This will be a two-arm investigator-initiated randomized controlled study of patients with nHCM and LV ejection fraction ≥50% and NYHA II-III symptoms, normal intrinsic conduction system and pre-existing suitable dual-chamber implantable cardioverter defibrillators (ICD) systems. Patients will be randomly assigned to either personalized accelerated pacing (using the myPACE+ algorithm with mono-fractional exponent) or usual care groups. At baseline and after 3 months of pacing all patients will undergo a CPET, echocardiogram, blood work for NT-proBNP levels and complete the KCCQ-OSS and HCMSQ, questionnaires. The investigator team hypothesizes that personalized accelerated pacing will be safe and improve symptoms and heart-failure related quality of life, physical activity, pVO2, biomarkers (i.e. NT-proBNP), diastolic parameters and cardiac structure.