ISCHEMIA: new questions from a landmark trial

Immune System and Microvascular Remodeling in Humans

Low-grade inflammatory processes and related oxidative stress may have a key role in the pathogenesis of hypertension and hypertension-mediated organ damage. Innate immune cells, such as neutrophils, dendritic cells, monocytes/macrophages, as well as unconventional T lymphocytes like γδ T cells contribute to hypertension and may trigger vascular inflammation. Adaptive immunity has been demonstrated to participate in elevation of blood pressure and in vascular and kidney injury. In particular, effector T lymphocytes (Th1, Th2, and Th17) may play a relevant role in promoting hypertension and microvascular remodeling, whereas T-regulatory lymphocytes may have a protective role. Effector cytokines produced by these immune cells lead to increased oxidative stress, endothelial dysfunction and contribute to target organ damage in hypertension. A possible role of immune cell subpopulations in the development and regression of microvascular remodeling has also been proposed in humans with hypertension. The present review summarizes the key immune mechanisms that may participate in the pathophysiology of hypertension-mediated inflammation and vascular remodeling; advances in this field may provide the basis for novel therapeutics for hypertension.

Vascularisation of pluripotent stem cell-derived myocardium: biomechanical insights for physiological relevance in cardiac tissue engineering

The myocardium is a diverse environment, requiring coordination between a variety of specialised cell types. Biochemical crosstalk between cardiomyocytes (CM) and microvascular endothelial cells (MVEC) is essential to maintain contractility and healthy tissue homeostasis. Yet, as myocytes beat, heterocellular communication occurs also through constantly fluctuating biomechanical stimuli, namely (1) compressive and tensile forces generated directly by the beating myocardium, and (2) pulsatile shear stress caused by intra-microvascular flow. Despite endothelial cells (EC) being highly mechanosensitive, the role of biomechanical stimuli from beating CM as a regulatory mode of myocardial-microvascular crosstalk is relatively unexplored. Given that cardiac biomechanics are dramatically altered during disease, and disruption of myocardial-microvascular communication is a known driver of pathological remodelling, understanding the biomechanical context necessary for healthy myocardial-microvascular interaction is of high importance. The current gap in understanding can largely be attributed to technical limitations associated with reproducing dynamic physiological biomechanics in multicellular in vitro platforms, coupled with limited in vitro viability of primary cardiac tissue. However, differentiation of CM from human pluripotent stem cells (hPSC) has provided an unlimited source of human myocytes suitable for designing in vitro models. This technology is now converging with the diverse field of tissue engineering, which utilises in vitro techniques designed to enhance physiological relevance, such as biomimetic extracellular matrix (ECM) as 3D scaffolds, microfluidic perfusion of vascularised networks, and complex multicellular architectures generated via 3D bioprinting. These strategies are now allowing researchers to design in vitro platforms which emulate the cell composition, architectures, and biomechanics specific to the myocardial-microvascular microenvironment. Inclusion of physiological multicellularity and biomechanics may also induce a more mature phenotype in stem cell-derived CM, further enhancing their value. This review aims to highlight the importance of biomechanical stimuli as determinants of CM-EC crosstalk in cardiac health and disease, and to explore emerging tissue engineering and hPSC technologies which can recapitulate physiological dynamics to enhance the value of in vitro cardiac experimentation.

Applicability and Eligibility of the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) for Patients who Underwent Revascularization with Percutaneous Coronary Intervention

In the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial, an early invasive strategy did not decrease mortality compared to a conservative strategy for stable ischemic heart disease (SIHD) patients with moderate-to-severe ischemia, and the role of revascularization would be revised. However, the applicability and potential influence of this trial in daily practice remains unclear. Our objective was to assess the eligibility and representativeness of the ISCHEMIA trial on the patients with percutaneous coronary intervention (PCI). From a multicenter registry, we extracted a consecutive 13,223 SIHD patients with PCI (baseline cohort). We applied ISCHEMIA eligibility criteria and compared the baseline characteristics between the eligible patients and the actual study participants (randomized controlled trial (RCT) patients). In 3463 patients with follow-up information (follow-up cohort), the 2 year composite of major adverse cardiac events was evaluated between the eligible patients and RCT patients, as well as eligible and non-eligible patients in the registry. In the baseline cohort, 77.3% of SIHD patients with moderate-to-severe ischemia were eligible for the ISCHEMIA. They were comparable with RCT patients for baseline characteristics and outcomes unlike the non-eligible patients. In conclusion, the trial results seem applicable for the majority of PCI patients with moderate-to-severe ischemia except for the non-eligible patients.

[Guidelines for the Diagnosis and Management of Chronic Coronary Syndromes in Primary Health Care - the Issue of Acceptability for the Russian Federation]

In 2019, the European Society for Cardiology (ESC) published guidelines with a new term, "chronic coronary syndromes" (CCS). These guidelines presented 6 clinical scenarios, which are most common in outpatient practice. The diagnostic approach described in these guidelines shifts from the standardization to the rationality of individualized solutions on using various diagnostic methods. The diagnostic approach suggested in the ESC guidelines requires extensive medical discussion and consensus because this will definitely entail a) further increase in indexes that reflect the morbidity of ischemic heart disease (IHD) due to unconfirmed diagnoses and b) administration of unreasoned therapy. This article presents statements of the guidelines, which cannot be automatically transmitted to the existing medical practice and should be discussed and adjusted by experts of the Russian Society of Cardiology.