Myocardial scar and insulin resistance predict cardiovascular events in severe ischaemic myocardial dysfunction: a perfusion-metabolism positron emission tomography study.
BACKGROUND
Clinical outcome can be predicted by metabolism-perfusion positron emission tomography (PET) in patients with severe ischaemic left ventricular dysfunction. This study determined whether the amount of viable or non-viable myocardium detected with a PET scan or clinical-functional parameters might predict cardiovascular events.


METHODS
All patients had previous myocardial infarction (>6 months previously) and left ventricular ejection fraction (LVEF) <40%. Metabolism-perfusion PET, echocardiogram and coronary angiography were provided. All subjects underwent short euglycaemic-hyperinsulinaemic clamp before the metabolism study. The dysfunctioning segment was defined as hibernating myocardium when metabolism was normal-moderately reduced with impaired perfusion (mismatch flow-metabolism). Cardiac death, hospital admission for myocardial infarction or heart failure were considered cardiovascular events.


RESULTS
Ninety-three patients (71 males, aged 64.2 years) were studied. The LVEF was 30.2+/-7.7%; 48 (51.6%) suffered an anterior myocardial infarction. Fifty-three (54.1%) subjects were treated with coronary revascularization; all had optimal medical therapy. Cardiovascular events occurred in 20/93 patients at 1-year follow-up (event group). Age (P=0.7), diabetes mellitus (P=0.6) and rate of coronary revascularization (P=0.3) were not different in the two groups. Patients who experienced cardiovascular events had larger non-viable myocardium (5.8+/-2.7 vs. 4.1+/-2.6, P=0.01), lower metabolic rate glucose (1.3+/-0.6 vs. 1.7+/-0.7 ml . kg . min, P=0.04) but similar hibernating myocardium (1.6+/-1.6 vs. 1.7+/-2, P=0.8) and baseline LVEF (28.1+/-4.8 vs. 30.7+/-8.3%, P=0.08). Having more then five non-viable segments and a metabolic rate for glucose of <0.9 mg . kg . min predicted a worse prognosis (P=0.04, log rank, 3.89; and P=0.004, log rank, 8.1, respectively).


CONCLUSIONS
Non-viable myocardium revealed with PET predicts mid-term clinical prognosis. Insulin resistance seems to influence the outcome.
Feola
Mauro
M
Department of Cardiovascular Diseases, Ospedale Santa Croce-Carle, Via Coppino 26, Cuneo, Italy. m_feola@virgilio.it
Biggi
Alberto
A
Chauvie
Stéphane
S
Vado
Antonello
A
Leonardi
Giovanni
G
Rolfo
Fabrizio
F
Ribichini
Flavio
F
D015897:Comorbidity; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D015995:Prevalence; D011379:Prognosis; D011877:Radionuclide Imaging; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000453:epidemiology*