Irish Defence Forces combat medical technician training: experience of a novel university medical school-based programme

AIMS

This study explores the opinions and experiences of Irish Defences Forces' (IDF) graduates from University College Dublin's Diploma in Military Medicine Care (DMMC). It aims to identify which aspects of medical education are relevant for the development of military graduates in the role of Combat Medical Technician (CMT) in future.

METHODS

A validated Clinical Learning Environment Score tool was adapted and incorporated into an online survey. This was sent electronically to 71 graduates. Responses were anonymous.

RESULTS

38 (54%) graduates responded. Student feedback was positive regarding teaching and clinical placements in the DMMC. In total 16 (42%) students reported use of their new skills in their daily work. Of the 9 (24%) deployed overseas, all used their new skills. Emergency and occupational health skills were used more frequently, while advanced skills were used rarely.

CONCLUSION

An increased emphasis on frequently used skills should be considered. Links to healthcare services would be of benefit to graduates in skills maintenance. Key advanced skills, such as intravenous cannulation and advanced airway management are rarely used but mechanisms to maintain them will improve the relevance of the programme to the CMT role. A change in how the IDF acknowledges qualifications may support more graduates in advancing and maintaining their career in the military medical workforce.

P2707Invasive coronary physiology during primary percutaneous coronary intervention in patients treated with intracoronary alteplase or placebo: the double-blind T-TIME physiology substudy

Background

Impaired microcirculatory reperfusion worsens prognosis post-primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). Intracoronary (IC) alteplase targets persisting thrombus post-reperfusion & distal embolisation. In the T-TIME trial microvascular obstruction on cardiac magnetic resonance (CMR) did not differ with IC alteplase vs placebo.

Purpose

To prospectively determine if index of microcirculatory resistance (IMR) is lower & coronary flow reserve (CFR) or resistive reserve ratio (RRR) are higher (improved) with IC alteplase, & to provide mechanistic insights.

Methods

A pre-planned substudy of the main protocol. From 2016–2017, STEMI patients from 3 UK hospitals ≤6 hrs ischaemic time were randomised in a 1:1:1 dose-ranging, double-blind design. Following standard care reperfusion, alteplase (10 or 20mg) or placebo was infused over 5–10 mins proximal to the culprit lesion pre-stenting. IMR (primary outcome), CFR & RRR (secondary outcomes) were measured in the culprit artery post-PCI. Physiology results were obscured from clinicians acquiring the data, to maintain blinding. CMR was performed 2 days & 3 months post-STEMI. Subgroup analyses were prespecified including by ischaemic time (<2 hours, 2–4 hrs, >4 hrs) & IMR threshold >32.

Results

In 144 patients (mean age 59 yrs, 80% male), IMR, CFR or RRR post-PCI did not differ with alteplase vs placebo (Table). Patients with ischaemic time <2 hrs had a dose related increase in CFR (placebo 1.2 [IQR 1.1–1.7], alteplase 10mg 1.4 [IQR 1.0–1.8], alteplase 20mg 2.0 [IQR 1.8–2.3] p=0.01 for interaction) & RRR (placebo 1.5 [IQR 1.3–1.9], alteplase 10mg 1.6 [1.1–2.2], alteplase 20mg 2.2 [2.0–2.6], p=0.03 for interaction). In subjects with post-PCI IMR>32, % ST-resolution at 60 mins was worse with alteplase 10mg vs placebo (23.1±53.9 vs 50.9±31.5) & in those with IMR≤32% ST-resolution at 60 mins was better with alteplase 20mg vs placebo (68.0±30.7 vs 39.1±43.2), p=0.002 for interaction. The CMR findings in the substudy & overall trial populations were consistent.

Main results Placebo Alteplase 10mg Alteplase 20mg (n=53) (n=41) (n=50) IMR, median (IQR) 33.0 (17.0–57.0) 22.0 (17.0–42.0) 37.0 (20.0–57.8) p=0.15 p=0.78 CFR, median (IQR) 1.3 (1.1–1.8) 1.4 (1.1–1.9) 1.5 (1.1–2.0) p=0.92 p=0.74 RRR, median (IQR) 1.6 (1.3–2.2) 1.6 (1.4–2.6) 1.8 (1.3–2.4) p=0.69 p=0.81 P-values for comparison of alteplase with placebo.

Conclusions

In acute STEMI with ischaemic time ≤6 hrs, IMR, CFR or RRR post-PCI did not differ with alteplase vs placebo. In those with shorter ischaemic times (<2 hrs) CFR & RRR, but not IMR, were improved with alteplase. We observed interactions between alteplase dose, ischaemic time & mechanisms of effect.

Acknowledgement/Funding

Dr Maznyczka is funded by a fellowship from the British Heart Foundation (FS/16/74/32573). T-TIME was funded by grant 12/170/4 from NIHR-EME

127Prevalence of coronary artery disease and coronary microvascular dysfunction in heart failure with preserved ejection fraction

Background/Introduction

The prevalence of epicardial coronary artery disease (CAD) and coronary microvascular dysfunction (CMD) have not been studied systematically in an unselected cohort of patients with heart failure and preserved ejection fraction (HFpEF). Both types of coronary disease may play an important role in the pathophysiology and prognosis of HFpEF.

Methods

This prospective multi-centre observational study enrolled near-consecutive patients hospitalized with HFpEF. Patients underwent invasive coronary angiography. Where possible, patients also had guidewire-based assessment of fractional flow reserve, coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) performed, followed by vasoreactivity testing with intracoronary acetylcholine.

Results

A total of 75 patients underwent invasive coronary angiography. Guidewire-based assessment of FFR/CFR/IMR was performed in 62 patients, and vasoreactivity testing was possible in 41 patients. Obstructive epicardial CAD was identified in 38 patients (51%). CMD (defined as a CFR <2.0 and/or IMR ≥25) was present in 66% of patients assessed and was similarly prevalent in those with and without obstructive epicardial disease (62% vs. 69%, p 0.52). During vasoreactivity testing, 24% of those assessed had evidence of coronary microvascular endothelial dysfunction. Patients with obstructive CAD were more often male (63% vs. 38%, p 0.028), and had a history of CAD (50% vs. 19%, p 0.005), diabetes mellitus (63% vs. 41%, p 0.05), and a higher E/e' on echocardiography (median 14.4 vs. 12.3, p 0.044) than those without obstructive coronary disease. Patients with CMD had higher B-type natriuretic peptide levels (median 569 vs. 197 pg/ml, p 0.036) than those without microvascular dysfunction.

Selected baseline characteristics No obstructive CAD (n=37) Obstructive CAD (n=38) p-value No CMD (n=21) CMD (n=41) p-value Age (mean, years) 72 73 0.4 74 72 0.41 Female, n (%) 23 (62%) 14 (37%) 0.028 11 (52%) 22 (54%) 0.92 CAD history, n (%) 7 (19%) 19 (50%) 0.005 7 (33%) 12 (29%) 0.74 Diabetes mellitus, n (%) 15 (41%) 24 (63%) 0.05 11 (52%) 22 (54%) 0.92 BNP (median, pg/ml) 323 315 0.9 197 569 0.036 Ejection fraction (median, %) 59 58 0.35 60 56 0.064 E/e' (median) 12.3 14.4 0.044 14.2 12.4 0.74

Study flow diagram

Conclusion

Both epicardial CAD and CMD are common in HFpEF and each may be a therapeutic target in this condition. Although it has been hypothesized that CMD may be due to endothelial dysfunction, our findings suggest that CMD is predominantly due to structural abnormalities in HFpEF.

Acknowledgement/Funding

Chief Scientist Office

6030Effects of adjunctive treatment with low-dose alteplase during primary percutaneous coronary intervention according to ischaemic time

Background

Microvascular obstruction affects half of patients with acute ST-segment elevation myocardial infarction and confers an adverse prognosis.

Purpose

We aimed to determine whether the efficacy and safety of a therapeutic strategy involving low-dose intra-coronary alteplase infused early after coronary reperfusion associates with ischaemic time.

Methods

We conducted a prospective, multicentre, parallel group, 1:1:1 randomised, dose-ranging trial in patients undergoing primary percutaneous coronary intervention. Ischaemic time, defined as the time from symptom onset to coronary reperfusion, was a pre-specified sub-group of interest. Between March 17, 2016, and December 21, 2017, 440 patients presenting at 11 hospitals in the UK were enrolled with follow up to 3 months. Patients with acute myocardial infarction due to occlusion of a major coronary artery presenting ≤6 hours from symptom onset were randomly assigned to treatment with placebo, alteplase 10mg or alteplase 20mg. The primary outcome was the amount of microvascular obstruction disclosed by cardiac magnetic resonance imaging at 2–7 days. Secondary outcomes included infarct size, myocardial haemorrhage, left ventricular ejection fraction, and troponin T area-under-the curve.

Results

440 patients were randomized (figure), the primary endpoint was achieved in 396 (90%), seventeen (3.9%) withdrew and all other patients were followed up to 3 months. In the primary analysis, the amount of microvascular obstruction did not differ between the groups. Their ischaemic times were: ≤2 hours, n=98; ≥2–<4 hours, n=215; and ≥4–6 hours, n=83.

In patients with an ischaemic time ≥4 hours, treatment with alteplase (10 mg, n=26; 20 mg, n=30) was associated with a dose dependent increase in the amount (mean) of microvascular obstruction (% left ventricular mass) compared to placebo (n=27) 1.14 vs. 3.11 vs. 5.20; mean difference on square root scale 0.81 (95% CI 0.21, 1.42), p=0.009. The interaction test between ischaemic time and treatment (active vs. placebo) was not statistically significant p=0.06, however when the interaction was assessed for a trend across treatment groups this did reach statistical significance, p=0.018.

Furthermore, a higher proportion of patients presenting ≥4–6 hours treated with 20 mg of alteplase had myocardial haemorrhage (59.3%) compared to the placebo group (28.0%), odds ratio 3.81 (95% CI 1.19, 12.25), p=0.025. The amount of haemorrhage was also greater; estimated mean difference 3.49 (95% CI 1.22, 5.75), p=0.0026. No between-treatment group differences for myocardial haemorrhage were observed in patients presenting with shorter ischaemic times.

Study flow diagram

Conclusions

In patients presenting with an ischaemic time ≥4 hours, adjunctive treatment with low-dose intra-coronary alteplase during primary PCI was associated with increases in microvascular obstruction and myocardial haemorrhage. The mechanism may involve haemorrhagic transformation within the infarct core.

Acknowledgement/Funding

NIHR EME programme (reference: 12/170/45); British Heart Foundation (BHF reference FS/16/74/32573)

249High-sensitivity cardiac troponin and the universal definition of myocardial infarction: a randomised controlled trial

Background

The Universal Definition of Myocardial Infarction recommends the 99th centile diagnostic threshold using a high-sensitivity cardiac troponin (hs-cTn) assay and the classification of patients by the etiology of myocardial injury. Whether implementation of this definition improves risk stratification, treatment or outcomes is unknown.

Methods

In a stepped-wedge cluster randomized controlled trial, we implemented a high-sensitivity troponin assay and the recommendations of the Universal Definition in 48,282 consecutive patients with suspected acute coronary syndrome across ten hospitals. In a pre-specified secondary analysis, we compared the primary outcome of myocardial infarction or cardiovascular death, and secondary outcome of non-cardiovascular death at one year across diagnostic categories as per the Fourth Universal Definition. We applied competing risks methodology in all analyses, using a cumulative incidence function and determining the cause-specific hazard ratio (csHR) for competing outcomes.

Results

Cardiac troponin concentrations were elevated in 21.5% (10,360/48,282) of all trial participants. Implementation increased the diagnosis of type 1 myocardial infarction by 11% (510/4,471), type 2 myocardial infarction by 22% (205/916), acute myocardial injury by 36% (443/1,233) and chronic myocardial injury by 43% (389/898). The risk and rate of the primary outcome was highest in those with type 1 myocardial infarction, whereas the risk and rate of non-cardiovascular death was highest in those with acute myocardial injury (Table, Figure). Despite increases in anti-platelet therapy and coronary revascularization after implementation, the primary outcome was unchanged in patients with type 1 myocardial infarction (csHR 1.00, 95% CI 0.82 to 1.21), or in any other category.

Adjusted csHR for competing outcomes Myocardial infarction or cardiovascular death Non-cardiovascular death Adjusted csHR (95% CI) Adjusted csHR (95% CI) Type 1 myocardial infarction 5.64 (5.12 to 6.22) 0.83 (0.72 to 0.96) Type 2 myocardial infarction 3.50 (2.94 to 4.15) 1.72 (1.44 to 2.06) Acute myocardial injury 4.38 (3.80 to 5.05) 2.65 (2.33 to 3.00) Chronic myocardial injury 3.88 (3.31 to 4.55) 2.06 (1.77 to 2.40) Cox regression models adjusted for age, sex, diabetes, ischaemic heart disease, season, days since trial onset and site of recruitment (as a random effect).

Cumulative incidence and number at risk

Conclusions

Implementation of the recommendations of the Universal Definition identified patients with different risks of future cardiovascular and non-cardiovascular events, but did not improve outcomes. Greater understanding of the underlying mechanisms and effective strategies for the investigation and treatment of patients with myocardial injury and infarction are required if we are to improve outcomes.

Acknowledgement/Funding

British Heart Foundation

Influence of Diagnostic Method on Outcomes in Phase 3 Clinical Trials of Bezlotoxumab for the Prevention of Recurrent Clostridioides difficile Infection: A Post Hoc Analysis of MODIFY I/II

Background

The optimum diagnostic test method for Clostridioides difficile infection (CDI) remains controversial due to variation in accuracy in identifying true CDI. This post hoc analysis examined the impact of CDI diagnostic testing methodology on efficacy outcomes in phase 3 MODIFY I/II trials.

Methods

In MODIFY I/II (NCT01241552/NCT01513239), participants received bezlotoxumab (10 mg/kg) or placebo during anti-CDI treatment for primary/recurrent CDI (rCDI). Using MODIFY I/II pooled data, initial clinical cure (ICC) and rCDI were assessed in participants diagnosed at baseline using direct detection methods (enzyme immunoassay [EIA]/cell cytotoxicity assay [CCA]) or indirect methods to determine toxin-producing ability (toxin gene polymerase chain reaction [tgPCR]/toxigenic culture).

Results

Of 1554 participants who received bezlotoxumab or placebo in MODIFY I/II, 781 (50.3%) and 773 (49.7%) were diagnosed by tgPCR/toxigenic culture and toxin EIA/CCA, respectively. Participants diagnosed by toxin EIA/CCA were more likely to be inpatients, older, and have severe CDI. In bezlotoxumab recipients, ICC rates were slightly higher in the toxin EIA/CCA subgroup (81.7%) vs tgPCR/toxigenic culture (78.4%). Bezlotoxumab significantly reduced the rCDI rate vs placebo in both subgroups; however, the magnitude of reduction was substantially larger in participants diagnosed by toxin EIA/CCA (relative difference, –46.6%) vs tgPCR/toxigenic culture (–29.1%). In bezlotoxumab recipients, the rCDI rate was lower in the toxin EIA/CCA subgroup (17.6%) vs tgPCR/toxigenic culture (23.6%; absolute difference, –6.0%; 95% confidence interval, –12.4 to 0.3; relative difference, –25.4%).

Conclusions

Diagnostic tests that detect fecal C. difficile toxins are of fundamental importance to accurately diagnosing CDI, including in clinical trial design, ensuring that therapeutic efficacy is not underestimated.

Survey of screening methods, rates and policies for the detection of carbapenemase-producing Enterobacteriaceae in English hospitals

Multi-drug-resistant Gram-negative bacteria are of major clinical concern. The increasing prevalence of carbapenemase-producing Enterobacteriaceae (CPE), resistant to all beta-lactams including carbapenems and able to colonize the large intestine, represents a key threat. Rapid, accurate detection of intestinal CPE colonization is critical to minimize transmission, and hence reduce costly, difficult-to-treat CPE infections. There is currently no 'gold standard' CPE detection method. A survey of diagnostic laboratories in England found considerable heterogeneity in diagnostic CPE testing methods and procedures.

The effects of remote ischaemic preconditioning on coronary artery function in patients with stable coronary artery disease

Background

Remote ischaemic preconditioning (RIPC) is a cardioprotective intervention invoking intermittent periods of ischaemia in a tissue or organ remote from the heart. The mechanisms of this effect are incompletely understood. We hypothesised that RIPC might enhance coronary vasodilatation by an endothelium-dependent mechanism.

Methods

We performed a prospective, randomised, sham-controlled, blinded clinical trial. Patients with stable coronary artery disease (CAD) undergoing elective invasive management were prospectively enrolled, and randomised to RIPC or sham (1:1) prior to angiography. Endothelial-dependent vasodilator function was assessed in a non-target coronary artery with intracoronary infusion of incremental acetylcholine doses (10^− 6, 10^− 5, 10^− 4 mol/l). Venous blood was sampled pre- and post-RIPC or sham, and analysed for circulating markers of endothelial function. Coronary luminal diameter was assessed by quantitative coronary angiography. The primary outcome was the between-group difference in the mean percentage change in coronary luminal diameter following the maximal acetylcholine dose (Clinicaltrials.gov identifier: NCT02666235).

Results

75 patients were enrolled. Following angiography, 60 patients (mean ± SD age 57.5 ± 8.5 years; 80% male) were eligible and completed the protocol (n = 30 RIPC, n = 30 sham). The mean percentage change in coronary luminal diameter was − 13.3 ± 22.3% and − 2.0 ± 17.2% in the sham and RIPC groups respectively (difference 11.32%, 95%CI: 1.2– 21.4, p = 0.032). This remained significant when age and sex were included as covariates (difference 11.01%, 95%CI: 1.01– 21.0, p = 0.035). There were no between-group differences in endothelial-independent vasodilation, ECG parameters or circulating markers of endothelial function.

Conclusions

RIPC attenuates the extent of vasoconstriction induced by intracoronary acetylcholine infusion. This endothelium-dependent mechanism may contribute to the cardioprotective effects of RIPC.

Prognostic significance of anaemia in patients with heart failure with preserved and reduced ejection fraction: results from the MAGGIC individual patient data meta-analysis

BACKGROUND

Anaemia is common among patients with heart failure (HF) and is an important prognostic marker.

AIM

We sought to determine the prognostic importance of anaemia in a large multinational pooled dataset of prospectively enrolled HF patients, with the specific aim to determine the prognostic role of anaemia in HF with preserved and reduced ejection fraction (HF-PEF and HF-REF, respectively).

DESIGN

Individual person data meta-analysis.

METHODS

Patients with haemoglobin (Hb) data from the MAGGIC dataset were used. Anaemia was defined as Hb < 120 g/l in women and <130 g/l in men. HF-PEF was defined as EF ≥ 50%; HF-REF was EF < 50%. Cox proportional hazard modelling, with adjustment for clinically relevant variables, was undertaken to investigate factors associated with 3-year all-cause mortality.

RESULTS

Thirteen thousand two hundred and ninety-five patients with HF from 19 studies (9887 with HF-REF and 3408 with HF-PEF). The prevalence of anaemia was similar among those with HF-REF and HF-PEF (42.8 and 41.6% respectively). Compared with patients with normal Hb values, those with anaemia were older, were more likely to have diabetes, ischaemic aetiology, New York Heart Association class IV symptoms, lower estimated glomerular filtration rate and were more likely to be taking diuretic and less likely to be taking a beta-blocker. Patients with anaemia had higher all-cause mortality (adjusted hazard ratio [aHR] 1.38, 95% confidence interval [CI] 1.25-1.51), independent of EF group: aHR 1.67 (1.39-1.99) in HF-PEF and aHR 2.49 (2.13-2.90) in HF-REF.

CONCLUSIONS

Anaemia is an adverse prognostic factor in HF irrespective of EF. The prognostic importance of anaemia was greatest in patients with HF-REF.