The Index of Microcirculatory Resistance After Primary PCI: A Pooled Analysis of Individual Patient Data.

BACKGROUND: Despite treatment with primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI), the risk of heart failure and late death remains high. Microvascular dysfunction, as assessed by the index of microcirculatory resistance (IMR), after primary PCI for STEMI has been associated with worse outcomes. It is unclear whether IMR after primary PCI predicts cardiac death. OBJECTIVES: The aims of this analysis were: 1) to determine if IMR is an independent predictor of cardiac death; 2) to assess the optimal cutoff value of IMR after STEMI; and 3) to compare IMR with several cardiac magnetic resonance parameters, including infarct size. METHODS: In a collaborative, pooled analysis of individual patient data from 6 cohorts that measured IMR directly after primary PCI, cardiac mortality up to 5 years was estimated using Kaplan-Meier analyses. The primary endpoint was cardiac death using the predefined IMR cutoff value of 40. RESULTS: In total, 1,265 patients were included in this study with a median follow-up of 2.8 years (IQR: 1.2-5.0 years). Cardiac death at 5 years occurred in 2.2% and 4.9% of patients (HR: 2.81; 95% CI: 1.34-5.88; P = 0.006) in the IMR ≤40 and IMR >40 groups, respectively. The composite of cardiac death or hospitalization for heart failure occurred in 4.9% and 8.9% (HR: 1.98; 95% CI: 1.20-3.29; P = 0.008) in the IMR ≤40 and IMR >40 groups, respectively. IMR was an independent predictor of cardiac death, whereas coronary flow reserve was not. The optimal cutoff value of IMR for the prediction of cardiac death in this cohort was 70 (HR: 4.73; 95% CI: 2.27-9.83; P < 0.001). Infarct size was 17.6% ± 13.3% and 23.9% ± 14.6% of the left ventricular mass in the IMR ≤40 and IMR >40 groups, respectively (P < 0.001). Microvascular obstruction and intramyocardial hemorrhage occurred more frequently in the IMR >40 group than in the IMR ≤40 group. CONCLUSIONS: In this large, pooled analysis of individual patient data, IMR measured directly after primary PCI in STEMI was an independent predictor of cardiac death. IMR may be used as a tool to identify patients at the time of primary PCI who are at highest risk for late cardiac mortality and who might benefit most from additional cardioprotective therapies and monitoring.

Handgrip exercise in patients scheduled for cardiac surgery to attenuate troponin release: a feasibility study.

Cardiac surgery, including surgical aortic valve repair (SAVR) and coronary artery bypass grafting (CABG), are associated with ischemia-reperfusion (I/R) injury. Single bouts of exercise, including handgrip exercise, may protect against I/R injury. This study explored 1) the feasibility of daily handgrip exercise in the week before SAVR and/or CABG and 2) its impact on cardiac I/R injury, measured as postoperative cardiac troponin-T (cTnT) release. Sixty-five patients undergoing elective SAVR and/or CABG were randomized to handgrip exercise + usual care (intervention, n = 33) or usual care alone (control, n = 32). Handgrip exercise consisted of daily 4 × 5-min handgrip exercise (30% maximal voluntary contraction) for 2-7 days before cardiac surgery. Feasibility was assessed using validated questionnaires. Postoperative cTnT release was assessed at 0, 6, 12, 18, and 24 h [primary outcome area under the curve (cTnTAUC)]. Most patients (93%) adhered to handgrip exercise and 77% was satisfied with this intervention. Handgrip exercise was associated with lower cTnTAUC (402,943 ± 225,206 vs. 473,300 ± 232,682 ng · min/L), which is suggestive of a medium effect size (Cohen's d 0.31), and lower cTnTpeak (313 [190-623] vs. 379 [254-699] ng/L) compared with controls. We found that preoperative handgrip exercise is safe and feasible for patients scheduled for SAVR and/or CABG and is associated with a medium effect size to reduce postoperative cardiac I/R injury. This warrants future studies to assess the potential clinical impact of exercise protocols before cardiac surgery.NEW & NOTEWORTHY Daily handgrip exercise in the week before elective cardiac surgery is safe and feasible. Handgrip exercise is associated with a medium effect size for less troponin-T release. Future larger-sized studies are warranted to explore the impact of (handgrip) exercise prior to cardiac surgery on clinical outcomes and direct patient benefits.

Imatinib attenuates reperfusion injury in a rat model of acute myocardial infarction.

Following an acute myocardial infarction, reperfusion of an occluded coronary artery is often accompanied by microvascular injury, leading to worse long-term prognosis. Experimental studies have revealed the potential of tyrosine-kinase inhibitor imatinib to reduce vascular leakage in various organs. Here, we examined the potential of imatinib to attenuate microvascular injury in a rat model of myocardial reperfusion injury. Isolated male Wistar rat hearts (n = 20) in a Langendorff system and male Wistar rats (n = 37) in an in vivo model were randomly assigned to imatinib or placebo and subjected to ischaemia and reperfusion. Evans-blue/Thioflavin-S/TTC staining and Cardiac Magnetic Resonance Imaging were performed to assess the extent of reperfusion injury. Subsequently, in vivo hearts were perfused ex vivo with a vascular leakage tracer and fluorescence and electron microscopy were performed. In isolated rat hearts, imatinib reduced global infarct size, improved end-diastolic pressure, and improved rate pressure product recovery compared to placebo. In vivo, imatinib reduced no-reflow and infarct size with no difference between imatinib and placebo for global cardiac function. In addition, imatinib showed lower vascular resistance, higher coronary flow, and less microvascular leakage in the affected myocardium. At the ultrastructural level, imatinib showed higher preserved microvascular integrity compared to placebo. We provide evidence that low-dose imatinib can reduce microvascular injury and accompanying myocardial infarct size in a rat model of acute myocardial infarction. These data warrant future work to examine the potential of imatinib to reduce reperfusion injury in patients with acute myocardial infarction.

Effect of ticagrelor and prasugrel on remote myocardial inflammation in patients with acute myocardial infarction with ST-elevation: a CMR T1 and T2 mapping study.

PURPOSE: Acute myocardial ischaemia triggers a non-specific inflammatory response of remote myocardium through the increase of plasma concentrations of acute-phase proteins, which causes myocardial oedema. As ticagrelor has been shown to significantly decrease circulating levels of several pro-inflammatory cytokines in patients after acute myocardial infarction with ST-elevation (STEMI), we sought to investigate a potential suppressive effect of ticagrelor over prasugrel on cardiac magnetic resonance (CMR) T1 and T2 values in remote myocardium. METHODS: Ninety STEMI patients were prospectively included and randomised to receive either ticagrelor or prasugrel maintenance treatment after successful primary percutaneous coronary intervention. Patients underwent CMR after 2-7 days. The protocol included long and short axis cine imaging, T1 mapping, T2 mapping and late gadolinium enhancement imaging. RESULTS: After excluding 30 patients due to either missing images or insufficient quality of the T1 or T2 maps, 60 patients were included in our analysis. Of those, 29 patients were randomised to the ticagrelor group and 31 patients to the prasugrel group. In the remote myocardium, T1 values did not differ between groups (931.3 [919.4-950.4] ms for ticagrelor vs. 932.6 [915.5-949.2] ms for prasugrel (p = 0.94)), nor did the T2 values (53.8 ± 4.6 ms for ticagrelor vs. 53.7 ± 4.7 ms for prasugrel (p = 0.86)). Also, in the infarcted myocardium, T1 and T2 values did not differ between groups. CONCLUSION: In revascularised STEMI patients, ticagrelor maintenance therapy did not show superiority over prasugrel in preventing early remote myocardial inflammation as assessed by CMR T1 and T2 mapping.

Long-term Effect of Face-to-Face vs Virtual Reality Cardiopulmonary Resuscitation (CPR) Training on Willingness to Perform CPR, Retention of Knowledge, and Dissemination of CPR Awareness: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Increased bystander cardiopulmonary resuscitation (CPR) is essential to improve survival after cardiac arrest. Although most studies focus on technical CPR skills, the randomized Lowlands Saves Lives trial prespecified a follow-up survey on other important aspects that affect the widespread performance of CPR. Objective: To investigate bystander willingness to perform CPR on a stranger, theoretical knowledge retention, and dissemination of CPR awareness 6 months after undergoing short face-to-face and virtual reality (VR) CPR trainings. Design, Setting, and Participants: A prespecified 6-month posttraining survey was conducted among 320 participants in the Lowlands Saves Lives trial, a randomized comparison between 20-minute face-to-face, instructor-led CPR training and VR training. Participants were recruited at the Lowlands music festival, with a designated area to conduct scientific projects (August 16-18, 2019; the Netherlands). Statistical analysis was performed from March 1, 2020, to July 31, 2021. Interventions: Two standardized 20-minute protocols on CPR and automated external defibrillator use: instructor-led face-to-face training using CPR manikins or VR training using the Resuscitation Council (UK)-endorsed Lifesaver VR smartphone application and a pillow to practice compressions. Main Outcomes and Measures: Primary outcomes were willingness to perform CPR on a stranger, theoretical knowledge retention, and dissemination of CPR awareness as reported by the entire cohort. As secondary analyses, the results of the 2 training modalities were compared. Results: Of 381 participants, 320 consented to this follow-up survey; 188 participants (115 women [61%]; median age, 26 years [IQR, 22-32 years]) completed the entire survey and were accordingly included in the secondary analysis. The overall proportion of participants willing to perform CPR on a stranger was 77% (144 of 188): 81% (79 of 97) among face-to-face participants and 71% (65 of 91) among VR participants (P = .02); 103 participants (55%) reported feeling scared to perform CPR (P = .91). Regarding theoretical knowledge retention, a median of 7 (IQR, 6-8) of 9 questions were answered correctly in both groups (P = .81). Regarding dissemination of CPR awareness, 65% of participants (123 of 188) told at least 1 to 10 family members or friends about the importance of CPR, and 15% (29 of 188) had participated in certified, instructor-led training at the time of the survey, without differences between groups. Conclusions and Relevance: In this 6-month posttraining survey, young adult participants of short CPR training modules reported high willingness (77%) to perform CPR on a stranger, with slightly higher rates for face-to-face than for VR participants. Theoretical knowledge retention was good, and the high dissemination of awareness suggests that these novel CPR training modules staged at a public event are promising sensitizers for involvement in CPR, although further challenges include mitigating the fear of performing CPR. Trial Registration: ClinicalTrials.gov Identifier: NCT04013633.

Cardiac MRI to Visualize Myocardial Damage after ST-Segment Elevation Myocardial Infarction: A Review of Its Histologic Validation.

Cardiac MRI is a noninvasive diagnostic tool using nonionizing radiation that is widely used in patients with ST-segment elevation myocardial infarction (STEMI). Cardiac MRI depicts different prognosticating components of myocardial damage such as edema, intramyocardial hemorrhage (IMH), microvascular obstruction (MVO), and fibrosis. But how do cardiac MRI findings correlate to histologic findings? Shortly after STEMI, T2-weighted imaging and T2* mapping cardiac MRI depict, respectively, edema and IMH. The acute infarct size can be determined with late gadolinium enhancement (LGE) cardiac MRI. T2-weighted MRI should not be used for area-at-risk delineation because T2 values change dynamically over the first few days after STEMI and the severity of T2 abnormalities can be modulated with treatment. Furthermore, LGE cardiac MRI is the most accurate method to visualize MVO, which is characterized by hemorrhage, microvascular injury, and necrosis in histologic samples. In the chronic setting post-STEMI, LGE cardiac MRI is best used to detect replacement fibrosis (ie, final infarct size after injury healing). Finally, native T1 mapping has recently emerged as a contrast material-free method to measure infarct size that, however, remains inferior to LGE cardiac MRI. Especially LGE cardiac MRI-defined infarct size and the presence and extent of MVO may be used to monitor the effect of new therapeutic interventions in the treatment of reperfusion injury and infarct size reduction. © RSNA, 2021 Online supplemental material is available for this article.

Rationale and design of the PRAETORIAN-COVID trial: A double-blind, placebo-controlled randomized clinical trial with valsartan for PRevention of Acute rEspiraTORy dIstress syndrome in hospitAlized patieNts with SARS-COV-2 Infection Disease.

There is much debate on the use of angiotensin receptor blockers (ARBs) in severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2)-infected patients. Although it has been suggested that ARBs might lead to a higher susceptibility and severity of SARS-CoV-2 infection, experimental data suggest that ARBs may reduce acute lung injury via blocking angiotensin-II-mediated pulmonary permeability, inflammation, and fibrosis. However, despite these hypotheses, specific studies on ARBs in SARS-CoV-2 patients are lacking. METHODS: The PRAETORIAN-COVID trial is a multicenter, double-blind, placebo-controlled 1:1 randomized clinical trial in adult hospitalized SARS-CoV-2-infected patients (n = 651). The primary aim is to investigate the effect of the ARB valsartan compared to placebo on the composite end point of admission to an intensive care unit, mechanical ventilation, or death within 14 days of randomization. The active-treatment arm will receive valsartan in a dosage titrated to blood pressure up to a maximum of 160 mg bid, and the placebo arm will receive matching placebo. Treatment duration will be 14 days, or until the occurrence of the primary end point or until hospital discharge, if either of these occurs within 14 days. The trial is registered at clinicaltrials.gov (NCT04335786, 2020). SUMMARY: The PRAETORIAN-COVID trial is a double-blind, placebo-controlled 1:1 randomized trial to assess the effect of valsartan compared to placebo on the occurrence of ICU admission, mechanical ventilation, and death in hospitalized SARS-CoV-2-infected patients. The results of this study might impact the treatment of SARS-CoV-2 patients globally.

Effect of Face-to-Face vs Virtual Reality Training on Cardiopulmonary Resuscitation Quality: A Randomized Clinical Trial.

Importance: Bystander cardiopulmonary resuscitation (CPR) is crucial for survival after cardiac arrest but not performed in most cases. New, low-cost, and easily accessible training methods, such as virtual reality (VR), may reach broader target populations, but data on achieved CPR skills are lacking. Objective: To compare CPR quality between VR and face-to-face CPR training. Design, Setting, and Participants: Randomized noninferiority trial with a prospective randomized open blinded end point design. Participants were adult attendees from the science section of the Lowlands Music Festival (August 16 to 18, 2019) in the Netherlands. Analysis began September 2019. Interventions: Two standardized 20-minute protocols on CPR and automated external defibrillator use: instructor-led face-to-face training or VR training using a smartphone app endorsed by the Resuscitation Council (United Kingdom). Main Outcomes and Measures: During a standardized CPR scenario following the training, we assessed the primary outcome CPR quality, measured as chest compression depth and rate using CPR manikins. Overall CPR performance was assessed by examiners, blinded for study groups, using a European Resuscitation Council-endorsed checklist (maximum score, 13). Additional secondary outcomes were chest compression fraction, proportions of participants with mean depth (50 mm-60 mm) or rate (100 min-1-120 min-1) within guideline ranges, and proportions compressions with full release. Results: A total of 381 participants were randomized: 216 women (57%); median (interquartile range [IQR]) age, 26 (22-31) years. The VR app (n = 190 [49.9%]) was inferior to face-to-face training (n = 191 [50.1%]) for chest compression depth (mean [SD], VR: 49 [10] mm vs face to face: 57 [5] mm; mean [95% CI] difference, -8 [-9 to -6] mm), and noninferior for chest compression rate (mean [SD]: VR: 114 [12] min-1 vs face to face: 109 [12] min-1; mean [95% CI] difference, 6 [3 to 8] min-1). The VR group had lower overall CPR performance scores (median [IQR], 10 [8-12] vs 12 [12-13]; P < .001). Chest compression fraction (median [IQR], 61% [52%-66%] vs 67% [62%-71%]; P < .001) and proportions of participants fulfilling depth (51% [n = 89] vs 75% [n = 133], P < .001) and rate (50% [n = 87] vs 63% [n = 111], P = .01) requirements were also lower in the VR group. The proportion of compressions with full release was higher in the VR group (median [IQR], 98% [59%-100%] vs 88% [55%-99%]; P = .002). Conclusions and Relevance: In this randomized noninferiority trial, VR training resulted in comparable chest compression rate but inferior compression depth compared with face-to-face training. Given the potential of VR training to reach a larger target population, further development is needed to achieve the compression depth and overall CPR skills acquired by face-to-face training. Trial Registration: ClinicalTrials.gov identifier: NCT04013633.

Pathophysiology and diagnosis of coronary microvascular dysfunction in ST-elevation myocardial infarction.

Early mechanical reperfusion of the epicardial coronary artery by primary percutaneous coronary intervention (PCI) is the guideline-recommended treatment for ST-elevation myocardial infarction (STEMI). Successful restoration of epicardial coronary blood flow can be achieved in over 95% of PCI procedures. However, despite angiographically complete epicardial coronary artery patency, in about half of the patients perfusion to the distal coronary microvasculature is not fully restored, which is associated with increased morbidity and mortality. The exact pathophysiological mechanism of post-ischaemic coronary microvascular dysfunction (CMD) is still debated. Therefore, the current review discusses invasive and non-invasive techniques for the diagnosis and quantification of CMD in STEMI in the clinical setting as well as results from experimental in vitro and in vivo models focusing on ischaemic-, reperfusion-, and inflammatory damage to the coronary microvascular endothelial cells. Finally, we discuss future opportunities to prevent or treat CMD in STEMI patients.

Correction: Dissecting the Effects of Ischemia and Reperfusion on the Coronary Microcirculation in a Rat Model of Acute Myocardial Infarction.

[This corrects the article DOI: 10.1371/journal.pone.0157233.].

Dissecting the Effects of Ischemia and Reperfusion on the Coronary Microcirculation in a Rat Model of Acute Myocardial Infarction.

BACKGROUND: Microvascular injury (MVI) after coronary ischemia-reperfusion is associated with high morbidity and mortality. Both ischemia and reperfusion are involved in MVI, but to what degree these phases contribute is unknown. Understanding the etiology is essential for the development of new potential therapies. METHODS AND FINDINGS: Rats were divided into 3 groups receiving either 30 minutes ischemia, 90 minutes ischemia or 30 minutes ischemia followed by 60 minutes reperfusion. Subsequently hearts were ex-vivo perfused in a Langendorff-model. Fluorescence and electron microscopy was used for analysis of capillary density, vascular permeability and ultrastructure. Most MVI was observed after 30 minutes ischemia followed by 60 minutes reperfusion. In comparison to the 30' and 90' ischemia group, wall thickness decreased (207.0±74 vs 407.8±75 and 407.5±71, p = 0.02). Endothelial nuclei in the 30'-60' group showed irreversible damage and decreased chromatin density variation (50.5±9.4, 35.4±7.1 and 23.7±3.8, p = 0.03). Cell junction density was lowest in the 30'-60' group (0.15±0.02 vs 2.5±0.6 and 1.8±0.7, p<0.01). Microsphere extravasation was increased in both the 90' ischemia and 30'-60' group. CONCLUSIONS: Ischemia alone for 90 minutes induces mild morphological changes to the coronary microcirculation, with increased vascular permeability. Ischemia for 30 minutes, followed by 60 minutes of reperfusion, induces massive MVI. This shows the direct consequences of reperfusion on the coronary microcirculation. These data imply that a therapeutic window exists to protect the microcirculation directly upon coronary revascularization.

CD34 expression modulates tube-forming capacity and barrier properties of peripheral blood-derived endothelial colony-forming cells (ECFCs).

Endothelial colony-forming cells (ECFC) are grown from circulating CD34(+) progenitors present in adult peripheral blood, but during in vitro expansion part of the cells lose CD34. To evaluate whether the regulation of CD34 characterizes the angiogenic phenotypical features of PB-ECFCs, we investigated the properties of CD34(+) and CD34(-) ECFCs with respect to their ability to form capillary-like tubes in 3D fibrin matrices, tip-cell gene expression, and barrier integrity. Selection of CD34(+) and CD34(-) ECFCs from subcultured ECFCs was accomplished by magnetic sorting (FACS: CD34(+): 95 % pos; CD34(-): 99 % neg). Both fractions proliferated at same rate, while CD34(+) ECFCs exhibited higher tube-forming capacity and tip-cell gene expression than CD3(4-) cells. However, during cell culture CD34(-) cells re-expressed CD34. Cell-seeding density, cell-cell contact formation, and serum supplements modulated CD34 expression. CD34 expression in ECFCs was strongly suppressed by newborn calf serum. Stimulation with FGF-2, VEGF, or HGF prepared in medium supplemented with 3 % albumin did not change CD34 mRNA or surface expression. Silencing of CD34 with siRNA resulted in strengthening of cell-cell contacts and increased barrier function of ECFC monolayers as measured by ECIS. Furthermore, CD34 siRNA reduced tube formation by ECFC, but did not affect tip-cell gene expression. These findings demonstrate that CD34(+) and CD34(-) cells are different phenotypes of similar cells and that CD34 (1) can be regulated in ECFC; (2) is positively involved in capillary-like sprout formation; (3) is associated but not causally related to tip-cell gene expression; and (4) can affect endothelial barrier function.