Microthrombi as a Major Cause of Cardiac Injury in COVID-19: A Pathologic Study.

BACKGROUND: Cardiac injury is common in patients who are hospitalized with coronavirus disease 2019 (COVID-19) and portends poorer prognosis. However, the mechanism and the type of myocardial damage associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain uncertain. METHODS: We conducted a systematic pathological analysis of 40 hearts from hospitalized patients dying of COVID-19 in Bergamo, Italy, to determine the pathological mechanisms of cardiac injury. We divided the hearts according to presence or absence of acute myocyte necrosis and then determined the underlying mechanisms of cardiac injury. RESULTS: Of the 40 hearts examined, 14 (35%) had evidence of myocyte necrosis, predominantly of the left ventricle. Compared with subjects without necrosis, subjects with necrosis tended to be female, have chronic kidney disease, and have shorter symptom onset to admission. The incidence of severe coronary artery disease (ie, >75% cross-sectional narrowing) was not significantly different between those with and without necrosis. Three of 14 (21.4%) subjects with myocyte necrosis showed evidence of acute myocardial infarction, defined as ≥1 cm2 area of necrosis, whereas 11 of 14 (78.6%) showed evidence of focal (>20 necrotic myocytes with an area of ≥0.05 mm2 but <1 cm2) myocyte necrosis. Cardiac thrombi were present in 11 of 14 (78.6%) cases with necrosis, with 2 of 14 (14.2%) having epicardial coronary artery thrombi, whereas 9 of 14 (64.3%) had microthrombi in myocardial capillaries, arterioles, and small muscular arteries. We compared cardiac microthrombi from COVID-19-positive autopsy cases to intramyocardial thromboemboli from COVID-19 cases as well as to aspirated thrombi obtained during primary percutaneous coronary intervention from uninfected and COVID-19-infected patients presenting with ST-segment-elevation myocardial infarction. Microthrombi had significantly greater fibrin and terminal complement C5b-9 immunostaining compared with intramyocardial thromboemboli from COVID-19-negative subjects and with aspirated thrombi. There were no significant differences between the constituents of thrombi aspirated from COVID-19-positive and -negative patients with ST-segment-elevation myocardial infarction. CONCLUSIONS: The most common pathological cause of myocyte necrosis was microthrombi. Microthrombi were different in composition from intramyocardial thromboemboli from COVID-19-negative subjects and from coronary thrombi retrieved from COVID-19-positive and -negative patients with ST-segment-elevation myocardial infarction. Tailored antithrombotic strategies may be useful to counteract the cardiac effects of COVID-19 infection.

Effect of Respiratory Impairment on the Outcomes of Primary Percutaneous Coronary Intervention in Patients With ST-Segment Elevation Myocardial Infarction and Coronavirus Disease-2019 (COVID-19).

BACKGROUND: Coronavirus Disease-2019 (COVID-19) may impair outcomes of patients with ST-segment elevation myocardial infarction (STEMI). The extent of this phenomenon and its mechanisms are unclear.Methods and Results:This study prospectively included 50 consecutive STEMI patients admitted to our center for primary percutaneous coronary intervention (PCI) at the peak of the Italian COVID-19 outbreak. At admission, a COVID-19 test was positive in 24 patients (48%), negative in 26 (52%). The primary endpoint was in-hospital all-cause mortality. Upon admission, COVID-19 subjects had lower PO2/FiO2 (169 [100-425] vs. 390 [302-477], P<0.01), more need for oxygen support (62.5% vs. 26.9%, P=0.02) and a higher rate of myocardial dysfunction (ejection fraction <30% in 45.8% vs. 19.2%, P=0.04). All patients underwent emergency angiography. In 12.5% of COVID-19 patients, no culprit lesions were detected, thus PCI was performed in 87.5% and 100% of COVID-19 positive and negative patients, respectively (P=0.10). Despite a higher rate of obstinate thrombosis in the COVID-19 group (47.6% vs. 11.5%, P<0.01), the PCI result was similar (TIMI 2-3 in 90.5% vs. 100%, P=0.19). In-hospital mortality was 41.7% and 3.8% in COVID-19 positive and negative patients, respectively (P<0.01). Respiratory failure was the leading cause of death (80%) in the COVID-19 group, frequently associated with severe myocardial dysfunction. CONCLUSIONS: In-hospital mortality of COVID-19 patients with STEMI remains high despite successful PCI, mainly due to coexisting severe respiratory failure. This may be a critical factor in patient management and treatment selection.

Extent and progression of atherosclerosis in carotid and subclavian arteries: the Carotid Artery Subclavian Artery study.

AIMS: To define the prevalence, progression, and the relationship between carotid and subclavian artery atherosclerosis and to identify factors associated with disease progression in a population of asymptomatic patients. METHODS: Among all consecutive patients without a history of cardiovascular disease admitted to our hospital for duplex ultrasound examinations of the supra-aortic arteries, from January to December 2012, we retrospectively identified 530 patients with two evaluations at least 3 years apart. Each artery was graded according to stenosis degree, as absent or less than 20%, 20-49%, 50-69%, 70-99% and total occlusion. Disease progression was defined for any class increase at any time interval. Patients were grouped according to the presence of a more than 20% stenosis of the supra-aortic district at baseline, as controls, without atherosclerosis: n = 111, 21%; isolated carotid artery disease: n = 390, 74%; concomitant subclavian artery-carotid artery disease: n = 29, 5%. There were no cases with isolated subclavian artery atherosclerosis. RESULTS: The mean time-lapse between the two evaluations was 3.1 ±â€Š0.3 years; we documented disease progression in 32 patients (6%), all limited to the carotid artery (P = 0.009 vs. controls, with no differences between isolated carotid artery disease and concomitant carotid and subclavian artery disease). Hypertension was significantly (P < 0.001) associated with disease progression, regardless of the single or double district involvement. CONCLUSION: The subclavian artery is far less prone to atherosclerosis than the carotid artery, and features lesser disease progression. Understanding factors for the different susceptibility to atherosclerosis in these two close arterial districts provides insight into local factors prompting vascular disease.

Pathological Evidence for SARS-CoV-2 as a Cause of Myocarditis: JACC Review Topic of the Week.

To investigate whether severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)-induced myocarditis constitutes an important mechanism of cardiac injury, a review was conducted of the published data and the authors' experience was added from autopsy examination of 16 patients dying of SARS-CoV-2 infection. Myocarditis is an uncommon pathologic diagnosis occurring in 4.5% of highly selected cases undergoing autopsy or endomyocardial biopsy. Although polymerase chain reaction-detectable virus could be found in the lungs of most coronavirus disease-2019 (COVID-19)-infected subjects in our own autopsy registry, in only 2 cases was the virus detected in the heart. It should be appreciated that myocardial inflammation alone by macrophages and T cells can be seen in noninfectious deaths and COVID-19 cases, but the extent of each is different, and in neither case do such findings represent clinically relevant myocarditis. Given its extremely low frequency and unclear therapeutic implications, the authors do not advocate use of endomyocardial biopsy to diagnose myocarditis in the setting of COVID-19.

[Role of optical coherence tomography to optimize complex coronary interventions]. / Ruolo della tomografia a coerenza ottica nelle procedure di angioplastica coronarica e stenting.

Optical coherence tomography (OCT) is an innovative catheter-based imaging technology that uses light and fiberoptic to obtain unique details of the coronary arteries and stents on a microscope scale. OCT is an efficient method to rapidly map the extension and type of coronary artery disease with the potential to guide complex percutaneous coronary interventions (PCI). It can reliably detect and quantify atherosclerotic plaque characteristics, differentiate early from late stage of atherosclerotic disease and distinguish atherosclerotic (plaque rupture, erosion, calcified nodule) versus non atherosclerotic causes (spontaneous coronary dissection, intramural hematoma) of acute coronary syndromes. Further, it is very sensitive and accurate in detecting calcium and measuring the most relevant parameters (thickness, proximity to the lumen, circumferential extension) that may impact stent expansion. Based on automatic lumen measures and angiographic co-registration, OCT is used to plan and map the procedural strategy of stent implantation in complex lesion cohorts, with identification of the imaging features that require corrective actions to optimize stent results. OCT is a cardinal tool in patients presenting with stent failure (restenosis and thrombosis) to differentiate mechanical from biological causes with the potential of tailored treatment of the root mechanisms.

The epicardial adipose tissue and the coronary arteries: dangerous liaisons.

The adipose tissue (AT) is an endocrine organ that produces adipocytokines (adipokines), able to influence metabolic homeostasis. In the conventional classification, there are two large AT depots, characterized by different paracrine activities: the subcutaneous AT, which would mostly produce cytokines with protective properties against cardiovascular disease; and the visceral AT, responsible for the secretion of cytokines with proinflammatory, prothrombotic, and proatherogenic effects. A third component, the epicardial AT (EAT) is now receiving increasing attention due to its unique anatomical and functional proximity to the myocardium and the coronary arteries. In rodents, the EAT protects the heart from exposure to high levels of free fatty acids, and provides energy to the myocardium under high metabolic demands. The observation that atherosclerotic plaques are more prevalent in regions of coronary arteries surrounded by the EAT, while they tend to be less present in segments penetrating the myocardium (the septal branches and segments under myocardial bridges), has led to the hypothesis of a possible role of the EAT in promoting the development of atherosclerosis through endocrine and paracrine effects, in addition to the role of biomechanical forces affecting transendothelial lipid permeability into the intima. In this article, we review the clinical and molecular evidence linking the EAT and coronary artery disease through a systematic review of the literature. We, here, discuss current diagnostic techniques in evaluating the interaction between EAT and the onset of coronary artery disease and ischaemic heart disease. Finally, we review current knowledge on the underlying mechanisms by which the EAT may affect coronary atherosclerosis, and potential clinical implications of this interaction, making the EAT an attractive target for new therapeutics in cardiovascular disease.

The value of imaging in subclinical coronary artery disease.

Although the treatment of acute coronary syndromes (ACS) has advanced considerably, the ability to detect, predict, and prevent complications of atherosclerotic plaques, considered the main cause of ACS, remains elusive. Several imaging tools have therefore been developed to characterize morphological determinants of plaque vulnerability, defined as the propensity or probability of plaques to complicate with coronary thrombosis, able to predict patients at risk. By utilizing both intravascular and noninvasive imaging tools, indeed prospective longitudinal studies have recently provided considerable knowledge, increasing our understanding of determinants of plaque formation, progression, and instabilization. In the present review we aim at 1) critically analyzing the incremental utility of imaging tools over currently available "traditional" methods of risk stratification; 2) documenting the capacity of such modalities to monitor atherosclerosis progression and regression according to lifestyle modifications and targeted therapy; and 3) evaluating the potential clinical relevance of advanced imaging, testing whether detection of such lesions may guide therapeutic decisions and changes in treatment strategy. The current understanding of modes of progression of atherosclerotic vascular disease and the appropriate use of available diagnostic tools may already now gauge the selection of patients to be enrolled in primary and secondary prevention studies. Appropriate trials should now, however, evaluate the cost-effectiveness of an aggressive search of vulnerable plaques, favoring implementation of such diagnostic tools in daily practice.

Localizing factors in atherosclerosis.

Atherosclerotic vascular disease is the leading cause of death worldwide. Although the entire vascular bed is constantly exposed to the same risk factors, atheromatous lesions present a distinct intra-individual pattern of localization and progression, being consistently more frequent in specific segments of the arterial vascular bed. This peculiar distribution may be related to selective sensitivity of such locations to the influence of risk factors or to histopathological and flow differences, and has relevant clinical implications, as the prognosis of the disease varies according to localization. We here review the theories that have been formulated to explain such preferential locations, as its understanding can be useful to pursue diagnostic screening strategies and focused preventive measures.