Implications of computed tomography reconstruction algorithms on coronary atheroma quantification: Comparison with intravascular ultrasound

BACKGROUND

Advances in coronary computed tomography angiography (CCTA) reconstruction algorithms are expected to enhance the accuracy of CCTA plaque quantification. We aim to evaluate different CCTA reconstruction approaches in assessing vessel characteristics in coronary atheroma using intravascular ultrasound (IVUS) as the reference standard.

METHODS

Matched cross-sections (n ​= ​7241) from 50 vessels in 15 participants with chronic coronary syndrome who prospectively underwent CCTA and 3-vessel near-infrared spectroscopy-IVUS were included. Twelve CCTA datasets per patient were reconstructed using two different kernels, two slice thicknesses (0.75 ​mm and 0.50 ​mm) and three different strengths of advanced model-based iterative reconstruction (IR) algorithms. Lumen and vessel wall borders were manually annotated in every IVUS and CCTA cross-section which were co-registered using dedicated software. Image quality was sub-optimal in the reconstructions with a sharper kernel, so these were excluded. Intraclass correlation coefficient (ICC) and repeatability coefficient (RC) were used to compare the estimations of the 6 CT reconstruction approaches with those derived by IVUS.

RESULTS

Segment-level analysis showed good agreement between CCTA and IVUS for assessing atheroma volume with approach 0.50/5 (slice thickness 0.50 ​mm and highest strength 5 ADMIRE IR) being the best (total atheroma volume ICC: 0.91, RC: 0.67, p ​< ​0.001 and percentage atheroma volume ICC: 0.64, RC: 14.06, p ​< ​0.001). At lesion-level, there was no difference between the CCTA reconstructions for detecting plaques (accuracy range: 0.64-0.67; p ​= ​0.23); however, approach 0.50/5 was superior in assessing IVUS-derived lesion characteristics associated with plaque vulnerability (minimum lumen area ICC: 0.64, RC: 1.31, p ​< ​0.001 and plaque burden ICC: 0.45, RC: 32.0, p ​< ​0.001).

CONCLUSION

CCTA reconstruction with thinner slice thickness, smooth kernel and highest strength advanced IR enabled more accurate quantification of the lumen and plaque at a segment-, and lesion-level analysis in coronary atheroma when validated against intravascular ultrasound.

CLINICALTRIALS

gov (NCT03556644).

End-diastolic segmentation of intravascular ultrasound images enables more reproducible volumetric analysis of atheroma burden

BACKGROUND

Volumetric intravascular ultrasound (IVUS) analysis is currently performed at a fixed frame interval, neglecting the cyclic changes in vessel dimensions occurring during the cardiac cycle that can affect the reproducibility of the results. Analysis of end-diastolic (ED) IVUS frames has been proposed to overcome this limitation. However, at present, there is lack of data to support its superiority over conventional IVUS.

OBJECTIVES

The present study aims to compare the reproducibility of IVUS volumetric analysis performed at a fixed frame interval and at the ED frames, identified retrospectively using a novel deep-learning methodology.

METHODS

IVUS data acquired from 97 vessels were included in the present study; each vessel was segmented at 1 mm interval (conventional approach) and at ED frame twice by an expert analyst. Reproducibility was tested for the following metrics; normalized lumen, vessel and total atheroma volume (TAV), and percent atheroma volume (PAV).

RESULTS

The mean length of the analyzed segments was 50.0 ± 24.1 mm. ED analysis was more reproducible than the conventional analysis for the normalized lumen (mean difference: 0.76 ± 4.03 mm³ vs. 1.72 ± 11.37 mm³ ; p for the variance of differences ratio < 0.001), vessel (0.30 ± 1.79 mm³ vs. -0.47 ± 10.26 mm³ ; p < 0.001), TAV (-0.46 ± 4.03 mm³ vs. -2.19 ± 14.39 mm³ ; p < 0.001) and PAV (-0.12 ± 0.59% vs. -0.34 ± 1.34%; p < 0.001). Results were similar when the analysis focused on the 10 mm most diseased segment. The superiority of the ED approach was due to a more reproducible detection of the segment of interest and to the fact that it was not susceptible to the longitudinal motion of the IVUS probe and the cyclic changes in vessel dimensions during the cardiac cycle.

CONCLUSIONS

ED IVUS segmentation enables more reproducible volumetric analysis and quantification of TAV and PAV that are established end points in longitudinal studies assessing the efficacy of novel pharmacotherapies. Therefore, it should be preferred over conventional IVUS analysis as its higher reproducibility is expected to have an impact on the sample size calculation for the primary end point.

Simulation training for clinicians returning to practice

Many doctors take time out of clinical practice, and then have decreased confidence and poor performance ratings on their return. Simulation training provides a safe and effective learning platform for healthcare professionals to become immersed in realistic scenarios that provide an opportunity to develop technical and non-technical skills. A standardised, 1-day, multi-fidelity, interprofessional, simulation training course was developed and delivered at four sites, focusing on human factors, patient safety and acute clinical scenarios relevant for clinicians returning to practice in internal medicine. A total of 56 participants, with a median time out of training of 3.6 years, attended seven courses. Quantitative and qualitative analysis showed a significant pre/post-course increase in candidates' self-reported confidence in returning to practice along with learning in non-technical skills. The carefully designed standardised format may facilitate wider expansion of such training.

A Springboard for physicians returning to practice

BACKGROUND

Many physicians take time out of training and have decreased confidence and poor performance ratings on their return. Courses employing multiple educational methods have been shown to be effective in easing learners into new clinical roles during transition periods but, to date, there is limited evidence for courses to support trainees returning to practice (RTP).

METHODS

A 2-day course, named Springboard, was developed, specifically to address the needs of trainee physicians RTP. It employed a blended, multi-modal approach to learning, including lectures, workshops, case-based sessions, interactive panel discussions, small group teaching, peer-led practical advice sessions and simulation training. Springboard was delivered eight times between 2014 and 2019 with a total of 540 doctors attending. We analysed participant pre-and post-course questionnaire feedback.

RESULTS

Reasons for doctors taking time out of training included parental leave, research, fellowships in education and leadership, health-related absence and career breaks. Time out of training ranged between 3 months and 6 years. A significant pre/post-course increase in candidates' self-reported leadership skills and confidence in being prepared to return to practice was demonstrated alongside an appreciation of a multi-modal, 'boot camp' course delivered by expert faculty and a networking experience.

DISCUSSION

Dedicated training courses tailored to the needs of physicians RTP provide an opportunity for improving confidence relating to many areas of clinical and non-clinical practice as well as providing an environment for networking and sharing experiences. Further work would be valuable to establish the potential of providing this on a larger scale.

Training educational supervisors to support physician trainees returning to practice

Physicians take time out of training for a variety of reasons and, on their return, they often lack confidence and feel 'out of touch'. These trainees require enhanced support and concerns have been raised about trainers' lack of skills and knowledge in this area. A standardised workshop was developed and delivered to address this with a mixed-methods evaluation approach used to analyse data from participants before and after training. Quantitative analysis showed significant pre- to post-course improvements in trainers' ability to understand, explain and manage issues pertaining to trainees taking time out of training. Qualitative analysis yielded three 'learning' themes surrounding knowledge, understanding and awareness of support needed for returning trainees and three 'action' themes surrounding disseminating information, providing resources and actively supporting returning trainees. Framework analysis of follow-up interviews demonstrated not only retention of topics learned but also positive changes in behaviour.

Evaluation of training programmes mapped to the new internal medicine curriculum

In preparation for the internal medicine training (IMT) programme introduced in 2019, the core medical training (CMT) programme in London was made 'IMT-ready' in 2018 by creating new rotations that reflected the compulsory requirements of the first 2 years of the IMT curriculum, including provision of the requisite number of critical care placements. Core medical trainees completed posts within the 'IMT-ready' programme between August 2018 and August 2019, during which time the trainee experience was evaluated. A total of 497 responses were received. Of these, 96% of trainees were on an 'acute unselected take' on-call rota, 79% were able to attend outpatient clinics, 80% had the opportunity to practise procedural skills and 88% had the opportunity to apply palliative care skills. Clear areas for improvement were identified that predominantly focused on the need to optimise trainee attendance of outpatient clinics and the number of patients seen during an acute take. With respect to future career intentions, only 63% of trainees planned on applying to a group 1 (with general medicine) higher medical specialty. Thematic analysis of trainees in critical care placements highlighted an appreciation of the level of senior support, feeling well integrated into the team, a positive experience of induction and excellent opportunities for performing procedures.

Randomised, double-blind, placebo-controlled study investigating the effects of inorganic nitrate on vascular function, platelet reactivity and restenosis in stable angina: protocol of the NITRATE-OCT study

INTRODUCTION

The mainstay treatment for reducing the symptoms of angina and long-term risk of heart attacks in patients with heart disease is stent implantation in the diseased coronary artery. While this procedure has revolutionised treatment, the incidence of secondary events remains a concern. These repeat events are thought to be due, in part, to continued enhanced platelet reactivity, endothelial dysfunction and ultimately restenosis of the stented artery. In this study, we will investigate whether a once a day inorganic nitrate administration might favourably modulate platelet reactivity and endothelial function leading to a decrease in restenosis.

METHODS AND DESIGN

NITRATE-OCT is a double-blind, randomised, single-centre, placebo-controlled phase II trial that will enrol 246 patients with stable angina due to have elective percutaneous coronary intervention procedure with stent implantation. Patients will be randomised to receive 6 months of a once a day dose of either nitrate-rich beetroot juice or nitrate-deplete beetroot juice (placebo) starting up to 1 week before their procedure. The primary outcome is reduction of in-stent late loss assessed by quantitative coronary angiography and optical coherence tomography at 6 months. The study is powered to detect a 0.22±0.55 mm reduction in late loss in the treatment group compared with the placebo group. Secondary end points include change from baseline assessment of endothelial function measured using flow-mediated dilation at 6 months, target vessel revascularisation (TVR), restenosis rate (diameter>50%) and in-segment late loss at 6 months, markers of inflammation and platelet reactivity and major adverse cardiac events (ie, myocardial infarction, death, cerebrovascular accident, TVR) at 12 and 24 months.

ETHICS AND DISSEMINATION

The study was approved by the Local Ethics Committee (15/LO/0555). Trial results will be published according to the CONSORT statement and will be presented at conferences and reported in peer-reviewed journals.

TRIAL REGISTRATION NUMBERS

NCT02529189 and ISRCTN17373946, Pre-results.

Very Low Complication Rates with a Manual, Nurse-Led Protocol for Femoral Sheath Removal Following Coronary Angiography

OBJECTIVE

We aimed to provide contemporary information on the complication rates after femoral artery sheath removal using a specific, nurse-led protocol, which is universally applicable and can be readily adopted by other units.

BACKGROUND

Previous studies have reported a wide range of complication rates following femoral sheath removal after cardiac catheterisation. A variety of methods has been used for access site management and therefore it is difficult to compare complication rates between units.

METHOD

Data were collected prospectively on patients undergoing diagnostic coronary angiography via the transfemoral route in a single centre. Sheaths were removed by trained cardiac nurses with direct application of manual pressure over the femoral artery in accordance with a specific protocol. We also investigated the same endpoints in patients who received an arteriotomy closure device (ACD) during the study period.

RESULTS

None of the 516 patients who had their femoral sheaths removed with manual compression developed a major haematoma or complication. A minor haematoma developed in 1.6% of patients. Similarly, none of the 484 patients who received an ACD developed a major haematoma and 0.8% developed a minor haematoma. Mean arterial blood pressures were higher in patients that developed a haematoma.

CONCLUSION

Our study shows that a manual, nurse-led system of femoral sheath removal following diagnostic coronary angiography is very safe and effective and that this remains a viable method of access site management.

Syncope secondary to left ventricular outflow tract obstruction, an interesting presentation of infective endocarditis

We describe a case of a 74-year-old woman who presented with symptoms of fever and lethargy, associated with an episode of cardiac syncope and exertional shortness of breath (SOB). She was diagnosed with Staphylococcus aureus infective mural endocarditis (IE) and subsequent transoesophageal echocardiogram (TOE) confirmed this diagnosis. As the vegetative mass arose from the septal wall, an unusual location, it caused left ventricular outflow tract (LVOT) obstruction and therefore behaved similarly to a subaortic valvular stenosis. There were no conduction abnormalities on the ECG and no clinical or echocardiographic features of congestive heart failure. The finding of LVOT obstruction explained the unusual presentation with syncope and exertional SOB making this case unique. Owing to the large vegetative mass and thereby its high risk of septic emboli, the patient underwent successful surgical resection of the mass with resolution of the obstruction. She successfully completed intravenous antibiotics and was discharged from hospital.

An incidental finding of a calcified right-atrial mass in a young patient treated with chemotherapy 20 years ago

We describe a case of a young woman presenting with lethargy and pleuritic chest pain. She had a medical history of leukaemia treated successfully 20 years ago with chemotherapy via a long line. Although initial investigations suggested a diagnosis of pulmonary embolism (PE; on CT pulmonary angiogram (CTPA)) and a possible thrombus in the right atrium, her symptoms appeared out of proportion in relation to this diagnosis. Further imaging using transthoracic echocardiography suggested the presence of a calcified mass in the right atrium. She underwent successful surgical resection of the mass which was found to be attached to the lateral wall of the right atrium. She made an uneventful recovery and continued on warfarin therapy for 6 months in view of the diagnosis of PE on CTPA. We believe the calcified mass was probably caused by the presence of a long line at the time of her chemotherapy.

An unusual cause of sustained ventricular tachycardia in a 27-year-old man

We present an interesting, unusual and complex case of a young man who initially presented with symptoms suggestive of tuberculosis and later developed malignant ventricular arrhythmias. A diagnosis of cardiac sarcoidosis was made only after histological evidence was paired with his presentation of monomorphic ventricular tachycardia. In this case we highlight the current challenges faced in the choice of investigations and diagnostic criteria. Additionally, we have identified the difficulties in treatment and long-term management of such a multisystem disorder. Ultimately by doing so, we hope to encourage clinicians to be aware of making a diagnosis of cardiac sarcoidosis.

Could it be Quetiapine-induced Peripartum Cardiomyopathy?

Peri-partum Cardiomyopathy (PPCM) is a rare and life threatening complication of pregnancy. There are only two cases registered with the World Health Organization of cases of cardiomyopathy in patients taking Quetiapine. Here we discuss an interesting case of potential Quetiapine induced cardiomyopathy.

Underuse of thrombolytic therapy in acute myocardial infarction and left bundle branch block

Thrombolytic therapy reduces mortality in patients with acute myocardial infarction (AMI) and left bundle branch block (LBBB). The difficulty in accurately diagnosing AMI in patients with LBBB, however, might result in their undertreatment. Among 3,890 patients hospitalized with chest pain, 241 (6.2%) had LBBB at presentation. The only variable independently associated with AMI among patients with LBBB was in-hospital left ventricular failure (odds ratio [OR]: 4.32, 95% confidence interval [CI]: 1.95-9.57, p < 0.0005). Only 16 (29%) of the LBBB patients with AMI received thrombolytic therapy compared with 583 (78%) of the 747 patients with ST-elevation AMI (p < 0.0005). A further 19 (10%) LBBB patients without AMI also received thrombolysis. Difficulty in making an accurate early diagnosis in patients with LBBB ensures that the majority of those with AMI fail to receive thrombolytic therapy while others without AMI are treated inappropriately. Improved diagnostic and therapeutic strategies are needed for patients with acute coronary syndromes and LBBB.

Acute myocarditis presenting as acute coronary syndrome: role of early cardiac magnetic resonance in its diagnosis

BACKGROUND

In patients presenting with acute cardiac symptoms, abnormal ECG and raised troponin, myocarditis may be suspected after normal angiography.

AIMS

To analyse cardiac magnetic resonance (CMR) findings in patients with a provisional diagnosis of acute coronary syndrome (ACS) in whom acute myocarditis was subsequently considered more likely.

METHODS AND RESULTS

79 patients referred for CMR following an admission with presumed ACS and raised serum troponin in whom no culprit lesion was detected were studied. 13% had unrecognised myocardial infarction and 6% takotsubo cardiomyopathy. The remainder (81%) were diagnosed with myocarditis. Mean age was 45±15 years and 70% were male. Left ventricular ejection fraction (EF) was 58±10%; myocardial oedema was detected in 58%. A myocarditic pattern of late gadolinium enhancement (LGE) was detected in 92%. Abnormalities were detected more frequently in scans performed within 2 weeks of symptom onset: oedema in 81% vs 11% (p<0.0005), and LGE in 100% vs 76% (p<0.005). In 20 patients with both an acute (<2 weeks) and convalescent scan (>3 weeks), oedema decreased from 84% to 39% (p<0.01) and LGE from 5.6 to 3.0 segments (p=0.005). Three patients presented with sustained ventricular tachycardia, another died suddenly 4 days after admission and one resuscitated 7 weeks following presentation. All 5 patients had preserved EF.

CONCLUSIONS

Our study emphasises the importance of access to CMR for heart attack centres. If myocarditis is suspected, CMR scanning should be performed within 14 days. Myocarditis should not be regarded as benign, even when EF is preserved.

Hemoglobin concentration is an independent determinant of heart failure in acute coronary syndromes: cohort analysis of 2310 patients

BACKGROUND

Anemia is an important determinant of heart failure and death after ST elevation myocardial infarction (STEMI). The frequency of anemia and its impact on these outcomes across the range of acute coronary syndromes (ACS), however, have not been defined.

METHODS

This is a cohort study of 2310 patients with ACS stratified by quartiles of admission hemoglobin concentration [Hb]): Q1, <12.5 g/dL; Q2, 12.5-13.6 g/dL; Q3, 13.7-14.7 g/dL; Q4, >14.7 g/dL.

RESULTS

There were 29.7% of women and 23.2% of men who were anemic. Rates of STEMI increased across [Hb] quartile groups from 25.0% (Q1) to 35.5% (Q4) as rates of unstable angina decreased from 52.0% (Q1) to 40.7% (Q4) (P < .0005). Despite this, rates of left ventricular failure (LVF) were inversely related to [Hb] in all diagnostic groups, patients with unstable angina (Q1, 14.2%; Q4, 4.4%; P < .0005) showing a similar trend to patients with non-STEMI (Q1, 26.8%; Q4, 10.4%; P < .0005) and STEMI (Q1, 33.8%; Q4, 20.6%; P < .0005). The age-adjusted odds of LVF in Q4 compared with Q1 were 0.64 (95% confidence interval, 0.45-0.90). Inhospital cardiac mortality was 3.0% and was not influenced by [Hb].

CONCLUSIONS

Anemia is a common comorbidity in patients presenting with ACS, and it is a powerful independent determinant of LVF. The association with LVF occurs not only in STEMI but also in less severe diagnostic groups.

Impact of the National Service Framework for coronary heart disease on treatment and outcome of patients with acute coronary syndromes

OBJECTIVES

To evaluate the impact the National Service Framework (NSF) for coronary heart disease has had on emergency treatment and outcomes in patients presenting with acute coronary syndromes.

DESIGN

Retrospective cohort study.

SETTING

Coronary care units of two district general hospitals.

RESULTS

Data from 3371 patients were recorded, 1993 patients in the 27 months before the introduction of the NSF and 1378 patients in the 24 months afterwards. After the introduction of the NSF in-hospital mortality was significantly reduced (95 patients (4.8%) v 43 (3.2%), p = 0.02). This was associated with a reduction in the development of Q wave myocardial infarction (40.6% v 33.3%, p < 0.0001) and in the incidence of left ventricular failure (15.9% v 12.3%, p = 0.003). The proportion of patients receiving thrombolysis increased (69.4% v 84.7%, p < 0.0001) with a decrease in the time taken to receive it (proportion thrombolysed within 20 minutes 12.1% v 26.6%, p < 0.0001). The prescription of beta blockers (51.9% v 65.8%, p < 0.0001), angiotensin converting enzyme inhibitors (37% v 66.4%, p < 0.0001), and statins (55.2% v 72.7%, p < 0.0001) improved and the proportion of patients referred for invasive investigation increased (18.3% v 27.0%, p < 0.0001). Trend analysis showed that improvements in mortality and thrombolysis were directly associated with publication of the NSF, whereas the improvements seen in prescription of beta blockers and statins were the continuation of pre-existing trends.

CONCLUSIONS

In the two years that followed publication of the NSF the initial treatment and outcome of patients presenting with acute coronary syndromes improved. Some of the improvements can be attributed to the NSF but others are continuations of pre-existing trends.

The effect of diabetes on heart rate and other determinants of myocardial oxygen demand in acute coronary syndromes

AIMS

To compare major determinants of myocardial oxygen demand (heart rate, blood pressure and rate pressure product) in patients with and without diabetes admitted with acute coronary syndromes.

METHODS

A cross-sectional study of the relation between diabetes and haemodynamic indices of myocardial oxygen demand in 2542 patients with acute coronary syndromes, of whom 1041 (41.0%) had acute myocardial infarction and 1501 (59.0%) unstable angina.

RESULTS

Of the 2542 patients, 701 (27.6%) had diabetes. Major haemodynamic determinants of myocardial oxygen demand were higher in patients with than without diabetes: heart rate 80.0 +/- 20.4 vs. 75.2 +/- 19.2 beats/minute (P < 0.0001); systolic blood pressure 147.3 +/- 30.3 vs. 143.2 +/- 28.5 mmHg (P = 0.002); rate-pressure product 11533 +/- 4198 vs. 10541 +/- 3689 beats/minute x mmHg (P < 0.0001). Multiple regression analysis confirmed diabetes as a significant determinant of presenting heart rate [multiplicative coefficient (MC) 1.05; 95% confidence interval (CI) 1.03-1.07; P < 0.0001], rate pressure product (MC 1.09; CI 1.05-1.12; P < 0.0001) and systolic blood pressure, which was estimated to be 3.9 mmHg higher than in patients without diabetes (P=0.003). These effects of diabetes were independent of a range of baseline variables including acute left ventricular failure and mode of presentation (unstable angina or myocardial infarction).

CONCLUSIONS

In acute coronary syndromes, heart rate and other determinants of myocardial oxygen demand are higher in patients with than without diabetes, providing a potential contributory mechanism of exaggerated regional ischaemia in this high-risk group.

Renal function and risk stratification in acute coronary syndromes

In this prospective cohort study we analyzed the impact of admission renal function on the hospital course of 2,503 patients with unstable angina pectoris (UAP) and acute myocardial infarction (AMI). The patients were stratified into quartile groups (Q1 to Q4) defined by baseline corrected creatinine clearance (cCrCl) values of 51.4, 63.8, and 76.8 mg/min/72 kg. The proportions of patients with a discharge diagnosis of AMI increased with declining cCrCl, from 35.5% in Q4 to 46.0% in Q1 (p <0.0001). The frequency of left ventricular (LV) failure (Q4 4.5%, Q1 31.0%, p <0.0001) and cardiac death (Q4 0.5%, Q1 9.5%, p <0.0001) also increased linearly with decreasing cCrCl, with no evidence that the prognostic impact of renal dysfunction was different in AMI or UAP (p for interaction 0.15). Logistic regression analysis confirmed the independent effects of cCrCl on outcome, with odds of LV failure and cardiac death for patients in Q4 being 0.34 (95% confidence intervals 0.16 to 0.72) and 0.14 (95% confidence intervals 0.03 to 0.74), respectively, relative to patients in Q1. No threshold was detected for the adverse effects of renal dysfunction on outcomes; the log odds of LV failure and cardiac death against quartiles of cCrCl both showed significant linear trends (p <0.0001) with each change in quartile, resulting in risk reductions of 55% (odds [SE] 0.45 [0.03]) and 65% (odds [SE]: 0.35 [0.05]), respectively. In conclusion, renal function showed a graded association with LV failure and hospital death that was independent of diagnosis (UAP or AMI) and other baseline variables. There was no detectable threshold of renal dysfunction for these adverse prognostic effects.

A single serum glucose measurement predicts adverse outcomes across the whole range of acute coronary syndromes

OBJECTIVES

To analyse the relation between serum glucose concentration and hospital outcome across the whole spectrum of acute coronary syndromes.

METHODS

This was a prospective cohort study of 2127 patients presenting with acute coronary syndromes. The patients were stratified into quartile groups (Q1 to Q4) defined by serum glucose concentrations of 5.8, 7.2, and 10.0 mmol/l. The relation between quartile group and major in-hospital complications was analysed.

RESULTS

The proportion of patients with acute myocardial infarction increased incrementally across the quartile groups, from 21.4% in Q1 to 47.9% in Q4 (p < 0.0001). The trend for frequency of in-hospital major complications was similar, particularly left ventricular failure (LVF) (Q1 6.4%, Q4 25.2%, p < 0.0001) and cardiac death (Q1 0.7%, Q4 6.1%, p < 0.0001). The relations were linear, each glucose quartile increment being associated with an odds ratio of 1.46 (95% confidence interval (CI) 1.27 to 1.70) for LVF and 1.52 (95% CI 1.17 to 1.97) for cardiac death. Although complication rates were higher for a discharge diagnosis of acute myocardial infarction than for unstable angina, there was no evidence that the effects of serum glucose concentration were different for the two groups, there being no significant interaction with discharge diagnosis in the associations between glucose quartile and LVF (p = 0.69) or cardiac death (p = 0.17). Similarly there was no significant interaction with diabetic status in the associations between glucose quartile and LVF (p = 0.08) or cardiac death (p = 0.09).

CONCLUSION

Admission glycaemia stratified patients with acute coronary syndromes according to their risk of in-hospital LVF and cardiac mortality. There was no detectable glycaemic threshold for these adverse effects. The prognostic correlates of admission glycaemia were unaffected by diabetic status and did not differ significantly between patients with acute myocardial infarction and those with unstable angina.

Effect of diabetes on serum potassium concentrations in acute coronary syndromes

OBJECTIVES

To compare serum potassium concentrations in diabetic and non-diabetic patients in the early phase of acute coronary syndromes.

BACKGROUND

Acute phase hypokalaemia occurs in response to adrenergic activation, which stimulates membrane bound sodium-potassium-ATPase and drives potassium into the cells. It is not known whether the hypokalaemia is attenuated in patients with diabetes because of the high prevalence of sympathetic nerve dysfunction.

METHODS

Prospective cohort study of 2428 patients presenting with acute coronary syndromes. Patients were stratified by duration of chest pain, diabetic status, and pretreatment with beta blockers.

RESULTS

The mean (SD) serum potassium concentration was significantly higher in diabetic than in non-diabetic patients (4.3 (0.5) v 4.1 (0.5) mmol/l, p < 0.0001). Multivariate analysis identified diabetes as an independent predictor of a serum potassium concentration in the upper half of the distribution (odds ratio 1.66, 95% confidence interval 1.38 to 2.00). In patients presenting within 6 hours of symptom onset, there was a progressive increase in plasma potassium concentrations from 4.08 (0.46) mmol/l in patients presenting within 2 hours, to 4.20 (0.47) mmol/l in patients presenting between 2-4 hours, to 4.24 (0.52) mmol/l in patients presenting between 4-6 hours (p = 0.0007). This pattern of increasing serum potassium concentration with duration of chest pain was attenuated in patients with diabetes, particularly those with unstable angina. Similar attenuation occurred in patients pretreated with beta blockers.

CONCLUSION

In acute coronary syndromes, patients with diabetes have significantly higher serum potassium concentrations and do not exhibit the early dip seen in non-diabetics. This may reflect sympathetic nerve dysfunction that commonly complicates diabetes.

Restricted weekend service inappropriately delays discharge after acute myocardial infarction

BACKGROUND

Early discharge after myocardial infarction is safe and feasible. Factors that delay discharge need to be identified in order to improve care and reduce bed occupancy.

OBJECTIVE

To investigate the potential of the restricted weekend service that operates in most hospitals to delay patient discharge.

DESIGN

Prospective cohort study.

SUBJECTS AND SETTING

2541 consecutive patients with acute myocardial infarction admitted to the coronary care unit of three local district hospitals over a 12 year period.

RESULTS

Clinical factors affecting the duration of stay were age, sex, and severity of infarction. Thus older patients and women stayed significantly longer, as did patients with enzymatically large infarcts. Day of week also had an important influence on duration of stay. Discharge occurred most often on a Friday (p = 0.006) and least often over the weekend (p = 0.0001). Patients were preferentially discharged on a Friday if the length of stay was more than 72 hours. Thus patients admitted on a Sunday or Monday were usually discharged the following Friday, corresponding to a median duration of stay of five or four days, respectively. For patients admitted on Tuesday to Saturday, weekend discharge was avoided and the median duration of stay was six to eight days.

CONCLUSIONS

For patients with acute myocardial infarction, discharge decisions were influenced appropriately by clinical indicators of risk, but inappropriately by the day of the week. Thus weekend discharge was generally avoided, leading to variations in length of stay that were largely determined by the day of the week on which admission occurred rather than clinical need.

How should age affect management of acute myocardial infarction? A prospective cohort study

BACKGROUND

About 75% of patients with acute myocardial infarction are older than 70 years, but patients in this age group are commonly treated less vigorously than younger patients. This differential treatment may partly reflect clinicians' misconceptions about the outlook of such patients, and the importance of age in clinical decisions. We examined how age does and should affect the management of patients and risk stratification in acute myocardial infarction.

METHODS

In this prospective cohort study, we recruited 1225 consecutive patients admitted with acute myocardial infarction to a district general hospital in east London. The primary endpoint was death. We used tabulation and regression methods to analyse the association between age group and clinical variables.

FINDINGS

Patients aged 70 years or older took a longer time to arrive in hospital and were less likely to receive thrombolysis or discharge beta-blockers than patients younger than 60 years: odds ratio 0.63 (95% CI 9.45-0.88) for thrombolysis and 0.25 (0.16-0.37) for beta-blockade, adjusted for sex, diabetes, previous acute myocardial infarction, Q wave infarction, and left-ventricular failure. Left-ventricular failure was the strongest independent predictor of death within 1 year of infarction with a hazard ratio of 4.76 (3.53-6.43), adjusted for age, sex, diabetes, and Q wave infarction. Patients aged 70 years or older without left-ventricular failure had significantly better survival at 1 year after acute myocardial infarction than patients under 60 years with left-ventricular failure. 70.8% (62.2-78.2) of the older patients who survived to hospital discharge were still alive 3 years later.

INTERPRETATION

Elderly patients with acute myocardial infarction were treated less vigorously than younger patients. The prognosis of acute myocardial infarction, however, was substantially affected by the development of left-ventricular failure and other clinical indices, such that many older patients had a better outlook than younger patients with adverse clinical factors. In planning risk-based management, consideration of age independently of clinical status is inappropriate.

Imaging of pulmonary vascular disease by intravascular ultrasound

To assess the ability of intravascular ultrasound (IVUS) to image changes in the pulmonary arterial wall associated with pulmonary hypertension (PHT), 10 subjects requiring diagnostic right and left heart catheterization were studied. In addition to measurements of pulmonary artery pressure and pulmonary vascular resistance and pulmonary angiography, when indicated, all underwent simultaneous IVUS imaging in the pulmonary arterial system using a 20 MHz ultrasound transducer mounted on a 2 mm diameter catheter. Four patients had normal pulmonary artery pressures and 6 had varying degrees of PHT. Satisfactory ultrasound images were obtained in 9 out of the 10 patients. In those with normal pulmonary artery pressures ultrasound showed a thin vessel wall with no distinction between separate layers. In patients with systemic PHT, a three-layered vessel wall was apparent and areas compatible with intimal proliferation were seen. In a patient with pulmonary embolic disease areas consistent with mural thrombus were detected at sites of luminal narrowing on the pulmonary angiogram. IVUS is capable of imaging some of the morphological changes in the wall of the pulmonary artery known to occur in longstanding PHT and may therefore become a useful adjunct to haemodynamic measurements and pulmonary angiography for the in vivo assessment of pulmonary vascular disease.