Introduction: Obstructive hypertrophic cardiomyio-pathy is an extremely heterogeneous disease with phe-notypical expression that varies much in distribution and amplitude of the myocardial hypertrophy. CMR with its excellent spatial resolution can assure a thorou-gh analysis of the septal morphology as well as of the abberant muscular bundles and crypts. We are using a preoperative MR reconstruction of the septal anatomy in order to plan the surgical management of the mus-cular resection and the optimal approach to relieve the LVOT gradient.

Methods: We enrolled 64 consecutive patients with HOCM and indication to surgical treatment. We used a standardized preoperative multimodality imaging protocol to all patients consisting of: TTE, CMR, co-ronarography and TEE. Excluded from the study were patients with prior septal ablation or contraindication to CMR (not-MR compatible devices). In each patient a CMR was performed (GE Signa Voyager 1,5Tesla scanner) with an ECG-gated SSFP cine in 2-, 3- and 4-chambers and a short axis contigous stack of 6mm slices from the atrioventricular ring to apex.

Results: T he baseline characteristics of the enrolled patients are described as well as the used CMR-algo-rithm. An exhaustive analysis of different morphologic aspects observed through cardiac MR as well as the role of LGE-CMR in visualizing the distribution and quantification of fibrosis were assessed. The presence of myocardial crypts and their precise localization were noted, in matter to be able to avoid them intraoperati-ve. Also, we analyzed the expression of HCM regarding the papillary muscle morphology. We are also briefly describing the various scenarios in which CMR proved to be an indispensable tool in managing and planning the surgical assessment of the HCM with the technique „in one piece myomectomy“.

Conclusions: CMR is a powerful imaging technique by its unique capacity in thoroughly describing the magnitude of LV wall thickness at different segments, especially in focal regions, as well as the presence of the myocardial crypts, areas of fibrosis and muscular bundles. Standardization of the preoperative protocol of HOCM using CMR to plan the surgical treatment may bring an additional benefit by Increasing the precision of the surgical act in order to succesfully reliefing the gradient and reducing the risk of iatrogenic septal defect.