Makindo Medical Notes

Related Subjects: Chronic Heart Failure | Heart Failure and Pulmonary Oedema | Loop Diuretics | Entresto Sacubitril with Valsartan | Ivabradine | Furosemide | Angiotensin Converting Enzyme Inhibitors | Cardiac Resynchronisation Therapy (CRT) Pacemaker |

❤️‍🩹 Cardiac Resynchronisation Therapy (CRT) improves symptoms, exercise tolerance, and quality of life, and reduces mortality in patients with moderate-to-severe symptomatic heart failure (NYHA III–IV), sinus rhythm, LVEF <35%, and LBBB with wide QRS.

ℹ️ About

• Also called biventricular pacing or pacing in heart failure.
• Aims to restore ventricular synchrony when the ventricles contract out of phase.
• Often combined with an implantable cardioverter-defibrillator (CRT-D) for patients at risk of malignant arrhythmias.

🩺 Aetiology / Rationale

• Ventricular dyssynchrony (esp. due to LBBB) worsens LV function by inefficient contraction.
• CRT paces both ventricles ➝ coordinated contraction ➝ improved cardiac output.
• RV lead placed at apex, LV lead via coronary sinus to lateral LV wall.
• Resynchronisation helps prevent adverse remodelling of the failing LV.

✅ Indications for CRT

• NYHA III–IV heart failure despite optimal medical therapy.
• LVEF <35% with dilated LV.
• QRS >130 ms, esp. with LBBB morphology.
• In sinus rhythm (benefit in AF is less predictable).

📈 Effects & Mechanism

• Resynchronises ventricular contraction ➝ more efficient systolic function.
• Improves LV stroke volume and reduces mitral regurgitation by better papillary muscle coordination.
• Can promote reverse remodelling of dilated LV.

🌟 Clinical Benefits

• Improves exercise tolerance (6-minute walk distance, peak VO₂).
• Improves quality of life.
• Reduces heart failure hospital admissions.
• Reduces mortality in selected patients (e.g. CARE-HF, COMPANION trials).

💡 Teaching Pearl: Think of CRT when you see the triad of: 1️⃣ Symptomatic HF despite good medical therapy 2️⃣ LVEF <35% 3️⃣ Broad QRS with LBBB