Visualization of discrete microinfarction after percutaneous coronary intervention associated with mild creatine kinase-MB elevation.
BACKGROUND
Mild elevations in creatine kinase-MB (CK-MB) are common after successful percutaneous coronary interventions and are associated with future adverse cardiac events. The mechanism for CK-MB release remains unclear. A new contrast-enhanced MRI technique allows direct visualization of myonecrosis.


RESULTS
Fourteen patients without prior infarction underwent cine and contrast-enhanced MRI after successful coronary stenting; 9 patients had procedure-related CK-MB elevation, and 5 did not (negative controls). The mean age of all patients was 61 years, 36% had diabetes, 43% had multivessel coronary artery disease, and all had a normal ejection fraction. Twelve patients (86%) received an intravenous glycoprotein IIb/IIIa inhibitor; none underwent atherectomy, and all had final TIMI 3 flow. Of the 9 patients with CK-MB elevation, 5 had a minor side branch occlusion during stenting, 2 had transient ECG changes, and none developed Q-waves. The median CK-MB was 21 ng/mL (range, 12 to 93 ng/mL), which is 2.3x the upper limit of normal. Contrast-enhanced MRI demonstrated discrete regions of hyperenhancement within the target vessel perfusion territory in all 9 patients. Only one developed a new wall motion abnormality. The median estimated mass of myonecrosis was 2.0 g (range, 0.7 to 12.2 g), or 1.5% of left ventricular mass (range, 0.4% to 6.0%). Hyperenhancement persisted in 5 of the 6 who underwent a repeat MRI at 3 to 12 months. No control patient had hyperenhancement.


CONCLUSIONS
Contrast-enhanced MRI provides an anatomical correlate to biochemical evidence of procedure-related myocardial injury, despite the lack of ECG changes or wall motion abnormalities. Mild elevation of CK-MB after percutaneous coronary intervention is the result of discrete microinfarction.
Ricciardi
M J
MJ
Feinberg Cardiovascular Institute and the Department of Medicine, Northwestern University, Chicago, IL, USA.
Wu
E
E
Davidson
C J
CJ
Choi
K M
KM
Klocke
F J
FJ
Bonow
R O
RO
Judd
R M
RM
Kim
R J
RJ
D000328:Adult; D000368:Aged; D019917:Blood Vessel Prosthesis Implantation / Q000009:adverse effects*; D017023:Coronary Angiography; D003402:Creatine Kinase / Q000097:blood*; D052279:Creatine Kinase, MB Form; D004452:Echocardiography; D004562:Electrocardiography; D006801:Humans; D007089:Image Enhancement; D007527:Isoenzymes / Q000097:blood; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000175:diagnosis* / Q000209:etiology*; D009336:Necrosis; D011237:Predictive Value of Tests; D015607:Stents; D019210:Troponin I / Q000097:blood
D007527:Isoenzymes; D019210:Troponin I; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form