The ability of contemporary cardiologists to judge the ischemic impact of a coronary lesion visually

Background: Landmark trials showed that invasive pressure measurement (Fractional Flow Reserve, FFR) was a better guide to coronary stenting than visual assessment. However, present-day interventionists have benefited from extensive research and personal experience of mapping anatomy to hemodynamics. Aims: To determine if visual assessment of the angiogram performs as well as invasive measurement of coronary physiology. Methods: 25 interventional cardiologists independently visually assessed the single vessel coronary disease of 200 randomized participants in The Objective Randomized Blinded Investigation with optimal medical Therapy of Angioplasty in stable angina trial (ORBITA). They gave a visual prediction of the FFR and Instantaneous Wave-free Ratio (iFR), denoted vFFR and viFR respectively. Each judged each lesion on 2 occasions, so that every lesion had 50 vFFR, and 50 viFR assessments. The group consensus visual estimates (vFFR-group and viFR-group) and individual cardiologists' visual estimates (vFFR-individual and viFR-individual) were tested alongside invasively measured FFR and iFR for their ability to predict the placebo-controlled reduction in stress echo ischemia with stenting. Results: Placebo-controlled ischemia improvement with stenting was predicted by vFFR-group (p < 0.0001) and viFR-group (p < 0.0001), vFFR-individual (p < 0.0001) and viFR-individual (p < 0.0001). There were no significant differences between the predictive performance of the group visual estimates and their invasive counterparts: p = 0.53 for vFFR vs FFR and p = 0.56 for viFR vs iFR. Conclusion: Visual assessment of the angiogram by contemporary experts, provides significant additional information on the amount of ischaemia which can be relieved by placebo-controlled stenting in single vessel coronary artery disease

Anatomical, haemodynamic, biochemical and imaging characteristics of the coronary collateral circulation in acute and chronic atherosclerotic disease processes

Aim: Although frequently identified during coronary angiography, the mechanisms by which coronary collaterals develop, and their prognostic implications are, to date, unknown. This body of work aims to determine the prevalence and predictors of coronary collateral recruitment in the setting of ST elevation myocardial infarction (STEMI) and chronic total occlusion (CTO) and to determine their prognostic impact. Furthermore, to identify biochemical, cellular and haemodynamic processes by which collaterals are recruited and mature, and influence haemodynamics in the coronary circulation. Methods: Anatomical grading of collaterals using the Rentrop classification was performed in a large cohorts of patients with STEMI and CTO to determine predictors, reproducibility and prognostic implications of collaterals. Data linkage with other health parameters including a history of obstructive sleep apnoea (OSA) and prior coronary artery bypass grafting (CABG) was performed to determine impact of comorbidities and haemodynamic modulation on collateral recruitment. Subsequent systematic reviews and meta-analyses were performed. Invasive haemodynamic assessment of coronary blood flow and pressure in the presence and absence of collaterals was correlated with endothelial, haematological, biochemical and proteomic markers in both human and animal studies. Results: The important and novel findings are; - The presence of acutely recruited robust collaterals in the setting of STEMI are associated with a reduction in mortality and improved left ventricular function. - In the setting of a CTO, robust collaterals do not reduce mortality or risk of future ischaemic events, but do increase likelihood of successful percutaneous revascularisation. - Collateral maturation is driven by an elevation in shear stress, alterations in blood flow and tissue ischaemia. - The presence of collaterals results in a consistent increase in coronary blood flow in the donor vessel, with resultant effect on both pressure and flow derived indices of ischaemia assessment commonly used in clinical practice. - Recruitment and maturation of coronary collaterals are associated with upregulation of endothelial derived chemoattractant proteins, growth factors and transcription factors. - Coronary artery bypass grafting to a donor vessel, results in poorer collateral recruitment, likely driven by alterations in coronary blood flow and endothelial shear stress - The presence of OSA is associated with more robust coronary collaterals in both the setting of STEMI and CTO, however in more severe forms of OSA, characterised by severe and prolonged hypoxia, collateral recruitment is attenuated. Conclusions: Coronary collaterals impart significant prognostic implications in the setting of acute and chronic coronary artery disease, recruited as a result of alterations in coronary haemodynamics and tissue ischaemia with resultant downstream activation of growth factors, chemokines and transcription factors. Ongoing research is necessary to determine whether this prognostic advantage can be translated into meaningful therapeutic targets along with a greater understanding of clinical implications of collaterals

Cardiovascular Disease in the Post-COVID-19 Era - the Impending Tsunami?

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, which causes coronavirus disease 2019 (COVID-19), has rapidly grown into a worldwide pandemic, ever since first being described in Wuhan, China at the end of 2019. At time of writing (10 April, 2020), the rapid spread of the virus throughout the world has resulted in over 1.6 million infections and over 95,000 deaths world-wide; in Australia, there have been 6,203 confirmed cases with 53 deaths, with a mortality rate of 0.85%, much less than the world average of around 6%. Given the ferocity and devastating effects on health care systems abroad, Australia has implemented a series of measures to reduce the rate of spread and prepare the health care system for the pandemic. This has included cancelling elective surgery, social distancing and a nation-wide shut down of non-essential service

Outcomes of deferred revascularisation following negative fractional flow reserve in diabetic and non-diabetic patients: a meta-analysis

Abstract Background Fractional Flow Reserve (FFR) is a widely applied invasive physiological assessment, endorsed by major guidelines to aid in the decision to perform or defer revascularisation. While a threshold of  > 0.8 has been applied universally, clinical outcomes may be affected by numerous factors, including the presence of diabetes. This meta-analysis aims to investigate the outcomes of diabetic versus non-diabetic patients in whom revascularisation was deferred based on negative FFR. Methods We performed a meta-analysis investigating the outcomes of diabetic and non-diabetic patients in whom revascularisation was deferred based on negative FFR. A search was performed on MEDLINE, PubMed and EMBASE, and peer-reviewed studies that reported MACE for diabetic and non-diabetic patients with deferred revascularisation based on FFR  > 0.8 were included. The primary end point was MACE. Results The meta-analysis included 7 studies in which 4275 patients had revascularisation deferred based on FFR > 0.8 (1250 diabetic). Follow up occurred over a mean of 3.2 years. Diabetes was associated with a higher odds of MACE (OR = 1.66, 95% CI 1.35–2.04, p =   0.8, the presence of diabetes portends an increased long-term risk of MACE compared to non-diabetic patients. Trail registration URL:  https://www.crd.york.ac.uk/PROSPERO/ ; Unique identifier: CRD42022367312

Immediate recruitment of dormant coronary collaterals can provide more than half of normal resting perfusion during coronary occlusion in patients with coronary artery disease

Background: Dormant coronary collaterals are highly prevalent and clinically beneficial in cases of coronary occlusion. However, the magnitude of myocardial perfusion provided by immediate coronary collateral recruitment during acute occlusion is unknown. We aimed to quantify collateral myocardial perfusion during balloon occlusion in patients with coronary artery disease (CAD). Methods: Patients without angiographically visible collaterals undergoing elective percutaneous transluminal coronary angioplasty (PTCA) to a single epicardial vessel underwent two scans with 99mTc-sestamibi myocardial perfusion single-photon emission computed tomography (SPECT). All subjects underwent at least three minutes of angiographically verified complete balloon occlusion, at which time an intravenous injection of the radiotracer was administered, followed by SPECT imaging. A second radiotracer injection followed by SPECT imaging was performed 24 h after PTCA. Results: The study included 22 patients (median [interquartile range] age 68 [54-72] years. The perfusion defect extent was 19 [11-38] % of the LV, and the collateral perfusion at rest was 64 [58-67]% of normal. Conclusion: This is the first study to describe the magnitude of short-term changes in coronary microvascular collateral perfusion in patients with CAD. On average, despite coronary occlusion and an absence of angiographically visible collateral vessels, collaterals provided more than half of the normal perfusion

Both surgical and percutaneous revascularization improve prognosis in patients with a coronary chronic total occlusion (CTO) irrespective of collateral robustness

The impact of surgical or percutaneous coronary revascularization on prognosis in patients with a chronic total occlusion (CTO) remains uncertain. Particularly, whether revascularization of those with robust coronary collaterals improves prognosis is unknown. The objective of this study was to determine the predictors and prognostic impact of revascularization of a CTO, and to determine the clinical impact of robust coronary collaterals. Patients with a CTO diagnosed on coronary angiography between Jul 2010 and Dec 2019 were included in this study. Management strategy of the CTO was defined as percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG) or medical management. The degree of collateral robustness was determined by the Rentrop grading classification. Demographic, angiographic and clinical outcomes were recorded. A total of 954 patients were included in the study, of which 186 (19.5%) patients underwent CTO PCI, 296 (31.0%) patients underwent CABG and 472 (49.5%) patients underwent medical management of the CTO. 166 patients (17.4%) had Rentrop grade zero or one collaterals, 577 (60.5%) patients had Rentrop grade two and 211 (22.1%) had Rentrop grade three collaterals. The independent predictors of medical management of the CTO were older age, greater stenosis in the donor vessel, an emergent indication for angiography, a non-LAD CTO and female sex. The degree of collateral robustness was not associated with long-term mortality, while patients who were revascularized either through CABG or PCI had a significantly lower mortality compared to medical management alone (p < 0.0001). In patients with a CTO, the presence of robust collaterals is not associated with prognosis, while both surgical and percutaneous revascularization is associated with improved prognosis. Further research into the optimal revascularization strategy for a CTO is required

Transcatheter aortic valve implantation: current trends and future directions

Transcatheter aortic valve implantation (TAVI) has been increasingly utilized for the treatment of severe symptomatic aortic stenosis in inoperable and high surgical risk patients. Recent advances in valve technology include repositionable scaffolds and smaller delivery systems, as well as improvement in periprocedural imaging. These advances have resulted in reduction of vascular complications, rates of paravalvular aortic regurgitation and periprocedural stroke and improved overall outcomes. Increasingly, TAVI is the preferred treatment for high-risk surgical patients with severe aortic stenosis. Consequently, there is growing interest for the use of TAVI in lower surgical risk patients. Furthermore, the role of TAVI has expanded to include valve-in-valve procedures for the treatment of degenerative bioprosthetic valves and bicuspid aortic valves. Questions remain in regard to the optimal management of concurrent coronary artery disease, strategies to minimize valve leaflet restriction and treatment of conduction abnormalities as well as identifying newer indications for its use