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Invasive coronary physiology has been applied by interventional cardiologists to guide the management of coronary artery disease (CAD), with well-defined thresholds applied to determine whether CAD should be managed with optimal medical therapy (OMT) alone or OMT and percutaneous coronary intervention (PCI). There are multiple modalities in clinical use, including hyperaemic and non-hyperaemic indices. Despite endorsement in the major guidelines, there are various factors which impact and confound the readings of invasive coronary physiology, both within the coronary tree and beyond. This review article aims to summarise the mechanisms by which these factors impact invasive coronary physiology, and distinguish factors that contribute to ischaemia from confounding factors. The potential for mis-classification of ischaemic status is highlighted. Lastly, the authors identify targets for future research to improve the precision of physiology-guided management of CAD.

Aims: Assess the correlation between diameter stenosis, lesion length, location, diffuse coronary disease and with fractional flow reserve (FFR). Methods/Results: We performed quantitative coronary analysis analysis on 384 lesions with stable coronary artery disease undergoing FFR assessment. Vessels were 59.1% left anterior descending artery (LAD), 16.1% left circumflex artery and 14.8% right coronary artery. Median diameter stenosis was 58% ± 2.5 and median lesion length was 10 mm ± 7.36. 21% of vessels were diffusely diseased. Lesions were 33.6% proximal, 44% mid-vessel and 12% distal. Median FFR was 0.85. Diameter stenosis correlated with lower FFR (p < 0.005, odds ratio [OR]: 2.4 [95% CI: 0.99–5.63]). There was no association between lesion length, location, number of proximal side branches and FFR. Vessels with diffuse disease had a nonsignificant trend for lower FFR (0.84 vs 0.85, p = 0.375, OR: 1.26 [95% CI: 0.76–2.09]). LAD lesions had significantly lower FFR compared with non-LAD (p < 0.001, OR: 2.55 [95% CI: 1.61–4.04]); including left circumflex artery and right coronary artery lesions (p = 0.001, OR: 3.4 [95% CI: 1.7–6.9]) and p = 0.02, OR: 2.55 [95% CI: 1.17–4.34]). Conclusion: FFR is not related to lesion length, location or number of proximal branches.

Introduction: Cardiac complications of COVID-19 include acute cardiac injury, myopericarditis, cardiomyopathy and arrhythmias. This study aimed to describe the incidence of cardiac complications in patients admitted to hospital with COVID-19 in Australia. Methods: AUS-COVID is a multicentre observational cohort study across 21 Australian hospitals including all index hospitalisations with laboratory-proven COVID-19 in patients aged 18 years or older. All consecutive patients entered in the AUS-COVID Registry by 28 th January 2021 were included in the present study. Results: Six hundred and forty-four hospitalised patients (62.5 ± 20.1 years old, 51.1% male) with COVID-19 were enrolled in the study. Overall in-hospital mortality was 14.3%. Twenty (3.6%) patients developed new atrial fibrillation or flutter during admission and 9 (1.6%) patients were diagnosed with new heart failure or cardiomyopathy. Three (0.5%) patients developed high grade atrioventricular (AV) block. Two (0.3%) patients were clinically diagnosed with pericarditis or myopericarditis. Among the 295 (45.8%) patients with at least one troponin measurement, 99 (33.6%) had a peak troponin above the upper limit of normal (ULN). In-hospital mortality was higher in patients with raised troponin (32.3% vs 6.1%, p Conclusions: Among patients with COVID-19 requiring hospitalisation in Australia, troponin elevation was common but clinical cardiac sequelae were uncommon. The incidence of atrial arrhythmias and troponin elevation was greatest in patients 65 years and older. Trial registration: AUS-COVID. ACTRN12620000486921. http://www.anzctr.org.au/

Introduction: To assess whether hypertension is an independent risk factor for mortality amongst patients hospitalised with COVID-19 and to evaluate the impact of angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) on mortality in patients with a background of hypertension. Methods: This observational cohort study included all consecutive index hospitalisations with laboratory proven COVID-19 aged 18 years or older across 21 Australian hospitals entered in the AUS-COVID Registry by 22nd January 2021. Patients were excluded if their past medical or medication history was not available or if they were transferred to another hospital in which case mortality outcomes were not available. Registry data were analysed for in-hospital mortality in patients with comorbidities including hypertension, and baseline treatment with ACE inhibitors or ARBs. Results: 546 consecutive patients (62.9±19.8 years old, 51.8% male) hospitalised with COVID-19 were enrolled. In the multivariable model, significant predictors of mortality were age (aOR 1.09, 95% CI 1.07-1.12, p Conclusions: In patients hospitalised with COVID-19, pre-existing hypertension was the most prevalent comorbidity but was not independently associated with mortality. Similarly, the baseline use of ACE inhibitors or ARBs had no independent association with in-hospital mortality.

AimsDormant 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. The aim of this study was to quantify collateral myocardial perfusion during balloon occlusion in patients with coronary artery disease (CAD).Methods and resultsPatients 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 hours after PTCA.The study included 22 patients (median [interquartile range] age 68 [54-72] years, 10 (45%) female). The perfusion defect extent was 19 [11–38] % of the LV, and the collateral perfusion at rest was 64 [58-67]% of normal.ConclusionThis 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.Graphical abstractDormant collaterals are highly prevalent but the magnitude of myocardial perfusion provided by immediate coronary collateral recruitment during acute occlusion in humans is unknown. Patients without angiographically visible collaterals underwent intravenous injection with 99mTc-sestamibi during coronary balloon inflation followed by SPECT imaging. A control scan was performed 24 hours later..Median collateral perfusion during coronary occlusion was 64% of normal.

We aimed to evaluate the safety and feasibility of rotational atherectomy (RA) in patients with severe aortic stenosis (AS).Heavily calcified coronary lesions are commonly encountered in elderly patients with severe AS who are being considered for transcatheter aortic valve implantation. The use of RA in these patients is controversial as they may be at a higher risk of complications.We retrospectively enrolled patients with severe AS who underwent RA across two hospitals from March 2010 to September 2019. Patients with severe AS prior to or within 8 weeks of RA were included.Twenty-seven (27) consecutive patients (83±5.2 yrs 63% male) with severe AS (peak velocity 4.1±0.5 m/s, mean gradient 40.0±10.2 mmHg) were enrolled and 31 lesions were treated with RA across 30 separate procedures. Three (3) (11.1%) patients had left ventricular ejection fraction ≤30%. Nine (9) (30%) procedures involved percutaneous coronary intervention of multiple arteries, with most lesions in the right coronary artery (51.6%) and left anterior descending artery (32.3%). Three (3) (9.7%) lesions were in the left main stem. RA-facilitated stenting was successful in all lesions. There were no episodes of coronary perforation or slow-flow/no-reflow. There was one episode of coronary dissection in an artery that did not undergo RA, which was successfully treated with a drug-eluting stent. There were no deaths within 30 days and three deaths (11.1%) within 1 year.Rotational atherectomy in patients with severe AS is feasible and has a low rate of procedural complications.