Accuracy of 99mTc-tetrofosmin myocardial tomography in the evaluation of coronary artery disease

BACKGROUND

Technetium 99m-labeled myocardial agents have been proposed as an alternative to thallium 201. The aim of this study was to assess retrospectively the accuracy of exercise myocardial 99mTc-tetrofosmin scintigraphy with tomographic imaging (SPECT) in a large group population in the evaluation of coronary artery disease. Furthermore we evaluated the relation between the severity of scintigraphic impaired myocardial perfusion and the angiographic coronary artery stenoses in patients without myocardial infarction and with stenosis localized exclusively in the proximal segment of the 3 main coronary arteries.

METHODS AND RESULTS

The study group consisted of 235 consecutive patients, 204 (87%) of whom were men, with a mean age of 57+/-10 years, and with suspected or known coronary artery disease, who underwent 99mTc-tetrofosmin SPECT and coronary angiography. Furthermore, 61 patients in a low-likelihood group for coronary artery disease were also studied. Significant disease was defined by > or = 50% luminal coronary artery stenosis in > or = 1 native coronary artery or major branch or in a saphenous vein graft or arterial mammary graft. The overall sensitivity was 95%, specificity was 76%, and predictive accuracy was 95%. The normalcy rate for the low-likelihood group was 93%. Sensitivity was 71% for the left anterior descending artery, 61% for the left circumflex artery, and 73% for the right coronary artery. Specificity was 94% for the left anterior descending artery, 96% for the left circumflex artery, and 91% for the right coronary artery. Predictive accuracy was 79% for the left anterior descending artery, 78% for the left circumflex artery, and 81 % for the right coronary artery. In patients without myocardial infarction linear regression analysis between scintigraphy and angiography showed a significant correlation in patients with severe proximal coronary artery stenosis (r = 0.53, P < .002), but not in those with moderate proximal stenosis (r = 0.31, P = NS).

CONCLUSIONS

This study shows that 99mTc-tetrofosmin SPECT is accurate in the detection of coronary artery disease. The relation of the severity of scintigraphic impaired myocardial perfusion and angiographic coronary artery stenosis, however, may differ significantly in patients with proximal stenosis of different severity.

Pregnancy in heart transplant recipients

The aim of this report is to present data from Italian cardiac transplant centers assessing pregnancy after cardiac transplantation. Our retrospective survey included 10 pregnancies occurring in 7 patients during January 1991 to February 2002. Eight pregnancies were completed successfully and 2 abortions were reported (frequency rate 20%). No complications were observed during pregnancy or after delivery. Of 8 infants studied, 6 (75%) were born at term and 2 (25%) pre-term. One baby presented congenital talipes valgus. Pediatric development was uneventful. The data from the literature and our series show that a multidisciplinary approach is mandatory. The course of pregnancy is usually normal and the maternal and fetal outcomes are usually favorable. Although no fetal malformations have been reported, prolonged follow-up of these infants is required.

Comparison of technetium 99m-tetrofosmin and thallium-201 single photon emission computed tomographic imaging for the assessment of viable myocardium in patients with left ventricular dysfunction

BACKGROUND

Tetrofosmin is a new technetium 99m-labeled myocardial perfusion agent that has demonstrated favorable imaging characteristics in recent clinical trials. However, it is not certain whether 99mTc-tetrofosmin compared with thallium 201 would underestimate myocardial viability in regions with left ventricular dysfunction.

METHODS

To this end 15 patients (mean age 52+/-7 years) with coronary artery disease and left ventricular dysfunction (ejection fraction 35%+/-8%) documented on angiography underwent both quantitative rest-redistribution 201Tl and rest 99mTc-tetrofosmin single photon emission computed tomography imaging. RESULTS; Of 240 total segments on rest-redistribution 201Tl protocol 139 (58%) segments had irreversible 201Tl defects. Of these segments 79 (57%) had only mild to moderate reduction of 201Tl uptake (51% to 85% of normal uptake), whereas the remaining 60 (43%) had severely reduced tracer uptake (< or = 50% of normal uptake). On 99mTc-tetrofosmin protocol 180 (75%) segments had abnormal 99mTc-tetrofosmin uptake; of these segments 120 (67%) had mild to moderate reduction of 99mTc-tetrofosmin uptake, whereas 60 (33%) had severely reduced activity. Among hypokinetic regions concordance between 201Tl and 99mTc-tetrofosmin regarding myocardial viability with a cutoff point of 50% of peak activity was obtained in 28 (90%) of 31 segments (K' = 0.80), leaving only 3 of 31 regions discordant (p = NS). Similarly, among akinetic or dyskinetic regions concordance between the two tracers regarding myocardial viability was achieved in 54 (93%) regions (K' = 0.75), leaving only 4 of the 58 regions discordant (p = NS).

CONCLUSIONS

These data show that when the severity of uptake was considered within abnormal segments, a similar amount of 201Tl viable regions were observed by 99mTc-tetrofosmin. Thus these two agents may provide comparable information about myocardial viability when quantitative analysis of defect severity is performed.

Accuracy of exercise testing in the assessment of the severity of myocardial ischemia as determined by means of technetium-99m tetrofosmin SPECT scintigraphy

BACKGROUND

The separation of patients with suspected or known coronary artery disease into low- and high-risk subgroups by means of noninvasive testing is highly relevant in the selection of patients who require further diagnostic or therapeutic investigation. We evaluated whether exercise electrocardiographic variables during exercise testing might be a means of predicting the severity of myocardial ischemia as assessed with myocardial scintigraphy.

METHODS AND RESULTS

We retrospectively reviewed 816 consecutive patients (mean age, 57+/-10 years) who underwent exercise technetium-99m tetrofosmin single photon emission computed tomography (SPECT) for the assessment of suspected or known coronary artery disease. Eight independent significant predictors of the extent and severity of reversible perfusion defects (ischemic perfusion score), which when integrated in a diagnostic algorithm satisfactorily discriminated patients with no reversible perfusion defects (sensitivity, 75%; specificity, 80%) and patients with severe impaired myocardial perfusion (> or =11 ischemic perfusion score; sensitivity, 77%; specificity, 82%), were identified by means of stepwise discriminant analysis. However, patients with mildly to moderately impaired myocardial perfusion (> or =21 but <11 ischemic perfusion score) were poorly discriminated (sensitivity, 50%; specificity, 78%). The set of variables that were significant (P<.0001) for prediction included sex, myocardial infarction, exercise angina, the maximal amount of ST segment depression, rate-pressure product threshold criteria, slope of ST segment depression, ST/heart rate index, and peak exercise heart rate.

CONCLUSIONS

The results of the use of clinical and electrocardiographic exercise variables satisfactorily agrees with the results from scintigraphy only for patients with no reversible perfusion defects and with severely impaired myocardial perfusion. However, it fails as an approach with universal applicability.

Cyclosporine and graft coronary artery disease after heart transplantation

Risk factors for graft coronary artery disease after heart transplant are discussed in relationship to cyclosporine dosages. Patients receiving a mean cyclosporine dose higher than 4 mg/kg/day had lower incidence of graft coronary disease than patients receiving lower dosages.

Heart rate-independent prolongation of QTc interval in women with syndrome X

BACKGROUND

Cardiac syndrome X is usually diagnosed in the presence of typical exertional chest pain, a positive response to exercise testing, and normal coronary angiograms. The underlying pathogenic mechanisms are speculative, but myocardial ischemia and increased sympathetic activity have been implicated.

HYPOTHESIS

The present study examined whether QTc interval is prolonged in women with syndrome X when confounding factors such as heart rate, gender, and environmental conditions are accounted for.

METHODS

Maximum QTc interval and its relationship to clinical and exercise variables were evaluated in 32 women with syndrome X (exertional chest pain, positive exercise testing, and completely normal coronary arteries) and 34 normal controls.

RESULTS

Patients with syndrome X had significantly longer QTc interval (440 +/- 24 ms) than normal subjects (410 +/- 26 ms, p < 0.004). However, this QTc prolongation appears to be heart rate-independent as patients with syndrome X showed longer QT and QTc intervals than controls despite an identical heart rate. No relation was found between QTc prolongation and clinical or exercise test variables in patients with syndrome X.

CONCLUSION

Although increased sympathetic drive is present in syndrome X, and this variable is likely to modulate QTc duration, the mechanism and clinical implications of QTc interval prolongation in syndrome X remain speculative.

Atrial Natriuretic Peptide in Diabetic and Nondiabetic Patients With and Without Heart Transplantation

BACKGROUND

Natriuretic peptides are useful markers for risk stratification of patients with heart disease. However, conflicting results have been reported about circulating atrial natriuretic peptide (ANP) concentration in heart transplant recipients.

METHODS

To ascertain the effects of diabetes and acute insulin administration on plasma ANP concentrations in a model of heart denervation, we studied 12 diabetic (D-OHT) and 6 nondiabetic heart-transplanted (OHT) patients using the euglycemic-hyperinsulinemic clamp and oral glucose tolerance tests. Five patients with type 2 diabetes without heart transplantation (D) and 9 healthy subjects (NOR) matched for anthropometric features served as the controls.

RESULTS

Means baseline plasma ANP concentration was higher in D-OHT (82 +/- 15 pg/mL) than in OHT or NOR (27 +/- 4 or 30 +/- 5; P < .01), but was not different than D (69 +/- 12; P = .82). During the clamp plasma ANP showed similar increases in all groups (49 +/- 4, 39 +/- 3, 59 +/- 4, and 49 +/- 3% in D-OHT, OHT, D, and NOR; P < .02 vs basal, P = NS among groups). Plasma osmolarity and catecholamines were also not different among groups and did not increase during the clamp. Fasting plasma ANP concentrations correlated with plasma glucose concentrations measured 120 minutes after oral glucose tolerance testing.

CONCLUSIONS

Among heart transplantation recipients fasting plasma ANP concentrations were not different at 5 to 6 years after the surgical procedure than in nondiabetic controls. Increased ANP concentrations were observed among recipients with diabetes and among nontransplanted diabetic patients. Although the insulin-induced increment in ANP concentrations was not different among groups, circulating ANP was strongly associated with glucose tolerance status.

Continuous retrograde warm blood reperfusion reduces cardiac troponin I release after heart transplantation: a prospective randomized study

During heart surgery, cardiac troponin I (cTn-I) measurement provides a tool to evaluate different cardioprotective techniques. To investigate myocardial protection during heart transplantation (HTx), cTn-I and creatine kinase (CK)-MB release was measured in 42 patients randomized to receving either continuous retrograde warm blood reperfusion or no reperfusion after cold cardioplegia. A significant linear correlation was found between donor heart ischemic time and peaks and the area under the curve of cTn-I and CK-MB release. In patients with an ischemic time longer than 90 min, cTn-I release was significantly lower in those receiving continuous retrograde warm cardioplegia than in controls. No significant difference was observed for CK-MB, tCK, and myoglobin. Our data suggest that the measurement of postoperative cTn-I release may provide a method to evaluate ischemic cardiac damage after HTx. When the ischemic time is longer than 90 min, warm retrograde blood cardioplegia provides better myocardial protection than no reperfusion.

[Dissolution of acute stent thrombosis by abciximab bolus]

Abciximab, REOPRO, a potent inhibitor of platelet aggregation via glycoprotein IIb/IIIa inhibition, has shown to be effective in the prevention of short and long-term complications of percutaneous coronary interventions. Very few reports on the role of this drug in the setting of acute stent thrombosis have been published. We report 1 case of the effectiveness of REOPRO in the complete lysis of stent thrombus with reperfusion of the coronary vessel and its collaterals. This case suggests an important role of platelets in the setting of acute stent thrombosis and a thrombolytic effect of REOPRO.

Diagnostic value of exercise electrocardiography for predicting a positive scintigraphic test in patients with complete right bundle branch block

BACKGROUND

The diagnostic value of exercise electrocardiography (ECG) in patients with complete right bundle block (cRBBB) remains controversial. The aim of this study was to investigate the diagnostic accuracy of exercise ECG for predicting ischemia in the presence of cRBBB.

METHODS

From a series of 1300 consecutive patients attending for exercise ECG and 99mTc-tetrofosmin single photon emission computed tomography (SPECT), we identified 38 male patients with cRBBB and 38 matched controls with normal intraventricular conduction. Patients with left ventricular hypertrophy or previous revascularization were excluded. Exercise ECG (modified Bruce protocol) was considered positive at > or = 1 mm ST horizontal or downsloping depression in > or = 2 adjacent leads. SPECT imaging at rest and post-exercise was performed at least 48 hours apart.

RESULTS

The odds ratio for ischemia comparing patients with positive and negative exercise ECGs was 11.0 (95% confidence interval 2.49-48.64, p = 0.002) in controls and 2.49 (95% confidence interval 0.64-9.08, p = 0.32) in cRBBB. The prior probability of ischemia was 0.37 in controls and 0.58 with cRBBB. The posterior probability after a positive test was 0.65 in controls and 0.68 in cRBBB. Thus, the utility of the test (posterior probability minus prior probability) was greater in controls (+0.28) than in cRBBB (+0.1). This difference was most pronounced in the anterior leads V1-V4 (controls +0.63 vs cRBBB +0.01) but less significant in the lateral leads V5-V6 (controls +0.26 vs cRBBB +0.21). Similar analysis also indicated reduced diagnostic value of negative exercise ECGs in cRBBB patients.

CONCLUSIONS

The diagnostic value of exercise ECG is reduced in patients with cRBBB, although ST-segment changes in the lateral ECG territory provide superior predictive accuracy to those in the anterior leads. The use of SPECT as a first-line investigation may be justified in patients with cRBBB.

[Endothelin-1 variation in the coronary circulation during angioplasty with a stent implant]

Endothelin-1 (ET-1) is an endothelium-derived mediator with vasoconstrictive and mitogenic activity which stimulates vascular smooth muscle cell proliferation. The aim of this study was to evaluate ET-1 production during percutaneous transluminal coronary angioplasty (PTCA) and elective stent implantation. We hypothesized that the additional vessel wall trauma induced by stent deployment might be associated with a greater production of ET-1. To this end, ET-1 levels were measured in 18 patients undergoing PTCA and stenting (12 with left anterior descending coronary artery stenosis and 6 with circumflex artery lesion). The sampling sites were the coronary ostium and coronary sinus in basal conditions (before the procedure), during first balloon inflation, and 5, 20, 60 min after the end of first balloon inflation. At baseline, ET-1 levels were higher in the coronary sinus than in coronary ostium (1.58 +/- 0.22 vs 1.29 +/- 0.20 pg/ml, p < 0.001). During first balloon inflation, ET-1 coronary sinus levels significantly diminished with respect to the basal levels (1.08 +/- 0.32 vs 1.58 +/- 0.22 pg/ml, p < 0.001). Further significant variations of ET-1 levels were not detected neither following the first balloon inflation nor after stent deployment. In conclusion, the culprit lesion seems to produce most of ET-1 circulating in the coronary tree. This is demonstrated by higher ET-1 levels in the coronary sinus compared to coronary ostium at baseline, and even more by the significant ET-1 reduction in the coronary sinus during first balloon inflation. Despite our expectations, we did not detect any significant ET-1 increase during stent deployment.

[Significance of electrocardiographic projection of ST-segment depression during exercise test in the prediction of the location of regional myocardial ischemia]

There is still some controversy whether ST segment depression during exercise testing might predict the location of myocardial ischemia. From a population of 1196 patients who underwent myocardial 99mTc-tetrofosmin exercise SPECT scintigraphy, 22 consecutive patients (20 males and 2 females, mean age 54 +/- 10 years) with no previous myocardial infarction, positive exercise testing (> or = 1 mm ST segment depression) performed in pharmacologic wash-out and angiographically documented isolated single vessel coronary artery disease (> or = 70% diameter stenosis in a main coronary artery) were selected. None of the patients showed > or = 1 mm ST segment depression exclusively in inferior leads (II-III-aVF). Eight patients (36%) showed > or = 1 mm ST segment depression exclusively in precordial leads (Group 1). The remaining 14 patients (64%) showed > or = 1 mm ST segment depression in both inferior and precordial leads (Group 2). No differences between groups were observed regarding peak exercise test parameters such as heart rate (124 +/- 28 vs 135 +/- 21 b/min, NS), rate-pressure product (22592 +/- 5323 vs 23118 +/- 4197 mmHg x b/min, NS) and exercise time (14.5 +/- 3.9 vs 15.1 +/- 2.9 min, NS) and the number of stress-induced reversible and partially reversible defects (3.3 +/- 3.4 vs 4.6 +/- 2.8, NS). All reversible and partially reversible defects were seen in the related coronary artery stenosis region. Among Group 1, 5 patient (62.5%) showed a > or = 70% stenosis of left descending coronary artery, 1 patient (12.5%) of left circumflex and 2 patients (25%) of right coronary artery. Similarly, among Group 2, 9 patients (64.3%) showed a significant stenosis of left descending coronary artery, 1 patient (7.1%) of left circumflex and 4 patients (28.6%) of right coronary artery. Thus, we were not able to show a relation between exercise ST segment depression and the location of myocardial ischemia as assessed by myocardial 99mTc-tetrofosmin SPECT scintigraphy in a population of patients selected on the basis of single coronary artery disease.

[Safety, feasibility and efficacy of a new single-wire stent in the treatment of complex coronary lesions: the angiostent]

The angiostent is a single wire, flexible, highly radiopaque, balloon expandable stent. To evaluate the feasibility and safety of the deployment of this new stent, we report the clinical and procedural results of 70 procedures performed in 51 native coronary arteries of 48 patients, with objective evidence of ischemia. The target lesion was located in the left anterior descending artery in 18 (36%) cases, in the circumflex artery in 16 (31%) cases and in the right coronary artery in 17 (33%) cases. Mean reference vessel diameter was 3.2 +/- 0.4 mm and the minimal luminal diameter was 0.4 +/- 0.3 mm, with a mean diameter stenosis of 86 +/- 10%. Type B2 and C lesions were encountered in 56% of the cases. More than one angiostent was implanted in 14 vessels and multiple stenting was accomplished with the use of different stents in 8 coronary arteries. No major complications were reported. The post-procedural minimal luminal diameter was 3.2 +/- 0.4 mm with a mean diameter stenosis of 1.4 +/- 3.7%. In 25 cases (49%) major side branches raised from the stented segment and in all but one remained patent. In conclusion, the implantation of the angiostent is safe, feasible and effective, as it can be easily deployed at the lesion site, used for the treatment of complex lesions and preserves the patency of jailed side-branches.