Microvascular Obstruction and Intramyocardial Hemorrhage in Reperfused Myocardial Infarctions: Pathophysiology and Clinical Insights From Imaging

Microvascular injury immediately following reperfusion therapy in acute myocardial infarction (MI) has emerged as a driving force behind major adverse cardiovascular events in the postinfarction period. Although postmortem investigations and animal models have aided in developing early understanding of microvascular injury following reperfusion, imaging, particularly serial noninvasive imaging, has played a central role in cultivating critical knowledge of progressive damage to the myocardium from the onset of microvascular injury to months and years after in acute MI patients. This review summarizes the pathophysiological features of microvascular injury and downstream consequences, and the contributions noninvasive imaging has imparted in the development of this understanding. It also highlights the interventional trials that aim to mitigate the adverse consequences of microvascular injury based on imaging, identifies potential future directions of investigations to enable improved detection of disease, and demonstrates how imaging stands to play a major role in the development of novel therapies for improved management of acute MI patients.

Sustained Mechanical Aspiration Thrombectomy for High Thrombus Burden Coronary Vessel Occlusion: The Multicenter CHEETAH Study

BACKGROUND

Poor myocardial reperfusion due to distal embolization and microvascular obstruction after percutaneous coronary intervention is associated with increased risk of morbidity and mortality. Prior trials have not shown a clear benefit of routine manual aspiration thrombectomy. Sustained mechanical aspiration may mitigate this risk and improve outcomes. The objective of this study is to evaluate sustained mechanical aspiration thrombectomy before percutaneous coronary intervention in high thrombus burden acute coronary syndrome patients.

METHODS

This prospective study evaluated the Indigo CAT RX Aspiration System (Penumbra Inc, Alameda CA) for sustained mechanical aspiration thrombectomy before percutaneous coronary intervention at 25 hospitals across the USA. Adults presenting within 12 hours of symptom onset with high thrombus burden and target lesion(s) located in a native coronary artery were eligible. The primary end point was a composite of cardiovascular death, recurrent myocardial infarction, cardiogenic shock, or new or worsening New York Heart Association class IV heart failure within 30 days. Secondary end points included Thrombolysis in Myocardial Infarction thrombus grade, Thrombolysis in Myocardial Infarction flow, myocardial blush grade, stroke, and device-related serious adverse events.

RESULTS

From August 2019 through December 2020, a total of 400 patients were enrolled (mean age 60.4 years, 76.25% male). The primary composite end point rate was 3.60% (14/389 [95% CI, 2.0-6.0%]). Rate of stroke within 30 days was 0.77%. Final rates of Thrombolysis in Myocardial Infarction thrombus grade 0, Thrombolysis in Myocardial Infarction flow 3, and myocardial blush grade 3 were 99.50%, 97.50%, and 99.75%, respectively. No device-related serious adverse events occurred.

CONCLUSIONS

Sustained mechanical aspiration before percutaneous coronary intervention in high thrombus burden acute coronary syndrome patients was safe and was associated with high rates of thrombus removal, flow restoration, and normal myocardial perfusion on final angiography.

Use of Thrombus Aspiration for Patients With Acute Coronary Syndrome: Insights From the Nationwide J-PCI Registry

Background

There is significant regional or institutional variation in the use of thrombus aspiration (TA) in patients undergoing percutaneous coronary intervention (PCI). We investigated the temporal trend in TA use and its association with clinical outcomes in acute coronary syndrome using the nationwide J‐PCI (Japanese PCI) registry.

Methods and Results

Between 2016 and 2018, patients with acute coronary syndrome undergoing PCI (n=282 606; median age, 71.0 years; interquartile range, 62.0–79.0 years; women, 24.7%) at 1124 hospitals were stratified on the basis of whether TA was performed (TA and non‐TA). The patients were subdivided according to clinical presentation (ST‐segment–elevation myocardial infarction, non–ST‐segment–elevation myocardial infarction, and unstable angina). Successful PCI, defined as the achievement of TIMI (Thrombolysis in Myocardial Infarction) 3 flow, and in‐hospital mortality were assessed. During the study period, 83 422 patients (29.5%) underwent TA (52.9%, 23.5%, and 5.2% for ST‐segment–elevation myocardial infarction, non–ST‐segment–elevation myocardial infarction, and unstable angina, respectively), and the TA implementation rate remained relatively stable throughout. Patients treated with TA had higher rate of successful PCI than non‐TA (98.7% versus 97.8%; P<0.001). TA was not associated with in‐hospital death among patients with ST‐segment–elevation myocardial infarction (adjusted odds ratio [aOR], 1.02 [95% CI, 0.94–1.12]). However, TA use was associated with higher rates of in‐hospital death in patients with non–ST‐segment–elevation myocardial infarction ( aOR, 1.51 [95% CI, 1.23–1.86]) or unstable angina ( aOR, 1.95 [95% CI, 1.37–2.79]).

Conclusions

In our retrospective analysis of the nationwide PCI registry, TA use was associated with a higher achievement of successful PCI without impairing in‐hospital mortality among patients with ST‐segment–elevation myocardial infarction. Nevertheless, its use should be cautioned in less‐established indications (eg, non–ST‐segment–elevation myocardial infarction and unstable angina).

Routine Use of the “Penumbra” Thrombectomy Device in Myocardial Infarction: A Real-World Experience—ROPUST Study

Objectives

Evaluation of the safety and efficacy of the Penumbra device as an adjunct to percutaneous coronary intervention (PCI) in patients with myocardial infarction (MI) and a large thrombus burden that requires thrombectomy.

Background

For patients with acute MI, PCI is the primary reperfusion method. Large thrombus burden has always been a limitation of successful reperfusion. However, the use of current aspiration devices has been associated with an increased incidence of stroke.

Methods

We performed a retrospective chart review at the University Hospitals Medical Center in Cleveland. Our study included data from patients who underwent PCI for ST segment elevation myocardial infarction (STEMI) and non-ST segment elevation myocardial infarction (NSTEMI) assisted by the Penumbra Cat RX device (a wide-lumen thrombus aspiration catheter) between May 2019 and February 2021. The primary outcome was the final thrombolysis in myocardial infarction (TIMI) flow. The secondary endpoints were a composite of adverse cardiac events at 6 months. About 50% of the patients did undergo transfemoral PCI as per preference of individual operators. The Penumbra thrombectomy device can be used both by radial and femoral approach and does not need any different guide catheter use.

Results

TIMI flow 3 was achieved in 111 patients (90.2%). The secondary endpoint occurred in 11 patients (8.9%, 3 MI, 8 heart failure hospitalizations). There were no stroke events or device-related complications. The door-to-balloon time was not affected by usage of the Penumbra device. Failure in the restoration of TIMI 3 flow was associated with the use of balloon angioplasty prior to the application of the Penumbra device, leading to distal embolization.

Conclusions

The Penumbra Cat RX provides safe and effective thrombus removal with better clinical outcomes, even in high-risk patients with acute coronary syndrome.

Effect of Coronary Thrombus Aspiration in Non ST Elevation Acute Coronary Syndrome Patients on Three-Year Survival- Does it add any Benefit?

We assessed the effect of thrombus aspiration (TA) during percutaneous coronary intervention (PCI) on in-hospital and 3-year mortality in consecutive non-ST segment elevation myocardial infarction (n = 189) and unstable angina pectoris (n = 148) patients (n = 337) between 2011 and 2016. In total, 153 patients (45.4%) underwent TA. The number of patients with postoperative thrombolysis in terms of myocardial infarction grade 3 blood flow (P < .001) and myocardial blush grade 3 (P < .001) were significantly higher in all TA groups. At 6-, 12- and 24-month post-PCI, the mean left ventricular ejection fraction was significantly higher in the all TA groups versus the stand alone PCI group (P < .001). Thrombus aspiration was associated with a significant improvement both in epicardial flow, myocardial perfusion and left ventricular ejection fraction. Thrombus aspiration during PCI in all acute coronary syndrome (except ST segment elevation) patients was associated with better survival compared with stand alone PCI group at 3-year follow-up (P = .019).

Acute coronary syndrome with large thrombus successfully managed with no-stenting revascularization based on intravascular imaging in a patient with hyperhomocysteinemia: a case report

Background

Hyperhomocysteinemia is caused by genetic and environmental factors, which can result in systemic arteriosclerosis and arteriovenous thrombosis including acute coronary syndrome. Thrombus burden in patients with acute coronary syndrome and hyperhomocysteinemia might involve the culprit lesion as compared with those without any coagulopathy. The primary percutaneous coronary intervention with stent implantation had been established as the treatment strategy for patients with acute coronary syndrome. However, in patients with acute coronary syndrome with high thrombus burden or uncontrolled coagulopathy, stent implantation might lead to slow-flow phenomenon or stent thrombosis. Therefore, the treatment strategy in these patients was not established.

Case presentation

A 49-year-old Japanese man with history of splenic infarction of unknown cause had continued anticoagulant therapy since its diagnosis, but stopped taking the medication several months ago. He presented with sudden-onset chest dorsalgia. Contrast computed tomography showed a small pulmonary embolism and his troponin I level was elevated on initial laboratory test. Coronary angiography revealed a contrast defect caused by a large thrombus from the proximal to mid portion of the left anterior descending artery. Near-infrared spectroscopy–intravascular ultrasonography showed a large amount of thrombus without lipid plaque. Therefore, revascularization was performed using a thrombus-aspiration catheter and intracoronary thrombolysis. In addition, , hyperhomocysteinemia and a deep vein thrombosis occurred. He was diagnosed with acute coronary syndrome complicated with pulmonary embolism and deep vein thrombosis simultaneously induced by hyperhomocysteinemia. After 1 week of antithrombotic therapy, near-infrared spectroscopy–intravascular ultrasonography and optical coherence tomography revealed a decreased thrombus and no significant residual organic stenosis in the left anterior descending artery. He continued conservative therapy with antithrombotic medications including aspirin and warfarin and had no cardiovascular events after discharge. Follow-up coronary angiography and optical coherence tomography at 9 months revealed complete disappearance of the thrombus and no severe stenosis.

Conclusions

Hyperhomocysteinemia should be considered as a cause of arterial vein thrombosis of unknown cause. The antithrombotic therapy and percutaneous revascularization without stenting based on intravascular imaging might be a safe and effective treatment option in patients with acute coronary syndrome complicated with hyperhomocysteinemia.

Long-term outcome after thrombus aspiration in non-ST-elevation myocardial infarction: results from the TATORT-NSTEMI trial : Thrombus aspiration in acute myocardial infarction

AIMS

To investigate the long-term prognostic value of aspiration thrombectomy in conjunction with primary percutaneous coronary intervention (PCI) compared to conventional PCI in patients with non-ST-elevation myocardial infarction (NSTEMI).

METHODS

In the randomized TATORT-NSTEMI (Thrombus aspiration in thrombus containing culprit lesions in non-ST-elevation myocardial infarction) trial, NSTEMI patients with thrombus containing culprit lesions were randomized to either PCI with aspiration thrombectomy or conventional PCI. The endpoint was a combination of all-cause death, reinfarction and new congestive heart failure.

RESULTS

From 440 patients initially randomized, outcome data were available in 432 (98.2%) patients at a median follow-up of 4.9 (interquartile range [IQR] 4.4-5.0) years. Thrombectomy was associated with a significant reduction of the combined endpoint compared to conventional PCI (19.9% vs. 30.7%, p = 0.01). This finding was primarily driven by a reduced rate of reinfarction with thrombectomy (3.4% vs. 10.3%, p = 0.01). Thrombectomy was still independently associated with the combined endpoint after multivariable adjustment (hazard ratio [HR] 0.47, 95% confidence interval [CI] 0.30-0.76, p = 0.002). Findings were consistent across all analyzed subgroups (p values for interaction all > 0.05).

CONCLUSIONS

In NSTEMI, thrombus aspiration is associated with favorable clinical outcome during long-term follow-up.

CLINICAL TRIAL REGISTRATION

NCT01612312.

Determinants of Slow Flow in Percutaneous Coronary Intervention to the Culprit Lesion of Non-ST Elevation Myocardial Infarction

Slow flow is a serious complication in percutaneous coronary intervention (PCI) and is associated with poor clinical outcomes. Our previous study revealed that the ratio of stent diameter to vessel diameter was the determinant of slow flow in intravascular ultrasound (IVUS)-guided PCI to the culprit lesion of ST elevation myocardial infarction (STEMI). The purpose of this study was to verify whether the ratio of stent diameter to vessel diameter is the determinant of slow flow in IVUS-guided PCI to the culprit lesion of non-STEMI (NSTEMI). We included 150 NSTEMI patients and divided into the slow flow group (n = 17) and the non-slow flow group (n = 133). The ratio of stent diameter to vessel diameter was significantly larger in the slow flow group (0.77 ± 0.11) than the non-slow flow group (0.71 ± 0.11) (P = 0.03). Multivariate logistic regression analysis revealed that the ratio of stent diameter to vessel diameter (per 0.1 increase: OR 2.06, 95% CI 1.23-3.46, P = 0.006) was the determinant of slow flow after controlling covariates. In conclusion, the ratio of stent diameter to vessel diameter was the determinant of slow flow in IVUS-guided PCI to the culprit lesion of NSTEMI. Unlike other parameters, the ratio of stent diameter to vessel diameter is the modifiable parameters. We may consider the modest stent expansion strategy rather than the aggressive stent expansion strategy in IVUS-guided PCI to the culprit lesion of NSTEMI.

German contribution to development and innovations in the management of acute myocardial infarction and cardiogenic shock

Treatment of acute coronary syndromes has evolved over time leading to a significantly reduced mortality. Multiple major trials have been performed in Germany leading to new treatment strategies in acute coronary syndromes including cardiogenic shock. This review article will summarize major trials and their impact on guideline recommendations in acute myocardial infarction highlighting reperfusion strategies, antiplatelet regimens, prognosis assessment and also mechanical circulatory support in stable infarction patients and in cardiogenic shock.

Rosuvastatin Improves Vaspin Serum Levels in Obese Patients with Acute Coronary Syndrome

Adipose tissue-derived serine protease inhibitor (vaspin), which has endocrine and local roles in atherosclerosis growth, is also synthesized by adipose tissue; it was found that vaspin was negatively correlated with blood pressure in obese patients, while vaspin levels were decreased in endothelial dysfunction. The aim of the present study was to determine rosuvastatin modulation effects on serum vaspin levels in acute coronary syndrome (ACS) with class I obesity. A total number of seventy patients with acute coronary syndrome previously and currently treated with rosuvastatin was compared to 40 patients with IHD not treated by rosuvastatin as a control. Vaspin serum levels were higher in rosuvastatin-treated patients with acute coronary syndrome compared to the patients with acute coronary syndrome not treated by rosuvastatin, p < 0.01. Additionally, in the rosuvastatin-treated group, patients with STEMI showed higher vaspin serum levels compared to NSTEMI p < 0.01. Conclusion: Rosuvastatin significantly increases vaspin serum levels in acute coronary syndrome.