Influence of Cardiovascular Risk Factors, Comorbidities, Medication Use and Procedural Variables on Remote Ischemic Conditioning Efficacy in Patients with ST-Segment Elevation Myocardial Infarction

Effects of Tirofiban in Patients with Acute Myocardial Infarction and Diabetes Mellitus undergoing Primary Percutaneous Coronary Intervention

OBJECTIVE

This study evaluated the efficacy and safety of early vs. late tirofiban administration in the treatment of patients with acute ST-elevation myocardial infarction (STEMI) and diabetes mellitus (DM) undergoing primary percutaneous coronary intervention (pPCI).

METHODS

120 patients with STEMI and DM treated with pPCI were randomly divided into an observation group (n=60) and a control group (n=60). The observation group and the control group were intravenously injected with a bolus of tirofiban preoperatively or intraoperatively, respectively; both groups were then given an intravenous infusion over 24 h at 0.15 μg/kg/min. Thrombolysis in myocardial infarction (TIMI) grade flow, myocardial perfusion index, and functional heart parameters, as well as major adverse cardiovascular events and bleeding, were compared between the two groups.

RESULTS

Functional heart parameters, including left ventricular ejection fraction and cardiac output, were significantly improved in the observation group 6 months after discharge. Thrombus aspiration, inflammatory factors, and cardiac troponin I (cTNI) were more significantly decreased in the observation group than in the control group. The sum-ST-segment elevation at 2 h after pPCI treatment in the observation group was better than that in the control group. There was no significant difference in the incidence of adverse reactions and bleeding between the two groups.

CONCLUSION

The administration of tirofiban before reperfusion therapy compared with after reperfusion therapy is more effective in reducing the hyperthrombotic load, thrombus aspiration, inflammatory factors, and cTNI and can effectively improve myocardial perfusion and heart function.

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.

Comparison of intracoronary versus intravenous tirofiban in acute ST-elevation myocardial infarction patients undergoing primary percutaneous coronary intervention

OBJECTIVE

This study aimed to investigate the effect of intracoronary (IC) tirofiban compared to intravenously administered tirofiban in STEMI patients treated with PPCI.

METHODS

This study included 180 STEMI patients who were underwent PPCI. Patients were randomized into an IC group (n = 90) and intravenous (IV) group (n = 90). During the procedure, the both groups were administered IC or IV injections of tirofiban, respectively, followed by an IV infusion of tirofiban for 24 hours. Changes in TIMI flow grading, TMP grade 3, Sum-STR two hours after the operation, the number of thrombus aspirations during the operation, myocardial enzyme, inflammatory factors,cardiac functional parameters, MACE and bleeding were investigated.

RESULTS

Following treatment, TIMI flow grading and TMP grade 3 were improved in the IC tirofiban compared to the IV group (P = 0.022 and P = 0.014, respectively). Additionally, the Sum-STR two hours after operation, the incidence of MACEs, levels of AST, CRP, ESR, and TNI in the IC group was improved, compared with the IV group (all P < 0.05). Furthermore. Cardiac function including CO and LVEF were significantly improved in the IC group 6 months after discharge.

CONCLUSION

This study found that IC administration of tirofiban in patients with STEMI who underwent PPCI improved TIMI, TMP flow and cardiac function 6 months after discharge, and reduced CRP, ESR, and TNI. However, the incidence of bleeding between the two groups was comparable. These findings suggest that IC administration should be applied in certain acute STEMI patients.

With a Little Help From My Friends: the Role of the Renal Collateral Circulation in Atherosclerotic Renovascular Disease

The collateral circulation can adapt to bypass major arteries with limited flow and serves a crucial protective role in coronary, cerebral, and peripheral arterial disease. Emerging evidence indicates that the renal collateral circulation can similarly adapt and thereby limit kidney ischemia in atherosclerotic renovascular disease. These adaptations predominantly include recruitment of preexisting microvessels for arteriogenesis, with de novo vessel formation playing a limited role. Yet, adaptations of the renal collateral circulation in renovascular disease are often insufficient to fully compensate for the limited flow within an obstructed renal artery and may be hampered by the severity of obstruction or patient comorbidities. Experimental strategies have attempted to circumvent limitations of collateral formation and improve the prognosis of patients with various ischemic vascular territories. These have included pharmacological approaches such as endothelial growth factors, renin-angiotensin-aldosterone system blockade, and If-channel-blockers, as well as interventions like preconditioning, exercise, enhanced external counter-pulsation, and low-energy shock-wave therapy. However, few of these strategies have been implemented in atherosclerotic renovascular disease. This review summarizes current understanding regarding the development of renal collateral circulation in atherosclerotic renovascular disease. Studies are needed to apply lessons learned in other vascular beds in the setting of atherosclerotic renovascular disease to develop new treatment regimens for this patient group.

Can Clinical and Functional Outcomes Be Improved with an Intelligent "Internet Plus"-Based Full Disease Cycle Remote Ischemic Conditioning Program in Acute ST-elevation Myocardial Infarction Patients Undergoing Percutaneous Coronary Intervention? Rationale and Design of the i-RIC Trial

BACKGROUND

Acute ST-elevation myocardial infarction (STEMI) is associated with a high incidence of complications as well as a considerable hospitalization rate and economic burden. Preliminary evidence suggests that remote ischemic conditioning (RIC) is a promising non-invasive intervention that may effectively and safely reduce myocardial infarct size, subsequent cardiac events and complications, and mortality. However, RIC's cardio-protective effect remains under debate, especially for single timepoint RIC programs. Adequately powered large-scale randomized controlled trials investigating clinical outcomes are thus needed to clarify the role of full disease cycle RIC programs.

METHODS

The intelligent "Internet Plus"-based full disease cycle remote ischemic conditioning (i-RIC) trial is a pragmatic, multicenter, randomized controlled, parallel group, clinical trial. The term, intelligent "Internet Plus"-based full disease cycle, refers to smart devices aided automatic and real-time monitoring of remote ischemic pre-, per- or post-conditioning intervention for patients with STEMI undergoing percutaneous coronary intervention (PCI). Based on this perspective, 4700 STEMI patients from five hospitals in China will be randomized to a control and an intervention group. The control group will receive PCI and usual care, including pharmacotherapy, before and after PCI. The intervention group will receive pre-, per-, and post-operative RIC combined with long-term i-RIC over a one-month period in addition. A smartphone application, an automated cuff inflation/deflation device and "Internet Plus"-based administration will be used in the long-term phase. The primary outcome is the combined cardiac death or hospitalization for heart failure rate. Secondary outcomes include clinical and functional outcomes: major adverse cardiac and cerebrovascular events rate, all-cause mortality, myocardial reinfarction rate, readmission rate for heart failure and ischemic stroke rate, unplanned revascularization rate, plasma concentration of myocardial infarction-related key biomarkers, infarct size, cardiac function, cardiopulmonary endurance, health-related quality of life, total hospital length of stay, total medical cost, and compliance with treatment regime.

DISCUSSION

The i-RIC trial is designed to test the hypothesis that clinical and functional outcomes can be improved with the i-RIC program in STEMI patients undergoing PCI. The concept of RIC is expected to be enhanced with this intelligent "Internet Plus"-based program focusing on the full disease cycle. If the i-RIC program results in superior improvement in primary and secondary outcomes, it will offer an innovative treatment option for STEMI patients and form the basis of future recommendations.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry ( http://www.chictr.org.cn ): ChiCTR2000031550, 04 April 2020.

Perioperative Cardioprotection: Clinical Implications

Perioperative cardioprotection aims to minimize the consequences of myocardial ischemia-reperfusion injury. In isolated tissue and animal experiments, several treatments have been identified providing cardioprotection. Some of these strategies have been confirmed in clinical proof-of-concept studies. However, the final translation of cardioprotective strategies to really improve clinical outcome has been disappointing: large randomized controlled clinical trials mostly revealed inconclusive, neutral, or negative results. This review provides an overview of the currently available evidence regarding clinical implications of perioperative cardioprotective therapies from an anesthesiological perspective, highlighting nonpharmacological as well as pharmacological strategies. We discuss reasons why translation of promising experimental results into clinical practice and outcome improvement is hampered by potential confounders and suggest future perspectives to overcome these limitations.

The Primary Management Strategies for ST-Elevation Myocardial Infarction Patients in Saudi Arabia: A Sub-Study of the Saudi Acute Myocardial Infarction Registry

Background and objective

Not all patients with ST-elevation myocardial infarction (STEMI) in Saudi Arabia are managed with a primary percutaneous coronary intervention (PPCI). We analyzed the management strategies for STEMI patients in the Saudi Acute Myocardial Infarction Registry (STARS). The strategies include PPCI, revascularization with thrombolytic therapy, and conservative management. This study involved a sub-study of the STARS.

Methods

STEMI patients were categorized into three groups. Group 1 was managed with PPCI, group 2 with revascularization with thrombolytic therapy, and group 3 with conservative approaches. The data were collected at presentation, at one month, and at one year after discharge.

Results

The sample consisted of 1,471 patients. The mean age of the participants was 54 ±12 years; 51% were Saudi citizens, and the majority (89%) were male. Their background revealed a high coronary risk profile, with 48% diagnosed with diabetes mellitus (DM) and 44% with hypertension (HTN); 54% were active or ex-smokers, 30% had a high lipid profile, and 74% were overweight. PPCI was performed in 42%, and 29% were managed with revascularization using thrombolytic therapy. A conservative approach was followed in 29% of the patients. Patients who had a stroke were treated conservatively due to the risk of bleeding. The patients in group 1 were mostly hypertensive with recurrent angina and a history of prior revascularization, with PPCI or coronary artery bypass grafting (CABG). The crude all-cause mortality at one year was 11%; it was 7% at one month for group 1, 8% for group 2, and 9% for group 3, which was not statistically significant.

Conclusions

Controlling the risk factors and improving access to PPCI in hospitals are fundamental in the management of STEMI patients. PPCI is still underused. Guideline-directed medical therapy (GDMT) is a reasonable approach if PPCI is not available.

Differences in intrinsic aerobic capacity alters sensitivity to ischemia-reperfusion injury but not cardioprotective capacity by ischemic preconditioning in rats

INTRODUCTION

Aerobic capacity is a strong predictor of cardiovascular mortality. Whether aerobic capacity influences myocardial ischemia and reperfusion (IR) injury is unknown.

PURPOSE

To investigate the impact of intrinsic differences in aerobic capacity and the cardioprotective potential on IR injury.

METHODS

We studied hearts from rats developed by selective breeding for high (HCR) or low (LCR) capacity for treadmill running. The rats were randomized to: (1) control, (2) local ischemic preconditioning (IPC) or (3) remote ischemic preconditioning (RIC) followed by 30 minutes of ischemia and 120 minutes of reperfusion in an isolated perfused heart model. The primary endpoint was infarct size. Secondary endpoints included uptake of labelled glucose, content of selected mitochondrial proteins in skeletal and cardiac muscle, and activation of AMP-activated kinase (AMPK).

RESULTS

At baseline, running distance was 203±7 m in LCR vs 1905±51 m in HCR rats (p<0.01). Infarct size was significantly lower in LCR than in HCR controls (49±5% vs 68±5%, p = 0.04). IPC reduced infarct size by 47% in LCR (p<0.01) and by 31% in HCR rats (p = 0.01). RIC did not modulate infarct size (LCR: 52±5, p>0.99; HCR: 69±6%, p>0.99, respectively). Phosphorylaion of AMPK did not differ between LCR and HCR controls. IPC did not modulate cardiac phosphorylation of AMPK. Glucose uptake during reperfusion was similar in LCR and HCR rats. IPC increased glucose uptake during reperfusion in LCR animals (p = 0.02). Mitochondrial protein content in skeletal muscle was lower in LCR than in HCR (0.77±0.10 arbitrary units (AU) vs 1.09±0.07 AU, p = 0.02), but not in cardiac muscle.

CONCLUSION

Aerobic capacity is associated with altered myocardial sensitivity to IR injury, but the cardioprotective effect of IPC is not. Glucose uptake, AMPK activation immediately prior to ischemia and basal mitochondrial protein content in the heart seem to be of minor importance as underlying mechanisms for the cardioprotective effects.