What is the difference between a Pacemaker (PPM) Cardiac Resynchronization Therapy-Defibrillator (CRT-D) and an Implantable Cardioverter-Defibrillator (ICD) in treating patients with heart failure and arrhythmias?

From the Guidelines

The choice between a Pacemaker (PPM) Cardiac Resynchronization Therapy-Defibrillator (CRT-D) and an Implantable Cardioverter-Defibrillator (ICD) depends on the patient's specific cardiac condition, with CRT-Ds being the preferred choice for patients with heart failure, ventricular dyssynchrony, and arrhythmia risk. The main difference between these devices lies in their functionality and the type of heart conditions they are designed to treat.

• A pacemaker (PPM) is used to treat bradyarrhythmias, delivering small electrical impulses to maintain a minimum heart rate.
• An Implantable Cardioverter-Defibrillator (ICD) is primarily used to prevent sudden cardiac death by monitoring heart rhythm and delivering high-energy shocks to terminate life-threatening ventricular arrhythmias.
• A Cardiac Resynchronization Therapy-Defibrillator (CRT-D) combines the functions of both devices, adding cardiac resynchronization therapy to coordinate contractions between the right and left ventricles, improving cardiac output in heart failure patients with ventricular dyssynchrony.

According to the most recent guidelines, including those from the European Society of Cardiology 1, CRT-Ds are typically used in patients with reduced ejection fraction (≤35%), prolonged QRS duration (typically >130ms), and moderate to severe heart failure symptoms despite optimal medical therapy. The decision to use a CRT-D over an ICD should be based on the patient's risk of sudden cardiac death and non-sudden cardiac death, as well as other factors such as age, comorbidities, and life expectancy 1. In general, CRT-Ds are preferred over ICDs in patients with heart failure and ventricular dyssynchrony, as they have been shown to improve symptoms, exercise capacity, and quality of life, while also reducing hospitalizations and mortality 1.

Some key points to consider when selecting between CRT-D and ICD include:

• The patient's underlying cardiac condition and risk factors for sudden cardiac death
• The presence of ventricular dyssynchrony and the potential benefit of cardiac resynchronization therapy
• The patient's age, comorbidities, and life expectancy
• The potential risks and benefits of each device, including the risk of inappropriate therapy and the need for regular device checks and optimization.

Overall, the choice between a CRT-D and an ICD should be individualized based on the patient's specific needs and circumstances, and should involve a thorough discussion of the potential risks and benefits of each device.

From the Research

Overview of PPM CRT-D and ICD

• PPM CRT-D (Cardiac Resynchronization Therapy-Defibrillator) and ICD (Implantable Cardioverter-Defibrillator) are both implantable devices used to treat patients with heart failure and arrhythmias.
• The main difference between the two devices is that a PPM CRT-D provides pacing for cardiac resynchronization therapy, in addition to defibrillation capabilities, whereas an ICD only provides defibrillation therapy 2.

Indications for PPM CRT-D and ICD

• PPM CRT-D is indicated in patients with heart failure, left ventricular systolic dysfunction, and a QRS duration greater than 120 ms, who have NYHA class III or IV symptoms despite optimal medical therapy 2.
• ICD is recommended in individuals with a history of cardiac arrest, ventricular fibrillation, or hemodynamically unstable ventricular tachycardia, as well as in patients with ischemic heart disease or nonischemic cardiomyopathy, an LVEF of 30% or less, and NYHA class II or III symptoms on optimal medical therapy 2.

Device Selection

• The choice of device depends on the specific etiology of the patient's heart failure and the presence of bradyarrhythmias or tachyarrhythmias 3.
• Patients with heart failure and reduced ejection fraction may benefit from treatment with β-blockers, which can reverse the neurohumoral effects of the sympathetic nervous system and provide prognostic and symptomatic benefits 4.

Pacing Options

• Cardiac pacing is an effective treatment for patients with bradycardia due to sinus node dysfunction or atrioventricular block, and the optimal ventricular pacing site to mimic normal human ventricular physiology remains a topic of research 5.
• His-bundle pacing has emerged as a leading candidate for physiological pacing, providing nearly normal electrical activation of both ventricles and avoiding ventricular dyssynchrony 5.

Outcomes with LBBB and Reduced LVEF

• Patients with left bundle branch block (LBBB) and a mildly to moderately reduced left ventricular ejection fraction (LVEF) have poor clinical outcomes, with significantly higher rates of mortality, LVEF drop, and need for an implantable cardioverter-defibrillator compared to patients without conduction system disease 6.
• This group may benefit from cardiac resynchronization therapy, which can be provided by a PPM CRT-D device 6.