Dysfunction of the coronary microvasculature has become increasingly recognized as an important mechanism of myocardial ischemia in patients without obstructive coronary artery disease. The causes ...and management of coronary microvascular dysfunction remain poorly understood and are still largely based on extrapolation of epicardial coronary artery disease data. Quantification of myocardial blood flow and flow reserve have improved diagnosis, though important questions remain. In this review, we explain current understanding of the spectrum of pathophysiology of coronary microvascular dysfunction, summarize current diagnostic techniques to assess for coronary microvascular dysfunction, and appraise the limited data on management options specifically for patients with coronary microvascular dysfunction.
The recurrence of angina after percutaneous coronary intervention affects 20-35% of patients with stable coronary artery disease; however, few data are available in the setting of ST-segment ...elevation myocardial infarction. We evaluated the relation between coronary microvascular obstruction and the recurrence of angina at follow-up.
We prospectively enrolled patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention. Microvascular obstruction was defined as thrombolysis in myocardial infarction flow less than 3 or 3 with myocardial blush grade less than 2. The primary endpoint was the recurrence of angina at follow-up. Moreover, angina status was evaluated by the Seattle angina questionnaire summary score (SAQSS). Therapy at follow-up and the occurrence of major adverse cardiovascular events were also collected.
We enrolled 200 patients. Microvascular obstruction occurred in 52 (26%) of them. Follow-up (mean time 25.17±9.28 months) was performed in all patients. Recurrent angina occurred in 31 (15.5%) patients, with a higher prevalence in patients with microvascular obstruction compared with patients without microvascular obstruction (13 (25.0%) vs. 18 (12.2%),
=0.008). Accordingly, SAQSS was lower and the need for two or more anti-anginal drugs was higher in patients with microvascular obstruction compared with patients without microvascular obstruction. At multiple linear regression analysis a history of previous acute coronary syndrome and the occurrence of microvascular obstruction were the only independent predictors of a worse SAQSS. Finally, the occurrence of major adverse cardiovascular events was higher in patients with microvascular obstruction compared with patients without microvascular obstruction.
The recurrence of angina in ST-segment elevation myocardial infarction patients treated with primary percutaneous coronary intervention is an important clinical issue. The occurrence of microvascular obstruction portends a worse angina status and is associated with the use of more anti-anginal drugs.
We assessed the relationship between exposure to air pollutants and mechanisms of coronary instability evaluated by optical coherence tomography (OCT) in patients with acute coronary syndrome (ACS).
...Air pollution is an emerging key player in determining the residual risk of coronary events. However, pathophysiological mechanisms linking air pollution and coronary events have been not adequately investigated.
Patients with ACS undergoing OCT imaging were retrospectively selected. Mechanism of culprit lesion instability was classified as plaque rupture (PR) or intact fibrous cap (IFC) by OCT, and the presence of macrophage infiltrates (MØI) and thin-cap fibroatheroma (TCFA) at the culprit site was also assessed. Based on each case's home address, exposure to several pollutants was evaluated, including particulate matter 2.5 (PM2.5), PM10, and carbon monoxide (CO). Only patients with >2 years of available data on air pollution exposure prior to ACS were enrolled.
We included 126 patients (median age: 67.0 years of age; IQR: 55.5-76.0; 97 male patients 77.0%). Sixty-six patients (52.4%) had PR as the mechanism of plaque instability. Patients with PR were exposed to significantly higher PM2.5 levels than to IFC, and PM2.5 was independently associated with PR (odds ratio: 1.194; 95% CI: 1.036 to 1.377; P = 0.015). Moreover, exposure to higher levels of PM2.5 was independently associated with the presence of TCFA and of MØI at the culprit site. Interestingly, PM2.5, PM10, and Co levels were positively and significantly correlated with serum levels of C-reactive protein.
We provide novel insights into the missing link between air pollution and increased risk of coronary events. In particular, exposure to higher concentrations of air pollutants is associated with the presence of vulnerable plaque features and with plaque rupture as a mechanism of coronary instability. An enhanced systemic and plaque inflammatory activation may explain these findings.
BACKGROUND:Bioresorbable coronary stents have been introduced into clinical practice to improve the outcomes of patients treated with percutaneous coronary intervention. The everolimus-eluting ...bioresorbable vascular scaffold (BVS) is the most studied of these stent platforms; however, recent trials comparing BVS with everolimus-eluting metallic stents (EES) raised concerns about BVS safety. We aimed to assess the efficacy and safety of BVS versus EES in patients undergoing percutaneous coronary intervention.
METHODS:We searched Medline, Embase, the Cochrane Central Register of Controlled Trials, scientific sessions abstracts, and relevant Web sites for randomized trials with a follow-up of ≥2 years investigating percutaneous coronary interventions with BVS versus EES. The primary outcomes of our analysis were definite/probable stent thrombosis (ST) and target lesion failure (TLF; device-oriented composite end point of cardiac death, target vessel myocardial infarction, or ischemia-driven target lesion revascularization TLR). Secondary outcomes were target vessel myocardial infarction, TLR, and cardiac death. We calculated the risk estimates for main outcomes according to a fixed-effect model.
RESULTS:We included 7 trials comprising data for 5583 patients randomized to receive either a BVS (n=3261) or an EES (n=2322). Median follow-up was 24 months (range, 24–36 months). Patients treated with BVS had a higher risk of definite/probable ST compared with patients treated with EES (odds ratio, 3.33; 95% confidence interval, 1.97–5.62; P<0.00001). In particular, patients with BVS had a higher risk of subacute, late, and very late ST, whereas the risk of acute ST was similar. Patients treated with BVS compared with EES had a higher risk at 2 years of TLF (odds ratio, 1.47; 95% confidence interval, 1.14–1.90; P=0.003), driven mainly by an increased risk of target vessel myocardial infarction (odds ratio, 1.73; 95% confidence interval, 1.31–2.28; P=0.0001; I=0%) and of TLR (odds ratio, 1.27; 95% confidence interval, 1.00–1.62; P=0.05). Of importance, the risk of TLF and TLR for patients with BVS was higher between 1 and 2 years, whereas there was no difference in the first year. Risk of cardiac death was similar between the 2 groups.
CONCLUSIONS:Our meta-analysis of randomized trials with a follow-up of ≥2 years demonstrated a higher risk of ST and of TLF in patients treated with BVS compared with EES. Of note, BVS had a higher risk of subacute, late, and very late ST, whereas the risk of TLF and TLR was higher between 1 and 2 years.
The rate-limiting step of the hydriding of catalysed Mg has been ascertained through a key experiment in which the density of nuclei of the product phase was artificially modified. The various ...microstructures observed allow accurate identification of the reaction rate-limiting step for different hypotheses. The experimental work was based on kinetics analysis coupled with scanning electron microscopy metallographic observation. It is found that the reaction barrier is located at the external surface of the powder particles, suggesting decoration with catalyst as a possible solution.
Abstract
Context
Coronary collateral (CC) vessel development appears to be protective with regard to adverse cardiovascular events and survival in patients with coronary chronic total occlusion ...(CTO). The influence of type 2 diabetes mellitus (T2DM) on CC growth has been controversial. In particular, the role of diabetic microvascular complications (DMC) in determining coronary collateralization has not been elucidated.
Objective
To investigate whether patients with DMC presented differences in CC vessel presence and grading as compared with patients without DMC.
Methods
We conducted a single-center observational study, including consecutive T2DM patients, without previous cardiovascular history, undergoing a clinically indicated coronary angiography for chronic coronary syndrome (CCS) and angiographic evidence of at least one CTO. Patients were subdivided into 2 study groups according to the presence/absence of at least one DMC (neuropathy, nephropathy, or retinopathy). The presence and grading of angiographically visible CC development from the patent vessels to the occluded artery were assessed using the Rentrop classification.
Results
We enrolled 157 patients (mean age 68.6 ± 9.8 years; 120 76.4% men). Patients with DMC (75 47.8%) had a higher prevalence of CC (69 92.0% vs 62 75.6%, P = .006) and high-grade CC (55 73.3% vs 39 47.6%, P = .001) compared with those without, and we found a positive association between the number of DMC in each patient and the prevalence of high-grade CC.
Conclusion
Among T2DM patients with coronary CTO, the presence of DMC was associated with a high CC development.
Air pollution is emerging as an important risk factor for acute coronary syndrome (ACS). In this study, we investigated the association between short-term air pollution exposure and mechanisms of ...coronary plaque instability evaluated by optical coherence tomography (OCT) imaging in ACS patients.
Patients with ACS undergoing OCT imaging were retrospectively selected. Mechanism of culprit lesion instability was classified as plaque rupture (PR) or intact fibrous cap (IFC) by OCT. Based on each case's home address, the mean daily exposures to several pollutants, including particulate matter 2.5 (PM2.5), on the same day of ACS and in the immediate days (up to 6 days) prior to the index ACS, were collected.
139 ACS patients were included 69 (49.6%) had PR and 70 (50.4%) IFC. Patients with PR, compared to those with IFC, had higher PM2.5 exposure levels on the same day of ACS, without differences in the immediate 6 days before index ACS. At multivariate analysis, PM2.5 exposure on the same day of ACS was the only independent predictor of PR OR = 1.912 per SD (8.6 μg/m3), CI95 % (1.087–3.364), p = 0.025. Patients with PR presented a steady increase in PM2.5 daily exposure levels in the days preceding the occurrence of ACS, with a peak the day of ACS (p for trend = 0.042)
This study demonstrates for the first time that a higher short-term PM2.5 exposure, on the same day of ACS, is associated with an increased risk of PR as a pathobiological mechanism of coronary plaque instability.
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•Air pollution is emerging as an important risk factor for acute coronary syndrome (ACS).•Acute PM2.5 exposure, especially on the same day of ACS, is associated with an increased risk of plaque rupture as mechanism of coronary plaque instability.•Mitigation strategies are crucial to reduce the burden of ischemic heart disease, especially in patients with a higher risk of cardiovascular events.
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