Abstract 13134: Prognostic Utility of Myocardial Single Photon Emission Computed Tomography (SPECT) with Iodine-123-Beta-Methyl Iodophenyl-Pentadecanoic Acid (BMIPP) in Risk Stratification of Hypertrophic Cardiomyopathy

Abstract

Background: Risk stratification is an important issue in patients with hypertrophic cardiomyopathy (HCM). Iodine-123-beta-methyl iodophenyl-pentadecanoic acid (BMIPP) is used to assess myocardial fatty acid utilization. However, the validity of impaired fatty acid metabolism in prediction of sudden death and heart failure in HCM has not been proven in a large number of patients.

Objective: The aim of this study was to evaluate the utility of BMIPP myocardial SPECT in predicting the long-term outcome in patients with HCM.

Method: We studied 146 consecutive HCM patients who underwent dual myocardial SPECT using BMIPP and 201-thallium chloride (Tl), between January 2007 and December 2008. All images were analyzed qualitatively in a blind manner. A positive finding was defined as reduced uptake on the BMIPP image compared with the TI perfusion image. In quantitative analysis, a polar map was divided into 17 segments. Each segment was graded on a 5-point scale and mismatch score was calculated from the differences between the BMIPP and TI scores using an automated program “Heart Score View” (Nihon Medi-Physics Co Ltd, Tokyo, Japan). Primary end point was the composite of cardiac death, hospitalization for heart failure, sustained ventricular tachycardia or ventricular fibrillation, and appropriate ICD therapy.

Results: All the patients were divided into positive finding group (Group A: n=126) and negative finding group (Group B; n=20). In Kaplan-Meier analysis, during a mean follow-up period of 3.0 ± 1.2 years, all cardiac events were significantly more frequently documented in Group A compared with Group B (29.0% vs. 0.0%, log-rank test, p < 0.05). Furthermore, in Group A, cutoff value of mismatch score was determined by ROC analysis. Patients with higher mismatch score (4 or higher) had significantly more cardiac events than patients with lower mismatch score (24.1% vs. 10.2%, p < 0.05).

Conclusion: Abnormal uptake of BMIPP in HCM patients predicts adverse cardiac outcome. Dual SPECT using BMIPP and Tl is a useful modality for risk stratification in HCM patients.