Prognostic implications of the difference between left ventricular ejection fractions after stress and at rest in addition to the quantification of myocardial perfusion abnormalities obtained with gated SPECT.

BACKGROUND: The prognostic significance of the difference between poststress and at rest left ventricular ejection fraction (ΔLVEF) in patients sent for diagnostic myocardial perfusion study (MPS) is not well characterized. The purpose of this study was to prospectively evaluate the ability of ΔLVEF in further risk stratifying these patients in addition to the severity/extent of myocardial perfusion abnormalities expressed as the total perfusion deficit at stress (sTPD), according to the type of stress used. METHODS AND RESULTS: Two-day 99mTc-MIBI MPS after stress and rest were obtained for 507 patients subdivided according to the type of stress used, sTPD values, and ΔLVEF. Subsequent cardiac events were determined through a standardized questionnaire applied 1, 2, and 6 years after MPS. Independent of the type of stress used, the 6-year event rate with progressive perfusion and functional abnormalities combined was significant for total events, all-cause death, cardiac death, and revascularization but not for myocardial infarct. When ΔLVEF decreased by more than -10%, only those individuals with sTPD of 5% or less had increased 6-year total event rates [5.9% vs 15% for those submitted to treadmill test (P < 0.001) and 8.3% vs 19% when submitted to pharmacological stress (P = 0.001)]. An sTPD greater than 5% was the only variable predictive of total events when multivariate analysis was applied (P < 0.001 for treadmill exercise and P = 0.033 for dipyridamole). CONCLUSIONS: Estimation of ΔLVEF in addition to sTPD seems to improve risk stratification for future events when ΔLVEF decreases by more than -10% for those individuals with normal or near-normal myocardial perfusion (sTPD ≤ 5%). An sTPD greater than 5% was a better prognostic indicator of future events when compared with ΔLVEF for individuals with greater perfusion abnormality at stress.

Attenuation correction reveals gender-related differences in the normal values of transient ischemic dilation index in rest-exercise stress sestamibi myocardial perfusion imaging.

BACKGROUND: Transient ischemic dilation (TID) has been established as an important independent marker of severe and extensive coronary artery disease (CAD) in myocardial perfusion imaging (MPI). The accuracy of the TID index is dependent on a well-determined threshold (normal limits) between normal and abnormal values for each study protocol. To date, the effects of neither gender nor attenuation correction (AC) on TID normal limits have been established. Thus, the objectives of this study were to determine if AC processing changes the normal value of the TID index and if there were gender-related differences in the TID index of normal patients who had undergone rest/exercise-stress technetium-99m sestamibi MPI. METHODS AND RESULTS: Seventy-five patients (33 women, 42 men; mean age, 57.7 +/- 11.7 y and 55.9 +/- 10.0 y, respectively) with less than a 5% likelihood of CAD, who had undergone low-dose rest/high-dose exercise-stress Tc-99m sestamibi MPI, were studied. All studies were acquired using simultaneous emission/transmission scans and were corrected for attenuation, scatter, and resolution effects using the ExSPECT II method. Both the AC and non-AC studies were analyzed using the Emory Cardiac Toolbox (ECTb; Syntermed, Inc, Atlanta, Ga) quantitative software. The TID index was calculated automatically as the ratio of stress mean left ventricular volumes to rest mean left ventricular volumes by ECTb. Patients were grouped by gender and the TID indices from AC and non-AC studies were compared. Linear regressions of the TID index and body mass index were analyzed to exclude differences in body size between male and female patients as a confounding factor in gender-related differences in TID. The TID index upper normal limits were calculated as the mean value plus 2 standard deviations (SDs). AC processing did not change the TID index significantly whether the genders were combined or separated (AC TID = 0.97 +/- 0.14 vs non-AC TID = 0.98 +/- 0.12 for all patients). Female patients showed higher mean TID indices than male patients in both AC (1.01 +/- 0.15 vs 0.95 +/- 0.12) and non-AC studies (1.00 +/- 0.15 vs. 0.97 +/- 0.10), but this difference was statistically significant only in AC studies (p = .03). TID indices remained constant across the range of body mass index studied. The TID index upper normal limit was 1.31 for female and 1.18 for male patients. CONCLUSION: TID normal values for rest/exercise-stress Tc-99m sestamibi MPI are gender-dependent and not affected by AC processing. Thus, diagnosticians should take into account these gender-related differences, as compared with the traditional value generated from mostly male populations, to ensure both men and women have the same overall accuracy of using the TID index in the diagnosis and prognosis of CAD.

Incremental prognostic value of left ventricular function by myocardial ECG-gated FDG PET imaging in patients with ischemic cardiomyopathy.

BACKGROUND: The purpose of this study was to determine the independent value of left ventricular (LV) functional parameters derived from gated fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) to predict prognosis in patients with ischemic cardiomyopathy undergoing myocardial viability assessment. METHODS AND RESULTS: We studied 90 consecutive patients with coronary artery disease and low LV ejection fraction (26% +/- 7%) undergoing gated FDG PET to assess myocardial viability for potential revascularization. The primary endpoint for this analysis was the occurrence of cardiac death, myocardial infarction, or worsening heart failure (HF) to New York Heart Association class IV. During follow-up (22 +/- 14 months), 21 patients had an event (17 died, 4 had myocardial infarctions, and 4 had worsening HF). On Cox regression analysis, the event-free survival rate at 2 years was lower for patients with an end-diastolic volume (EDV) of 260 mL or greater (relative risk, 2.7; P = .014), end-systolic volume (ESV) of 200 mL or greater (relative risk, 2.5; P = .021), and LV mass of 143 g or greater (relative risk, 1.6; P = .009). In a risk-adjusted model, EDV (chi 2 = 68, P < .0001) and ESV (chi 2 = 75, P = .035) added a significant amount in the estimation of events over the perfusion-FDG mismatch pattern (chi 2 = 40, P < .001). In a stratified Cox model, patients with PET mismatch, LV ejection fraction lower than 25%, and EDV of 260 mL or greater had the lowest survival rate (P = .006). These patients showed an apparent survival benefit with revascularization but without an improvement in HF symptoms. CONCLUSION: LV functional parameters determined by gated FDG PET have incremental prognostic value over viability information in patients with ischemic cardiomyopathy. Our data suggest that patients with residual viability and advanced cardiac remodeling are at high clinical risk. In these patients the apparent survival benefit of revascularization may not be associated with a measurable improvement in HF symptoms.

Quantitative Tc-99m sestamibi attenuation-corrected SPECT: development and multicenter trial validation of myocardial perfusion stress gender-independent normal database in an obese population.

BACKGROUND: A gender-independent stress normal database and criteria for abnormality for attenuation-corrected rest-stress technetium 99m sestamibi same-day myocardial perfusion imaging were developed by evaluation of 112 patients, validated against an obese population of 95 patients from four different clinical sites, and compared with conventional gender-matched database quantification of non-attenuation-corrected studies. METHODS AND RESULTS: These 95 validation patients (63 men) were used for prospective quantitative evaluation (mean weight, 213 +/- 57 lb; mean body mass index, 32 +/- 9 kg/m(2)). This group included 21 patients (12 men) with a lower than 5% likelihood of coronary artery disease (mean weight, 226 +/- 72 lb; mean body mass index, 34 +/- 13 kg/m(2)) and 74 who underwent cardiac catheterization within 2 months (35 with normal coronaries or coronary lesions <70%). These studies were processed twice, once by use of conventional reconstruction and gender-specific database quantification and a second time by use of attenuation correction and a single gender-independent attenuation-corrected normal database. The attenuation-corrected normal database and criteria for abnormality were developed by evaluation of 48 and 78 patients, respectively. No statistically significant differences were found when comparing attenuation-corrected perfusion distributions of normal men and women, whereas significant differences were found in the same uncorrected studies. Compared with quantitative analysis of the uncorrected studies, quantitative analysis of the attenuation-corrected studies by use of a gender-independent normal database demonstrated a significant improvement in normalcy rate (90% vs 52%, P =.006) and specificity (57% vs 29%, P =.015) in this obese population at no significant loss in sensitivity (90% vs 97%, P = not significant). CONCLUSION: Attenuation-corrected studies can be quantified with a single gender-independent normal database and a single criterion for abnormality without loss of sensitivity and with significantly better specificity and normalcy rate.