Who is a good candidate for CRT-D, and what are the contraindications?

Good candidates include patients with symptomatic heart failure with reduced ejection fraction (HFrEF, typically ≤35%), a widened QRS complex on ECG (≥130 ms), and New York Heart Association class II–IV symptoms despite optimal medical therapy. Contraindications include severe aortic stenosis, acute myocarditis, or life expectancy less than 6 months due to non-cardiac conditions. Patients with chronic atrial fibrillation or right bundle branch block may have reduced benefit, so individual assessment by a cardiologist is essential.