The elusive gradient: limitations of cardiac magnetic resonance in assessing intraventricular obstruction in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a myocardial disease characterized by unexplained left ventricular hypertrophy, myocyte disarray, and interstitial fibrosis. A dynamic left ventricular outflow tract obstruction is present in approximately two-thirds of patients, and is typically associated with systolic anterior motion of the mitral valve. A distinct subgroup exhibits mid-ventricular obstruction, frequently associated with apical aneurysm and a higher risk of sudden cardiac death. Recognition and quantification of intraventricular gradients are critical for risk stratification and therapeutic decision-making in HCM. We present two distinct cases of obstructive HCM evaluated through echocardiography and cardiac magnetic resonance (CMR), highlighting the strengths and limitations of each modality. Our aim is to emphasize the importance of a multimodal imaging approach for accurately assessing the most complex phenotypes of HCM, especially when evaluating intraventricular gradients.