay is found in approximately 20-30% of patients with symptomatic heart failure. Conduction delay causes dyssynchronous left ventricular contractions, which lead to left ventricular dysfunction, adverse cardiac remodelling and eventually high mortality [2][3][4]. Conduction delay may also lead to mitral valve regurgitation, thus increasing symptoms of heart failure. The prevalence of left ventricular dyssynchrony in heart failure has been shown to increase with reduced left ventricul...