Effect of remote ischaemic conditioning on infarct size and remodelling in ST-segment elevation myocardial infarction patients: the CONDI-2/ERIC-PPCI CMR substudy

Recombinant human soluble domain of CD39L3 and ticagrelor: cardioprotective effects in experimental myocardial infarction

BACKGROUND AND AIMS

The ecto-nucleoside triphosphate diphosphohydrolases of the CD39 family degrade ATP and ADP into AMP, which is converted into adenosine by the extracellular CD73/ecto-5-nucleotidase. This pathway has been explored in antithrombotic treatments but little in myocardial protection. We have investigated whether the administration of solCD39L3 (AZD3366) confers additional cardioprotection to that of ticagrelor alone in a pre-clinical model of myocardial infarction (MI).

METHODS

Ticagrelor-treated pigs underwent balloon-induced MI (90 min) and, before reperfusion, received intravenously either vehicle, 1 mg/kg AZD3366 or 3 mg/kg AZD3366. All animals received ticagrelor twice daily for 42 days. A non-treated MI group was run as a control. Serial cardiac magnetic resonance (baseline, Day 3 and Day 42 post-MI), light transmittance aggregometry, bleeding time, and histological and molecular analyses were performed.

RESULTS

Ticagrelor reduced oedema formation and infarct size at Day 3 post-MI vs. controls. A 3 mg/kg AZD3366 provided an additional 45% reduction in oedema and infarct size compared with ticagrelor and a 70% reduction vs. controls (P < .05). At Day 42, infarct size declined in all ticagrelor-administered pigs, particularly in 3 mg/kg AZD3366-treated pigs (P < .05). Left ventricular ejection fraction was diminished at Day 3 in placebo pigs and worsened at Day 42, whereas it remained unaltered in ticagrelor ± AZD3366-administered animals. Pigs administered with 3 mg/kg AZD3366 displayed higher left ventricular ejection fraction upon dobutamine stress at Day 3 and minimal dysfunctional segmental contraction at Day 42 (χ2P < .05 vs. all). Cardiac and systemic molecular readouts supported these benefits. Interestingly, AZD3366 abolished ADP-induced light transmittance aggregometry without affecting bleeding time.

CONCLUSIONS

Infusion of AZD3366 on top of ticagrelor leads to enhanced cardioprotection compared with ticagrelor alone.

The Infarct-Limiting Effect of Remote Ischemic Conditioning in Rats Is Not Affected by Aspirin

PURPOSE

Remote ischemic conditioning (RIC) has been shown to be a powerful cardioprotective therapy in animal models. However, a protective effect in patients presenting with acute myocardial infarction has failed to be confirmed. A recent pre-clinical study reported that aspirin which is routinely given to patients undergoing reperfusion therapy blocked the infarct-limiting effect of ischemic postconditioning. The present study was designed to test whether aspirin could also be blocking the infarct-limiting effect of RIC.

METHODS

This was investigated in vivo using male Sprague Dawley rats (n = 5 to 6 per group) subjected to either 30 min of regional myocardial ischemia, followed by 120-min reperfusion, or additionally to a RIC protocol initiated after 20-min myocardial ischemia. The RIC protocol included four cycles of 5-min hind limb ischemia interspersed with 5-min reperfusion. Intravenous aspirin (30 mg/kg) or vehicle (saline) was administered after 15-min myocardial ischemia.

RESULTS

RIC significantly reduced infarct size (IS) normalized to the area at risk, by 47%. Aspirin administration did not affect IS nor did it attenuate the infarct-limiting effect of RIC.

CONCLUSION

Aspirin administration in the setting of myocardial infarction is not likely to interfere with the cardioprotective effect of RIC.

Chinese expert consensus on the diagnosis and treatment of coronary microvascular diseases (2023 Edition)

Since the four working groups of the Chinese Society of Cardiology issued first expert consensus on coronary microvascular diseases (CMVD) in 2017, international consensus documents on CMVD have increased rapidly. Although some of these documents made preliminary recommendations for the diagnosis and treatment of CMVD, they did not provide classification of recommendations and levels of evidence. In order to summarize recent progress in the field of CMVD, standardize the methods and procedures of diagnosis and treatment, and identify the scientific questions for future research, the four working groups of the Chinese Society of Cardiology updated the 2017 version of the Chinese expert consensus on CMVD and adopted a series of measures to ensure the quality of this document. The current consensus has raised a new classification of CMVD, summarized new epidemiological findings for different types of CMVD, analyzed key pathological and molecular mechanisms, evaluated classical and novel diagnostic technologies, recommended diagnostic pathways and criteria, and therapeutic strategies and medications, for patients with CMVD. In view of the current progress and knowledge gaps of CMVD, future directions were proposed. It is hoped that this expert consensus will further expedite the research progress of CMVD in both basic and clinical scenarios.

Impact of myocardial deformation on risk prediction in patients following acute myocardial infarction

Background

Strain analyses derived from cardiovascular magnetic resonance-feature tracking (CMR-FT) provide incremental prognostic benefit in patients sufferring from acute myocardial infarction (AMI). This study aims to evaluate and revalidate previously reported prognostic implications of comprehensive strain analyses in a large independent cohort of patients with ST-elevation myocardial infarction (STEMI).

Methods

Overall, 566 STEMI patients enrolled in the CONDITIONING-LIPSIA trial including pre- and/or postconditioning treatment in addition to conventional percutaneous coronary intervention underwent CMR imaging in median 3 days after primary percutaneous coronary intervention. CMR-based left atrial (LA) reservoir (Es), conduit (Ee), and boosterpump (Ea) strain analyses, as well as left ventricular (LV) global longitudinal strain (GLS), circumferential strain (GCS), and radial strain (GRS) analyses were carried out. Previously identified cutoff values were revalidated for risk stratification. Major adverse cardiac events (MACE) comprising death, reinfarction, and new congestive heart failure were assessed within 12 months after the occurrence of the index event.

Results

Both atrial and ventricular strain values were significantly reduced in patients with MACE (p < 0.01 for all). Predetermined LA and LV strain cutoffs enabled accurate risk assessment. All LA and LV strain values were associated with MACE on univariable regression modeling (p < 0.001 for all), with LA Es emerging as an independent predictor of MACE on multivariable regression modeling (HR 0.92, p = 0.033). Furthermore, LA Es provided an incremental prognostic value above LVEF (a c-index increase from 0.7 to 0.74, p = 0.03).

Conclusion

External validation of CMR-FT-derived LA and LV strain evaluations confirmed the prognostic value of cardiac deformation assessment in STEMI patients. In the present study, LA strain parameters especially enabled further risk stratification and prognostic assessment over and above clinically established risk parameters.

Clinical Trial Registration

ClinicalTrials.gov, identifier NCT02158468.

The impact of time-of-day reperfusion on remote ischemic conditioning in ST-elevation myocardial infarction: a RIC-STEMI substudy

Daytime variation affects the tolerance of cardiomyocytes to ischemia-reperfusion injury (IRI). This study aims to evaluate the impact of time-of-day reperfusion on clinical outcomes of remote ischemic conditioning (RIC) as an adjuvant to primary percutaneous coronary intervention(PPCI) in ST-elevation myocardial infarction(STEMI) patients. A post-hoc analysis of a prospective, single-center parallel 1:1 randomized trial (RIC-STEMI) was performed. This analysis included 448 STEMI patients previously randomized to either PPCI alone (PPCI group) (n = 217) or RIC as an adjuvant to PPCI (RIC + PPCI group) (n = 231). Moreover, the sample was divided according to the time of PPCI: night-morning (22 h-11h59min) (n = 216) or afternoon (12 h-21h59min) (n = 232) groups. The primary follow-up endpoint was a composite of cardiac death and hospitalization due to heart failure. There were no significant differences in the clinical characteristics and the follow-up outcomes between groups. The afternoon period (HR = 0.474; 95% CI 0.230-0.977; p = 0.043) and RIC (HR = 0.423; 95% CI 0.195-0.917; p = 0.029) were independent predictors of the primary follow-up endpoint. An univariate analysis showed a lower frequency of primary follow-up endpoint, just in the afternoon period (10.3%vs0.9%; p = 0.002), in the RIC + PPCI group. A multivariate analysis revealed that RIC was an independent predictor of the primary follow-up endpoint in the afternoon group (HR = 0.098; 95% CI 0.012-0.785; p = 0.029), but not in the night-morning group. In addition, the afternoon period was not an independent predictor of the primary follow-up endpoint when the multivariate analysis was performed in the PPCI group. In conclusion, this study showed an important cardioprotective effect of RIC, namely in the afternoon period, suggesting that the afternoon period enhances the cardioprotection induced by RIC.

Safety and efficacy of remote ischemic conditioning combined with endovascular thrombectomy for acute ischemic stroke due to large vessel occlusion of anterior circulation: A multicenter, randomized, parallel-controlled clinical trial (SERIC-EVT): Study protocol

RATIONALE/AIM

Many patients undergoing successful recanalization after endovascular thrombectomy (EVT) do not have a good outcome; additional neuroprotection might benefit this group. Remote ischemic conditioning (RIC) stimulates endogenous protective mechanisms and may have a neuroprotective in acute brain ischemia. The safety and efficacy of RIC combined with endovascular thrombectomy (SERIC-EVT) trial is investigating the safety and efficacy of RIC for patients with acute ischemic stroke (AIS) who underwent EVT due to large vessel occlusion of the anterior circulation.

METHODS

SERIC-EVT is a multicenter, randomized, parallel-controlled, and blinded endpoint clinical trial. Patients are recruited from 10 hospitals in Jilin Province, Northeast China. Patients with anterior circulation AIS undergoing EVT due to large vessel occlusion are randomized in a 1:1 ratio to RIC or sham-RIC. Participants will receive standard medical treatment and an inflation pressure of 200 mmHg (RIC group) or 60 mmHg (sham-RIC group) twice daily for seven consecutive days.

STUDY OUTCOMES

The primary outcome is the proportion of patients with modified Rankin Scale (mRS) score of 0-2 on day 90. Secondary outcome measures include the National Institute of Health Stroke Scale, Barthel Index, and mRS scores obtained at 24 h, 7 days, 30 ± 3 days, and 90 ± 3 days post-EVT, recanalization rate, expanded Thrombolysis in Cerebral Infarction score, and symptomatic intracranial hemorrhage post-EVT. Mortality and all adverse events, including skin changes and pain scores, within the first 90 days will be used as safety outcome measures.

SAMPLE SIZE ESTIMATES

Based on previous studies, we estimate a 14% difference in functional independence (the mRS ⩽2) between RIC and sham-RIC groups. Considering a significance level of 5% and power of 80%, and one-fifth of patients lost to follow up, the planned sample size is 498 patients (249 per group).

DISCUSSION

RIC might be a strategy that improves 3-month clinical outcomes in AIS patients who have undergone EVT due to large vessel occlusion of anterior circulation. SERIC-EVT will determine whether this is the case.

Effect of remote ischaemic conditioning on left ventricular function in ST-segment elevation myocardial infarction patients: The CONDI-2 echocardiographic sub-study

Background

Remote ischaemic conditioning (RIC) applied to the arm by inflation and deflation of a pneumatic cuff has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction undergoing primary percutaneous coronary intervention (PPCI). However, the effect of RIC on left ventricular ejection fraction (LVEF) following infarct healing remains unknown.

Objective

To investigate whether RIC applied in the ambulance before PPCI can improve left ventricular (LV) function in STEMI patients 3 months following infarction.

Methods

Echocardiography was performed in a total of 694 patients from the CONDI-2 study a median of 112 days (IQR 63) after the initial admission. LVEF and LV end-diastolic and end-systolic volumes were calculated using the modified Simpsons biplane method of disks. LV global longitudinal strain (GLS) was estimated using 2-dimensional cine-loops with a frame rate > 55 frames/second, measured in the three standard apical views.

Results

There was no difference in the measured echocardiographic parameters in the RIC group as compared to the control group, including LV EF, LV GLS, tricuspid annular plane systolic excursion or left ventricular volumes. In the control group, 32% had an ejection fraction < 50% compared to 37% in the RIC group (p = 0.129).

Conclusion

In this largest to date randomized imaging study of RIC, RIC as an adjunct to PPCI was not associated with a change in echocardiographic measures of cardiac function compared to standard PPCI alone.

A comprehensive and longitudinal cardiac magnetic resonance imaging study of the impact of coronary ischemia duration on myocardial damage in a highly translatable animal model

OBJECTIVES

We performed a comprehensive assessment of the effect of myocardial ischemia duration on cardiac structural and functional parameters by serial cardiac magnetic resonance (CMR) and characterized the evolving scar.

BACKGROUND

CMR follow-up on the cardiac impact of time of ischemia in a closed-chest animal model of myocardial infarction with human resemblance is missing.

METHODS

Pigs underwent MI induction by occlusion of the left anterior descending (LAD) coronary artery for 30, 60, 90 or 120 min and then revascularized. Serial CMR was performed on day 3 and day 42 post-MI. CMR measurements were also run in a sham-operated group. Cellular and molecular changes were investigated.

RESULTS

On day 3, cardiac damage and function were similar in sham and pigs subjected to 30 min of ischemia. Cardiac damage (oedema and necrosis) significantly increased from 60 min onwards. Microvascular obstruction was extensively seen in animals with ≥90 min of ischemia and correlated with cardiac damage. A drop in global systolic function and wall motion of the jeopardized segments was seen in pigs subjected to ≥60 min of ischemia. On day 42, scar size and cardiac dysfunction followed the same pattern in the animals subjected to ≥60 min of ischemia. Adverse left ventricular remodelling (worsening of both LV volumes) was only present in animals subjected to 120 min of ischemia. Cardiac fibrosis, myocyte hypertrophy and vessel rarefaction were similar in the infarcted myocardium of pigs subjected to ≥60 min of ischemia. No changes were observed in the remote myocardium.

CONCLUSION

Sixty-minute LAD coronary occlusion already induces cardiac structural and functional alterations with longer ischemic time (120 min) causing adverse LV remodelling.

How can the adult zebrafish and neonatal mice teach us about stimulating cardiac regeneration in the human heart?

The proliferative capacity of mammalian cardiomyocytes diminishes shortly after birth. In contrast, adult zebrafish and neonatal mice can regenerate cardiac tissues, highlighting new potential therapeutic avenues. Different factors have been found to promote cardiomyocyte proliferation in zebrafish and neonatal mice; these include maintenance of mononuclear and diploid cardiomyocytes and upregulation of the proto-oncogene c-Myc. The growth factor NRG-1 controls cell proliferation and interacts with the Hippo-Yap pathway to modulate regeneration. Key components of the extracellular matrix such as Agrin are also crucial for cardiac regeneration. Novel therapies explored in this review, include intramyocardial injection of Agrin or zebrafish-ECM and NRG-1 administration. These therapies may induce regeneration in patients and should be further explored.

The protective effect of remote ischemic conditioning is lost in patients with hypercholesterolemia

Remote ischemic conditioning (RIC), brief repetitive cycles of ischemia and reperfusion in remote tissues, is known to induce robust protection against myocardial ischemia-reperfusion (I/R) injury in preclinical studies. However, translation of the beneficial effects to the clinical setting has been challenging. A possibility is that comorbidities, including hypercholesterolemia, interfere with the protective mechanisms of RIC. The aim of this study was to test if hypercholesterolemia attenuates the efficacy of RIC in patients with hypercholesterolemia. Patients with familial hypercholesterolemia (FH) with high (≥5.5 mmol/L) low-density lipoprotein cholesterol (LDL-C), FH with low (≤2.5 mmol/L) and healthy control subjects (n = 12 in each group) were included. Flow-mediated vasodilatation (FMD) of the brachial artery was evaluated, before and after a 20-min period of forearm ischemia and 20 min reperfusion (I/R) as a measure of endothelial function. Study subjects were randomized to a RIC protocol consisting of four cycles of 5 min of leg ischemia or sham using a crossover design. Forearm I/R induced significant reduction in FMD in all three groups during the sham procedure. RIC protected from endothelial dysfunction induced by forearm ischemia-reperfusion in healthy controls [FMD baseline 2.8 ± 2.3 vs. FMD after I/R + RIC 4.5 ± 4.0%; means (SD)] and in patients with FH with low LDL-C (4.5 ± 3.5 vs. 4.4 ± 4.2%). By contrast, RIC fails to protect against I/R-induced endothelial dysfunction in patients with FH and high LDL-C (3.9 ± 3.0 vs. 1.1 ± 1.5%; P < 0.01). These findings provide the first evidence in humans that the protective effect of RIC is lost in patients with elevated cholesterol.NEW & NOTEWORTHY We investigated the impact of hypercholesterolemia on the protective effect of RIC on ischemia-reperfusion injury in a well-characterized patient population with isolated hypercholesterolemia. The results show that the protective effect of RIC is absent in patients with hypercholesterolemia but is apparent in patients with hypercholesterolemic following treatment with lipid-lowering drugs. The results are of importance for the understanding of how comorbidities affect the therapeutic potential of RIC.

Do We Really Need Aspirin Loading for STEMI?

Aspirin loading (chewable or intravenous) as soon as possible after presentation is a class I recommendation by current ST elevation myocardial infarction (STEMI) guidelines. Earlier achievement of therapeutic antiplatelet effects by aspirin loading has long been considered the standard of care. However, the effects of the loading dose of aspirin (alone or in addition to a chronic maintenance oral dose) have not been studied. A large proportion of myocardial cell death occurs upon and after reperfusion (reperfusion injury). Numerous agents and interventions have been shown to limit infarct size in animal models when administered before or immediately after reperfusion. However, these interventions have predominantly failed to show significant protection in clinical studies. In the current review, we raise the hypothesis that aspirin loading may be the culprit. Data obtained from animal models consistently show that statins, ticagrelor, opiates, and ischemic postconditioning limit myocardial infarct size. In most of these studies, aspirin was not administered. However, when aspirin was administered before reperfusion (as is the case in the majority of studies enrolling STEMI patients), the protective effects of statin, ticagrelor, morphine, and ischemic postconditioning were attenuated, which can be plausibly attributable to aspirin loading. We therefore suggest studying the effects of aspirin loading before reperfusion on the infarct size limiting effects of statins, ticagrelor, morphine, and/ or postconditioning in large animal models using long reperfusion periods (at least 24 h). If indeed aspirin attenuates the protective effects, clinical trials should be conducted comparing aspirin loading to alternative antiplatelet regimens without aspirin loading in patients with STEMI undergoing primary percutaneous coronary intervention.

Effects of late, repetitive remote ischaemic conditioning on myocardial strain in patients with acute myocardial infarction

Late, repetitive or chronic remote ischaemic conditioning (CRIC) is a potential cardioprotective strategy against adverse remodelling following ST-segment elevation myocardial infarction (STEMI). In the randomised Daily Remote Ischaemic Conditioning Following Acute Myocardial Infarction (DREAM) trial, CRIC following primary percutaneous coronary intervention (P-PCI) did not improve global left ventricular (LV) systolic function. A post-hoc analysis was performed to determine whether CRIC improved regional strain. All 73 patients completing the original trial were studied (38 receiving 4 weeks' daily CRIC, 35 controls receiving sham conditioning). Patients underwent cardiovascular magnetic resonance at baseline (5-7 days post-STEMI) and after 4 months, with assessment of LV systolic function, infarct size and strain (longitudinal/circumferential, in infarct-related and remote territories). At both timepoints, there were no significant between-group differences in global indices (LV ejection fraction, infarct size, longitudinal/circumferential strain). However, regional analysis revealed a significant improvement in longitudinal strain in the infarcted segments of the CRIC group (from - 16.2 ± 5.2 at baseline to - 18.7 ± 6.3 at follow up, p = 0.0006) but not in corresponding segments of the control group (from - 15.5 ± 4.0 to - 15.2 ± 4.7, p = 0.81; for change: - 2.5 ± 3.6 versus + 0.3 ± 5.6, respectively, p = 0.027). In remote territories, there was a lower increment in subendocardial circumferential strain in the CRIC group than in controls (- 1.2 ± 4.4 versus - 2.5 ± 4.0, p = 0.038). In summary, CRIC following P-PCI for STEMI is associated with improved longitudinal strain in infarct-related segments, and an attenuated increase in circumferential strain in remote segments. Further work is needed to establish whether these changes may translate into a reduced incidence of adverse remodelling and clinical events. Clinical Trial Registration: http://clinicaltrials.gov/show/NCT01664611 .