急性心肌梗死后存活心肌对梗死相关血管晚期血运重建术后左室功能的影响

目的探讨存活心肌对急性心肌梗死(AMI)后梗死相关血管(IRA)晚期血运重建术后远期左室功能以及左室重构的影响.方法69例AMI未接受早期再灌注治疗者,于发病10～21 d行IRA经皮冠状动脉血运重建(PCI)术,术前于AMI发病后5～10 d应用小剂量多巴酚丁胺(5和10μg·min-1·kg-1)超声心动图负荷试验检测存活心肌,并分别测定和计算给药前后左室腔大小、左室射血分数(LVEF)以及室壁运动积分(WMS).按有无存活心肌分为存活心肌组和无存活心肌组,超声心动图随访术后6个月时两组左室腔大小、LVEF和WMS的变化.结果157个运动异常节段中89个节段(57%)有存活心肌,有存活心肌组26例(占38%),无存活心肌组43例(占62%).存活心肌组术后6个月LVEF较术前明显提高(P＜0.05),收缩末期容积指数(LVESVI)和WMS明显降低(P＜0.05和P＜0.01);而无存活心肌组LVEF较术前明显降低(P＜0.01),LVESVI和左室舒张末期容积指数(LVEDVI)较术前明显增加(P＜0.05),WMS无明显变化.存活心肌组多巴酚丁胺负荷时的LVEF和WMS明显改善,且与6个月时的测定值相近;而无存活心肌组PCI前应用多巴酚丁胺LVEF和WMS均无明显变化.结论AMI后有存活心肌者晚期血运重建有利于改善远期左室功能和减少左室重构.心肌梗死后早期小剂量多巴酚丁胺负荷状态下左室收缩功能的提高预示晚期血运重建术后心功能改善.     

Viable Myocardium Impact on Left Ventricular Function after Late Revascularization of Infarct-related Artery in Acute Myocardial Infarction

Objectives The long-term benefit of late reperfusion of infarct-related artery (IRA) after acute myocardial infarction (AMI) is controversial, and the benefit mechanisms remain uncertain. Low dose dobutamine stress echocardiography (LDSE) can identify viable myocardium and predict improvement of wall motion after revascularization. Methods Sixty-nine patients with first AMI who did not received early reperfusion therapy were studied by LDSE at 5 to 10 days after AMI. Wall motion abnormality and left ventricular size were measured at the same time. Successful PCI were done in all patients at 10 to 21 days after AMI onset. Patients were divided in two groups based on the presence or absence of viable myocardium. Echocardiography was repeated six months later. Results There were 157 motion abnormality segments. 89 segments (57%) were viable during LDSE. 26 patients (38%) with viability and 43 (62%) without. In viable group, left ventricular ejection fraction (LVEF) was increased (P < 0.05), and left ventricular end systolic volume index (LVESVI) and wall motion score (WMS) were decreased (P < 0.05 and P < 0.01) significantly at 6 months compared with baseline. But in patients without viability, LVEF was decreased (P < 0.01), and LVESVI and left ventricular end diastolic volume index (LVEDVI) were increased (P<0.05) significantly after 6 months, and the WMS did not changed (P > 0.05). LVEF increased (P< 0.05) and WMS decreased (P < 0.05) on LDSE during acute phase in patients with viability, but they were not changed in the nonviable group. Conclusions Late revascularization of IRA in patients with presence of viable myocardium after AMI is associated with long-term preservation left ventricular function and less ventricular remodeling. Improvement of left ventricular systolic function on LDSE indicates late phase recovery of left ventricular function after late revascularization.     

Low-dose dobutamine in patients with acute myocardial infarction identifies viable but not contractile myocardium and predicts the magnitude of improvement in wall motion abnormalities in response to coronary revascularization

To assess the effects of coronary revascularization on viable but noncontractile myocardium, we examined 21 patients with a documented anterior acute myocardial infarction who had a significant improvement in wall motion abnormality evaluated by two-dimensional echocardiography in the infarct-related artery in response to low-dose dobutamine infusion. All patients had a significant residual stenosis in the infarct-related artery. In response to low-dose dobutamine, there was a marked improvement in contractility in the infarct-related area segments and this was reflected by a decrease in echocardiographic score index from 1.5 +/- 0.15 to 1.09 +/- 0.08 (p = 0.0001). Of these 21 patients, 13 underwent successful revascularization: 10 had percutaneous transluminal coronary angioplasty (PTCA) and three had coronary artery bypass grafts (CABG) (group I). Eight patients received medical therapy only (group II). At 40 +/- 15 days of follow-up, both groups had improvement in their segmental wall motion abnormalities. However, the improvement in group I was greater than that in group II, 1.1 +/- 0.13 and 1.35 +/- 0.1, respectively (p = 0.0002). We conclude that: (1) low-dose dobutamine infusion may identify viable but noncontractile myocardium in patients with acute myocardial infarction and (2) in these patients revascularization causes a greater improvement in left ventricular function over time when compared with a nonrevascularized group.     

Prognostic implications of myocardial contractile reserve in patients with ischemic cardiomyopathy

The extent and degree of myocardial viability is an important parameter in the risk stratification of patients with significant left ventricular dysfunction due to coronary artery disease (CAD). Although several imaging modalities can identify viable myocardium, dobutamine stress echocardiography has gained considerable importance as an accurate, safe, and reliable method. In patients with significant left ventricular dysfunction secondary to CAD, identifying the presence and extent of contractile reserve and, therefore, viable myocardium, during low dose dobutamine infusion can predict recovery of left ventricular function postrevascularization, survival, and future cardiac events.     

Predictors of contractile recovery after revascularization in patients with anterior myocardial infarction who received thrombolysis

BACKGROUND:

Identification of viable myocardium after myocardial infarction has gained paramount importance with the current progress in coronary revascularization.

OBJECTIVE:

To explore the prognostic power of certain patient characteristics to predict myocardial contractile recovery after revascularization in patients presenting with acute anterior ST elevation myocardial infarction (STEMI) who received thrombolytic therapy.

METHODS:

Seventy-three consecutive patients presenting with first acute anterior STEMI who had received thrombolytic therapy and had significant coronary stenosis or occlusion of the infarct-related artery amenable for revascularization were enrolled. All patients underwent echocardiographic assessment of regional wall motion and left ventricular ejection fraction. Patients underwent coronary revascularization by either percutaneous angioplasty or surgical bypass. Echocardiography was repeated two to three months following revascularization. Patients were classified into two groups: group 1 had evidence of contractile recovery after revascularization at follow-up echocardiography and group 2 had no such evidence of recovery.

RESULTS:

Predictors of contractile recovery after revascularization included a shorter time from symptom onset to the institution of thrombolytic therapy, a lower baseline wall motion score index, the presence of grade 3 collaterals to the infarct-related artery and the use of beta-blockers. Instead, the presence of diabetes mellitus and a totally occluded infarct-related artery predicted poor contractile recovery.

CONCLUSIONS:

Myocardial contractile recovery after revascularization in patients presenting with first acute anterior STEMI may be predicted by the absence of diabetes, a shorter time from symptom onset to thrombolytic therapy, the use of beta-blockers, a lower initial wall motion index score and the presence of collaterals to the infarct-related artery.     

Clinical relevance of hibernating myocardium in ischemic left ventricular dysfunction

Patients with chronic ischemic left ventricular dysfunction may have a substantial amount of viable, hibernating myocardium, which is a state of chronic contractile dysfunction with reduced blood flow at rest. Coronary revascularization in these patients may result in improvement of left ventricular function; in the absence of viability, left ventricular function will not improve postrevascularization. Various noninvasive imaging techniques are available for detection of viable myocardium, including magnetic resonance imaging, dobutamine stress echocardiography, and nuclear imaging with single photon emission computed tomography or positron emission tomography. Because these techniques probe different characteristics of viable myocardium, the sensitivities and specificities of the techniques are not precisely identical; in general, dobutamine stress echocardiography has the highest specificity, whereas the nuclear techniques have the highest sensitivity. The presence of myocardial viability also is related to prognosis: patients with viable myocardium who undergo revascularization have a good prognosis, whereas patients with viable myocardium who are treated medically have poor outcome. Accordingly, assessment of viability is important in the therapeutic decision-making process of patients with chronic ischemic left ventricular dysfunction.     

Effect of recanalization of chronic total occlusions on global and regional left ventricular function in patients with or without previous myocardial infarction.

Previous studies have demonstrated improvement of regional wall motion and global left ventricular function after successful recanalization of chronic total occlusion in coronary artery. However, the difference of benefits of recanalization between infarct site and noninfarct site is unknown. This study assessed the changes in left ventricular ejection fraction, regional wall motion after successful angioplasty of chronic total occlusions with or without previous myocardial infarction. This study also evaluated the factors that influenced the outcome of left ventricular function. We retrospectively studied 75 patients with a successfully recanalized chronic total occlusion in native coronary artery. Left ventriculograms were obtained at baseline and after 6 months. Global and regional left ventricular function were determined. The patients were divided into two groups. Group 1 comprised patients without previous myocardial infarction in the territories of total occlusion vessel that was recanalized. Group 2 comprised patients with previous myocardial infarction in the territories of total occlusion vessel that was recanalized. Left ventricular ejection fraction increased from 53.2% +/- 16.3% at baseline to 57.3% +/- 20.1% at 6-month follow-up in the whole group (P = 0.001). In group 1 patients, the evolution of left ventricular (LV) ejection fraction increased from 59.5% +/- 13.7% to 67.3% +/- 14.6% (P < 0.001). In group 2 patients, the evolution of LV ejection fraction increased, but not significantly, from 48.9% +/- 16.2% to 50.5% +/- 16.9% (P = NS). The evolution of LV ejection fraction increased from 47.6% +/- 17.4% to 50.8% +/- 17.5% (P < 0.05) in the subgroup of recanalization in infarct-related vessel that had rich collateral circulation and had long-term patency. The regional wall motion all significantly improved in group 1 patients (P < 0.05). The regional wall motion did not change in group 2 patients (P = NS). The influence of recanalization of chronic coronary occlusions on the improvement of left ventricular global function was different between myocardial infarction and nonmyocardial infarction patients. The left ventricular function did not improve in myocardial infarction patient. Regional wall motion improved in patients without previous myocardial infarction. For reliable improvement of left ventricular function after recanalization of chronic total occlusions, evidence (not only by symptom or treadmill test) of viable myocardium in recanalized vessel is important. It is also important to keep patency of infarct-related vessel that has good collateral circulation for improving the left ventricular function.     

Low-dose dobutamine radionuclide ventriculography for prediction of myocardial viability: quantitative analysis of regional left ventricular function

BACKGROUND: It is important to distinguish viable myocardium from necrotic tissue in order to decide upon therapy in patients with ischemic heart disease. HYPOTHESIS: We verified the hypothesis that quantitative analysis of regional left ventricular function using low-dose dobutamine radionuclide ventriculography (RNV) can sensitively predict myocardial viability and compared its usefulness with thallium-201 (201Tl) single-photon emission computed tomography (201Tl-SPECT). METHODS: Radionuclide ventriculography at rest and during low-dose dobutamine infusion (5 micrograms/kg/min), 201Tl-SPECT, and coronary angiography were performed in 51 subjects with severe ischemia-related stenosis of coronary arteries and 3 subjects without coronary artery disease. 201Tl uptake was assessed as normal (control), low perfusion (LP), or defect. We compared the response of regional function to dobutamine with the regional 201Tl uptake. The accuracy of both methods for identifying viable myocardium was investigated in 17 patients who underwent successful coronary revascularization, with a resulting improvement in wall motion. RESULTS: The increase in regional ejection fraction (delta r-EF) in response to dobutamine was significantly greater in the control (12 +/- 6%) and LP (16 +/- 11%) regions than in the defect (5 +/- 10%) regions. The increase in one-third regional ejection fraction (delta r-1/3EF) was also significantly higher in the control (14 +/- 7%) and LP (10 +/- 8%) regions than in the defect regions (5 +/- 6%). We defined myocardial viability as a delta r-EF > 5% or a delta r-1/3EF > 2%. The sensitivity and specificity of the delta r-EF for identification of myocardial viability were 91.4 and 55.5%, respectively. The sensitivity and specificity of the delta r-1/3EF were 91.4 and 66.6%, respectively; the corresponding values for 201Tl SPECT were 74.2 and 77.8%. CONCLUSION: Low-dose dobutamine RNV with quantitative analysis of regional left ventricular function was more sensitive for identification of viable myocardium than 201Tl-SPECT.     

Reversible left ventricular dysfunction

The extent and degree of myocardial viability are important parameters in the risk stratification of patients with significant left ventricular dysfunction secondary to coronary artery disease. Although several imaging modalities can identify viable myocardium, dobutamine stress echocardiography has gained considerable importance as an accurate, safe, and reliable method. In patients with significant left ventricular dysfunction secondary to coronary artery disease, identification of the presence and extent of contractile reserve and, therefore, viable myocardium during low-dose dobutamine infusion can predict the recovery of left ventricular function after revascularization, survival rate, and future cardiac events.     

糖尿病和非糖尿病急性前壁心肌梗死晚期成功血运重建术后左室功能的变化及其与存活心肌的关系

目的:比较糖尿病和非糖尿病前壁急性心肌梗死(AMI)晚期成功血运重建术对心肌梗死后远期左室功能和预后的影响以及与存活心肌的关系.方法:选择依据病史、心电图和心肌损伤标志物等检查证实为首次发作的前壁AMI,并于发病后2周左右接受冠状动脉介入治疗术(PCI)的患者共计125例,其中参照WHO诊断标准确诊为并发糖尿病者(A组)43例,未并发糖尿病者(B组)82例.PCI前行超声心动图检查,了解左室功能和梗死相关区域存活心肌的情况.详细分析和记录PCI前后冠状动脉造影的结果.并分别于PCI前和术后6 h、24 h采取静脉血检测血清CK-MB和肌钙蛋白T水平.术后6个月重复超声心动图检查,了解左室功能和室壁活动异常的变化,并随访其间主要心血管事件的发生情况.结果:冠状动脉造影显示,与B组相比,A组PCI后即刻靶血管TIMI 2级血流所占的比例较多,TIMI 3级较少(分别为P<0.05和P<0.01).术后CK-MB和肌钙蛋白T增高者A组明显多于B组(25.6%∶9.8%,P<0.05).小剂量多巴酚丁胺超声负荷试验结果示A组中62.8%和B组中56.1%的患者有存活心肌,2组相比差异无统计学意义(P>0.05).急性期2组左室射血分数(LVEF)、左室舒张末期容积指数(LVEDVI)、收缩末期容积指数(LVESVI)以及室壁运动积分(WMS)基本相同(均P>0.05).术后6个月随访,B组WMS明显减少,LVEF明显增高;而A组LVEF和WMS均无明显改善,LVEDVI反而增加;2组相比LVEDVI、LVESVI、LVEF和WMS均有明显差异(分别P<0.05和P<0.01).随访期间2组主要心血管事件的发生率差异无统计学意义(18.6%∶11.0%,P>0.05).结论:糖尿病AMI晚期成功血运重建对远期左室功能的改善作用较非糖尿病者差,其结果可能与糖尿病患者晚期PCI后缺血心肌未能得到有效再灌注或再灌注加重心肌损伤有关,而术前存活心肌可能不是影响其疗效的主要原因.     

Clinical importance of viability assessment in chronic ischemic heart failure

Background and hypothesis: Revascularization has provided an effective treatment of depressed left ventricular function in patients with chronically ischemic or “viable” myocardium. Assessment of viable myocardium can be achieved by several noninvasive techniques including dobutamine stress echo or radionuclides such as flurodeoxyglucose (F¹⁸DG). F¹⁸DG uptake studies are based on the assumption that enhanced glucose uptake in areas of diminished blood flow provides evidence of viable myocardium. To determine the clinical utility of viability assessment in the management of chronic ischemic left ventricular dysfunction, we reviewed the findings and short-term treatment of a series of patients referred for heart failure evaluation who had subsequent F¹⁸DG uptake scans. Methods: We retrospectively reviewed 59 consecutive F¹⁸DG viability studies in a series of patients who had documented coronary artery disease and depressed left ventricular function. Single photon emission computerized tomography (SPECT) with F¹⁸DG was performed in the patients and these images were compared to SPECT images of resting myocardial perfusion using thallium, sestamibi, or teboroxime. Clinical decisions based on the results of these scans were obtained from chart review. Thirty-day mortality was determined from chart review or contact with the patient's physician. The patients were divided into those without and with F¹⁸DG uptake consistent with viable ischemic myocardium. Further analysis included subgroups of patients who were advised to undergo transplantation, revascularization, or to continue medical therapy. Results: Of 34 patients referred for cardiac transplantation, 18 had viable myocardium and 13 underwent revascularization. In the entire study group, 34 of 59 (58%) had evidence of viable myocardium and 29 had subsequent revascularization procedures. Thirty-day survival for all revascularization patients was 86%. Conclusion: Assessment of myocardial viability with F¹⁸DG SPECT imaging in patients with ischemic left ventricular dysfunction led to a clinical decision for revascularization in approximately half the patients with severe coronary disease and left ventricular dysfunction who were evaluated for myocardial viability in our institution.     

Radionuclide Imaging for the Assessment of Myocardial Viability in Chronic LV Dysfunction

Clinical decision making for the selection of patients with coronary artery disease and depressed left ventricular (LV) function for coronary revascularization is very critical but at times difficult. There is strong evidence of an increased event rate (myocardial infarction, death, unstable angina) in one fourth of patients with viable myocardium who are treated medically compared with only one sixteenth after revascularization. Documentation of the presence of viable myocardium best allows identification of patients who are most likely to benefit from coronary revascularization as evident by postoperative improvement in LV systolic function, exercise capacity, quality of life, or survival. On the other hand, identifying patients who would not demonstrate significant improvement is equally important in view of the high morbidity and mortality rates associated with surgery in such patients. Noninvasive imaging to determine the presence and extent of viable myocardium has become an important component of the assessment of patients with coronary artery disease and depressed LV function. About 40% of such patients have the potential for significant improvement after successful surgical revascularization. This review summarizes the role of radionuclide myocardial perfusion imaging for the assessment of viable myocardium.     

Myocardial viability in patients with Q wave myocardial infarction and no residual ischemia.

BACKGROUND. Coronary revascularization in patients with persistent angina after myocardial infarction reduces the incidence of recurrent angina pectoris and myocardial infarction and improves left ventricular function. The results of revascularization after a Q wave myocardial infarction when there is no residual ischemia may depend on myocardial viability. METHODS AND RESULTS. To determine whether there was viable myocardium in the infarct area in the absence of clinical and scintigraphic evidence of myocardial ischemia, 15 asymptomatic patients with a Q wave myocardial infarction, no redistribution on stress 201Tl test, and single-vessel disease (greater than 70% stenosis) with persistent anterograde blood flow were randomized to percutaneous transluminal coronary artery angioplasty (PTCA) or conservative medical treatment. After 2 months of follow-up, mean coronary blood flow measured by Doppler catheter in the infarct-related artery was higher in the PTCA treatment group (33 +/- 6 ml/min, n = 8) than in the conservative treatment group (16 +/- 4 ml/min, n = 7; p less than 0.05 between groups). The 201Tl pathological-to-normal ratios measured on postexercise images did not change in patients treated conservatively during the follow-up period (delta = +1.1 +/- 2.2%; NS from baseline) but increased significantly in patients treated by PTCA (delta = +8.5 +/- 2.3%; p less than 0.01 from baseline; p less than 0.05 between groups). Segmental wall motion improved on left ventricular angiography 2 months after PTCA (delta = +11.5 +/- 2.2%; p less than 0.001 from baseline) significantly more than in the conservative treatment group (delta = +4.1 +/- 1.4%; p less than 0.05 between both groups). Improvements of 201Tl ratios and segmental wall motion indexes correlated significantly (r = 0.73, p = 0.002). The mild improvement of global left ventricular ejection fraction measured in the PTCA treatment group did not differ significantly from changes in the conservative treatment group. CONCLUSIONS. Successful angioplasty of the stenotic infarct artery in patients with a Q wave myocardial infarction and no residual ischemia improved coronary flow, 201Tl uptake in the infarct area, and regional wall motion. Therefore, myocardial viability may last several weeks, as long as residual blood flow persists in the infarct-related artery. Optimal assessment of viability by imaging techniques should identify patients who are most likely to benefit from revascularization.     

Clinical benefit of noninvasive viability studies of patients with severe ischemic left ventricular dysfunction

The population of patients who have congestive heart failure of ischemic origin is large and growing. It imposes a heavy burden on human suffering and economic costs such as the chronic use of costly medications, recurrent hospital admissions, and, eventually, death or the necessity of heart transplantation. Therefore, the development of methods for detecting viable myocardium may allow the accurate selection of those patients with coronary artery disease with severe left ventricular dysfunction who are most likely to benefit from revascularization, but also excludes patients who are unlikely to obtain any improvement with revascularization techniques. The presence of reversible dysfunctional myocardium that may improve after revascularization implies the concepts of stunned and hibernating myocardium. Recent evidence suggests that hibernation may not be a stable condition since it might evolve toward an irreversible dysfunction if it is not revascularized at the right moment. The techniques available for viability studies are single-photon emission computed tomography using thallium-201 or compounds labeled with technetium-99m, positron emission tomography, and dobutamine stress echocardiography. Newer and promising techniques are magnetic resonance imaging and contrast echocardiography, whose definitive roles are not clear yet. There is abundant evidence from several important studies showing that patients with a significant amount of viable myocardium have a poor outcome if they are treated medically. Conversely, if these patients are revascularized, their outcomes improve and their symptoms significantly decrease, with less necessity of medication, fewer admissions to the hospital, and even in some cases avoiding heart transplantation. On the other hand, patients with poor or no viability who are revascularized do not obtain significant benefit.     

The prognostic value of myocardial viability recognized by low dose dipyridamole echocardiography in patients with chronic ischaemic left ventricular dysfunction.

AIMS: The aim of this study was to assess the prognostic value of myocardial viability recognized as a contractile response to vasodilator stimulation in patients with left ventricular dysfunction in a large scale, prospective, multicentre, observational study. METHODS AND RESULTS: Three hundred and seven patients (mean age 60 +/- 10 years) with angiographically proven coronary artery disease, previous (>3 months) myocardial infarction and severe left ventricular dysfunction (ejection fraction <35%; mean ejection fraction: 28 +/- 7%) were enrolled in the study. Each patient underwent low dose dipyridamole echo (0.28 mg x kg(-1) in 4 min). Myocardial viability was identified as an improvement of >0.20 in the wall motion score index. By selection, all patients were followed up for a median of 36 months. One-hundred and twenty-four were revascularized either by coronary artery bypass grafting (n=83) or coronary angioplasty (n=41). The only end-point analysed was cardiac death. In the revascularized group, cardiac death occurred in one of the 41 patients with and in 16 of the 83 patients without a viable myocardium (2.4% vs 19.3%, P<0.01). Outcome, as estimated by Kaplan-Meier survival, was better for patients with, compared to patients without, a viable myocardium, who underwent coronary revascularization (97.6 vs 77.4%, P=0.01). Using a Cox proportional hazards model, the presence of myocardial viability was shown to exert a protective effect on survival (chi-square 4.6, hazard ratio 0.1, 95% CI 0.01-0.8, P<0.03). The survival rate in medically treated patients was lower than in revascularized patients irrespective of the presence of a viable myocardium (79.7% vs 86.2, P=ns). CONCLUSION: In severe left ventricular ischaemic dysfunction, myocardial viability, as assessed by low dose dipyridamole echo, is associated with improved survival in revascularized patients.     

Single photon emission computed tomography perfusion imaging for assessment of myocardial viability and management of heart failure

In the setting of coronary artery disease, some areas of dysfunctional myocardium may realize significant improvement in function as a consequence of revascularization. These areas represent viable myocardium, encompassing a spectrum of pathophysiology ranging from chronic stunning, in which resting blood flow is preserved, to hibernating myocardium, in which resting blood flow is decreased. The accurate preoperative evaluation of viable myocardium helps identify those patients with left ventricular dysfunction who will most benefit from coronary revascularization. Of the various modalities available for viability assessment, the nuclear medicine techniques ²⁰¹Thallium and ¹⁸Fluorodeoxyglucose positron emission tomography have emerged as the most sensitive. It has been consistently shown that in patients with a significant amount of viable myocardium, there is a substantial survival benefit in revascularization versus medical therapy. The likelihood of affecting a significant improvement decreases with time to revascularization, however, particularly in the setting of an enlarged left ventricle secondary to ventricular remodeling.     

Predictive value of low dose dobutamine transesophageal echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography for recovery of regional left ventricular function after successful revascularization

Objectives. This study was designed to assess the predictive value of myocardial viability diagnosed by dobutamine transesophageal echocardiography and fluorine (F)-18 fluorodeoxyglucose positron emission tomography for left ventricular functional recovery after revascularization in patients with chronic left ventricular dysfunction.Background. The identification of akinetic but viable myocardium is of particular importance for the selection of patients with a compromised left ventricle who will benefit from coronary revascularization.Methods. Multiplane rest and dobutamine transesophageal echocardiography (dobutamine, 5 and 10 μg/min per kg) studies and F-18 fluorodeoxyglucose positron emission tomographic studies at rest were performed in 42 patients with 1) previous myocardial infarction and regional akinesia, 2) a stenosed infarct-related coronary artery, and 3) a patent infarct-related vessel after revascularization. A basally akinetic segment was considered viable by transesophageal echocardiography if dobutamine-induced contractile reserve could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake ≥50% of the maximal uptake in a region with normal wall motion. Recovery of regional left ventricular function 4 t0 6 months after revascularization was diagnosed by transesophageal echocardiography if ≥50% of segments akinetic at baseline had improved wall thickening.Results. Dobutamine transesophageal echocardiography identified viable infarct regions in 25 (59%) of 42 patients, and F-18 fluorodeoxyglucose positron emission tomography in 30 (71%) of 42 patients, yielding diagnostic agreement in 86% of patients. Sensitivity and specificity for prediction of left ventricular functional recovery in individual patients was 92% and 88%, respectively, for dobutamine transesophageal echocardiography versus 96% and 69% for F-18 fluorodeoxyglucose positron emission tomography. Segments remaining akinetic after revascularization had a significantly lower (p < 0.001) F-18 fluorodeoxyglucose uptake (48 ± 15%) than that (73 ± 15%) of segments with recovery of regional left ventricular function.Conclusions. Both dobutamine transesophageal echocardiography and F-18 fluorodeoxyglucose positron emission tomography were highly sensitive in predicting functional recovery of chronically kinetic or dyskinetic myocardium after successful revascularization. Thus, dobutamine transesophageal echocardiography is a clinically valuable alternative to F-18 fluorodeoxyglucose positron emission tomography for assessing residual viability and predicting functional recovery after revascularization.     

QT Dispersion and Viable Myocardium in Patients with Prior Myocardial Infarction and Severe Left Ventricular Dysfunction

Background: QT dispersion (QTd) has been found to correlate to the amount of viable myocardium in patients with Q‐wave myocardial infarction and well‐preserved LV function. However, this relationship is unknown in patients with severe left ventricular dysfunction. Methods: Thirty‐four patients with prior large myocardial infarction and severe left ventricular dysfunction underwent Tc‐99m sestamibi single photon emission cardiac tomography (SPECT) and F‐18 fluorodeoxyglucose (FDG) SPECT. Viability was defined as a defect relative count density (DCD) of at least 20% greater on FDG SPECT. QTd, corrected QT dispersion (QTcd), and QT coefficient of variation (cv) in patients with viable myocardium was compared to those without viable mvocardium in the infarct area. Results: Thirteen patients were excluded from analysis for poor FDG images or inadequate ECG tracings. Of the remaining patients, 10 (48%) were found to have viability on FDG SPECT. QTd, QTcd, and QTcv in patients with viability were: 58 ± 22 ms, 61 ± 23 ms, and 4.81 ± 1.76%, respectively, which did not differ significantly from those in patients without viability (QTd = 56 ± 14 ms, QTcd = 70 ± 16 ms and Qtcv = 5.06 ± 1.20% (P = NS]). Moreover, neither FDG defect size, nor LVEF correlated with QTd. Conclusions: This study indicates no relationship between QTd and viability in patients with myocardial infarction and severe left ventricular dysfunction. A.N.E. 2002;7(1):53–59     

Resolution of late potentials with improvement in left ventricular systolic function in patients with first acute myocardial infarction

Background: Ventricular late potentials predict subsequent arrhythmic events and sudden death in postinfarction patients. Late potentials are recorded in the infarcted area, but it should be pointed out that they probably represent micropotentials in the area of delayed conduction found among isolated areas of scar tissue and normal myocardium. Hypothesis: The study was undertaken to investigate the relationship between chronic reversible myocardial ischemia, such as stunned or hibernating myocardium, and late potentials in 38 patients with a first myocardial infarction. Methods: The patients were divided into two groups, one with (Group 1) and one without (Group 2) resolution of late potentials recorded by signal-averaged electrocardiogram at 6 months after onset of myocardial infarction. We investigated the clinical, echocardiographic, and signal-averaged electrocardiographic characteristics of Groups 1 and 2. Results: In the chronic phase of myocardial infarction, a higher incidence of patency of the infarct-related artery and an improvement of wall motion score were found in Group 1, and left ventricular ejection fraction was better preserved in Group 1 than in Group 2. Conclusions: These results suggest that the resolution of late potentials was influenced by the improvement of left ventricular systolic function and patency of the infarct-related artery. We concluded that chronic reversible myocardial ischemia, such as stunned or hibernating myocardium, might be the substrate that generated late potentials.     

血运重建对冠心病合并心功能不全患者心肌收缩功能和心室重构的影响

目的探讨血运重建对冠心病合并左心功能不全患者心肌收缩功能和心室重构的影响。方法86例冠心病合并心功能不全患者术前应用超声心动图进行心功能、左心室(左室)几何形态和心肌活性评定,分为有存活心肌组和无存活心肌组,两组分别行血运重建或药物治疗。随访(13±5)个月后重新评价上述指标。结果57例有存活心肌的患者中行血运重建者较药物治疗者左室射血分数(LVEF)、存活节段数、左室球状指数(LVSI)明显提高;左室舒张末容积(LVEDV)、左室收缩末容积(LVESV)、左室重量(LVM)明显降低(P值均<0.01)。29例无存活心肌的患者中上述指标两种治疗间无显著性差异(P值均>0.05)。结论血运重建能改善冠心病合并左心功能不全但有存活心肌患者的心肌收缩功能和几何形态。