Survival benefit of coronary revascularization after myocardial perfusion SPECT: The role of ischemia.

BACKGROUND: Survival benefit of revascularization over medical therapy (MT) in patients with stable ischemic heart disease (SIHD) is uncertain. We evaluated the prognostic effects of revascularization in patients with SIHD undergoing single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI). METHODS: Of 47,894 patients, 7973 had ischemia ≥ 5% of the left ventricle. Of these, 1837 underwent early revascularization (≤ 60 days after SPECT-MPI). The rest were MT subgroup. Follow-up period was 4.04 ± 1.86 years. Statin therapy intensity and adherence were assessed. Outcomes were all-cause mortality, death + non-fatal myocardial infarction (MI), and MACE [major adverse cardiac event = death + MI + late revascularization (> 60 days after SPECT-MPI)]. RESULTS: Among patients with moderate-severe ischemia (≥ 10%), death rate was lower in early revascularization compared to MT subgroup (1.42%/year vs 3.12%/year, adjusted hazard ratio (HR) 0.67 (95% CI 0.50-0.90, P = .008). Death + MI and MACE rates were also lower, adjusted HR 0.69 (0.55-0.88, P = .003) and 0.80 (0.69-0.92, P = .003). Revascularization was beneficial in optimal statin therapy subgroup (death rate 1.04%/year vs 2.36%/year, adjusted HR 0.51 (0.30-0.86, P = .012). In mild ischemia (5%-9%), revascularization did not improve survival or MI-free survival, and was associated with higher MACE rate (8.86%/year vs 7.67%/year, adjusted HR 1.30 (1.12-1.52, P < .001). CONCLUSION: Compared to MT, revascularization was associated with reduced risk of death, death + MI, and MACE in patients with moderate-severe ischemia, incremental over optimal statin therapy. In mild ischemia, revascularization was associated with higher risk of MACE, driven by late revascularization, with no impact on death and death + MI.

Comparison of the diagnostic accuracies of very low stress-dose with standard-dose myocardial perfusion imaging: Automated quantification of one-day, stress-first SPECT using a CZT camera.

BACKGROUND: Previous studies have demonstrated accurate diagnosis of reduced dose myocardial perfusion imaging (MPI) using Cadmium-Zinc-Telluride (CZT) technology. We compared the diagnostic performances of very low stress-dose (<2 mSv) with standard-dose stress-first, quantitative MPI using a CZT camera. METHODS: Patients without known coronary artery- disease who underwent a stress-first Tc-99 m sestamibi CZT-MPI and invasive coronary angiography (ICA), and low-risk patients without ICA were included. A stress-rest standard-dose (10/30 mCi) MPI and a low-dose (5/15 mCi) MPI were compared. Normal limits for quantification were developed from 40 (20 males) low-risk patients, and total perfusion deficit (TPD) was derived. RESULTS: 208 patients who underwent MPI and ICA, and 76 low-risk patients were included. Of these, 128 had a standard-dose MPI and 156 had a low-dose MPI. Stress-doses in low-dose and standard-dose groups were 5.9 ± 1.2 vs 10.2 ± 0.5 mCi (1.7 ± 0.3 vs 3.0 ± 0.1 mSv), respectively, P < 0.001, and stress-rest effective radiation was 6.9 ± 1.1 vs 11.7 ± 0.4 mSv, respectively, P < 0.001. Sensitivity, specificity, and accuracy values in the low-dose and standard-dose groups were 86.1%, 76.6%, and 81.4%; and 90.6%, 78.1%, and 84.4%, respectively, P = ns. Using TPD prone, specificity values were 84.9% and 80.3%, respectively, P = ns. CONCLUSION: One-day stress-first MPI with 50% radiation reduction and a very low stress-dose (<2 mSv) using CZT technology and quantitative supine and prone analysis provided a high diagnostic value, similar to standard-dose MPI.

Use of electrocardiographic depolarization abnormalities for detection of stress-induced ischemia as defined by myocardial perfusion imaging.

High-frequency mid-QRS (HFQRS) analysis was recently introduced as a tool for identification of stress-induced ischemia. The diagnostic performance of this electrocardiographic technique has not been determined in a large cohort of patients. This study compared the diagnostic performance of HFQRS analysis to conventional ST-segment analysis in detecting exercise-induced ischemia. The study included 996 patients (56 ± 10 years of age, 670 men) referred for exercise myocardial perfusion imaging (MPI), which served as the gold standard of ischemia. High-resolution electrocardiogram was used for computer analysis of HFQRS signals. Number of electrocardiographic leads with ≥50% decrease of HFQRS intensity (L(50%)) was used as an index of ischemia. Perfusion images were evaluated semiquantitatively. Receiver operating characteristic analysis demonstrated an L(50%) ≥3 as the criterion that yielded optimal sensitivity and specificity for diagnosing moderate/severe ischemia. Compared to ST-segment analysis HFQRS analysis was more sensitive (69% vs 39%, p <0.005) and more specific (86% vs 82%, p <0.05). L(50%) correlated with amount of MPI ischemia (R(2) = 0.75, p <0.0001). Multivariate logistic regression analysis demonstrated a significant incremental diagnostic value for the addition of HFQRS data to a model containing pretest and conventional exercise parameters. L(50%) was the best predictor of mild or moderate/severe MPI ischemia. In conclusion, computerized HFQRS analysis improved the diagnostic performance of conventional stress electrocardiogram in detecting exercise-induced ischemia. Thus, this technique might aid in the noninvasive evaluation of coronary artery disease.