Cardiac Resynchronization Therapy in Adult Congenital Heart Disease With Systemic Right Ventricle: RIGHT-CRT

This study is evaluating the effectiveness of cardiac resynchronization therapy (CRT) — a type of specialized pacemaker — in patients with a congenital heart condition called systemic right ventricle, where the heart's right side does the work normally done by the left side, causing it to gradually weaken. **You may be eligible if...** - You are 18 years or older - You have a systemic right ventricle (a congenital heart condition) - You have already had a CRT device (pacemaker) implanted for at least 1 month - You have moderate to severe heart failure symptoms (NYHA class II–IV) with a weak right ventricle AND prolonged electrical delay, OR you have significant heart block with a high pacing burden - You are enrolled in the French social security system **You may NOT be eligible if...** - You are pregnant or breastfeeding - You are a woman of childbearing age without effective contraception - You have had heart surgery in the past 3 months or have major cardiac procedures planned in the next 6 months - You have uncontrolled persistent heart rhythm problems (atrial arrhythmia with planned ablation) - You are currently in acute heart failure - You are currently participating in another interventional clinical study Talk to your doctor to see if this trial is right for you.