Four-year follow-up of treatment with intramyocardial skeletal myoblasts injection in patients with ischaemic cardiomyopathy

Aims: Studies reporting improved left ventricular (LV) function of percutaneous skeletal myoblast (SkM) injection in patients with ischaemic cardiomyopathy had follow-up not exceeding 12 months, and did not include a control group. Our group has reported evidence for myoblast efficacy in the first five out of the 14 treated patients. The objective of the present evaluation was to assess if these effects were sustained at long-term follow-up. We compared function of patients treated with SkM 4 years earlier with a matched control group. Secondary endpoints included mortality, NYHA class, N-terminal pro-B-natriuretic peptide levels, incidence of arrhythmias, and quality of life. Methods and results: Fourteen patients with ischaemic cardiomyopathy who underwent SkM injection were compared with 28 non-randomized control patients matched for age, sex, location, and extent of myocardial infarction. Contrast echocardiography and tissue Doppler imaging (TDI) was performed to compare global and regional LV function. At 4-year follow-up, three patients (21%) had died in the treated group and 11 patients (39%) in the control group (P = 0.8). In the survivors, LV ejection fraction (EF) was 35 ± 10% and 37 ± 9% in the SkM group and 36 ± 8% and 36 ± 6% in the controls at baseline and 4 years follow-up, respectively (P = 0.96 between groups at follow-up). TDI-derived systolic velocity in the injected sites was 5.4 ± 1.8 cm/s in the SkM group when compared with 5.1 ± 1.6 cm/s in corresponding sites in the control group (P = 0.47). None of the secondary endpoints showed a difference between the groups. However, in the patients fitted with an internal cardioverter defibrillator, more arrhythmias leading to interventions occurred in the treated group than in the control group, 87% and 13%, respectively (P = 0.015). Conclusion: Percutaneous intramyocardial SkM injection in ischaemic cardiomyopathy has no sustained positive effect on resting global or regional LV function, respectively, at 4-year follow-up. Moreover, the procedure may induce a higher risk of developing serious arrhythmias, but larger patient series are required before more precise characterization of the safety and efficacy profile of the procedure is possible.

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