| In the first part of this thesis we compared patients with MI who met only c-TnT criteria to patients with MI who met CK-MB criteria, in a population-based cohort from Olmsted County, MN. Our aims were to: ;We accomplished this by prospective identification of 835 MIs in the community using standardized criteria including cardiac pain, ECG and biomarkers, from November, 2002 to May, 2006. We prospectively measured troponin and CK-MB in all; each patient was classified according to the criteria met. We performed echocardiograms (median of 1 day post-MI) in 482 patients (age 68 +/- 15 years; 45% women); 363 patients met CK-MB criteria while 119 met c-TnT criteria. The latter group had lower wall motion score index (1.3 +/- 0.4 vs 1.5 +/- 0.5 for CK-MB; p <0.01). Diastolic dysfunction was similar for the two groups. After one year of follow up, 142 patients developed post-MI HF. Patients meeting c-TnT criteria had a lower risk of HF after adjustment for age, sex and comorbidity (HR 0.56, 95% CI 0.37, 0.85, p<0.01), which persisted after further adjustments for systolic or diastolic function. In the community, the prospective application of the new MI definition identified patients meeting only c-TnT criteria who had better systolic function than cases meeting CK-MB criteria. Such MI cases have a lower risk of subsequent HF. These findings are relevant for risk stratification in clinical practice.;In the second part of this thesis, the aim (;We evaluated a subset of patients with first MI prospectively enrolled in a community-based cohort of MI in Olmsted County, MN. Serial c-TnT levels were obtained at presentation, <12 hours, 1 day, 2 days, and 3 days after onset of pain. Peak c-TnT was the maximum c-TnT value. The patient group was obtained by prospective recruitment of 121 patients (age 61 +/- 13; 31% women) with MI who underwent gated SPECT-MPI at a median (25%; 75%) of 10 (5; 15) days post-MI. The median infarct size was 1% (0%; 11%) and median gated LVEF was 54% (47%; 60%). 59 patients (49% of the population) had no measurable infarction by SPECT-MPI. The independent predictors for measurable SPECT-MPI infarct size included c-TnT at days 1, 2, 3 and peak c-TnT, but not at presentation or < 12 hours. Early values of c-TnT (at presentation and <12 hours) were not independent predictors of measurable SPECT-MPI MI size. Independent predictors of measurable SPECT-MPI infarct size included later c-TnT at days 1, 2, 3 and peak c-TnT. ROC analysis demonstrated a cut-off peak c-TnT of 1.5 ng/mL for detection of measurable infarct size.;The data from this study indicated that SPECT-MPI did not detect measurable infarct in nearly half of the patients with MI diagnosed by c-TnT criteria. The independent predictors for measurable SPECT-MPI infarct size included c-TnT at days 1, 2, 3 and peak c-TnT; ROC analysis demonstrated a cut-off peak c-TnT of 1.5 ng/mL for detection of measurable infarct size, using the third generation c-TnT assay. Finally, infarct size and peak c-TnT were independent predictors for major cardiac events at follow up.;In this thesis, the overall conclusion is that patients diagnosed with AMI by the new diagnostic criteria defined by c-Tn elevation have better left ventricular function, smaller infarct size and less adverse outcomes at follow-up. |
