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.

[Fast myocardial perfusion imaging of stress--first protocol using CZT-technology: a preliminary report of the correlation to invasive coronary angiography]

BACKGROUND

Myocardial perfusion imaging (MPI) is valuable for diagnosing coronary disease and assessing the risk of cardiac events. New technology based on semiconductors (Cadmium zinc telluride-CZT) enables reducing imaging time and improving image quality.

METHODS

We retrospectively identified 57 patients who underwent MPI at Assuta using a CZT camera and invasive coronary angiography (ICA) within 60 days following nuclear testing without an intervening cardiac event, and without history of coronary disease. In addition, 25 patients with low pretest likelihood who did not undergo ICA were included in the study. All 82 patients underwent fast-acquisition, stress-first Tc-99m sestamibi MPI using very short imaging time (stress: 5:00 min., prone: 3:40 min. and rest: 2:00 min]. A low-dose stress injection (9-12 mCi, ≤ 3.5 mSv) and high rest-dose (25-32 mCi) with adjustment to patient weight were administered. Semi-quantitative visual analysis utilized a 17-segment model, 0-4 scale (0 = normal uptake, 4 = absent uptake). The summed stress score (SSS) representing stress perfusion abnormality was converted to a percentage of abnormal myocardium (SSS% = SSS/68*100). ICA served as a gold standard for the nuclear perfusion findings.

RESULTS

The mean age was 60.1 ± 11 years and most subjects were men (58, 70.7%). Compared to low-risk patients, patients who underwent ICAwere older, and had a higher frequency of hypertension, diabetes mellitus and dyslipidemia. A low-dose stress-only test with low radiation exposure ≤ 3.5 mSv) was frequent among low-risk patients (18/25-72%). ROC analysis for identification of angiographic coronary disease by SSS% demonstrated area under curve of 0.923, 95% confidence interval 0.859-0.988, p < 0.001. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were: 91.4%, 81.2%, 78.3%, 97.2% and 86.6%, respectively.

CONCLUSION

Fast, low-dose stress MPI using CZT technology enables semi-quantitative analysis with high diagnostic value for coronary disease.

Initial and long-term results with the CrossFlex stent--data from a national registry

The Cordis CrossFlex trade mark stent is a balloon expandable helical coil made of stainless steel. OBJECTIVE: To assess the short- and long-term safety and efficacy of this stent by conducting a multi-center national registry. METHODS: One hundred and sixteen stents were implanted in 109 patients (mean age 59 3 10 years, 95 males). The lesions were classified as type B2 or C in 56 patients (51%). Successful deployment was achieved in 103 patients (94.5%). Failure was due to damage to the stent (two patients) or inability to reach the lesion (four patients). High-pressure deployment (>14 atm) was used in 68% of cases. RESULTS: Edge dissections occurred in nine patients after high-pressure deployment and necessitated implantation of a second stent. One patient with a large acute myocardial infarction died during hospitalization. Side branch occlusion occurred in five patients (4.6%). Subacute thrombosis occurred in two patients (1.8%) during the first four weeks. During a six-month follow-up period, 18 patients (16.5%) were rehospitalized with recurrent angina. Fifteen patients had coronary angiography and 13 (12.1%) needed additional target lesion revascularization (TLR). Twelve patients required a second PTCA for in-stent restenosis, and one needed a coronary artery bypass graft operation. CONCLUSIONS: The CrossFlex coronary stent can successfully be used in complex coronary lesions, with few short-term complications and a low TLR rate. Operators should be aware of the possibility of edge dissection during high-pressure implantation.

Effectiveness of coronary stent deployment without predilation

The feasibility of coronary stenting without predilation is demonstrated in 240 patients. In all, 249 stents were placed. Primary implantation was successful in 93% of cases. In 17 lesions the stents could not be advanced through the stenotic lesion. The unexpanded stents were removed through the guiding catheter, and stenting was performed after prediction. Minor complications (side branch compromise and intimal dissection), which were successfully treated, occurred in 26 patients (10.6%).

Coronary stent deployment without predilation: prevention of complications of venous graft angioplasty

Saphenous vein graft stenting without predilation may potentially decrease procedural complications such as distal embolization and no-reflow phenomenon. In this report the authors describe the deployment of stents (three Wallstents, one Palmaz-Schatz, one Multilink, and one NIR) without predilation in five patients with unstable angina pectoris due to high-grade stenosis in old saphenous vein grafts. Stent deployment was successful in all patients without procedure-related complications. Stenting without predilation appears to be feasible in old bypass grafts with significant stenosis. The potential of this new stenting technique to reduce the risk of stenting complications should be tested by a randomized trial.

One-year clinical and echocardiographic follow-up of patients with congestive cardiomyopathy treated with captopril compared to placebo

The beneficial hemodynamic and clinical effects of angiotensin-converting enzyme (ACE) inhibition in patients with severe congestive heart failure has recently been documented in large-scale studies. This mode of therapy when added to digitalis and diuretics improves survival. To evaluate the clinical effect and the changes in cardiac dimensions of captopril compared to placebo we followed 50 patients with severe congestive heart failure over 1 year using echo-Doppler cardiography. After randomization, 25 patients were started on captopril and 25 patients on placebo. At baseline and at 6 and 12 months, each patient underwent exercise tolerance test, radionuclide angiography to estimate left and right ventricular ejection fraction, M mode and two-dimensional echocardiography and Doppler cardiography to calculate cardiac dimensions and stroke volumes. During follow-up two patients in the captopril group and four in the placebo group died. Due to clinical deterioration nine patients in the placebo group had to be started on open-label captopril. Treatment with captopril was associated with a more significant improvement in functional class and exercise duration compared to placebo. Forward stroke volume estimated from Doppler echocardiography increased significantly by captopril from 47 +/- 3 to 55 +/- 3 ml and decreased in the placebo-treated patients from 49 +/- 5 to 44 +/- 4 ml. This improvement was associated with a trend towards reduced heart rate by captopril. Left ventricular end diastolic volume tended to increase in the placebo group and did not change in the captopril group. Calculated mitral regurgitant volume at 6 and 12 months tended to be lower in the captopril-treated patients. Thus captopril therapy proved efficacious in patients with severe congestive heart failure and resulted in increased forward stroke volume; it may have a beneficial effect on cardiac dimensions and on mitral regurgitation.

Left ventricular filling dynamics by Doppler echocardiography in dilated cardiomyopathy: one-year follow-up in patients treated with captopril compared to placebo

The role of impaired diastolic function in determining the pathophysiology of congestive cardiomyopathy was only recently appreciated. In the present study, echocardiography and Doppler cardiography were used to determine changes in cardiac size and transmitral filling dynamics over a 1-year period in patients with congestive cardiomyopathy and determine the effect of captopril on these changes. The study population consisted of 27 patients with congestive heart failure in spite of therapy with digitalis and diuretics (NYHA class 3.2). Fifteen patients were started on placebo and 12 on captopril. Noninvasive evaluation was performed at 6-month intervals. Left ventricular size and left ventricular ejection fraction did not change significantly in either group. Forward stroke volume improved significantly only in patients on captopril compared to placebo (p < 0.05). No significant changes in transmitral flow dynamics were observed in the placebo group whereas the captopril-treated group showed a decrease in the peak velocity, flow velocity integral and rate of rapid filling wave (E) and an increase in the peak, integral and rate of filling during atrial contraction (A). The E/A ratio did not change significantly over time in the placebo group, whereas a reduction in the ratio was noted in the captopril-treated patients. These changes are sustained over 1 year with concomitant improvement in stroke volume, exercise duration and functional class.