Use of Serum Creatine Kinase MM Isoforms for Predicting the Progression of Left Ventricular Dilation in Patients With Hypertrophic Cardiomyopathy

Serum creatine kinase (CK) isoforms were examined to detect the progression of left ventricular (LV) enlargement with reduced motion, resembling dilated cardiomyopathy (DCM), in hypertrophic cardiomyopathy (HCM). Changes in LV indices were determined annually by echocardiography in 51 patients until serum measurements (first follow-up period, 6.5 +/- 2.2 years). Serum creatine isoforms (CKMM1, CKMM2 and CKMM3) were measured with high-voltage electrophoresis in 35 of these patients from 1991 to 1992, and the data for these latter patients are reported here. Serum total CK, CKMB, lactate dehydrogenase and its isoenzyme LDH1 were also measured. The changes in LV indices were further monitored until January, 1995 (second follow-up). During the 2 follow-up periods, the patients in the on-going group showed a reduction in the LV ejection fraction (LVEF) to < 55% with LV end-diastolic dimension (LVDd) < 55 mm, and those in the DCM-like group showed a reduction in LVEF to < 55% and an increase in LVDd to > 55 mm. During the first follow-up period, LVEF and LVDd remained at > or = 55% and < 55 mm, respectively, in 26 patients (nonprogressive-disease group), while 3 patients entered the on-going group and 6 entered the DCM-like group. The CKMM3/CKMM1 ratios in the on-going and DCM-like groups were significantly higher than those in the control and nonprogressive-disease groups. The CKMM3/CKMM1 ratio was significantly correlated with the annual rate of change for the LV end-systolic dimension (LVDs), LVDd, and LVEF, with the closest correlation observed for the annual change in LVDs. Moreover, 5 patients in the nonprogressive-disease group with elevation of the CKMM3/CKMM1 ratio to > + 2SD above the mean for the controls had an elevated annual change in LVDs within +/- 1SD of the mean in the DCM-like group. These results indicate that the ratio of CKMM3 to CKMM1 can be used to predict the progression of LV enlargement in HCM.