Safety and Effects of Implanted (Autologous) Skeletal Myoblasts (MyoCell™) Using an Injection Catheter - SEISMIC — Presented at SCAI-ACC i2 Summit/ACC 2008


The goal of this trial was to evaluate treatment with autologous skeletal myoblast cells derived from a quadriceps muscle compared with medical therapy in patients with a myocardial scar.


Implantation of autologous skeletal myoblast cells into myocardial scar will be more effective in improving left ventricular function and reducing adverse events.

Study Design

Study Design:

Patients Enrolled: 47
Mean Follow Up: 6 months
Mean Patient Age: 59 years
Female: 8%
Mean Ejection Fraction: 31%

Patient Populations:

• Age ≥18 and ≤75 years old
• NYHA class II-III
• Need for revascularization ruled out within 30 days of screening
• Optimal pharmacological therapy for ≥60 days prior to screening
• Prior MI ≥90 days
• Placement of implantable cardioverter defibrillator ≥180 days prior to transplant
• Target region wall thickness of ≥5 mm by echocardiography
• LVEF ≥20% and ≤45% by multigated acquisition (MUGA)


• MI within 12 weeks of scheduled implant
• NYHA class I or IV
• Coronary artery bypass grafting within 3 months or percutaneous coronary intervention within 6 months of cell implant
• Any cardiac valve replacement or significant aortic stenosis
• Heart failure secondary to valvular disease
• Severe tortuosity of aorta, iliac, or femoral arteries
• Prior angiogenic therapy or myocardial laser therapy
• End-stage renal disease

Primary Endpoints:

• Incidence of procedural and device-related serious adverse events
• Change in LVEF
• Change in NYHA classification of heart failure
• Distance achieved during a 6-minute walk

Secondary Endpoints:

• Holter monitoring, 12-lead ECG data, and frequency of ventricular arrhythmias

• Safety of the MyoCath injection catheter

Drug/Procedures Used:

Patients with myocardial scar were randomized to receive implantation of autologous skeletal myoblast cells (n = 31) or medical therapy (n = 16).

Principal Findings:

At 6 months of follow-up, there were 10 episodes of ventricular fibrillation/ventricular tachycardia in both groups. The percentage of subjects with a serious adverse event was 50% in the myoblast group and 36% in the control group (p = NS). In the myoblast group, 94% of patients improved or did not change their New York Heart Association (NYHA) functional class, compared with 58% in the control group (p = NS). Left ventricular ejection fraction (LVEF) increased 0.3% in the myoblast group and decreased 0.1% in the control group (p = NS). Six-minute walking distance was improved by 60 m in the myoblast group and declined 0.2 m in the control group (p = NS).


The results of this study show that myoblast injection into myocardium is feasible. There is no obvious excess in serious adverse events. Potential improvements in walking distance, EF, and heart failure functional class remains to be demonstrated.


Final Results of a Phase II-a, Randomized, Open-Label Trial to Evaluate Intramyocardial Autologous Skeletal Myoblast Transplantation in Congestive Heart Failure Patients: The SEISMIC Trial. Presented by Dr. Patrick Serruys at the SCAI-ACC i2 Summit/American College of Cardiology Annual Scientific Session, Chicago, IL, March/April 2008.

Clinical Topics: Arrhythmias and Clinical EP, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Acute Heart Failure, Echocardiography/Ultrasound, Exercise

Keywords: Walking, Tachycardia, Ventricular, Follow-Up Studies, Cicatrix, Ventricular Function, Left, Myoblasts, Skeletal, Ventricular Fibrillation, Heart Failure, Stroke Volume, Quadriceps Muscle, Defibrillators, Implantable, Echocardiography

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