Relation of initial infarct size to extent of left ventricular remodeling in the year after acute myocardial infarction.
OBJECTIVE
This study attempted to determine the relation between infarct size after acute myocardial infarction and subsequent left ventricular remodeling using precise clinical measurements.


BACKGROUND
Animal studies have demonstrated that the degree of left ventricular remodeling after myocardial infarction is linearly related to infarct size. Clinical studies have not clearly replicated these results because of imprecise measurements and failure to adjust for patency of the infarct-related artery.


METHODS
Infarct size was measured from technetium-99m (Tc-99m) sestamibi perfusion images in 14 patients (12 with an anterior, 2 with an inferior infarction) by a threshold method previously described and expressed as percent of the left ventricle (32 +/- 17% left ventricle [mean +/- SD], range 6% to 58%). Absolute end-systolic volume, end-diastolic volume and ejection fraction were determined by electron beam computed tomographic images performed at discharge and at 6 weeks, 6 months and 1 year after myocardial infarction. All patients had documented infarct-related artery patency after reperfusion therapy.


RESULTS
At hospital discharge, there was no correlation between infarct size and end-systolic and end-diastolic volumes or ejection fraction. There was significant left ventricular dilation in the study group over the next year. As remodeling progressed, there was closer correlation between infarct size and ejection fraction and end-systolic volume measures (infarct size vs. end-systolic volume, from r = 0.43 at discharge to r = 0.80 at 1 year; infarct size vs. ejection fraction, from r = -0.39 at discharge to r = -0.84 at 1 year). There was a strong inverse correlation between infarct size at discharge and subsequent changes over the next year in end-systolic volume (r = 0.63, p = 0.02) and ejection fraction (r = -0.66, p = 0.01).


CONCLUSIONS
Infarct size as measured by Tc-99m sestamibi at hospital discharge after an index infarction is predictive of subsequent change in left ventricular volume and function in the year after myocardial infarction. Patients with a large infarct demonstrated the greatest degree of dilation in the setting of patency of the infarct-related artery.
Chareonthaitawee
P
P
Division of Cardiovascular Disease and Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905.
Christian
T F
TF
Hirose
K
K
Gibbons
R J
RJ
Rumberger
J A
JA
D000328:Adult; D000368:Aged; D015906:Angioplasty, Balloon, Coronary; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006352:Heart Ventricles / Q000473:pathology; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy; D009206:Myocardium / Q000473:pathology*; D011237:Predictive Value of Tests; D011877:Radionuclide Imaging; D013318:Stroke Volume; D017256:Technetium Tc 99m Sestamibi; D015912:Thrombolytic Therapy; D014654:Vascular Patency; D016277:Ventricular Function, Left
D017256:Technetium Tc 99m Sestamibi