Pathophysiology of hypertrophic cardiomyopathy

• LV outflow tract obstruction (LVOTO) in ≥70%: narrowed tract 2° hypertrophied septum + systolic anterior motion (SAM) of ant. MV leaflet (may be fixed, variable, or nonexistent) and papillary muscle displacement. Gradient (∇) worse w/ ↑ contractility (digoxin, β- agonists, exercise, PVCs), ↓ preload (eg, Valsalva maneuver) or ↓ afterload.

• Mitral regurgitation: due to SAM (mid-to-late, post.-directed regurg. jet) and/or abnl

mitral leaflets and papillary muscles (pansystolic, ant.-directed regurg. jet)

• Diastolic dysfunction: ↑ chamber stiffness + impaired relaxation

• Ischemia: small vessel dis., perforating artery compression (bridging), ↓ coronary perfusion