Cardiac Resynchronization Therapy With and Without Implantable Cardioverter-Defibrillator

Abstract

Cardiac resynchronization therapy (CRT) is recommended to reduce morbidity and mortality in patients with New York Heart Association class III/IV, who are symptomatic despite optimal medical therapy, and who had a reduced left ventricle (LV) ejection fraction and electrical dyssynchrony. The effects of CRT are reflected mainly by the degree and location of dyssynchrony and by working in insertion of optimal LV lead site. Echocardiography and Doppler echocardiography are considered to be good tools to measure LV dyssynchrony directly. However, the large randomized trials have shown that no single echocardiographic measure of dyssynchrony is recommended to improve patient selection for CRT beyond current guidelines. There were several unsolved issues on CRT, such as patient selection, electrical or electromechanical dyssynchrony criteria to patients for CRT, indication of patients with a narrow or slightly prolonged QRS width, indication of patients with atrial fibrillation, and indication of patients with mild heart failure or asymptomatic LV dysfunction, and device selection; CRT alone (CRT-P) or CRT in combination with implantable cardioverter therapy (CRT-D). This review paper summarized the concept of therapy, the current evidence regarding the indications, effectiveness and safety of CRT-P and CRT-D in patients with LV dysfunction, and unsolved issues.

Novel Strain Rate Index of Contractility Loss Caused by Mechanical Dyssynchrony - A Predictor of Response to Cardiac Resynchronization Therapy -

“…We analyzed only the immediate changes in LV systolic function by CRT whereas the response to CRT is usually a combination of both immediate changes in systolic function and short-term reduction of LV volumes. 27 Thus, it must be determined whether the SRDI is effective in predicting the longer term beneficial response to CRT. In addition, we evaluated LV systolic function by global longitudinal strain, because it is generally considered to be a more sensitive marker of systolic function than EF.…”

Actual conditions of implantable defibrillation therapy over 5 years in Japan

“…In Japan, the first guidelines for ICDs were published by the Japanese Circulation Society (JCS) in 2001 [20], a revised version was reported in its website in 2006 [21], and a further revised version was added in 2011 [22]. CRT‐Ds were approved in 2006 and the Japan Cardiac Device Therapy Registry (JCDTR) was started in the same year [23]. Interestingly, it has been reported that the actual implantation rates of these devices in Japan may be different from those of western countries [25].…”

“…Interestingly, it has been reported that the actual implantation rates of these devices in Japan may be different from those of western countries [25]. These differences in device utilization rates might be explained by variable factors such as acceptance of published guidelines, differences in clinical presentation of patients, access to electrophysiologists and other implantation specialists, the overall capacity of the workforce to support ICD implantation, acceptance by policymakers, cost‐effectiveness, financial constraints, and capitation [23]. However, little is known regarding the recent conditions associated with implantable defibrillators for the treatment of individual underlying heart diseases.…”

Nippon Storm Study design

“…This larger study aims to collect data on and investigate the general parameters of patients with ICSD, such as clinical backgrounds of patients (age, gender, and underlying heart disease), purposes of indication (primary or secondary), complications during implantation procedures, and incidence of appropriate and inappropriate therapies from the ICSD (Table 1). Approximately 10,000 patients have been registered in this trial [14]. The Nippon Strom Study was planned as a sub-study of the JCDTR focus on E-storms after ICSD implantation.…”