Prognosis of hypertrophic cardiomyopathy: Assessment by123I-BMIPP (β-methyl-p-(123I)iodophenyI pentadecanoic acid) myocardial single photon emission computed tomography

Abstract

123I-BMIPP (beta-methyl-iodophenyl pentadecanoic acid) has shown unique properties for potential use in assessing myocardial metabolism. Previous basic and clinical studies demonstrated that the disturbances of myocardial metabolism precede the occurrence of myocardial perfusion abnormalities by using 201Tl in hypertrophic myocardium. The present study was therefore undertaken to determine whether or not 123I-BMIPP myocardial SPECT is useful in predicting the prognosis of hypertrophic cardiomyopathy (HCM) in 65 patients in 6 facilities. There were 33 patients with non-obstructive HCM, 12 with obstructive HCM, 12 with apical HCM and 8 with dilated-phase HCM. Fasted patients at rest received an intravenous injection of 111 MBq of 123I-BMIPP. Twenty to thirty minutes later, myocardial SPECT was carried out. The BMIPP severity score (BMIPP SS) was evaluated semiquantitatively by using representative short axial SPECT images. We followed up the incidence of cardiac events for a mean period of 3.0 +/- 0.6 years. Cardiac events occurred in 13 patients. Of these, 11 developed heart failure and 6 died (4 from heart failure and 2 from sudden death). The BMIPP SS in the dilated-phase HCM was significantly lower than that for the nonsurvivors. The BMIPP SS was particularly high in patients with fatal heart failure. Furthermore, there was a close negative correlation between the BMIPP SS and percent fractional shortening measured by echocardiography (r = -0.49). Finally, the mortality over the three years increased according to the extent of the BMIPP SS. In conclusion, these results indicate that BMIPP SS is useful in evaluating the severity of HCM. We conclude that 123I-BMIPP is a valuable metabolic tracer in predicting the outcome of HCM.