Tsuguhisa Hatano

Important parameters in the detection of left main trunk disease using stress myocardial perfusion imaging

OBJECTIVES We sought noninvasively to diagnose left main trunk (LMT) disease using myocardial perfusion imaging (MPI). METHODS Five hundred and eight patients with suspected coronary artery disease (CAD) underwent both stress MPI and coronary angiography. The extent and severity of perfusion abnormalities were assessed using a 20-segment model. In addition, perfusion defects in both left anterior descending and left circumflex arterial territories were defined as a left main (LM) pattern defect, and those in 3-coronary arterial territories as a 3-vessel pattern defect. RESULTS In 42 patients with LMT disease, a summed stress score (19.4 ± 10.0 vs. 13.5 ± 10.0; p < 0.0001) and a summed rest score (12.1 ± 9.7 vs. 7.0 ± 7.8; p = 0.002) were greater than in 466 patients without LMT disease, while a summed difference score was similar (7.3 ± 7.7 vs. 6.5 ± 6.1; p = NS). The prevalence of an LM-pattern defect was low in both groups (12% vs. 8%; p = NS). However, a 3-vessel pattern defect (33% vs. 7%; p < 0.0001), lung uptake of radiotracers (38% vs. 11%; p < 0.0001), and transient ischemic dilation (31% vs. 13%; p = 0.003) were more frequently observed in patients with LMT disease than in those without. Logistic regression analysis showed that a 3-vessel pattern defect (OR=3.5, 95% CI = 1.4-8.8; p = 0.007), lung uptake of radiotracers (OR = 2.5, 95% CI = 1.1-5.7; p = 0.03), and previous myocardial infarction (MI) (OR = 2.4, 95% CI = 1.0-5.7; p = 0.05) were the most important parameters to detect LMT disease. After excluding 163 patients with previous MI, a repeat analysis revealed that lung uptake of radiotracers (OR = 8.2, 95% CI = 2.3-29.2; p = 0.001) and an LM-pattern defect (OR = 6.3, 95% CI = 1.4-27.2; p < 0.02) were independent predictors for LMT disease. CONCLUSION In the identification of LMT disease, lung uptake of radiotracers was a single best parameter, which was independent of the presence or absence of previous MI.

Differential effects comparing exercise and pharmacologic stress on left ventricular function using gated Tc-99m sestamibi SPECT

ObjectiveAlthough post-ischemic stunning has emerged as an important marker for severe coronary artery disease (CAD), differences in stress methods may have different effects on left ventricular (LV) volumes and function.MethodsTo assess differential effects comparing exercise and pharmacologic stress on the LV measurements, 99mTc-sestamibi gated single-photon emission computed tomography (SPECT) acquired more than 30 min after stress and at rest was evaluated in 38 patients undergoing adenosine triphosphate (ATP) stress (ATP group) and 38 age-and sex-matched patients subjected to exercise stress (Ex group) among 268 patients with normal SPECT findings.ResultsCoronary risk factors and LV volumetric measurements at baseline were similar in the two groups. Compared with volumetric measurements at rest, enddiastolic volume (EDV) increased (72 ± 21 ml to 74 ± 21 ml; P = 0.01), end-systolic volume increased (25 ± 12 ml to 28 ± 13 ml; P = 0.001), and ejection fraction (EF) decreased after stress (66% ± 8% to 63% ± 9%; P < 0.002) in the ATP group. In the Ex group, by contrast, no such change was observed. In addition, changes in EDV (3 ± 6 vs. −1 ± 5 ml; P = 0.01) and the stress-to-rest ratio of EDV (1.04 ± 0.09 vs. 0.99 ± 0.08; P < 0.02) after stress were greater in the ATP than in the Ex group.ConclusionsDifferential effects of stress methods on LV volumes persist more than 30 min after the stress. These findings should be kept in mind when interpreting post-ischemic stunning.

High-tension electrical injury to the heart as assessed by radionuclide imaging

To evaluate cardiac complications associated with electrical injury, 7 patients with high-tension electrical injury (6,600 V alternating current) underwent201Tl and123I-metaiodobenzylguanidine (MIBG) imaging in addition to conventional electrocardiographic and echocardiographic assessments. Electrocardiography showed transient atrial fibrillation, second degree atrioventricular block, ST-segment depression, and sinus bradycardia in each patient. Echocardiography showed mild hypokinesis of the anterior wall in only 2 patients, but201Tl and123I-MIBG myocardial scintigraphy whowed an abnormal scan image in 6/7 and 5/6 patients, respectively. Decreased radionuclide accumulation was seen primarily in areas extending from the anterior wall to the septum. Decreased radionuclide accumulation was smaller in extent and milder in degree in123I-MIBG than in201Tl imaging. These results suggest that even in patients without definite evidence of severe cardiac complications in conventional examinations, radionuclide imaging detects significant damage due to high-tension electrical injury, in which sympathetic nerve dysfunction might be milder than myocardial cell damage.

Diagnostic value of vasodilator-induced left ventricular dyssynchrony as assessed by phase analysis to detect multivessel coronary artery disease

Purpose: Phase analysis was recently developed to allow left ventricular(LV)mechanical dyssynchrony to be assessed by gated single-photon emission computed tomography(SPECT) . However, few studies have analyzed LV dyssynchrony during pharmacological stress and at rest by applying phase analysis to detect multivessel coronary artery disease(CAD)using the SyncTool TM . Methods: Adenosine triphosphate(ATP)loading electrocardiogram-gated 99m Tc-sestamibi SPECT was performed on 180 patients with suspected or known CAD. LV dyssynchrony was evaluated using the SyncTool TM ; the phase standard deviation(SD)and histogram bandwidth were derived. Results: The summed stress score(SSS) , summed difference score(SDS) , post-stress increase in phase SD, and histogram bandwidth were greater in 78 patients with multivessel CAD than in 102 patients with insignificant or single-vessel CAD. In the detection of multivessel CAD, SSS of >9 and SDS of >5 showed sensitivities of 74% and 74%,and specificities of 71% and 78% respectively, whereas an increase in phase SD>8.3°and in histogram bandwidth >16°after ATP loading had sensitivities of 62% and 74% and specificities of 77% and 68%, respectively. A multivariate logistic analysis revealed that the identification of multivessel CAD was superior with the combination of a post-ATP increase in phase SD, increase in histogram bandwidth, and SDS(sensitivity 82%, specificity 76%, chi-square=80.0)than with SDS alone (sensitivity 74%, specificity 78%, chi-square=58.9) . Conclusion: The addition of ATP-induced LV dyssynchrony parameters to conventional perfusion analysis enabled the superior identification of patients with multivessel CAD.

Clinical characteristics in patients showing ischemic electrocardiographic changes during adenosine triphosphate loading single-photon emission computed tomography

OBJECTIVES Although ischemic electrocardiographic (ECG) changes during dipyridamole or adenosine infusion have been reported as a marker for severe coronary artery disease (CAD), few studies have focused on ST-segment changes with adenosine triphosphate (ATP)-loading myocardial single-photon emission computed tomography (SPECT). METHODS AND SUBJECTS Between January 2003 and August 2008, 4650 consecutive patients underwent ATP-loading SPECT. After 1412 patients with left bundle branch block, pacemaker rhythm, or previous coronary revascularization were excluded, 16 out of 3238 patients (0.5%) showed ischemic ST-segment depression during ATP-loading myocardial SPECT. They were aged 67+/-11 years; 10 were men and 6 women. Of these patients, 8 demonstrated perfusion abnormalities, whereas the remaining 8 showed normal myocardial perfusion imaging. In 6 of the 8 patients with abnormal SPECT, coronary angiography was performed, revealing left main trunk disease in 1 patient, 3-vessel disease in 4, 1-vessel disease with proximal left ascending artery occlusion in 1, and an insignificant lesion in 1. By contrast, no major cardiac event was observed in the 8 patients with normal SPECT during follow-up for an average of 2 years. CONCLUSION The prevalence of ischemic ST-segment changes during ATP loading is very rare. However, this finding should be taken into account since almost half of the patients, particularly those with perfusion abnormalities, may have severe CAD which requires coronary revascularization.

The diagnostic utility of the Heston index in gated SPECT to detect multi-vessel coronary artery disease

OBJECTIVES Although the Heston index, derived left ventricular (LV) volumetric analysis, is reported to best represent transient LV dilation on non-gated single-photon emission computed tomography (SPECT), its diagnostic performance has not been proven to identify extensive coronary artery disease (CAD) as assessed by coronary angiogram. Accordingly, we sought to evaluate the diagnostic utility of Heston index to detect multi-vessel CAD. METHODS Post-stress and resting electrocardiogram-gated 99mTc-sestamibi SPECT was performed in 223 patients with suspected or known CAD. All of the patients underwent coronary angiography within 3 months of gated SPECT. The summed stress, summed rest, and summed difference scores were calculated using a 20-segment model. The left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) were calculated automatically with the QGS program. In addition, stress-to-rest ratios of EDV, ESV, and (ESVx5+EDV) were calculated; the latter was defined as Heston index. RESULTS In the 104 patients with multi-vessel CAD, the summed stress score (17.5+/-10.0 vs. 11.7+/-9.2, p<0.001), the summed difference score (9.1+/-6.3 vs. 4.3+/-4.2, p<0.0001), the Heston index (1.17+/-0.15 vs. 1.02+/-0.13, p<0.0001), the stress-to-rest ratio of EDV (1.05+/-0.10 vs. 0.99+/-0.09; p<0.0001), and that of ESV (1.23+/-0.21 vs. 1.04+/-0.17; p<0.0001, respectively) were greater than in the 119 patients with one-vessel CAD or insignificant lesion. The best cut-off value was determined as 1.09 for Heston index, giving a sensitivity of 76%, specificity of 77% for detection of multi-vessel CAD. Multiple stepwise logistic regression analysis showed that Heston index >or =1.09, summed stress score > or =14, and summed difference score > or =9 were the independent predictors of detecting multi-vessel CAD, yielding a sensitivity of 76% and specificity of 77% (global chi 2, 88.8). CONCLUSIONS The Heston index is simple and achieves higher diagnostic value in the detection of multi-vessel CAD, compared with conventional analysis alone.

Sex-specific approach to gated SPECT volumetric analysis after stress and at rest to detect high-risk coronary artery disease.

ObjectivesTo determine the role of quantitative analysis of poststress and resting left ventricular function using sex-specific criteria to detect high-risk coronary artery disease (CAD) as defined by the Duke CAD Prognostic Index. Methods and resultsStress technetium-99m-sestamibi-gated single-photon emission computed tomography and coronary angiography were performed in 407 consecutive patients (300 men, 107 women) with suspected CAD. The cut-off point for high-risk CAD was defined as a Duke CAD Prognostic Index of 42. The stress-to-rest ratios of end-diastolic volume (rEDV) and end-systolic volume (rESV) were analyzed. In 102 patients with high-risk CAD, the summed difference scores, rEDV and rESV, were greater than in 305 patients with low-risk to intermediate-risk CAD. The receiver operating characteristic curves revealed that the optimal cut-off points for rEDV and rESV to detect high-risk CAD were 1.10 and 1.11, respectively. Sex-specific rEDV was 1.08 in men, 1.11 in women, and sex-specific rESV was 1.09 in men and 1.20 in women. Multivariate discriminant analysis showed that the combination of sex-specific rEDV, sex-specific rESV, and summed difference scores greater than or equal to 8 best identified high-risk CAD, with a sensitivity of 75% and specificity of 76%. ConclusionThe addition of a sex-specific approach to left ventricular functional analysis using gated single-photon emission computed tomography on conventional perfusion analysis, may help better identify patients with high-risk CAD as defined by the Duke CAD Prognostic Index.