Right ventricular dysfunction secondary to acute massive pulmonary embolism detected by helical computed tomography pulmonary angiography

OBJECTIVE: Acute massive pulmonary embolism causes abrupt pulmonary arterial hypertension and right ventricular dysfunction (RVD). Patients with RVD have a worse prognosis than those with normal right ventricular function. Consequently, recognizing the RVD at the time of pulmonary embolism is useful for risk stratification and enables more aggressive therapy. The study compared the accuracy of helical computed tomographic (CT) scans with echocardiography in the detecting of RVD in patients with acute massive pulmonary embolism. MATERIALS AND METHODS: Specifically, this work reviewed the CT pulmonary angiograms of 14 patients who were positive for acute massive pulmonary embolism during a 52-month period. CT scans were reviewed for findings indicating RVD. Scans were considered positive for RVD if the right ventricle was dilated or there was leftward shift of the interventricular septum. Echocardiographic reports serving as the reference standard for the diagnosis of RVD were also reviewed. CT study results were then correlated with echocardiography results. RESULTS: Among 14 patients with massive pulmonary embolism, echocardiography identified 12 patients having RVD, whereas the remaining two patients were negative for RVD. Meanwhile, CT correctly identified 11 of 12 patients as having RVD, and was negative for RVD in the remaining 3 patients. Correlated with echocardiography, CT scan for RVD detection had a sensitivity of 91.6% and a specificity of 100%. CONCLUSIONS: CT can accurately detect RVD in patients with acute massive pulmonary embolism. However, this result requires confirmation using a larger prospective cohort study.     

Cardiac sympathetic dysfunction contributes to left ventricular remodelling after acute myocardial infarction

To investigate the role of the cardiac sympathetic nervous system in left ventricular remodelling, 50 patients with first-time acute myocardial infarction (AMI) and patency of the infarct-related artery after reperfusion underwent quantitative iodine-123 metaiodobenzylguanidine (MIBG) imaging at 4 days and 4 weeks (n=42), and quantitative technetium-99m tetrofosmin imaging at 2 days after AMI. They also underwent both ventriculography and coronary angiography on admission and about 4 weeks after AMI. On the basis of left ventricular end-systolic volume (LVESV), patients were divided into two groups. Patients with LVESV dilatation (n=20) had a significantly lower ejection fraction (P<0.003) and a significantly higher severity score of ^99mTc-tetrofosmin (P<0.04), and total severity (P<0.01), ( extent (P<0.007) and ( severity (P<0.0008) scores of MIBG than patients without LVESV dilatation (n=30). ( severity score of MIBG was directly correlated with change in LVESV at 4 weeks (r=0.63, P<0.0001). Stepwise linear discriminant function analysis showed that ( severity score of MIBG (P<0.0002) was the only discriminator of LVESV dilatation. Patients with LVESV dilatation had higher regional washout rates in both the infarct and the non-infarct zones than patients without such dilatation. Furthermore, no MIBG parameters changed significantly between 4 days and 4 weeks after AMI. In reperfused AMI, ( severity score of MIBG was related to the degree of ventricular dilatation and was the only powerful discriminator of ventricular dilatation. These results suggest that cardiac sympathetic nervous abnormality might contribute to left ventricular remodelling in reperfused AMI. MIBG imaging may allow identification of reperfused AMI patients at high risk for left ventricular remodelling.     

Cardiac sympathetic dysfunction contributes to left ventricular remodeling after acute myocardial infarction

To investigate the role of the cardiac sympathetic nervous system in left ventricular remodelling, 50 patients with first-time acute myocardial infarction (AMI) and patency of the infarct-related artery after reperfusion underwent quantitative iodine-123 metaiodobenzylguanidine (MIBG) imaging at 4 days and 4 weeks (n=42), and quantitative technetium-99m tetrofosmin imaging at 2 days after AMI. They also underwent both ventriculography and coronary angiography on admission and about 4 weeks after AMI. On the basis of left ventricular end-systolic volume (LVESV), patients were divided into two groups. Patients with LVESV dilatation (n=20) had a significantly lower ejection fraction (P<0.003) and a significantly higher severity score of 99mTc-tetrofosmin (P<0.04), and total severity (P<0.01), delta extent (P<0.007) and delta severity (P<0.0008) scores of MIBG than patients without LVESV dilatation (n=30). delta severity score of MIBG was directly correlated with change in LVESV at 4 weeks (r=0.63, P<0.0001). Stepwise linear discriminant function analysis showed that delta severity score of MIBG (P<0.0002) was the only discriminator of LVESV dilatation. Patients with LVESV dilatation had higher regional washout rates in both the infarct and the non-infarct zones than patients without such dilatation. Furthermore, no MIBG parameters changed significantly between 4 days and 4 weeks after AMI. In reperfused AMI, delta severity score of MIBG was related to the degree of ventricular dilatation and was the only powerful discriminator of ventricular dilatation. These results suggest that cardiac sympathetic nervous abnormality might contribute to left ventricular remodelling in reperfused AMI. MIBG imaging may allow identification of reperfused AMI patients at high risk for left ventricular remodelling.     

128层CT冠状动脉成像对左心室功能的评价

目的:应用冠状动脉成像原始数据,了解左心室形态变化,评价整体左心室功能。方法:收集90例患者冠状动脉成像原始数据,行MPR,观察左心室形态和各心肌节段的变化,并应用心功能分析软件自动计算出左心室收缩末期容积(ESV)、舒张末期容积(EDV)和射血分数(EF)。根据冠状动脉、左心室形态及整体左心室功能,将所有患者分为对照组、冠心病组、左心室肥厚组及心功能衰竭组,结合各组左心室形态变化,将左心室ESV、EDV和EF进行统计学比较和分析。结果:对照组患者冠状动脉和左心室形态正常;冠心病组左心室壁局限性增厚7例和变薄13例;左心室肥厚组左心室缩小、心室壁增厚;心功能衰竭组心室扩大、室壁普遍变薄。对照组、冠心病组、左心室肥厚组、心功能衰竭组平均EDV和ESV分别为(133.58±14.91)mL、(51.33±11.06)mL;(130.68±11.53)mL、(56.16±8.24)mL;(97.59±8.18)mL、(29.53±4.78)mL;(229.40±50.64)mL、(171.27±60.64)mL。冠心病组与对照组平均EDV和ESV比较,差异无统计学意义,左心室肥厚组及心功能衰竭组与对照组比较,差异均有统计学意义(P0.001)。对照组、冠心病组、左心室肥厚组、心功能衰竭组EF分别为(61.25±5.83)%、(56.37±6.79)%、(68.94±5.36)%和(26.33±8.30)%,差异均有统计学意义。结论:应用冠状动脉成像原始数据,结合冠状动脉及左心室形态改变,无创评价左心室整体功能,实用而可行,可为临床提供更多有价值的信息。     

Multidetector computed tomography predictors of late ventricular remodeling and function after acute myocardial infarction

Background

Despite advent of rapid arterial revascularization as 1st line treatment for acute myocardial infarction (AMI), incomplete restoral of flow at the microvascular level remains a problem and is associated with adverse prognosis, including pathological ventricular remodeling. We aimed to study the association between multidetector row computed tomography (MDCT) perfusion defects and ventricular remodeling post-AMI.

Methods

In a prospective study, 20 patients with ST-elevation AMI, treated by primary angioplasty, underwent arterial and late phase MDCT as well as radionuclide scans to study presence, size and severity of myocardial perfusion defects. Contrast echocardiography was performed at baseline and at 4 months follow-up to evaluate changes in myocardial function and remodeling.

Results

Early defects (ED), late defects (LD) and late enhancement (LE) were detected in 15, 7 and 16 patients, respectively and radionuclide defects in 15 patients. The ED area (r = 0.74), and LD area (r = 0.72), and to a lesser extent LE area (r = 0.62) correlated moderately well with SPECT summed rest score. By univariate analysis, follow-up end-systolic volume index and ejection fraction were both significantly related to ED and LD size and severity, but not to LE size or severity. By multivariate analysis, end-systolic volume index was best predicted by LD area (p < 0.05) and ejection fraction by LD enhancement ratio.

Conclusions

LD size and severity on MDCT are most closely associated with pathological ventricular remodeling after AMI and may thus play a role in early identification and treatment of this condition.     

Right ventricular mural thrombus caused by myocardial infarction diagnosed by computed tomography

Thrombi of the left ventricle are common sequelae to acute anterior myocardial infarctions that involve the apex of the heart and produce akinetic or dyskinetic wall thickening patterns. While infarctions of the right ventricle are being increasingly recognized in the setting of inferior myocardial infarcts, little data on in vivo clot formation in the right ventricle of the heart are available in these patients. In the current study we were able to demonstrate a right ventricular mural thrombus using gated computed tomography of the heart. Although an abnormality in the right ventricle extending from the septal margin of the ventricle into the outflow tract could be identified with standard blood pool computed tomographic images and from cross sectional echocardiograms, only with cardiac gating could the relationship between the mass (thrombus) and the noncontractile section of the right ventricular myocardium be clearly identified. We conclude that cardiac gating may help in the evaluation of cardiac masses, and in particular cardiac thrombi. This will be particular valuable in the setting of recent or remote infarction, as the relationship between wall-motion abnormalities and thrombus formation has been well documented.     

Transient left ventricular dysfunction in ischaemic myocardium after stress: comparative study with exercise and pharmacological stress gated myocardial single photon emission computed tomography

In ischaemic heart disease patients, transient left ventricular dysfunction is observed due to post-exercise stunning. The aim of this study was to determine whether transient left ventricular dysfunction could also be seen after short-acting pharmacological stress (adenosine triphosphate). A 1 day rest/stress gated myocardial single photon emission computed tomography was performed on 362 patients suspected of having ischaemic heart disease by exercise (n=199) or short-acting pharmacological stress (n=163). Left ventricular ejection fraction were estimated both at rest and stress. Based on perfusion findings, patients were subdivided into ischaemia, fixed defect and normal group. For the ischaemia and fixed defect group, left ventricular ejection fraction after stress was significantly decreased compared with the resting value by exercise stress (ischaemia group, 57.5+/-11.0 vs 60.4+/-10.4; fixed defect group, 47.7+/-16.7 vs 49.6+/-16.8; P<0.01), but not by pharmacological stress (ischaemia group, 55.8+/-13.4 vs 57.1+/-13.8; fixed defect group, 50.8+/-13.5 vs 50.6+/-13.1; P=NS). In the normal group, left ventricular ejection fraction after stress was not significantly changed by either exercise (65.7+/-10.4 vs 66.8+/-10.2; P=NS) or pharmacological stress (63.0+/-11.7 vs 64.0+/-12.1; P=NS). It is concluded that a transient decrease in left ventricular ejection fraction after stress was observed following post-exercise, not following a short-acting pharmacological stress in patients showing perfusion abnormalities. Transient left ventricular dysfunction may be the result of post-exercise stunning, not from subendocardial hypoperfusion induced by short-acting pharmacological stress.     

Risk stratification of patients with coronary artery disease and left ventricular dysfunction by exercise radionuclide angiography and exercise electrocardiography

Background

The results of multicenter trials indicate that patients with left ventricular dysfunction and either three-vessel or left main coronary artery disease have improved prognosis when treated surgically.

Objective

As part of a larger evaluation and follow-up study of coronary artery disease, the objective of this investigation was to determine whether exercise radionuclide angiography can be used, in patients with mild symptoms of coronary artery disease and left ventricular dysfunction at rest, to identify patients with three-vessel or left main coronary artery disease.

Methods and Results

Eighty-four consecutive patients were studied with angiographically defined coronary artery disease in whom left ventricular ejection fraction at rest ranged from 20% to 40%. Patients underwent exercise electrocardiography, rest and exercise radionuclide angiography, and 24-hour electrocardiographic monitoring. There were 22 patients with one-vessel, 31 with two-vessel, 27 with three-vessel, and four with left main coronary artery disease. All but four patients had a documented history of myocardial infarction. By univariate analysis, the following parameters were related to the anatomic severity of coronary artery disease: magnitude of ST segment depression with exercise (p<0.001), magnitude of change in ejection fraction with exercise (p<0.005), and occurrence of angina during exercise (p<0.005). However, because of the extensive overlap among anatomic subgroups, no single factor had both a satisfactory sensitivity and a satisfactory specificity in identifying patients with three-vessel and left main coronary artery disease. Multivariate stepwise regression analysis also failed to predict three-vessel or left main coronary artery disease satisfactorily (sensitivity 73% and specificity 73%; positive predictive accuracy 59% and negative predictive accuracy 83%). Nonetheless, this multivariate analysis provided important prognostic information. During medical therapy (mean follow-up 56 months), the patients with a high likelihood of three-vessel or left main coronary artery disease had a greater risk of death or reinfarction than had patients with a low likelihood (p<0.05). These functional data were better than coronary anatomy alone in providing risk stratification. Four of six patients with two-vessel disease who died were classified incorrectly by the multivariate analysis in the high-likelihood group for three-vessel or left main coronary artery disease, but classified correctly as being at high risk; whereas none of the patients with three-vessel disease who were misclassified in the low-likelihood group died during medical therapy.

Conclusion

Although exercise radionuclide angiography in patients with minimal symptoms of coronary artery disease and left ventricular dysfunction is not precise in predicting three-vessel or left main coronary artery disease, it provides important functional information regarding subsequent prognosis during medical therapy.     

心肌灌注及代谢显像检测存活心肌及对心肌梗死伴左室功能不全患者治疗策略的影响

目的用99Tcm-甲氧基异丁基异腈(MIBI)SPECT和18F-脱氧葡萄糖(FDG)PET心肌灌注/代谢显像对陈旧性心肌梗死伴左室功能不全患者心肌存活状况及治疗策略进行评价。方法70例陈旧性心肌梗死伴左室功能不全[左室射血分数(LVEF)为(35±10)%]患者,均行99Tcm-MIBISPECT、18F-FDGPET心肌灌注/代谢显像预测存活心肌。灌注缺损、代谢填充(灌注-代谢不匹配)为心肌存活;灌注、代谢均缺损(灌注-代谢匹配)为心肌无存活;同时进行超声心动图检查评价左室壁运动、LVEF、左室舒张末径(LVDd)及收缩末径(LVDs)。血运重建术或内科保守治疗后3-6个月进行超声心动图复查,评价左室壁运动改善情况及LVEF、LVDd及LVDs的变化。结果41例患者接受血运重建术,29例患者接受内科保守治疗。心肌代谢显像判定为存活心肌节段≥20%的46例患者中,31例接受血运重建术(A1组)、15例内科保守治疗(A2组);存活心肌节段<20%的24例患者中,10例接受血运重建术(B1组),14例内科保守治疗(B2组)。4组患者基本临床情况无差异。血运重建术后,A1组LVEF由(37.19±9.52)%增至(46.10±7.62)%(P<0.05),LVDd由(57.62±5.89)mm降至(52.38±4.42)mm(P<0.01),LVDs从(44.4±9.53)mm降至(38.35±8.02)mm(P<0.05),存活心肌节段运动情况记分由(10.67±8.14)分改善为(6.77±6.32)分(P<0.05);上述指标在A2、B1、B2组治疗前后未见明显改变(P>0.05)。结论99Tcm-MIBISPECT、18F-FDGPET显像对心肌存活的评价有助于心肌梗死伴左室功能不全患者治疗策略的选择。     

Heart tomography with 99mTc sestamibi and echocardiography with dobutamine in the identification of reversible left ventricular dysfunction in patients with acute myocardial infarction]

INTRODUCTION: We investigated the role of technetium-99m (99mTc) sestamibi cardiac imaging and dobutamine echocardiography in detecting myocardial viability early after acute myocardial infarction. MATERIAL AND METHODS: Nineteen patients (mean age 52 +/- 10 years) underwent coronary angiography, low-dose dobutamine echocardiography and rest 99mTc sestamibi imaging within 10 days of myocardial infarction. All patients were revascularized. Resting echocardiogram was repeated 8 months later to evaluate segmental functional recovery. RESULTS: Sixty-one of 108 akinetic or dyskinetic segments at baseline showed functional recovery after revascularization. Sensitivity in predicting segmental functional recovery was 87% for sestamibi imaging and 66% for dobutamine echocardiography (p < 0.001), while specificity and accuracy were comparable. Sestamibi activity was the strongest predictor of segmental functional recovery (p < 0.001). CONCLUSIONS: Dobutamine echocardiography predicts functional recovery after myocardial infarction. However, sestamibi imaging is useful to identify patients with dysfunctional segments without contractile reserve which may benefit by revascularization.     

Mid-diastolic left ventricular volume and mass: Normal values for coronary computed tomography angiography

Background

The adoption of prospectively ECG-triggered acquisition coronary computed tomography angiography (CTA) has resulted in the inability to measure left ventricle (LV) end-diastolic volume and LV ejection fraction. However other prognostic measures such as LV mass and LV mid-diastolic volume (LVMDV) can still be assessed. The objective of this study is to establish normal reference values for LVMDV and LV mass.

Risk stratification of patients with prior myocardial infarction and advanced left ventricular dysfunction by gated myocardial perfusion SPECT imaging

Background. The Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II) has shown that the prophylactic implantable cardiac defibrillator improves the survival rate of patients with prior myocardial infarction and advanced left ventricular (LV) dysfunction. However, a more accurate noninvasive predictor should be found to identify subgroups at high risk, one that would allow implantable cardiac defibrillator therapy to be directed specifically to the patients who would benefit most. Methods and Results. To elucidate whether technetium 99m tetrofosmin electrocardiogram-gated single photon emission computed tomography (SPECT) imaging at rest can determine the risk of arrhythmic death, 106 patients who met the MADIT-II criteria (LV ejection fraction ≤0.3, myocardial infarction τ;1 month earlier, and no sustained ventricular tachyarrhythmia) were recruited from a pool of 4628 consecutive patients who had undergone resting Tc-99m tetrofosmin SPECT imaging. By use of the endpoints of lethal arrhythmic events, which included documentation of sustained ventricular tachycardia, ventricular fibrillation, or diagnosis of sudden cardiac death, we performed follow-up for a mean of 30 months. Lethal arrhythmic events occurred in 14 patients. Patients with lethal arrhythmic events had a lower LV ejection fraction, greater LV end-systolic and end-diastolic volume indices, and a greater perfusion defect volume than the remaining patients. By receiver operating characteristic curve analysis, myocardial defect volume was the strongest predictor for the development of lethal arrhythmic events. Conclusion. Our results confirm that perfusion defect volume by Tc-99m tetrofosmin scintigraphy is the most pivotal predictor of the future occurrence of lethal arrhythmic events and of sudden cardiac death. Tc-99m tetrofosmin SPECT images may assist in identifying subsets of patients with a greater likelihood of arrhythmic death among patients with LV dysfunction.     

Attenuation correction improves the detection of viable myocardium by thallium-201 cardiac tomography in patients with previous myocardial infarction and left ventricular dysfunction

The aim of this study was to determine the influence of attenuation-corrected thallium-201 stress/redistribution/reinjection single-photon emission tomography (SPET) on the number of viable segments in patients with previous myocardial infarction and dysfunctional myocardium. Fifty-one patients with previous myocardial infarction and left ventricular dysfunction were included in the study. In all patients, ²⁰¹Tl non-corrected (NC) and attenuation-corrected (AC) SPET was performed using a stress/redistribution/reinjection protocol followed by coronary angiography. A semiquantitative analysis was performed using polar maps for NC and AC stress, redistribution and reinjection short-axis and vertical long-axis (apex) slices. Severe (perfusion defect below 50%/maximal count rate: PD_<50), mild and moderate persistent defects for redistribution and reinjection were evaluated for both NC and AC studies. A total of 1581 segments were evaluated by semiquantitative segmental analysis for both NC and AC studies for each redistribution and reinjection map. In the redistribution maps, NC revealed a total of 352 segments and AC a total of 222 segments with impaired perfusion below 50% of the maximal count rate (PD_<50). The mean number of affected segments was 6.9±5.5 in the case of NC and 4.4±4.8 in the case of AC (P<0.001). In the reinjection maps, NC revealed a total of 263 non-viable segments (PD_<50) and AC a total of 169 non-viable segments. The mean number of affected segments was 5.2±5.3 in the case of NC and 3.3±4.2 in the case of AC (P<0.001). Recovery of function was better predicted by AC than by NC in 20% of patients in the follow-up group. Therefore, the use of attenuation correction influences the extent of viable segments by showing more viable segments in either redistribution or reinjection maps. ²⁰¹Tl imaging without attenuation correction may underestimate the extent of tissue viability, which may contribute to the lower sensitivity compared to fluorine-18-fluorodeoxyglucose positron emission tomography, where attenuation correction is a routinely performed procedure. Received 26 October and in revised form 23 December 1998     

Prediction of recovery of left ventricular dysfunction after acute myocardial infarction: comparison between 99mTc-sestamibi cardiac tomography and low-dose dobutamine echocardiography.

The aim of this study was to evaluate the role of 99mTc-sestamibi cardiac imaging and dobutamine echocardiography in detecting myocardial viability early after acute myocardial infarction. METHODS: Forty-nine patients (mean age 52 +/- 10 y) underwent coronary angiography, low-dose dobutamine echocardiography, radionuclide angiography and rest 99mTc-sestamibi imaging within 10 d after myocardial infarction. Of these patients, 19 were revascularized and 30 were treated medically. Resting echocardiogram and radionuclide angiography were repeated 8 mo later to evaluate segmental functional recovery and changes in left ventricular (LV) ejection fraction, respectively. RESULTS: In revascularized patients, 61 of 108 akinetic or dyskinetic segments showed functional recovery. In these patients, sensitivity in predicting segmental functional recovery was 87% for sestamibi imaging and 66% for dobutamine echocardiography (P < 0.001), whereas specificity and accuracy were comparable. Sestamibi activity (> or =55% of peak) was the strongest predictor of segmental functional recovery (P < 0.001) and of LV ejection fraction improvement > or =5% (P < 0.01) after revascularization. In medically treated patients, 60 of 149 akinetic or dyskinetic segments showed functional recovery. In these patients, the majority (94%) of segments with contractile reserve on dobutamine were viable on sestamibi imaging and 86% of them improved function at follow-up. Functional recovery was poor in segments without contractile reserve either with (38%) or without (62%) preserved sestamibi uptake. Inotropic response was the best predictor of segmental (P < 0.001) and global (P < 0.01) LV functional improvement in medically treated patients. CONCLUSION: Dobutamine echocardiography predicts spontaneous functional recovery after acute myocardial infarction. However, sestamibi imaging is useful to identify patients with dysfunctional myocardium without contractile reserve who may benefit from coronary revascularization.     

应变率成像对急性前壁心肌梗死患者左心功能的评价

目的:观察急性前壁心肌梗死患者心肌应变率(SR)的变化特点,探讨应变率成像(SRI)技术定量评价急性心肌梗死(AMI)患者的左室局部心肌功的临床应用价值。方法:应用SRI对20例AMI患者和30例正常人左室各室壁节段纵向收缩期、舒张早期及房缩期的峰值应变率进行测定,并以冠脉造影结果为标准进行对比分析。结果:SRS:AMI组基底部、中部水平所有室壁较正常对照组显著性减低,心尖水平除下壁外其他室壁较对照组显著性减低;SRE:AMI组不同水平左室所有室壁较对照组显著性减低;SRA:基底部前间隔、后壁、前壁、下壁较对照组显著性减低,中部后间隔、后壁、前壁较对照组显著性减低,心尖水平后间隔、前壁、下壁AMI组较对照组显著性减低(P<0.01和0.05)。结论:SRI技术是临床无创、定量评价急性心肌梗死局部心肌功能的有效方法。     

Incremental prognostic value of left ventricular function analysis over non-invasive coronary angiography with multidetector computed tomography

Background

The purpose of this study was to determine the prognostic value of computed tomography coronary angiography (CTA)-derived left ventricular (LV) function analysis and to assess its incremental prognostic value over the detection of significant stenosis using CTA.

Methods

In 728 patients (400 males, mean age 55 ± 12 years) with known or suspected CAD, the presence of significant stenosis (≥ 50% stenosis) and LV function were assessed using CTA. LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV), and LV ejection fraction (LVEF) were calculated. LV function was assessed as a continuous variable and using cutoff values (LVEDV > 215 mL, LVESV > 90 mL, LVEF < 49%). The following events were combined in a composite end-point: all-cause mortality, non-fatal myocardial infarction, and unstable angina pectoris requiring hospitalization.

Results

On CTA, a significant stenosis was observed in 221 patients (30%). During follow-up [median 765 days, 25-75th percentile: 493-978] an event occurred in 45 patients (6.2%). After multivariate correction for clinical risk factors and CTA, LVEF < 49% and LVESV > 90 mL were independent predictors of events with an incremental prognostic value over clinical risk factors and CTA.

Conclusions

The present results suggest that LV function analysis provides independent and incremental prognostic information beyond anatomic assessment of CAD using CTA.     

Attenuation correction improves the detection of viable myocardium by thallium-201 cardiac tomography in patients with previous myocardial infarction and left ventricular dysfunction.

The aim of this study was to determine the influence of attenuation-corrected thallium-201 stress/redistribution/reinjection single-photon emission tomography (SPET) on the number of viable segments in patients with previous myocardial infarction and dysfunctional myocardium. Fifty-one patients with previous myocardial infarction and left ventricular dysfunction were included in the study. In all patients, 201Tl non-corrected (NC) and attenuation-corrected (AC) SPET was performed using a stress/redistribution/reinjection protocol followed by coronary angiography. A semiquantitative analysis was performed using polar maps for NC and AC stress, redistribution and reinjection short-axis and vertical long-axis (apex) slices. Severe (perfusion defect below 50%/maximal count rate: PD < 50), mild and moderate persistent defects for redistribution and reinjection were evaluated for both NC and AC studies. A total of 1581 segments were evaluated by semiquantitative segmental analysis for both NC and AC studies for each redistribution and reinjection map. In the redistribution maps, NC revealed a total of 352 segments and AC a total of 222 segments with impaired perfusion below 50% of the maximal count rate (PD < 50). The mean number of affected segments was 6.9 +/- 5.5 in the case of NC and 4.4 +/- 4.8 in the case of AC (P < 0.001). In the reinjection maps, NC revealed a total of 263 non-viable segments (PD < 50) and AC a total of 169 non-viable segments. The mean number of affected segments was 5.2 +/- 5.3 in the case of NC and 3.3 +/- 4.2 in the case of AC (P < 0.001). Recovery of function was better predicted by AC than by NC in 20% of patients in the follow-up group. Therefore, the use of attenuation correction influences the extent of viable segments by showing more viable segments in either redistribution or reinjection maps. 201Tl imaging without attenuation correction may underestimate the extent of tissue viability, which may contribute to the lower sensitivity compared to fluorine-18-fluorodeoxyglucose positron emission tomography, where attenuation correction is a routinely performed procedure.