Myocardial Contrast Echocardiography After Myocardial Infarction

Surveillance of adenosine stress myocardial contrast echocardiography following percutaneous coronary intervention

BACKGROUND

The ability of adenosine stress myocardial contrast echocardiography (AS-MCE) to reveal decreased coronary blood flow or perfusion defects (PDs) has not been explored for clinical implications after coronary revascularization. This study sought to identify the prognostic value of PDs in asymptomatic patients following percutaneous coronary intervention (PCI).

METHODS

We retrospectively analyzed 342 asymptomatic patients (67 years of mean age, 72% male) who underwent PCI with stents at least 9 months before AS-MCE between May 2019 and December 2020. Resting regional wall motion abnormality (rRWMA) and the patterns of PDs were assessed, and further PDs were classified as ischemic or fixed type. The primary endpoint was the composite of hospitalization for worsening heart failure, coronary revascularization, and cardiac death.

RESULTS

In AS-MCE (median time interval following PCI: 17.4 months), PDs were present in 93 (27.2%) out of 342 patients; 70 of ischemic PD (75.3%), 58 of fixed PD (62.4%). Those with PD showed a higher frequency of rRWMA than those without PD (53.8 vs. 15.7%, p < 0.001). During the median follow-up of 22.6 months, 26 (7.6%) patients experienced more associated clinical outcomes with PD than rRWMA. Cox analysis revealed that the combined findings of rRWMA and PD, and specifically, ischemic PD of ≥ 2 segments were associated with a high increase in adverse outcomes.

CONCLUSIONS

AS-MCE provided prognostic value in asymptomatic patients with prior PCI. PD might be complementary to rRWMA in risk stratification.

Photoacoustic Imaging of Myocardial Infarction Region Using Non-Invasive Fibrin-Targeted Nanoparticles in a Rat Myocardial Ischemia-Reperfusion Model

BACKGROUND AND PURPOSE

Myocardial infarction (MI) is a serious threat to public health. The early identification of MI is important to promote appropriate treatment strategies for patients. Recently, strategies targeting extracellular matrix (ECM) components have gained attention. Fibrin is an ECM protein involved after MI. In this work, we constructed fibrin-targeted nanoparticles (NPs) by co-assembling a fibrin-targeted peptide (CREKA) and indocyanine green (ICG) and used them to enhance photoacoustic (PA) imaging for noninvasive detection of the infarct region to help diagnose MI.

METHODS

ICG NPs modified with CREKA were prepared (CREKA-ICG-LIP NPs). Then, the fundamental characteristics, stability, safety, and targeting ability of the NPs were detected. Finally, in an ischemia-reperfusion (IR) injury model, the performance of the NPs in detecting the infarct region in the model on PA imaging was evaluated.

RESULTS

CREKA-ICG-LIP NPs were successfully constructed and showed excellent basic characteristics, a high safety level, and an excellent targeting ability. After intravenous injection, the CREKA-ICG-LIP NPs accumulated in the injured region in the IR model. Then, the PA signal in the infarct region could be detected by the ultrasound transducer of the Vevo LAZR Photoacoustic Imaging System.

CONCLUSION

This work provides new insights for non-invasive, real-time imaging techniques to detect the region of myocardial injury and help diagnose MI based on a PA imaging system with high sensitivity in optical imaging and deep penetration in ultrasound imaging.

Postoperative Assessment of Myocardial Function and Microcirculation in Patients with Acute Coronary Syndrome by Myocardial Contrast Echocardiography

BACKGROUND Postoperative myocardial function and microcirculation of acute coronary syndrome (ACS) was assessed by myocardial contrast echocardiography (MCE). MATERIAL AND METHODS Eighty-nine ACS patients treated with percutaneous coronary intervention (PCI) were detected by MCE and two-dimensional ultrasonography before and a month later after PCI respectively. Their myocardial perfusion was evaluated by myocardial contrast score (MSC) and contrast score index (CSI); cross-sectional area of microvessel (A), average myocardial microvascular impairment (β), and myocardial blood flow (MBF) were analyzed by cardiac ultrasound quantitative analysis (CUSQ), and fractional flow reserve (FFR) change was observed. Left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimension (LVEDD), and left ventricular end-systolic dimension (LVESD) were observed; the index of microcirculatory resistance (IMR), FFR, and coronary flow reserve (CFR) were detected to evaluate coronary microcirculation. RESULTS None of the 89 patients experienced no-reflow. Patients with normal myocardial perfusion mostly had normal or slightly decreased ventricular wall motion after PCI. A month after the operation, there was an increase in A, β, MBF, LVEF, E/A, IMR, FFR, and CFR (all P<0.05), while LVEDD, LVESD, diastolic gallop A peak, E/Ea, E/Ea×S, and Tei decreased (all P<0.05). LVEF and IMR were in positive correlations with A. LVEF, IMR, FFR and CFR were positively correlated with b and MBF (both r>0, P<0.05), while E/Ea×Sa and Tei were negatively correlated with b and MBF (r<0, P<0.05). CONCLUSIONS MCE can safely assess post-PCI myocardial function and microcirculation of ASC.

Measurement of myocardial perfusion and infarction size using computer-aided diagnosis system for myocardial contrast echocardiography

Proper evaluation of myocardial microvascular perfusion and assessment of infarct size is critical for clinicians. We have developed a novel computer-aided diagnosis (CAD) approach for myocardial contrast echocardiography (MCE) to measure myocardial perfusion and infarct size. Rabbits underwent 15 min of coronary occlusion followed by reperfusion (group I, n = 15) or 60 min of coronary occlusion followed by reperfusion (group II, n = 15). Myocardial contrast echocardiography was performed before and 7 d after ischemia/reperfusion, and images were analyzed with the CAD system on the basis of eliminating particle swarm optimization clustering analysis. The myocardium was quickly and accurately detected using contrast-enhanced images, myocardial perfusion was quantitatively calibrated and a color-coded map calibrated by contrast intensity and automatically produced by the CAD system was used to outline the infarction region. Calibrated contrast intensity was significantly lower in infarct regions than in non-infarct regions, allowing differentiation of abnormal and normal myocardial perfusion. Receiver operating characteristic curve analysis documented that -54-pixel contrast intensity was an optimal cutoff point for the identification of infarcted myocardium with a sensitivity of 95.45% and specificity of 87.50%. Infarct sizes obtained using myocardial perfusion defect analysis of original contrast images and the contrast intensity-based color-coded map in computerized images were compared with infarct sizes measured using triphenyltetrazolium chloride staining. Use of the proposed CAD approach provided observers with more information. The infarct sizes obtained with myocardial perfusion defect analysis, the contrast intensity-based color-coded map and triphenyltetrazolium chloride staining were 23.72 ± 8.41%, 21.77 ± 7.8% and 18.21 ± 4.40% (% left ventricle) respectively (p > 0.05), indicating that computerized myocardial contrast echocardiography can accurately measure infarct size. On the basis of the results, we believe the CAD method can quickly and automatically measure myocardial perfusion and infarct size and will, it is hoped, be very helpful in clinical therapeutics.

Prognostic Value of Speckle Tracking Echocardiography in Patients with ST-Elevation Myocardial Infarction Treated with Late Percutaneous Intervention

BACKGROUND

Left ventricular remodeling (LVr) is common after ST-segment elevation myocardial infarction (STEMI). The aim of this study was to evaluate the prognostic value of speckle tracking echocardiography (STE) for predicting LVr 6-9 months after late percutaneous coronary intervention (PCI) in patients with STEMI.

METHODS

Patients with first STEMI who accepted late PCI were enrolled. Echocardiography was performed within 48 hours of admission. Six to nine months after MI, an echocardiography examination was repeated. LVr was defined as >15% increase in LV end-systolic volume (LVESV) after 6 months.

RESULTS

One hundred and twenty-seven patients were divided into two groups: 86 patients without LVr and 41 patients with LVr. There were significant differences in the global longitudinal strain (GLS), SD of time to peak longitudinal systolic strain (longitudinal Ts-SD), longitudinal postsystolic index, radial strain (RS), and SD of time to peak radial systolic strain (Radial Ts-SD). In multivariate logistic regression analysis, the GLS(odds ratio [OR] = 0.39, 95% confidence interval [CI] = 0.26-0.57, P < 0.01), and RS(OR = 1.07, 95% CI = 1.02-1.13, P = 0.01) were determinants of LVr. A receiver operating characteristic curve showed that the GLS predicted LVr with an optimal cutoff value of -10.85 (sensitivity: 89.7%, specificity: 91.7%). During clinical follow-up for 16.9 ± 1.6 months, death or congestive heart failure developed in 12 patients (9.4%), and the baseline ejection fraction (OR = 1.91, 95% CI = 1.18-3.1, P = 0.009) and GLS (OR = 0.56, 95% CI = 0.34-0.91, P = 0.02) were independent predictors.

CONCLUSION

In patients with STEMI treated with late percutaneous coronary intervention, the GLS as measured by STE is a strong predictor of LVr and adverse events.

Relationship between early myocardial reperfusion assessed by videodensitometry and late left ventricular function. Results following invasive treatment of acute myocardial infarction

Introduction: It is known that there is a relationship between myocardial perfusion and left ventricular function. Aim: The aim of the current study was to examine the relationship between myocardial reperfusion as assessed by videodensitometry on coronary angiograms following invasive treatment of ST elevation myocardial infarction and magnetic resonance imaging-derived late left ventricular function. Method: The study included 25 patients with ST elevation myocardial infarction. A quantitative parameter of myocardial (re)perfusion was calculated by the ratio of maximal density (Gmax) and the time to reach maximum density (Tmax) following invasive treatment. Magnetic resonance imaging was performed 387±262 days after ST elevation myocardial infarction for the evaluation of left ventricular function in all cases. Results: Significant correlations were demonstrated between left ventricular ejection fraction and Gmax(r = 0.40, p = 0.05) and Gmax/Tmax(r = 0.41, p = 0.04) following vessel masking. Conclusions: The results demonstrate significant relationship between densitometric Gmax/Tmaxand late left ventricular function following ST elevation myocardial infarction. Orv. Hetil., 2014. 155(5), 187–193.

Spontaneous and procedural plaque embolisation in native coronary arteries: pathophysiology, diagnosis, and prevention

The detachment of atherothrombotic material from the atherosclerotic coronary plaque and downstream embolisation is an underrecognized phenomenon and it causes different degrees of impairment of the coronary microcirculation. During treatment of obstructive atherosclerotic plaque by percutaneous coronary intervention (PCI) distal embolisation (DE) is considered to be inevitable and it is associated with potential clinical and prognostic implications. This review aims to assess the main aspects of both spontaneous and procedural DE, analyze their different pathophysiology, provide specific insights on the main diagnostic tools for their identification, and finally focus on the main strategies for their treatment and prevention.