Cardiac Complications in Patients Hospitalised With COVID-19 in Australia.

OBJECTIVES: Describe the incidence of cardiac complications in patients admitted to hospital with COVID-19 in Australia. DESIGN: Observational cohort study. SETTING: Twenty-one (21) Australian hospitals. PARTICIPANTS: Consecutive patients aged ≥18 years admitted to hospital with laboratory confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. MAIN OUTCOME MEASURES: Incidence of cardiac complications. RESULTS: Six-hundred-and-forty-four (644) hospitalised patients (62.5±20.1 yo, 51.1% male) with COVID-19 were enrolled in the study. Overall in-hospital mortality was 14.3%. Twenty (20) (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 (3) (0.5%) patients developed high grade atrioventricular (AV) block. Two (2) (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<0.001). New onset atrial fibrillation or flutter (6.4% vs 1.0%, p=0.001) and troponin elevation above the ULN (50.3% vs 16.4%, p<0.001) were more common in patients 65 years and older. There was no significant difference in the rate of cardiac complications between males and females. 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.

Performance and Safety of Transfemoral TAVI With SAPIEN XT in Australian Patients With Severe Aortic Stenosis at Intermediate Surgical Risk: SOLACE-AU Trial.

BACKGROUND: To determine the safety and performance of the SAPIEN XT transcatheter heart valve (THV) in Australian patients with severe aortic stenosis (AS) and intermediate surgical risk. METHODS: Eligible patients in this multi-centre, prospective, consecutively enrolled, non-randomised, clinical trial, received transcatheter aortic valve replacement via femoral artery access. Follow-up visits were at discharge, 30 days, and 6, 12, and 24 months. The primary endpoint was Valve Academic Research Consortium-2 composite safety at 30 days: all-cause mortality, all stroke, life-threatening bleeding, acute kidney injury-Stage 3, coronary artery obstruction requiring intervention, major vascular complication, and valve-related dysfunction requiring repeat procedure. Other endpoints were device success (successful vascular access, delivery, and deployment; correct position; intended performance mean aortic valve gradient <20 mmHg, mild or less paravalvular aortic regurgitation [PAR]; and only one valve implanted) and New York Heart Association functional class (NYHA). Kaplan-Meier (KM) estimates were calculated for the primary endpoint. RESULTS: At baseline, mean patient (N=199) age was 85.5 years, mean Society of Thoracic Surgeon score was 5.9, and 78.4% were in NYHA class III/IV. The primary composite endpoint KM estimate was 12.1%. Device success was 88.8%. SAPIEN XT was implanted in the proper location in 98.5% (n=2: valve-in-valve procedures, n=1: no implant due to left main coronary artery occlusion). No device malfunctions were reported. The post procedure PAR was mild or less in 93.8% of patients. Mean aortic gradient decreased from baseline (50.0 mmHg) to 2 years (10.3 mmHg). Most patients (90.9%) were in NYHA class I/II at 30 days. New permanent pacemaker rate was 8.1%. Stroke at 30 days was 3.5% (1.5% disabling). CONCLUSION: SAPIEN XT was safe and improved heart failure symptoms and valve haemodynamics in this cohort of Australian patients.

Three-year clinical outcomes of patients treated with everolimus-eluting bioresorbable vascular scaffolds: Final results of the ABSORB EXTEND trial.

BACKGROUND: There is still limited data on the very long term clinical outcomes after ABSORB BRS in daily practice. We sought to evaluate the 3 year-performance of the Absorb bioresorbable vascular scaffolds for the treatment of low/moderate complexity patients enrolled in the ABSORB EXTEND trial. METHODS: ABSORB EXTEND is a prospective, single-arm, open-label clinical study in which 812 patients were enrolled at 56 sites. This study allowed the treatment of lesions ≤28 mm in length and reference vessel diameter of 2.0-3.8 mm (as assessed by on-line QCA). To determine the independent predictors of MACE, a multivariable logistic regression model was built using a stepwise (forward/backward) procedure. RESULTS: Average population age was 61 years and 26.5% had diabetes. Most patients had single target lesion (92.4%). Adequate scaffold deployment (PSP) was achieved in 14.2% of the cases. At three years, the composite endpoints of MACE and ischemia-driven target vessel failure were 9.2% and 10.6%, respectively. The cumulative rate of ARC definite/probable thrombosis was 2.2%, with 1.2% of the cases occurring after the 1st year. Independent predictors of MACE were hypertension and the need for "bail out" stent. CONCLUSION: At three-year follow-up, the use of ABSORB in low/moderate complex PCI was associated with low and acceptable rates of major adverse clinical events, despite the infrequent use of the recommended contemporary scaffold deployment technique. However, scaffold thrombosis rate was higher than reported with current generation of metallic DES. The study is registered on clinicaltrials.gov (unique identifier NCT01023789).

Balloon Aortic Valvuloplasty in the Transcatheter Valve Era: Single Centre Indications and Early Safety Data in a High Risk Population.

BACKGROUND: The introduction of transcatheter aortic valve implantation (TAVI) has generated a renewed interest in the techniques available to treat high-risk patients with severe aortic stenosis (AS). We report our single centre experience with balloon aortic valvuloplasty (BAV) focussing on indications, procedural success and 30-day outcomes. METHODS: We retrospectively reviewed all patients that underwent BAV procedures at our institution between August 2012 and August 2014. Procedural success and complications were adjudicated according to VARC-2 criteria. RESULTS: Fifty-one consecutive adult patients with severe symptomatic AS underwent a total of 55 BAV procedures. The patients had a mean age of 88±5.7 years and all had extensive comorbidities with a high surgical risk (mean logistic EuroSCORE of 25.22%±14.5%). Indications for BAV included palliation of symptoms n=42 (76%); bridge to definitive valve replacement (n=6, 11%); and evaluation of response (n=6, 11%). The procedure was completed in all patients with no intraprocedural deaths (within 24hours) and low 30-day mortality at 3.9% (n=2). Minor vascular complications occurred in 11.8% (n=6), whilst permanent pacemaker implantation was required in 5.8% (n=3). There were no cases of myocardial infarction, stroke, tamponade, severe aortic regurgitation or major vascular complications during 30-day follow-up. CONCLUSIONS: Balloon aortic valvuloplasty may be performed safely and effectively with high procedural success and low 30-day complications, even in a very high-risk and elderly cohort of patients in whom the role of TAVI is uncertain or inappropriate.

Design and Rationale for the Endothelin-1 Receptor Antagonism in the Prevention of Microvascular Injury in Patients with non-ST Elevation Acute Coronary Syndrome Undergoing Percutaneous Coronary Intervention (ENDORA-PCI) Trial.

PURPOSE: Peri-procedural myocardial infarction (PMI) occurs in a small but significant portion of patients undergoing percutaneous intervention (PCI). The underlying mechanisms are complex and may include neurohormonal activation and release of vasoactive substances resulting in disruption of the coronary microcirculation. Endothelin in particular has been found in abundance in atherosclerotic plaques and in systemic circulation following PCI, and may be a potential culprit for PMI through its action on microvascular vasoconstriction, and platelet and neutrophil activation. In this study we aim to characterize the behavior of the coronary microcirculation during a PCI with the index of microvascular resistance (IMR) and the effect of peri-procedural endothelin antagonism. METHODS: The ENDORA-PCI trial is a randomized, double-blind, placebo-controlled, single-center clinical trial designed to evaluate the efficacy of endothelin antagonism in attenuating the peri-procedural rise in IMR as a surrogate marker for PMI. The patients of interest are those with non-ST elevation acute coronary syndrome (NSTEACS) undergoing PCI, and we aim to recruit 52 patients overall to give the study a power of 80 % at an α level of 5 %. Patients will be randomized in a 1:1 fashion to either Ambrisentan, an endothelin antagonist, or placebo, prior to their PCI. IMR will be measured before and after PCI. The primary endpoint is the difference in peri-procedural changes in patients' IMR between the two groups. CONCLUSION: The ENDORA-PCI study will investigate whether endothelin antagonism with Ambrisentan attenuates the peri-procedural rise in IMR in patients with NSTEACS undergoing PCI, and thus potentially the risk of PMI.

Coronary stent technology: a narrative review.

Coronary angioplasty and coronary artery stents have revolutionised interventional cardiology. Contemporary coronary stent technology continues to seek to improve on the outcomes of the preceding generation of devices by refining their design, structure and component materials. These technologies include new generations of drug-eluting stents, non-polymeric stents, bioresorbable polymer-coated stents, and fully bioresorbable scaffolds. This review discusses the evolution of coronary stent technology, the efficacy and safety of currently available devices, and the rationale for new generation platforms as efforts continue to design the ideal coronary stent technology.

Phaeochromocytoma presenting with labile blood pressures following coronary artery bypass grafting.

Pheochromocytomas have been reported prior to and during coronary artery bypass surgery. We present a patient with an undiagnosed pheochromocytoma who presented with labile hypertension following coronary artery bypass surgery. This case calls attention to the inclusion of an undiagnosed pheochromocytoma in the differential diagnosis for all patients who develop labile hypertension in the postoperative period following cardiac surgery.

Drug-eluting Balloon Versus Second Generation Drug Eluting Stents in the Treatment of In-stent Restenosis: A Systematic Review and Meta-analysis.

BACKGROUND: In-stent restenosis (ISR) remains a significant mode of stent failure following PCI. The optimal treatment strategy, however, remains undefined and the role of drug-eluting balloons (DEB) in the management of ISR is also unclear. METHODS: A meta-analysis was performed to compare the efficacy of DEB in the treatment of ISR against second generation drug eluting stents (DES). RESULTS: Seven studies comprised of 1,065 patients were included for analysis. The follow-up period ranged from 12-25 months. The use of DEB was associated with an inferior acute gain in minimal luminal diameter (MLD) (0.36, 95% CI: 0.16-0.57mm), higher late loss in MLD (0.11, 0.02-0.19mm) and a higher binary restenosis rate at follow-up (risk ratio: 2.24, 1.49-3.37). No significant differences were noted in the overall incidence of the analysed clinical parameters between the two groups. When only the randomised controlled trials (RCT) were considered however, there was a strong trend towards higher target lesion revascularisation (TLR; 9.9% vs. 3.6%; RR: 2.5, p=0.07) and a significantly higher major adverse cardiovascular event (MACE) rate (15.7% vs. 8.8%; RR 1.78; p=0.02) with DEB. CONCLUSION: While equipoise has been demonstrated in selected clinical outcomes between DEB and second generation DES in the treatment of ISR, the suboptimal angiographic outcome at follow-up and the higher TLR and MACE rates associated with DEB observed in the RCT are concerning. The results of the present analysis should be regarded as preliminary, although the generalised adoption of DEB in the treatment of ISR currently cannot be recommended.

Periprocedural myocardial infarction is associated with increased mortality in patients with coronary artery bifurcation lesions after implantation of a drug-eluting stent.

OBJECTIVES: The present study aimed to investigate the association between periprocedural myocardial infarction (PMI), defined by creatine kinase (CK)-MB or troponin I (TNI) level elevations >5 times the 99 th percentile of the upper reference limit (URL) within 48 hr after implantation of a drug-eluting stent (DES), and one-year mortality in patients with coronary bifurcation. BACKGROUND: PMI is reported to be associated with increased one-year mortality after DES implantation. However, the prevalence and association of PMI with mortality after stenting bifurcation lesions remains unclear. METHODS: We prospectively followed 1,971 patients with true coronary bifurcations who underwent DES implantation as part of the multicenter DEFINITION study. These patients were grouped into categories based on PMI outcome: Non-PMI, CKMB-PMI, TNI-PMI, and CKMB/TNI-PMI. The primary endpoint was the rate of all-cause mortality at one year. RESULTS: PMI occurred in 11.4% of patients by CKMB criteria and 41.3% of patients by TNI criteria. At one-year follow-up, the mortality rate was 2.3% in the entire patient population. However, mortality was significantly higher in the CKMB-PMI (6.4%) and CKMB/TNI-PMI (6.1%) groups compared to the Non-PMI (1.7%) and TNI-PMI (2.1%) groups (all P < 0.05). A 10-fold increase in TNI levels resulted in similar PMI rate (5.2%) and mortality risk (adjusted HR 2.7, 95% CI 3.0-5.2) as a fivefold increase in CKMB levels. CONCLUSIONS: PMI, as defined by CKMB elevations following coronary bifurcation lesion stenting, was associated with increased one-year mortality. Additionally, to attain an equal frequency of PMI, the elevation in TNI levels needed to be twice as high as the elevation in CKMB levels.

Hyperbaric oxygen therapy for acute coronary syndrome.

BACKGROUND: Acute coronary syndrome (ACS), includes acute myocardial infarction and unstable angina, is common and may prove fatal. Hyperbaric oxygen therapy (HBOT) will improve oxygen supply to the threatened heart and may reduce the volume of heart muscle that perishes. The addition of HBOT to standard treatment may reduce death rate and other major adverse outcomes.This an update of a review previously published in May 2004 and June 2010. OBJECTIVES: The aim of this review was to assess the evidence for the effects of adjunctive HBOT in the treatment of ACS. We compared treatment regimens including adjunctive HBOT against similar regimens excluding HBOT. Where regimens differed significantly between studies this is clearly stated and the implications discussed. All comparisons were made using an intention to treat analysis where this was possible. Efficacy was estimated from randomised trial comparisons but no attempt was made to evaluate the likely effectiveness that might be achieved in routine clinical practice. Specifically, we addressed:Does the adjunctive administration of HBOT to people with acute coronary syndrome (unstable angina or infarction) result in a reduction in the risk of death?Does the adjunctive administration of HBOT to people with acute coronary syndrome result in a reduction in the risk of major adverse cardiac events (MACE), that is: cardiac death, myocardial infarction, and target vessel revascularization by operative or percutaneous intervention?Is the administration of HBOT safe in both the short and long term? SEARCH METHODS: We updated the search of the following sources in September 2014, but found no additional relevant citations since the previous search in June 2010 (CENTRAL), MEDLINE, EMBASE, CINAHL and DORCTHIM. Relevant journals were handsearched and researchers in the field contacted. We applied no language restrictions. SELECTION CRITERIA: Randomised studies comparing the effect on ACS of regimens that include HBOT with those that exclude HBOT. DATA COLLECTION AND ANALYSIS: Three authors independently evaluated the quality of trials using the guidelines of the Cochrane Handbook and extracted data from included trials. Binary outcomes were analysed using risk ratios (RR) and continuous outcomes using the mean difference (MD) and both are presented with 95% confidence intervals. We assessed the quality of the evidence using the GRADE approach. MAIN RESULTS: No new trials were located in our most recent search in September 2014. Six trials with 665 participants contributed to this review. These trials were small and subject to potential bias. Only two reported randomisation procedures in detail and in only one trial was allocation concealed. While only modest numbers of participants were lost to follow-up, in general there is little information on the longer-term outcome for participants. Patients with acute coronary syndrome allocated to HBOT were associated with a reduction in the risk of death by around 42% (RR: 0.58, (95% CI 0.36 to 0.92), 5 trials, 614 participants; low quality evidence).In general, HBOT was well-tolerated. No patients were reported as suffering neurological oxygen toxicity and only a single patient was reported to have significant barotrauma to the tympanic membrane. One trial suggested a significant incidence of claustrophobia in single occupancy chambers of 15% (RR of claustrophobia with HBOT 31.6, 95% CI 1.92 to 521). AUTHORS' CONCLUSIONS: For people with ACS, there is some evidence from small trials to suggest that HBOT is associated with a reduction in the risk of death, the volume of damaged muscle, the risk of MACE and time to relief from ischaemic pain. In view of the modest number of patients, methodological shortcomings and poor reporting, this result should be interpreted cautiously, and an appropriately powered trial of high methodological rigour is justified to define those patients (if any) who can be expected to derive most benefit from HBOT. The routine application of HBOT to these patients cannot be justified from this review.

Cardiologist operated ultrasound guided thrombin injection as a safe and efficacious first line treatment for iatrogenic femoral artery pseudoaneurysms.

OBJECTIVES: To assess the efficacy and safety of ultrasound guided thrombin injection (UGTI) as a first line treatment for post arterial cannulation iatrogenic femoral artery pseudoaneurysms (IFAP). BACKGROUND: IFAPs complicate up to 1% of diagnostic and 8% of interventional cardiac catheterisation procedures. UGTI remains a second line or non-attempted treatment after ultrasound guided manual compression (UGMC) and surgical repair in many centres. METHODS: A retrospective review was undertaken of 121 consecutive patients who received UGTI as a first line treatment for IFAPs following cardiac diagnostic, interventional or catheter ablation procedures between 1999 and 2011 at our centre. The mean patient age was 70.7 years and 63% were male. At the time of injection, 89% were on at least one antiplatelet or anticoagulant. Pseudoaneurysms had a mean maximum dimension of 26.7mm (range 10-122mm) and 25% were multilobed. UGTI was performed by an interventional cardiologist with a mean bovine thrombin dose of 648 IU (range 50-5000 IU). RESULTS: Primary success, defined as immediate IFAP thrombosis with UGTI, was achieved in 111 (92%) patients. Recurrence occurred in seven patients, three of whom required surgical repair. Multilobed IFAPs had significantly lower primary success rates than unilobed IFAPs (80% vs. 96%, p=0.016). Antiplatelet and anticoagulant use and IFAP size did not significantly affect outcomes. UGTI was not associated with any serious complications (such as thromboembolism, aneurysm rupture, venous thrombosis or abscess formation). CONCLUSION: Interventional cardiologist operated UGTI should be considered as a first line therapy for uncomplicated IFAPs following interventional and diagnostic cardiac procedures. Despite high rates of concomitant antiplatelet and antithrombotic therapy, initial thrombosis rates exceeded 90% and we did not experience serious complications.

Patent foramen ovale influences the presentation of decompression illness in SCUBA divers.

BACKGROUND: Few have examined the influence of patent foramen ovale (PFO) on the phenotype of decompression illness (DCI) in affected divers. METHODOLOGY: A retrospective review of our database was performed for 75 SCUBA divers over a 10-year period. RESULTS: Overall 4,945 bubble studies were performed at our institution during the study period. Divers with DCI were more likely to have positive bubble studies than other indications (p<0.001). Major DCI was observed significantly more commonly in divers with PFO than those without (18/1,000 v.s. 3/1,000, p=0.02). Divers affected by DCI were also more likely to require a longer course of hyperbaric oxygen therapy (HBOT) if PFO was present (p=0.038). If the patient experienced one or more major DCI symptoms, the odds ratio of PFO being present on a transoesophageal echocardiogram was 3.2 (p=0.02) compared to those who reported no major DCI symptoms. CONCLUSION: PFO is highly prevalent in selected SCUBA divers with DCI, and is associated with a more severe DCI phenotype and longer duration of HBOT. Patients with unexpected DCI with one or more major DCI symptoms should be offered PFO screening if they choose to continue diving, as it may have considerable prognostic and therapeutic implications.

Prognostic Significance of Peri-procedural Myocardial Infarction in the Era of High Sensitivity Troponin: A Validation of the Joint ACCF/AHA/ESC/WHF Universal Definition of Type 4a Myocardial Infarction with High Sensitivity Troponin T.

AIMS: This study aims to validate the joint ACCF/AHA/ESC/WHF Universal Definition of peri-procedural myocardial infarction (PMI) with high sensitivity troponin T (hsTnT). METHODS: A retrospective cohort study encompassing patients admitted to our institution between May 2012 and April 2013 was performed. RESULTS: 630 patients underwent percutaneous coronary interventions during the study period. Among them, 459 patients met the inclusion criteria and were eligible for analyses. 76.9% of these patients were male, while the mean age was 68.6. PMI was observed in 4.3% of the patients based on the Universal Definition. The predictors of PMI were chronic kidney disease (OR: 3.0, p=0.026), family history of cardiovascular disease (OR: 2.7, p=0.043) and use of IIb/IIIa inhibitors (OR 4.2, p=0.01). MACE was reported in 4.4% of the patients at 12 months, and was significantly and independently associated with PMI (OR 7.3, p=0.003) in a multivariate model which accounted for lesion complexity, patients' baseline clinical information, dual-antiplatelet status at follow-up and various procedural characteristics. The post-procedural hsTnT was much higher in those who suffered MACE than those who did not (156 v.s. 43 ng/L, p<0.001). CONCLUSION: PMI as defined by the current Universal Definition using hsTnT is an independent predictor of adverse clinical outcome at 12 months in patients undergoing PCI. Accordingly, PMI remains a clinically relevant factor in current practice and should be considered a key outcome measure in clinical trials and a potential target for therapy.

Abbreviated or Standard Dual Antiplatelet Therapy by Sex in Patients at High Bleeding Risk: A Prespecified Secondary Analysis of a Randomized Clinical Trial.

Importance: Abbreviated dual antiplatelet therapy (DAPT) reduces bleeding with no increase in ischemic events in patients at high bleeding risk (HBR) undergoing percutaneous coronary intervention (PCI). Objectives: To evaluate the association of sex with the comparative effectiveness of abbreviated vs standard DAPT in patients with HBR. Design, Setting, and Patients: This prespecified subgroup comparative effectiveness analysis followed the Management of High Bleeding Risk Patients Post Bioresorbable Polymer Coated Stent Implantation With an Abbreviated vs Standard DAPT Regimen (MASTER DAPT) trial, a multicenter, randomized, open-label clinical trial conducted at 140 sites in 30 countries and performed from February 28, 2017, to December 5, 2019. A total of 4579 patients with HBR were randomized at 1 month after PCI to abbreviated or standard DAPT. Data were analyzed from July 1 to October 31, 2022. Interventions: Abbreviated (immediate DAPT discontinuation, followed by single APT for ≥6 months) or standard (DAPT for ≥2 additional months, followed by single APT for 11 months) treatment groups. Main Outcomes and Measures: One-year net adverse clinical events (NACEs) (a composite of death due to any cause, myocardial infarction, stroke, or major bleeding), major adverse cardiac or cerebral events (MACCEs) (a composite of death due to any cause, myocardial infarction, or stroke), and major or clinically relevant nonmajor bleeding (MCB). Results: Of the 4579 patients included in the analysis, 1408 (30.7%) were women and 3171 (69.3%) were men (mean [SD] age, 76.0 [8.7] years). Ischemic and bleeding events were similar between sexes. Abbreviated DAPT was associated with comparable NACE rates in men (hazard ratio [HR], 0.97 [95% CI, 0.75-1.24]) and women (HR, 0.87 [95% CI, 0.60-1.26]; P = .65 for interaction). There was evidence of heterogeneity of treatment effect by sex for MACCEs, with a trend toward benefit in women (HR, 0.68 [95% CI, 0.44-1.05]) but not in men (HR, 1.17 [95% CI, 0.88-1.55]; P = .04 for interaction). There was no significant interaction for MCB across sex, although the benefit with abbreviated DAPT was relatively greater in men (HR, 0.65 [95% CI, 0.50-0.84]) than in women (HR, 0.77 [95% CI, 0.53-1.12]; P = .46 for interaction). Results remained consistent in patients with acute coronary syndrome and/or complex PCI. Conclusions and Relevance: These findings suggest that women with HBR did not experience higher rates of ischemic or bleeding events compared with men and may derive particular benefit from abbreviated compared with standard DAPT owing to these numerically lower rates of events. Trial Registration: ClinicalTrials.gov Identifier: NCT03023020.

New generation coronary stent technology--is the future biodegradable?

A new generation of drug eluting coronary stents are undergoing clinical trial evaluation and being introduced into clinical practice. These technologies comprise a broad range of innovations and include non-polymeric stents, biodegradable polymer coated stents and fully biodegradable scaffolds. The new devices are designed to improve long-term safety and efficacy and overcome limitations associated with a durable polymer and a persistent metallic stent scaffold. At the present time, none have demonstrated convincing superiority over current second generation drug eluting stents and large, long-term randomised controlled trials are required.

Investigation into the effect of hyperbaric hyperoxia on serum cardiac Troponin T levels as a biomarker of cardiac injury.

Introduction: There is clinical equipoise as to whether hyperoxia is injurious to the myocardium, both in the setting of acute ischaemic insults and on the stable myocardium. This study examined the effect of extreme hyperoxia - in the form of hyperbaric oxygen treatment - on the myocardium through measurement of high-sensitivity cardiac troponin. Methods: Forty-eight individuals were enrolled to undergo a series of 30 exposures to hyperbaric oxygen for treatment of non-cardiac pathologies. High-sensitivity troponin T was measured before and after each session. Results: There was no clinically significant difference in troponin measurements following acute or recurrent sequential exposures to extreme hyperoxia, despite the studied patient population having a high rate of previous ischaemic heart disease or cardiovascular risk factors. Conclusions: This study demonstrates that profound hyperoxaemia does not induce any measurable cardiac injury at a biochemical level. Neither is there a reduction in cardiac troponin to suggest a cardioprotective effect of hyperbaric hyperoxia. This provides some reassurance as to the cardiac safety of the routine use of hyperbaric oxygen treatment in management of non-cardiac pathology.