Development, evaluation and validation of machine learning algorithms to detect atypical and asymptomatic presentations of Covid-19 in hospital practice.

BACKGROUND: Diagnostic methods for Covid-19 have improved, both in speed and availability. Because of atypical and asymptomatic carriage of the virus and nosocomial spread within institutions, timely diagnosis remains a challenge. Machine learning models trained on blood test results have shown promise in identifying cases of Covid-19. AIMS: To train and validate a machine learning model capable of differentiating Covid-19 positive from negative patients using routine blood tests and assess the model's accuracy against atypical and asymptomatic presentations. DESIGN AND METHODS: We conducted a retrospective analysis of medical admissions to our institution during March and April 2020. Participants were categorized into Covid-19 positive or negative groups based on clinical, radiological features or nasopharyngeal swab. A machine learning model was trained on laboratory parameters and validated for accuracy, sensitivity and specificity and externally validated at an unconnected establishment. RESULTS: An Ensemble Bagged Tree model was trained on data collected from 405 patients (212 Covid-19 positive) producing an accuracy of 81.79% (95% confidence interval (CI) 77.53-85.55%), the sensitivity of 85.85% (CI 80.42-90.24%) and specificity of 76.65% (CI 69.49-82.84%). Accuracy was preserved for atypical and asymptomatic subgroups. Using an external data set for 226 patients (141 Covid-19 positive) accuracy of 76.82% (CI 70.87-82.08%), sensitivity of 78.38% (CI 70.87-84.72%) and specificity of 74.12% (CI 63.48-83.01%) was achieved. CONCLUSION: A machine learning model using routine laboratory parameters can detect atypical and asymptomatic presentations of Covid-19 and might be an adjunct to existing screening measures.

Diuretic lounge and the impact on hospital admissions for treatment of decompensated heart failure.

BACKGROUND: Heart failure is a prevalent condition associated with frequent and costly hospital admissions. Hospitalizations are primarily related to worsening fluid retention and often require admission for decongestion with intravenous diuretics. OBJECTIVE: To assess the safety of an outpatient intravenous diuresis service for heart failure patients, and its impact on emergency admissions and the cost of treatment. METHODS: We conducted a prospective observational cohort registry study on patients referred to the diuretic lounge at our acute hospital between May 2017 and April 2018. RESULTS: We analysed 245 patients treated in the diuretic lounge, of which 190 (77.6%) avoided hospitalization or any adverse events during the 60 days of follow up (77.6% vs. 22.4%; P < 0.001). The diuretic lounge service resulted in a significant decrease in emergency heart failure admissions compared to the previous 12 months (823 vs. 715 per annum; 68.6 ± 10.1 vs. 59.6 ± 14 per month; P = 0.04), and a numerical reduction in readmission rates (17.3% vs. 16.2%). The 13.1% decrease in admissions lead to financial savings of £315 497 per annum and £2921 per admission avoided. During the same time period, at the other acute hospital site in our trust, where no diuretic lounge service is available, the number of admissions did not significantly change (457 vs. 450 per annum; 37.5 ± 7.0 vs. 38.1 ± 7.6 per month; P = 0.81). CONCLUSION: Ambulatory administration of intravenous diuretics reduces emergency admissions and is a safe and cost-effective alternative to treat acute decomposition in heart failure patients.

Registry report of the prevalence of ECG abnormalities and their relation to patient characteristics in an asymptomatic population.

BACKGROUND: Cardiovascular disease is the leading cause of morbidity and mortality in developed countries. Many patients do not experience symptoms before a first major cardiovascular event. Resting electrocardiogram (ECG) may help identify asymptomatic individuals with a high risk of cardiovascular disease. OBJECTIVE: We sought to determine the prevalence of ECG abnormalities in an apparently symptom-free adult population within a prospective registry. METHODS: The registry consisted of 4739 consecutive apparently healthy individuals [age 62.8 ± 6.2 (SD) years; 54% female], referred by their General Practitioners between 2009 and 2013. Patient demographics, and clinical data were obtained, alongside blood tests and a resting ECG. RESULTS: ECG abnormalities were present in 1509 (31.8%) subjects and were commoner with increasing age (F = 0.161, p = 0.01), systolic (F = 0.134, p = 0.01) and diastolic (F = 0.44, p = 0.01) blood pressure and waist circumference (F = 0.53, p = 0.01). Left ventricular hypertrophy (LVH) was the most common abnormality (n = 281) and was positively associated with systolic (F = 0.12, p = 0.01) and diastolic blood pressure (F = 0.99, p = 0.01) and male gender (X2 = 60.5, p < 0.01). All ECG abnormalities (except for LVH) were associated with an increasing age, while right bundle branch block (F = 0.041, p = 0.01) and atrial fibrillation (n = 29; F = 0.036, p = 0.05) were associated with the presence of diabetes mellitus (n = 211). Only left bundle branch block (n = 50) was associated with angina (F = 0.05, p = 0.01). CONCLUSIONS: Unrecognized cardiac abnormalities are common in middle-aged men and women with no overt symptoms. ECG offers the potential to identify these abnormalities and provide earlier intervention and treatment, and possibly improve cardiovascular outcome.

Staphylococcus lugdunensis endocarditis following cardiac catheterisation.

We report the case of a 77 year old with Staphylococcus lugdunensis endocarditis following cardiac catheterisation via a femoral approach. We underline the association between this pathogen and inguinal skin breaks, and discuss the potential diagnostic pitfalls in clinical and laboratory diagnosis.

Intracerebral haematoma masquerading as ventricular standstill.

An 82 year old man was referred to the emergency room by his general practitioner for a right frontoparietal headache. The preceding day he had tripped and fallen, hitting the back of his head on the floor. Computed tomography showed a cortical contre coup haematoma. In view of ventricular standstill noted on ECG, a temporary pacing wire was inserted and a dual chamber permanent pacemaker was subsequently implanted. Intracerebral bleeding was treated conservatively and the patient made a good recovery. All patients admitted with head injury and sinus bradycardia or sinus arrest should be nursed at 15 degrees to 30 degrees with instructions to avoid the head up and supine positions. Furthermore, brain CT should be promptly recorded to assess for intracerebral haematoma and raised intracranial pressure and, if they are confirmed, these patients with cardiovascular compromise should benefit from close collaboration between neurosurgeon and cardiologist. Urgent pacing should be considered for all patients with head injury who experience symptomatic bradycardia or ventricular standstill.

Percutaneous transluminal renal artery angioplasty: who benefits most?

We set out to assess the long-term benefits of renal percutaneous transluminal angioplasty (PTA) in 107 consecutive hypertensive patients with atheromatous renal artery stenosis. During 12-month follow-up, blood pressure fell to normal levels in 10 (8.8%) patients and improved in 76 (67.3%); renal function improved or remained stable in 74% of patients. In patients with atheromatous disease, renal angioplasty was most successful in those with stenosis in a single functioning kidney, and in nine patients who presented with symptoms and signs of heart failure, in the absence of overt ischaemic or valvular heart disease. In the latter group, renal PTA resulted in a large loss of sodium and water, resolution of the 'apparent' heart failure, and a marked improvement in blood pressure and renal function. It is suggested that all hypertensive patients with haemodynamically significant renal artery stenosis (and/or mild to moderate impairment in renal function), should be considered for renal PTA. Patients with atheromatous stenosis in a single functioning kidney, and those who present with signs of sodium and water retention, are likely to benefit most.

Coronary heart disease in the statin and aspirin era: are results of clinical trials being put into practice?

BACKGROUND: We studied the impact of recent advances in coronary prevention by assessing cardiovascular risk factors and their management in 98% of patients admitted to a coronary care unit with acute myocardial infarction (AMI) between January and December 1998 [177 patients, mean age 66+/-1 (S.E.M.) years, 114 males]. METHODS AND RESULTS: Sixty-two patients had a history of coronary heart disease (CHD). One in four of them was still smoking and 27% had a recorded history of hyperlipidaemia. Only 12 patients with known CHD (19%) were on lipid-lowering treatment. Total cholesterol was above 5 mmol/l in 98/168 (58%) of the patients and LDL-cholesterol was above 3 mmol/l in 91/148 (62%) of the patients. Twenty-eight patients (16%) died during the hospital stay (age 74+/-2 years). Of 149 patients discharged from hospital, 101 (68%) were treated with a statin, including 85% of the patients with a total fasting cholesterol on admission above 5 mmol/l and 91% with LDL-cholesterol on admission above 3 mmol/l. Sixty-three percent of the patients on a statin were on a dose below that shown in clinical trials to reduce cardiovascular events. CONCLUSIONS: Unrecognised and ineffectively treated cardiovascular risk factors were common among patients with documented CHD who were admitted with AMI. Our study provides important background for the implementation of guidelines for the prevention of CHD.

Platelet sodium-hydrogen exchanger activity and left ventricular mass.

INTRODUCTION: The sodium-hydrogen exchanger (NHE) is integral to the processes that facilitate cell growth and may contribute to the development of left ventricular hypertrophy. The aim of this study was to examine the relationship between platelet sodium-hydrogen exchanger activity and left ventricular mass index (LVMI). METHODS: Twenty male untreated Caucasians (mean age +/- s.d.: 48 +/- 13; body mass index: 29 +/- 4 kg/m(2)) with a wide range of blood pressures were studied (mean BP: 152 +/- 22/93 +/- 15 mm Hg; range: 115-190/61-117 mm Hg). Sodium-hydrogen exchanger activity was determined as the rate of sodium-dependent recovery of intracellular pH in isolated platelets loaded with BCECF and acidified to pH 6.25 using nigericin. LVMI was calculated from measurements made by M-mode echocardiography. Associations between continuous variables were examined using parametric tests. RESULTS: The mean rate of pHi recovery was 0.15 +/- 0.03 dpHi/s (range: 0.09-0.21). Mean LVMI was 120 +/- 32 g/m(2) (range: 56-178) and was not significantly correlated with either systolic (r = 0.39, P = 0.09) or diastolic blood pressure (r = 0.27, P = 0.3). Platelet NHE activity was not significantly correlated with LVMI (r = 0.06; P = 0.8). Platelet NHE activity was not significantly different between subjects with (n = 7 with LVMI >131 g/m(2)) and without left ventricular hypertrophy (n = 13). CONCLUSIONS: The results of this study show that platelet NHE activity is not significantly correlated with LVMI. These data contrast with previously described correlations of LVMI with exchanger activity measured in leucocytes and erythrocytes; and indicate that the relationship between LVMI and exchanger activity may be specific to the cell type in which exchanger activity is measured.

A young woman with chest pain.

A case of a previously fit young woman admitted with chest pain, who was found at coronary angiography to have dissection of the left main stem which extended to the left anterior descending and circumflex coronary arteries, is presented. Emergency coronary artery bypass grafting was performed (vein grafts to the left anterior descending, the diagonal, and circumflex arteries). The patient made an uneventful recovery, and three years after initial presentation she remains free of cardiac symptoms.

"Apparent" heart failure: a syndrome caused by renal artery stenoses.

OBJECTIVE: To report on renal artery stenosis presenting as congestive heart failure. DESIGN: Case series. SETTING: Tertiary referral centre. PATIENTS: Nine hypertensive subjects (five male, four female) seen in the blood pressure unit, St George's Hospital, between 1991 and 1997 with clinical signs and symptoms of congestive cardiac failure but without overt coronary or valvar heart disease. Mean (SEM) age was 67 (3) years. Eight patients had renal artery revascularisation with percutaneous angioplasty and one had surgery. RESULTS: Renal revascularisation was followed by a large fall in blood pressure from 191/94 (7/3) to 150/75 (8/5) mm Hg two days after intervention (p < 0.01). There was also a large natriuresis and weight reduction. One week after revascularisation there was a mean loss in weight of 3.8 (0.6) kg. The largest fall in weight was seen in those patients with stenosis in a single functioning kidney. Furthermore, plasma atrial natriuretic factor fell from 120 (28) to 48 (9) pg/ml (p < 0.05; n = 6; normal value = 8.6 (0.8) pg/ml), and serum creatinine fell from 200 (37) to 140 (11) micromol/l (p < 0. 025). The clinical signs and symptoms of heart failure resolved and the diuretics were then withdrawn in all patients. On long term follow up, patients remained free from symptoms and signs of heart failure and the blood pressure was better controlled. CONCLUSIONS: In hypertensive patients with symptoms and signs of congestive heart failure who do not have obvious ischaemic or valvar heart disease, renal artery stenosis should be considered as a possible underlying cause. Relief of the stenosis can result in resolution of the apparent heart failure.