Eduard Kleinhans

Comparative evaluation of bicycle and dobutamine stress echocardiography with perfusion scintigraphy and bicycle electrocardiogram for identification of coronary artery disease.

In 66 patients with suspected coronary artery disease (CAD), exercise electrocardiography (ECG), exercise echocardiography, dobutamine stress echocardiography (dosage, 5 to 40 micrograms/kg/min), single-photon emission computed tomography (SPECT) using methoxy-isobutyl-isonitrile (MIBI) and coronary angiography were performed prospectively to compare methods for detecting CAD. CAD was defined as 70% luminal area stenosis in at least 1 coronary artery at coronary angiography. Significant CAD was present in 50 patients. Compared with exercise ECG, exercise echocardiography, dobutamine stress echocardiography and MIBI-SPECT had a significantly higher sensitivity (52% vs 80, 79 and 89%; p < 0.01, p < 0.01 and p < 0.001, respectively). There were no significant differences in sensitivity between exercise echocardiography, dobutamine stress echocardiography and MIBI-SPECT. Specificity of MIBI-SPECT was lowest (71%), whereas exercise ECG, exercise and dobutamine echocardiography had higher specificities (93, 87 and 81%, respectively). Significance, however, was not achieved. Differences in overall accuracy between exercise echocardiography (82%), dobutamine stress echocardiography (80%) and MIBI-SPECT (85%) were not significant. Comparison with accuracy of exercise ECG (62%) was significant (p < 0.05, p < 0.05 and p < 0.01, respectively). In 1-vessel disease, exercise ECG had a lower sensitivity (45%) than exercise and dobutamine echocardiography and MIBI-SPECT (79, 78 and 84%; p < 0.02, p < 0.02 and p < 0.01, respectively). Regarding the 24 patients with false-negative exercise ECG results, 67% had positive exercise echocardiography findings, 71% positive dobutamine echocardiography results and 84% positive technetium-99m MIBI-SPECT results.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of a platelet GPIIb/IIIa receptor antagonist on myocardial hypoperfusion during rotational atherectomy as assessed by myocardial Tc-99m sestamibi scintigraphy

OBJECTIVES This study evaluated the effect of the glycoprotein IIb/IIIa (GPIIb/IIIa) antagonist abciximab on myocardial hypoperfusion during percutaneous transluminal rotational atherectomy (PTRA). BACKGROUND PTRA may cause transient ischemia and periprocedural myocardial injury. A platelet-dependent risk of non-Q-wave infarctions after directional atherectomy has been described. The role of platelets for the incidence and severity of myocardial hypoperfusion during PTRA is unknown. METHODS Seventy-five consecutive patients with complex lesions were studied using resting Tc-99m sestamibi single-photon emission computed tomography prior to PTRA, during, and 2 days after the procedure. The last 30 patients received periprocedural abciximab (group A) and their results were compared to the remaining 45 patients (group B). For semiquantitative analysis, myocardial perfusion in 24 left ventricular regions was expressed as percentage of maximal sestamibi uptake. RESULTS Baseline characteristics did not differ between the groups. Transient perfusion defects were observed in 39/45 (87%) patients of group B, but only in 10/30 (33%) patients of group A (p < 0.001). Perfusion was significantly reduced during PTRA in 3.3 +/- 2.5 regions in group B compared to 1.4 +/- 2.5 regions in group A (p < 0.01). Perfusion in the region with maximal reduction during PTRA in groups B and A was 76 +/- 15% and 76 +/- 15% at baseline, decreased to 56 +/- 16% (p < 0.001) and 67 +/- 14%, respectively, during PTRA (p < 0.01 A vs. B), and returned to 76 +/- 15% and 80 +/- 13%, respectively, after PTRA. Nine patients in group B (20%) and two patients in group A (7%) had mild creatine kinase and/or troponin t elevations (p = 0.18). Patients with elevated enzymes had larger perfusion defects than did patients without myocardial injury (4.2 +/- 2.7 vs. 2.3 +/- 2.5 regions, p < 0.05). CONCLUSIONS These data indicate that GPIIb/IIIa blockade reduces incidence, extent and severity of transient hypoperfusion during PTRA. Thus, platelet aggregation may play an important role for PTRA-induced hypoperfusion.

Comparison of thallium-201 single-photon emission tomography after rest injection and fluorodeoxyglucose positron emission tomography for assessment of myocardial viability in patients with chronic coronary artery disease

This prospective study in 42 patients with chronic coronary artery disease and severe wall motion abnormalities (sWMA) on cineventriculography (24 patients with previous myocardial infarction; ejection fraction, 45%±13%) was designed to compare myocardial thallium-201 uptake after rest injection and normalized fluorodeoxyglucose (18FDG) uptake (after oral glucose load) for assessment of a rest 201Tl protocol to evaluate myocardial viability. The left ventricle was divided into the supply territory of the left anterior descending coronary artery (LAD) and the lateral wall and posterior territory (inferior, posterior and posteroseptal segments) because of the high variability of left circumflex and right coronary artery supply territories. Segmental 201Tl uptake in single-photon emission tomography (SPET) and segmental normalized 18FDG uptake (13 segments per patient) showed a close linear relationship in the LAD territory (r=0.79) and in the lateral wall (r=0.77), while the correlation in the posterior territory was considerably lower (r=0.52). 201Tl/18FDG concordance was defined as an 18FDG uptake exceeding 201Tl uptake by < 20%. Discordance was assumed if 18FDG exceeded 201Tl uptake by at least 20%. Concordant results were shown by 81% (439/541) of segments. In segments with severe 201Tl reduction (≤ 50% of peak, n=78) discordance was observed in 10% of segments in the LAD territory and lateral wall (n=62) and in 44% of segments in the posterior territory (n=16). In segments with moderate 201Tl reduction (51%−75%, n=205) discordance occured in 12% (LAD and lateral wall, n=126) or 46% (posterior territory, n=79) of segments, respectively. Severe defects were defined as the entire area with 201Tl uptake ≤50% within a defined territory. Discordance was observed in 6/43 (14%) of these. Of 90 areas with sWMA on cineventriculography, 12 showed discordant results. Ten of these 12 discordant areas affected septum or posterior wall. In areas with normal wall motion or only mild hypokinesis, discordance occured in the septum or posterior wall in 22% whereas the figure for the anterior or lateral wall was only 2%. These results point to a significant role of photon attenuation in 201Tl SPET imaging in the septum and posterior wall. It is concluded that 201Tl SPET using a rest protocol identifies viable myocardium in the supply area of the LAD and in the lateral wall with high accuracy compared to 18FDG positron emission tomography while disordance in the posterior territory may be governed by photon attenuation in the SPET study rather than by a pathophysiological difference.

99Tcm-methoxyisobutylisonitrile stress/rest SPECT in patients with constant complete left bundle branch block.

Numerous studies have revealed frequent false positive septal findings of 201Tl stress imaging in patients with left bundle branch block (LBBB) even with angiographically excluded significant coronary artery disease (CAD). To scrutinize this phenomenon for stress/rest 99Tcm-methoxyisobutylisonitrile (MIBI) single photon emission computed tomography (SPECT) was used to review 22 patients with constant LBBB. The findings were reversible septal defect in one patient, partially reversible septal defect in one patient and irreversible septal defects in eight patients. In four patients 99Tcm-MIBI scans were entirely normal. Thus, 12/22 (55%) patients revealed normal septal 99Tcm-MIBI uptake. Both patients with a stress-induced septal defect revealed a significant left anterior descending artery stenosis on coronary angiography. These preliminary results suggest, that 99Tcm-MIBI might be more specific and accurate than 201Tl in the evaluation of CAD in patients with LBBB because of apparently rare or absent false positive septal findings.

Sensitivity of Computed Tomography and Serial Scintigraphy in Cerebrovascular Disease

Computed tomography and serial scintigraphy with 99mTc-pertechnetate (radionuclide angiography and early and late static imaging) were compared in 214 patients with cerebrovascular disease. CT correctly identified 151 (95.0%) of 159 patients with completed ischemic stroke but was positive in only 11 (25%) of 44 patients with asymptomatic stenosis, transient ischemic attacks (TIA), or prolonged reversible ischemic neurological deficit (PRIND). Scintigraphy was positive in 93.1% of patients with completed stroke. CT detected 175 territories of vascular supply involved, scintigraphy 164. In patients with asymptomatic stenosis, TIA, or PRIND, scintigraphy was correct in 77.3% of cases. The combined evaluation offered a sensitivity of 97.5% in patients with completed stroke and 86.4% in those with asymptomatic stenosis, TIA, or PRIND. The rate of true-positive scintigraphic findings in patients with completed stroke did not change as the interval between ictus and study increased. In patients with intracerebral hematoma, CT was far more specific than scintigraphy. If cerebrovascular disease is suspected, radionuclide angiography should be performed first.

Methoxyisobutylisonitrile (MIBI) Tc 99m SPECT to establish a correlate to coronary flow reserve, the perfusion reserve, from global and regional myocardial uptake after exercise and rest

With99mTc-MIBI SPECT and a 4 h exercise (E; 150 MBq iv) and rest (R; 800 MBq iv) protocol global and regional left ventricular (LV) myocardial uptake was determined in 70 patients with angiographicall, confirmed coronary heart disease (CHD) and in 10 controls. The aim was to establish an E/R ratio as a correlate to coronary vascular reserve, representing perfusion reserve (PR). E/R ratios, obtained from total LV myocardium or from normal or impaired regions, were > 1.19 under all conditions, indicating the presence of higher flow during exercise than at rest (even in areas of low flow). Global PR separated (P<0.01) controls (1.63±0.21; mean ± SD) from severely diseased patients (1.29 ±0.14 in 2- or 3-vessel disease) only. Improved differential diagnosis was gained from calibrating the regional E/R ratio to regional differences (E minus R) of uptake. For the left ventricle regional PRs (RPR) for 25 ROIs of the target, framing the myocardium, were determined RPR at the regional maximum of99mTc-MIBI uptake was similar in both controls (1.66) and patients (1.63), indicating a high probability of meeting some areas with functionally normal perfusion in patients with CHD. RPR allowed sufficient separation (P<0.025) concerning the degree of coronary artery stenosis (RPR in occlusion, 0.26; stenosis >75%, 0.39; <75%, 0.56). In controls, the overall value for RPR was 1.14+0.28 (P< 0.001). LV global PR and RPR were useful in separating patients with CHD vs controls and in classifying the severity of vascular stenosis.

Cardiac stress-rest single-photon emission computed tomography with technetium 99m-labeled tetrofosmin: Influence of washout kinetics on regional myocardial uptake values of the rest study with a 1-day protocol

BackgroundThe purpose of this study was to evaluate (1) the washout kinetics of99mTc-labeled tetrofosmin, separately for myocardium with normal and reduced perfusion, and (2) its influence on quantitative analysis in a 1-day stress-rest protocol.Methods and ResultsTwenty-five patients with angiographically proved coronary artery disease underwent bicycle exercise stress testing with injection of 200 MBq99mTc-labeled tetrofosmin and first single-photon emission computed tomographic (SPECT) imaging 40 minutes after injection. A second SPECT was acquired 2.3±0.4 hours after the first one immediately before rest injection of 800 MBq99mTc-labeled tetrofosmin. The rest (third) SPECT was acquired 15 minutes thereafter. The relative washout fraction per time (WOFt) was calculated assuming linear washout kinetics. Thirty-three regional uptake values per study were calculated, normalized to the perfusion maximum (100%) in either the postexercise SPECT and the rest SPECT, for the latter with and without correction of remaining counts from stress injection. In regions with normal perfusion, WOFt was 11.5%±3.5% per hour. In regions with markedly reduced perfusion (relative uptake <50%, WOFt was 8.3%±9.9% per hour. The highest variation of the relative uptake values between rest SPECT with and without correction of remaining counts from stress injection was 5.4%±3.5% in regions with stress-induced ischemia.ConclusionTo use a 1-day protocol with a stress-rest radioactivity ratio of 1∶4 and an interval of more than 2 hours between the examinations, a correction for remaining counts from stress injection seems not to be necessary for the quantitative analysis of rest SPECT.

Results of Interventional Treatment of Stress Positive Coronary Artery Disease

The aim of this study was to define the impact of percutaneous coronary intervention (PCI) including stenting in patients with stress-positive stable coronary artery disease on long-term prognosis and symptoms. A group of 1,018 patients were identified from the angiographic and single-photon emission computed tomographic (SPECT) databases (technetium-99m sestamibi or tetrofosmin at rest and during stress) January 1, 2000, to December 31, 2003, to have significant coronary artery disease (>50% diameter stenosis on quantitative coronary angiography) and positive SPECT findings. Two hundred sixty-six patients were medically treated. Seven hundred fifty-two patients with positive SPECT findings who underwent PCI were matched to 266 patients of similar age, gender, number and location of stenotic arteries, left ventricular function, and size of SPECT perfusion defect who underwent medical treatment. Clinical events (death, nonfatal myocardial infarction, and revascularization) as well as clinical symptoms (angina or dyspnea, Canadian Cardiovascular Society class II to IV) were determined after a follow-up period of 6.4 +/- 1.2 years. In 524 of the 532 patients (98%), clinical follow-up was obtained. There were no differences between the PCI and medical groups in the frequencies of death (13.5% vs 10.9%) and myocardial infarction (5.3% vs 5.6%) during follow-up. PCI patients had more revascularization procedures <1 year after choice of treatment modality (14.7% vs 6.0%, p <0.002). During the subsequent follow-up period (>1 year), the 2 groups did not differ in the frequency of revascularization procedures. At the end of follow-up, patients in the PCI group complained less frequently of angina pectoris (38% vs 49%, p = 0.014). In conclusion, in patients with stress-positive stable coronary artery disease, PCI including stenting did not reduce mortality or rate of nonfatal myocardial infarction. The PCI group complained less frequently of angina pectoris at long-term follow-up.

Quantitative Stress Echocardiography in Chronic Aortic and Mitral Regurgitation.

It was the purpose of the present study to prove the feasibility and reliability of quantitative stressechocardiography as an alternative method to radionuclide angiography (RNA) in chronic regurgitant valvular lesions. Echocardiography and RNA are most commonly used to obtain various left ventricular (LV) morphometric and functional parameters that have been postulated to predict long‐term prognosis in patients with aortic and mitral valvular regurgitation. Supine bicycle ergometry with a workload ranging from 25–250 Watts was used to evaluate stress dependent LV volumes and ejection fractions (EFs) in patients with pure aortic (n = 18) and mitral regurgitation (n = 14). Most patients (23/32) underwent simultaneous right heart catheterization. Echocardiographic EFs were validated by RNA with good correlations (r = 0.81, P < 0.01). Patients with aortic regurgitation and functional class I/II (9), had a significant increase in EF during exercise (60%–67%, P < 0.001) and a reduction in end‐systolic volume (71–52 mL, P < 0.01). In comparison, patients with class III symptoms (9), had a drop in EF (53%–49%, P < 0.01), had larger baseline end‐systolic volume (104 mL, P = NS), which did not decrease during stress (104 vs 107 mL, P = NS). In patients with chronic mitral regurgitation baseline and exercise EF did not differ between class I/II (6) and class III (8), however, mildly symptomatic patients increased from 57%–67%, (P < 0.01) versus patients in class III (65% vs 69%, P = NS). Stroke volume index was not different at baseline (44 vs 33 mL/m2, P = NS); however, there were significant differences during exercise (70 vs 41 mL/m2, P = 0.05). Quantitative stress‐echocardiography is a noninvasive and safe alternative method to RNA, which allows reliable calculation of stress dependent LV volumes and EF. Determination of end‐systolic volumes may be of additional prognostic value. The combination of a high baseline EF and low stroke volume index with the inability to improve during exercise might reflect early stages of impaired LV function in patients with severe mitral regurgitation.

MRI Measurements of Left Ventricular Systolic Wall Thickening Compared to Regional Myocardial Perfusion as Determined by 201Tl SPECT in Patients with Coronary Artery Disease

Magnetic resonance imaging (MRI) of the left ventricle (LV) is an excellent method of measuring systolic wall thickening (SWT). The aim of the present study was (a) to describe a new approach for measurement of SWT and (b) to define the relationship between SWT and regional myocardial perfusion as determined by 201Tl SPECT. 79 patients -51 with and 28 without history of earlier myocardial infarction - underwent SPECT and, within the next two weeks. MRI. End-diastolic and end-systolic spin echo images were obtained by a reduced permutation technique. For MRI measurements, only long-axis sections through the LV in the equatorial plane were used. Slice orientation was selected according to the findings of SPECT, imaging the infarcted wall segment by single or double angulation. At 7 equidistant points around the LV wall SWT was measured and compared with the corresponding regional myocardial uptake values from SPECT in percent of maximal perfusion. Wall thickness of the anterior wall was normal. Because the majority of myocardial infarctions were posterior-inferior (55%), thickness of the posterior wall was markedly decreased. A close relationship of perfusion to SWT was found. Higher perfusion areas (greater than 50% of maximal TI uptake) corresponded with normal SWT (greater than 3.0 mm), a marked decrease of SWT (less than 1 mm) was found in areas with perfusion deficits (less than 40%). Thus, a 201TI uptake value at rest of 41-50% of the respective myocardial maximum acts as a threshold by discriminating normal from severely reduced SWT.