What is Cardiac Resynchronization Therapy (CRT)?

From the Guidelines

Cardiac Resynchronization Therapy (CRT) is a treatment for heart failure that involves the use of a device to coordinate the beating of the heart's chambers, improving symptoms, quality of life, and reducing hospitalizations and mortality.

Key Points

• CRT is recommended for patients with moderate to severe heart failure symptoms (NYHA class III or IV) and a QRS duration ≥120 ms, as it has been shown to reduce the risk of death and hospitalization for worsening heart failure 1.
• For patients with mild to moderate heart failure symptoms (NYHA class I or II), CRT is recommended only in those with a QRS duration ≥150 ms or ≥130 ms with a left bundle branch block (LBBB) pattern 1.
• CRT has been shown to improve symptoms, quality of life, and ventricular function, and reduce hospitalizations and mortality in patients with heart failure 1.
• The use of CRT in patients with atrial fibrillation is still uncertain, and more research is needed to determine its effectiveness in this population 1.
• CRT is typically used in combination with optimal medical therapy, including medications such as diuretics, ACE inhibitors, beta-blockers, and mineralocorticoid receptor antagonists (MRAs) 1.

Benefits and Risks

• The benefits of CRT include improved symptoms, quality of life, and reduced hospitalizations and mortality 1.
• The risks of CRT include device-related complications, such as lead malfunction or dislodgement, pacemaker problems, and infection 1.
• The success rate of CRT implantation is approximately 90%, with a low mortality rate of 0.4% 1.

From the Research

Definition and Purpose of Cardiac Resynchronization Therapy (CRT)

• Cardiac Resynchronization Therapy (CRT) is a treatment for heart failure that aims to improve symptoms, reduce hospitalizations, and increase survival by resynchronizing the heartbeat 2, 3, 4, 5, 6.
• CRT is typically used in patients with heart failure and electrical dyssynchrony, where the ventricles do not contract in a coordinated manner 2, 4.

Benefits and Effectiveness of CRT

• CRT has been shown to improve symptoms, reduce hospitalizations, and increase survival in patients with heart failure 2, 3, 4, 5, 6.
• The benefits of CRT can vary depending on the individual patient, with some patients experiencing significant improvements in symptoms and quality of life, while others may not respond as well 2, 3.
• The effectiveness of CRT can be influenced by factors such as the presence of left bundle branch block, QRS duration, etiology of cardiomyopathy, and baseline severity of functional impairment 2, 4.

Patient Selection and Implantation

• Patient selection for CRT is critical, and guidelines recommend considering factors such as symptoms, left ventricular ejection fraction, and QRS duration 4, 6.
• The implantation of a CRT device involves targeting the left ventricular lead to sites of greatest electrical and/or mechanical delay, and using quadripolar or bipolar leads 4.
• Post-implant care includes optimization of pacing parameters, mitigation of right ventricular pacing, and recognition and treatment of suboptimal biventricular pacing 4.

Emerging Therapeutic Approaches

• Emerging therapeutic approaches for CRT include the use of endocardial left ventricular pacing, novel left ventricular pacing options, and the integration of remote monitoring platforms 4, 6.
• Conduction system pacing and multi-site pacing are also being explored as potential alternatives to traditional CRT 6.