Mixed plaque on coronary CT angiography predicts atherosclerotic events in asymptomatic intermediate-risk individuals.

OBJECTIVE: Coronary CT angiography (CCTA) permits both qualitative and quantitative analysis of atherosclerotic plaque and may be a suitable risk modifier in assessing patients at intermediate risk of atherosclerotic cardiovascular disease. We sought to determine the association of plaque components with long-term major adverse cardiovascular events (MACEs) in asymptomatic intermediate-risk patients, compared with conventional coronary artery calcium (CAC) score. METHODS: 100 intermediate-risk patients underwent double-blinded CCTA. Follow-up was conducted at 10 years and data were cross-referenced with the National Death Index. The primary outcome was MACE, which was a composite of death, acute coronary syndrome (ACS), revascularisation and stroke. RESULTS: The median time from CCTA to follow-up was 9.5 years. 83 patients completed follow-up interview and mortality data were available on all 100 patients. MACE occurred in 17 (20.5%) patients, which included 2 (2%) deaths, 8 (10%) ACS, 3 (4%) strokes and 5 (6%) revascularisation procedures. 47 (57%) patients had mixed plaque, which was predictive of MACE (OR 4.68 (95% CI 1.19 to 18.5) p=0.028). The burden of non-calcified and mixed plaque, defined by non-calcified plaque segment stenosis score, was also a predictor of long-term MACE (OR 1.59 (95% CI 1.18 to 2.13) p=0.002). Neither calcified plaque (OR 3.92 (95% CI 0.80 to 19.3)) nor CAC score (OR 1.01 (95% CI 0.999 to 1.02)) was associated with long-term MACE. CONCLUSION: The presence and burden of mixed plaque on CCTA is associated with an increased risk of long-term MACE among asymptomatic intermediate-risk patients and is a superior predictor to CAC score.

The challenge of risk stratification in hypertrophic cardiomyopathy: Clinical, genetic and imaging insights from a quaternary referral centre.

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is the commonest genetic cardiomyopathy and may result in sudden cardiac death (SCD). Clinical risk stratification scores are utilised to estimate SCD risk and determine potential utility of a primary prevention implantable cardioverter defibrillator (ICD). METHODS: Patients with a confirmed diagnosis of HCM from a quaternary HCM service were defined according to clinical characteristics, genetic profiles and cardiac imaging results. European Risk-SCD score and American Heart Association / American College of Cardiology (AHA/ACC) Score were calculated. The primary outcome was cardiac arrest. RESULTS: 380 patients with HCM were followed up for a median of 6.4 years. 18 patients (4.7%) experienced cardiac arrest, with predictive factors being younger age (37.2 vs 54.4 years, p = 0.0041), unexplained syncope (33.3% vs 9.4%, p = 0.007), non-sustained ventricular tachycardia (50.0% vs 12.7%, p < 0.0001), increased septal thickness (21.5 vs 17.5 mm, p = 0.0003), and presence of a sarcomeric gene mutation (100.0% vs 65.8%, p = 0.038). The Risk-SCD and AHA/ACC scores had poor agreement (kappa coefficient 0.38). Risk-SCD score had poor sensitivity (44.4%), classifying 55.6% of patients with cardiac arrest as low-risk but was highly specific (93.7%). AHA/ACC risk score did not discriminate between groups significantly. 20 patients (5.3%) died, with most >60-year-olds having a non-cardiac cause of death (p = 0.0223). CONCLUSION: This study highlights limited (38%) agreement between the Risk-SCD and AHA/ACC scores. Most cardiac arrests occurred in ostensibly low or medium-risk patients under both scores. Appropriate ICD selection remains challenging. Incorporating newer risk markers such as HCM genotyping and myocardial fibrosis quantification by cardiac MRI may assist future risk refinement.

Takotsubo cardiomyopathy in the setting of thyroid storm.

A woman in her 50s with a background of chronic obstructive pulmonary disease secondary to smoking presented with intermittent chest tightness, dyspnoea and vomiting for 4 days. A presumed diagnosis of acute coronary syndrome (ACS) was made based on dynamic ischaemic ECG changes and elevation in high-sensitivity cardiac troponin T levels. She underwent emergent coronary angiography which demonstrated mild coronary artery disease with left ventriculography suggestive of mid-wall variant Takotsubo cardiomyopathy. Thyroid function tests performed to investigate sinus tachycardia were consistent with hyperthyroidism, and her thyroid-stimulating hormone receptor antibody was elevated. A diagnosis of thyroid storm was made in the setting of a newly diagnosed Graves' disease and the patient was subsequently commenced on guideline-based therapy. This case demonstrates that Takotsubo cardiomyopathy, a mimic of ACS, is a possible complication of thyroid storm and therefore hyperthyroidism should be considered in the list of differentials in patients presenting with Takotsubo cardiomyopathy.

Acute Coronary Syndrome in the COVID-19 Pandemic: Reduced Cases and Increased Ischaemic Time.

BACKGROUND: The COVID-19 pandemic has led to unprecedented stress on health care systems, and has affected acute coronary syndrome treatment at every step. This study aimed to examine the impact of COVID-19 on patient presentations with acute coronary syndromes during the first and second pandemic wave in Melbourne, Victoria. METHOD: A retrospective cohort study of adults presenting with cute coronary syndrome during the first pandemic wave from 1 March 2020 to 31 April 2020 and the second pandemic wave from 1 July 2020 to 31 August 2020 was compared to a control period from 1 March to 31 April 2019 at a single sub-tertiary referral centre in Melbourne, Victoria servicing a catchment area with a relatively high incidence of COVID-19 cases. RESULTS: Three-hundred-and-thirty-five (335) patients were hospitalised with acute coronary syndromes across all three time periods. The total number of patients presenting with an acute coronary syndrome was reduced during the pandemic, with a higher proportion of ST elevation myocardial infarctions. Ischaemic times increased with time from symptom onset to first medical contact rising from 191 minutes in the control period to 292 minutes in the first wave (p=0.06) and 271 minutes in the second wave (p=0.06). Coronary angiography with subsequent revascularisation significantly increased from 55% in the control period undergoing revascularisation to 69% in the first wave (p<0.001) and 74% in the second wave (p<0.001). CONCLUSION: A concerning reduction in acute coronary presentations occurred during the COVID-19 pandemic, associated with longer ischaemic times and a higher proportion requiring revascularisation. It is crucial that public awareness campaigns are instituted to address the contributing patient factors in future waves.

Non-hyperaemic assessment of coronary ischaemia: application of machine learning techniques.

Aims: Hyperaemic and non-hyperaemic pressure ratios (NHPR) are routinely used to identify significant coronary lesions. Machine learning (ML) techniques may help better understand these indices and guide future practice. This study assessed the ability of a purpose-built ML algorithm to classify coronary ischaemia during non-hyperaemia compared with the existing gold-standard technique (fractional flow reserve, FFR). Further, it investigated whether ML could identify components of coronary and aortic pressure cycles indicative of ischaemia. Methods and results: Seventy-seven coronary vessel lesions (39 FFR defined ischaemia, 53 patients) with proximal and distal non-hyperaemic pressure waveforms and FFR values were assessed using supervised and unsupervised learning techniques in combination with principal component analysis (PCA). Fractional flow reserve measurements were obtained from the right coronary artery (13), left anterior descending (46), left circumflex (11), left main (1), obtuse marginal (2), and diagonal (4). The most accurate supervised learning classification utilized whole-cycle aortic with diastolic distal blood pressure waveforms, yielding a classification accuracy of 86.9% (sensitivity 86.8%, specificity 87.2%, positive predictive value 86.8%, negative predictive value 87.2%). Principal component analysis showed subtle variations in coronary pressures at the start of diastole have significant relation to ischaemia, and whole-cycle aortic pressure data are important for determining ischaemia. Conclusions: Our ML algorithm classifies significant coronary lesions with accuracy similar to previous studies comparing time-domain NHPRs with FFR. Further, it has identified characteristics of pressure waveforms that relate to function. These results provide an application of ML to ischaemia requiring only standard data from non-hyperaemic pressure measurements.

Home- and hospital-based exercise training programme after Fontan surgery.

BACKGROUND: Exercise training has been shown to increase exercise capacity in survivors of Fontan surgery. The geographic distribution of the Fontan population has been a barrier to hospital-based exercise training programmes. The objective of this study was to establish whether a home exercise training programme could achieve similar improvements to a hospital programme. METHODS: Adolescents with a Fontan circulation aged 12-19 years were prospectively recruited in a hospital or home exercise training programme. Patients underwent cardiopulmonary exercise testing and completed the Paediatric Quality of Life Inventory at initial assessment and after completion of an 8-week programme. Both groups performed two 1-hour training sessions per week. Patients in the home training programme had their first session in the hospital, and then progressed independently with one phone consult per week and one home visit by a physiotherapist. RESULTS: In total, 17 patients, with a mean age of 15±3 years, completed the training programme (six hospital). Characteristics and baseline performance of patients were similar in both groups. Oxygen consumption at anaerobic threshold increased from 19.3±3.8 to 21.6±6.0 ml/kg/minute (p=0.02) and peak oxygen pulse increased from 8.8±2.5 to 9.5±2.7 ml/beat (p=0.049). Total quality of life scale improved from 68 to 74% (p=0.01) and psychosocial health improved from 67 to 74% (p=0.02). No patient experienced training-related complications. CONCLUSIONS: Exercise training is beneficial and most likely safe after Fontan, resulting in improved exercise capacity and self-reported quality of life. Home exercise training programmes are probably as effective as hospital programmes. Home exercise training programmes should be integrated in the follow-up care of patients undergoing Fontan surgery.

Should We Recommend Exercise after the Fontan Procedure?

BACKGROUND: The Fontan procedure, the last of a series of operations performed in patients with congenital heart defects, offers improved exercise capacity compared to baseline function but is still reduced compared to healthy peers. Exercise training may improve exercise tolerance but there is no consensus on the safety of this practice or the optimal training regimen. We performed a systematic literature review on the effects of exercise training in patients with a Fontan circulation. METHODS: Medline and Embase databases were systematically searched for articles regarding Fontan Procedure and cardiac rehabilitation. RESULTS: A total of 23 articles met all inclusion criteria; in total, 201 Fontan subjects were included. Characteristics of the exercise training programs varied significantly. There were no adverse effects related to training programs reported in the literature. Most studies reported benefit across various exercise parameters related to exercise tolerance. CONCLUSIONS: Exercise training is safe and beneficial in patients with a Fontan circulation. Exercise training should become a standard of care within this population. Physiological adaptation following exercise training needs to be investigated more extensively.