Real-world performance and accuracy of stress echocardiography: the EVAREST observational multi-centre study.

AIMS: Stress echocardiography is widely used to identify obstructive coronary artery disease (CAD). High accuracy is reported in expert hands but is dependent on operator training and image quality. The EVAREST study provides UK-wide data to evaluate real-world performance and accuracy of stress echocardiography. METHODS AND RESULTS: Participants undergoing stress echocardiography for CAD were recruited from 31 hospitals. Participants were followed up through health records which underwent expert adjudication. Cardiac outcome was defined as anatomically or functionally significant stenosis on angiography, revascularization, medical management of ischaemia, acute coronary syndrome, or cardiac-related death within 6 months. A total of 5131 patients (55% male) participated with a median age of 65 years (interquartile range 57-74). 72.9% of studies used dobutamine and 68.5% were contrast studies. Inducible ischaemia was present in 19.3% of scans. Sensitivity and specificity for prediction of a cardiac outcome were 95.4% and 96.0%, respectively, with an accuracy of 95.9%. Sub-group analysis revealed high levels of predictive accuracy across a wide range of patient and protocol sub-groups, with the presence of a resting regional wall motion abnormalitiy significantly reducing the performance of both dobutamine (P < 0.01) and exercise (P < 0.05) stress echocardiography. Overall accuracy remained consistently high across all participating hospitals. CONCLUSION: Stress echocardiography has high accuracy across UK-based hospitals and thus indicates stress echocardiography is being delivered effectively in real-world practice, reinforcing its role as a first-line investigation in the assessment of patients with stable chest pain.

Obesity-related ventricular remodelling is exacerbated in dilated and hypertrophic cardiomyopathy.

BACKGROUND: Obesity causes significant cardiac remodelling even in health, and yet the contribution of this maladaptation in the setting of an additional cardiomyopathic process is poorly understood. Cardiovascular magnetic resonance is the gold-standard tool for assessing cardiac geometry, especially in an obese population, and hence perfectly suited to investigate this important question. METHODS: Using data from our extensive imaging registry (n=1,554), we documented the relationship between increasing BMI and left ventricular (LV) remodelling in patients with dilated (DCM; n=529) and hypertrophic cardiomyopathy (HCM; n=297), compared to the normal heart (n=728). RESULTS: Regardless of cardiac status, increasing BMI resulted in similar increases in LV stroke volume (P>0.18). However, there was a difference in the degree of LV cavity dilatation associated with this change in stroke volume; when compared to normal hearts [increase in end-diastolic volume of 0.7 mL per unit of rising BMI (mL/kg/m2)], there was a threefold greater LV cavity dilatation in DCM (+2.2 mL/kg/m2) and twofold greater in HCM (+1.9 mL/kg/m2, all P<0.04). Whilst obesity was related to LV hypertrophy in all groups (normal +1.3 g, DCM +2.2g, HCM +2.3 g/kg/m2, all P<0.001), additional obesity-related concentric LV remodelling only occurred in normal hearts and DCM (normal +0.006 vs. +0.003 mass:volume ratio, both P<0.001). CONCLUSIONS: In both DCM and HCM, the increase in stroke volume required by obesity appears to be achieved by excessive LV cavity dilatation. The impact of obesity on LV geometry was more pronounced in concomitant cardiovascular disease, and therefore carries potential to become an important therapeutic target in cardiomyopathy.

Magnetic resonance phase contrast velocity mapping for flow quantification in irregular heart rhythms using radial k-space ultrashort echo time imaging.

BACKGROUND: Phase contrast velocity mapping sequences utilising ultrashort echo time (UTE) radial k-space sequences have been used to reduce intravoxel dephasing at high velocities. We evaluated the accuracy of the UTE flow sequence for mitral regurgitation (MR) quantification, including patients with atrial fibrillation. METHODS: Forty patients underwent cardiac MRI for indirect MR quantification by assessment of aortic flow using a UTE phase contrast sequence (TE 0.65 ms) combined with left ventricular stroke volume. Retrospective ECG-gating was used in sinus rhythm (30 patients), prospective ECG-triggering in atrial fibrillation (10). MR was also quantified by a standard phase contrast sequence (TE 2.85 ms, standard flow method) and by comparing stroke volumes (volumetric method). RESULTS: UTE flow-derived MR measurement showed modest agreement in sinus rhythm (95% limits of agreement: ±38.2 ml; ±29.8%) and atrial fibrillation (±33.7 ml; ±30.3%) compared to standard flow assessment. There was little systematic bias in sinus rhythm (mean offset -4.4 ml /-3.5% compared to standard flow assessment), but a slight bias towards greater regurgitation in atrial fibrillation (+15.2 ml /+14.0%). There were wider limits of agreement between the UTE flow method and volumetric method than between the regular flow method and the volumetric method in sinus rhythm (±48.4 ml; ±36.4%; mean offset: -12.2 ml /-9.0%) and similar limits of agreement in atrial fibrillation (±29.6 ml; 25.8%; +12.0 ml /+10.3%). CONCLUSIONS: UTE flow imaging is inferior to conventional flow techniques for MR assessment in patients with sinus rhythm as well as atrial fibrillation. However, the number of atrial fibrillation patients in this initial study is small.

Cardiac MRI improves cardiovascular risk stratification in hazardous occupations.

BACKGROUND: The benefit of cardiovascular magnetic resonance Imaging (CMR) in assessing occupational risk is unknown. Pilots undergo frequent medical assessment for occult disease, which threatens incapacitation or distraction during flight. ECG and examination anomalies often lead to lengthy restriction, pending full investigation. CMR provides a sensitive, specific assessment of cardiac anatomy, tissue characterisation, perfusion defects and myocardial viability. We sought to determine if CMR, when added to standard care, would alter occupational outcome. METHODS: A retrospective review was conducted of all personnel attending the RAF Aviation Medicine Consultation Service (AMCS) for assessment of a cardiac anomaly, over a 2-year period. Those undergoing standard of care (history, examination, exercise ECG, 24 h-Holter and transthoracic echocardiography), and those undergoing a CMR in addition, were identified. The influence of CMR upon the final decision regarding flying restriction was determined by comparing the diagnosis reached with standard of care plus CMR vs. standard of care alone. RESULTS: Of the ~ 8000 UK military aircrew, 558 personnel were seen for cardiovascular assessment. Fifty-two underwent CMR. A normal TTE did not reliably exclude abnormalities subsequently detected by CMR. Addition of CMR resulted in an upgraded occupational status in 62% of those investigated, with 37% returning to unrestricted duties. Only 8% of referrals were undiagnosed following CMR. All these were cases of borderline chamber dilatation and reduction in systolic function in whom diagnostic uncertainty remained between physiological exercise adaptation and early cardiomyopathy. CONCLUSIONS: CMR increases the likelihood of a definitive diagnosis and of return to flying. This study supports early use of CMR in occupational assessment for high-hazard occupations.

An introduction to aviation cardiology.

The management of cardiovascular disease (CVD) has evolved significantly in the last 20 years; however, the last major publication to address a consensus on the management of CVD in aircrew was published in 1999, following the second European Society of Cardiology conference of aviation cardiology experts. This article outlines an introduction to aviation cardiology and focuses on the broad aviation medicine considerations that are required to manage aircrew appropriately and optimally (both pilots and non-pilot aviation professionals). This and the other articles in this series are born out of a 3 year collaborative working group between international military aviation cardiologists and aviation medicine specialists, many of whom also work with and advise civil aviation authorities, as part of a North Atlantic Treaty Organization (NATO) led initiative to address the occupational ramifications of CVD in aircrew (HFM-251). This article describes the types of aircrew employed in the civil and military aviation profession in the 21st century; the types of aircraft and aviation environment that must be understood when managing aircrew with CVD; the regulatory bodies involved in aircrew licensing and the risk assessment processes that are used in aviation medicine to determine the suitability of aircrew to fly with medical (and specifically cardiovascular) disease; and the ethical, occupational and clinical tensions that exist when managing patients with CVD who are also professional aircrew.

Assessing aeromedical risk: a three-dimensional risk matrix approach.

Early aeromedical risk i was based on aeromedical standards designed to eliminate individuals ii from air operations with any identifiable medical risk, and led to frequent medical disqualification. The concept of considering aeromedical risk as part of the spectrum of risks that could lead to aircraft accidents (including mechanical risks and human factors) was first proposed in the 1980s and led to the development of the 1% rule which defines the maximum acceptable risk for an incapacitating medical event as 1% per year (or 1 in 100 person-years) to align with acceptable overall risk in aviation operations. Risk management has subsequently evolved as a formal discipline, incorporating risk assessment as an integral part of the process. Risk assessment is often visualised as a risk matrix, with the level of risk, urgency or action required defined for each cell, and colour-coded as red, amber or green depending on the overall combination of risk and consequence. This manuscript describes an approach to aeromedical risk management which incorporates risk matrices and how they can be used in aeromedical decision-making, while highlighting some of their shortcomings.

Management of established coronary artery disease in aircrew without myocardial infarction or revascularisation.

This paper is part of a series of expert consensus documents covering all aspects of aviation cardiology. In this manuscript, we focus on the broad aviation medicine considerations that are required to optimally manage aircrew with established coronary artery disease in those without myocardial infarction or revascularisation (both pilots and non-pilot aviation professionals). We present expert consensus opinion and associated recommendations. It is recommended that in aircrew with non-obstructive coronary artery disease or obstructive coronary artery disease not deemed haemodynamically significant, nor meeting the criteria for excessive burden (based on plaque morphology and aggregate stenosis), a return to flying duties may be possible, although with restrictions. It is recommended that aircrew with haemodynamically significant coronary artery disease (defined by a decrease in fractional flow reserve) or a total burden of disease that exceeds an aggregated stenosis of 120% are grounded. With aggressive cardiac risk factor modification and, at a minimum, annual follow-up with routine non-invasive cardiac evaluation, the majority of aircrew with coronary artery disease can safely return to flight duties.

The challenge of asymptomatic coronary artery disease in aircrew; detecting plaque before the accident.

Coronary events remain a major cause of sudden incapacitation, including death, in both the general population and among aviation personnel, and are an ongoing threat to flight safety and operations. The presentation is often unheralded, especially in younger adults, and is often due to rupture of a previously non-obstructive coronary atheromatous plaque. The challenge for aeromedical practitioners is to identify individuals at increased risk for such events. This paper presents the NATO Cardiology Working Group (HFM 251) consensus approach for screening and investigation of aircrew for asymptomatic coronary disease.A three-phased approach to coronary artery disease (CAD) risk assessment is recommended, beginning with initial risk-stratification using a population-appropriate risk calculator and resting ECG. For aircrew identified as being at increased risk, enhanced screening is recommended by means of Coronary Artery Calcium Score alone or combined with a CT coronary angiography investigation. Additional screening may include exercise testing, and vascular ultrasound imaging. Aircrew identified as being at high risk based on enhanced screening require secondary investigations, which may include functional ischaemia, and potentially invasive coronary angiography. Functional stress testing as a stand-alone investigation for significant CAD is not recommended in aircrew. Aircrew identified with coronary disease require further clinical and aeromedical evaluation before being reconsidered for flying status.

Management of established coronary artery disease in aircrew with previous myocardial infarction or revascularisation.

This manuscript focuses on the broad aviation medicine considerations that are required to optimally manage aircrew with established coronary artery disease (CAD) without myocardial infarction (MI) or revascularisation (both pilots and non-pilot aviation professionals). It presents expert consensus opinion and associated recommendations and is part of a series of expert consensus documents covering all aspects of aviation cardiology.Aircrew may present with MI (both ST elevation MI (STEMI) and non-ST elevation MI (NSTEMI)) as the initial presenting symptom of obstructive CAD requiring revascularisation. Management of these individuals should be conducted according to published guidelines, ideally with consultation between the cardiologist, surgeon and aviation medical examiner. Return to restricted flight duties is possible in the majority of aircrew; however, they must have normal cardiac function, acceptable residual disease burden and no residual ischaemia. They must also be treated with aggressive cardiac risk factor modification. Aircrew should be restricted to dual pilot operations in non-high-performance aircraft, with return to flying no sooner than 6 months after the event. At minimum, annual follow-up with routine non-invasive cardiac evaluation is recommended.

Management of cardiac conduction abnormalities and arrhythmia in aircrew.

Cardiovascular diseases i are the most common cause of loss of flying licence globally, and cardiac arrhythmia is the main disqualifier in a substantial proportion of aircrew. Aircrew ii often operate within a demanding physiological environment, that potentially includes exposure to sustained acceleration (usually resulting in a positive gravitational force, from head to feet (+Gz)) in high performance aircraft. Aeromedical assessment is complicated further when trying to discriminate between benign and potentially significant rhythm abnormalities in aircrew, many of whom are young and fit, have a resultant high vagal tone, and among whom underlying cardiac disease has a low prevalence. In cases where a significant underlying aetiology is plausible, extensive investigation is often required and where appropriate should include review by an electrophysiologist. The decision regarding restriction of flying activity will be dependent on several factors including the underlying arrhythmia, associated pathology, risk of incapacitation and/or distraction, the type of aircraft operated, and the specific flight or mission criticality of the role performed by the individual aircrew.

Heart muscle disease management in aircrew.

This manuscript focuses on the broad aviation medicine considerations that are required to optimally manage aircrew with suspected or confirmed heart muscle disease (both pilots and non-pilot aviation professionals). ECG abnormalities on aircrew periodic medical examination or presentation of a family member with a confirmed cardiomyopathy are the most common reason for investigation of heart muscle disease in aircrew. Holter monitoring and imaging, including cardiac MRI is recommended to confirm or exclude the presence of heart muscle disease and, if confirmed, management should be led by a subspecialist. Confirmed heart muscle disease often requires restriction toflying duties due to concerns regarding arrhythmia. Pericarditis and myocarditis usually require temporary restriction and return to flying duties is usually dependent on a lack of recurrent symptoms and acceptable imaging and electrophysiological investigations.

Contemporaneous management of valvular heart disease and aortopathy in aircrew.

Valvular heart disease (VHD) is highly relevant in the aircrew population as it may limit appropriate augmentation of cardiac output in high-performance flying and predispose to arrhythmia. Aircrew with VHD require careful long-term follow-up to ensure that they can fly if it is safe and appropriate for them to do so. Anything greater than mild stenotic valve disease and/or moderate or greater regurgitation is usually associated with flight restrictions. Associated features of arrhythmia, systolic dysfunction, thromboembolism and chamber dilatation indicate additional risk and will usually require more stringent restrictions. The use of appropriate cardiac imaging, along with routine ambulatory cardiac monitoring, is mandatory in aircrew with VHD.Aortopathy in aircrew may be found in isolation or, more commonly, associated with bicuspid aortic valve disease. Progression rates are unpredictable, but as the diameter of the vessel increases, the associated risk of dissection also increases. Restrictions on aircrew duties, particularly in the context of high-performance or solo flying, are usually required in those with progressive dilation of the aorta.

Congenital heart disease in aircrew.

This article focuses i on the broad aviation medicine considerations that are required to optimally manage aircrew ii with suspected or confirmed congenital heart disease (both pilots and non-pilot aviation professionals). It presents expert consensus opinion and associated recommendations and is part of a series of expert consensus documents covering all aspects of aviation cardiology. This expert opinion was born out of a 3 year collaborative working group between international military aviation cardiologists and aviation medicine specialists, as part of a North Atlantic Treaty Organization (NATO) led initiative to address the occupational ramifications of cardiovascular disease in aircrew (HFM-251) many of whom also work with and advise civil aviation authorities.

Non-coronary cardiac surgery and percutaneous cardiology procedures in aircrew.

This manuscript focuses on the broad aviation medicine considerations that are required to optimally manage aircrew following non-coronary surgery or percutaneous cardiology interventions (both pilots and non-pilot aviation professionals). Aircrew may have pathology identified earlier than non-aircrew due to occupational cardiovascular screening and while aircrew should be treated using international guidelines, if several interventional approaches exist, surgeons/interventional cardiologists should consider which alternative is most appropriate for the aircrew role being undertaken; liaison with the aircrew medical examiner is strongly recommended prior to intervention to fully understand this. This is especially important in aircrew of high-performance aircraft or in aircrew who undertake aerobatics. Many postoperative aircrew can return to restricted flying duties, although aircrew should normally not return to flying for a minimum period of 6 months to allow for appropriate postoperative recuperation and assessment of cardiac function and electrophysiology.

Aeromedical Transfer of Patients with Viral Hemorrhagic Fever.

For >40 years, the British Royal Air Force has maintained an aeromedical evacuation facility, the Deployable Air Isolator Team (DAIT), to transport patients with possible or confirmed highly infectious diseases to the United Kingdom. Since 2012, the DAIT, a joint Department of Health and Ministry of Defence asset, has successfully transferred 1 case-patient with Crimean-Congo hemorrhagic fever, 5 case-patients with Ebola virus disease, and 5 case-patients with high-risk Ebola virus exposure. Currently, no UK-published guidelines exist on how to transfer such patients. Here we describe the DAIT procedures from collection at point of illness or exposure to delivery into a dedicated specialist center. We provide illustrations of the challenges faced and, where appropriate, the enhancements made to the process over time.