Speed of cooling after cardiac arrest in relation to the intervention effect: a sub-study from the TTM2-trial.

BACKGROUND: Targeted temperature management (TTM) is recommended following cardiac arrest; however, time to target temperature varies in clinical practice. We hypothesised the effects of a target temperature of 33 °C when compared to normothermia would differ based on average time to hypothermia and those patients achieving hypothermia fastest would have more favorable outcomes. METHODS: In this post-hoc analysis of the TTM-2 trial, patients after out of hospital cardiac arrest were randomized to targeted hypothermia (33 °C), followed by controlled re-warming, or normothermia with early treatment of fever (body temperature, ≥ 37.8 °C). The average temperature at 4 h (240 min) after return of spontaneous circulation (ROSC) was calculated for participating sites. Primary outcome was death from any cause at 6 months. Secondary outcome was poor functional outcome at 6 months (score of 4-6 on modified Rankin scale). RESULTS: A total of 1592 participants were evaluated for the primary outcome. We found no evidence of heterogeneity of intervention effect based on the average time to target temperature on mortality (p = 0.17). Of patients allocated to hypothermia at the fastest sites, 71 of 145 (49%) had died compared to 68 of 148 (46%) of the normothermia group (relative risk with hypothermia, 1.07; 95% confidence interval 0.84-1.36). Poor functional outcome was reported in 74/144 (51%) patients in the hypothermia group, and 75/147 (51%) patients in the normothermia group (relative risk with hypothermia 1.01 (95% CI 0.80-1.26). CONCLUSIONS: Using a hospital's average time to hypothermia did not significantly alter the effect of TTM of 33 °C compared to normothermia and early treatment of fever.

Testing ChatGPT ability to answer laypeople questions about cardiac arrest and cardiopulmonary resuscitation.

INTRODUCTION: Cardiac arrest leaves witnesses, survivors, and their relatives with a multitude of questions. When a young or a public figure is affected, interest around cardiac arrest and cardiopulmonary resuscitation (CPR) increases. ChatGPT allows everyone to obtain human-like responses on any topic. Due to the risks of accessing incorrect information, we assessed ChatGPT accuracy in answering laypeople questions about cardiac arrest and CPR. METHODS: We co-produced a list of 40 questions with members of Sudden Cardiac Arrest UK covering all aspects of cardiac arrest and CPR. Answers provided by ChatGPT to each question were evaluated by professionals for their accuracy, by professionals and laypeople for their relevance, clarity, comprehensiveness, and overall value on a scale from 1 (poor) to 5 (excellent), and for readability. RESULTS: ChatGPT answers received an overall positive evaluation (4.3 ± 0.7) by 14 professionals and 16 laypeople. Also, clarity (4.4 ± 0.6), relevance (4.3 ± 0.6), accuracy (4.0 ± 0.6), and comprehensiveness (4.2 ± 0.7) of answers was rated high. Professionals, however, rated overall value (4.0 ± 0.5 vs 4.6 ± 0.7; p = 0.02) and comprehensiveness (3.9 ± 0.6 vs 4.5 ± 0.7; p = 0.02) lower compared to laypeople. CPR-related answers consistently received a lower score across all parameters by professionals and laypeople. Readability was 'difficult' (median Flesch reading ease score of 34 [IQR 26-42]). CONCLUSIONS: ChatGPT provided largely accurate, relevant, and comprehensive answers to questions about cardiac arrest commonly asked by survivors, their relatives, and lay rescuers, except CPR-related answers that received the lowest scores. Large language model will play a significant role in the future and healthcare-related content generated should be monitored.

Assessing the Impact of Prolonged Averaging of Coronary Continuous Thermodilution Traces.

Continuous Thermodilution is a novel method of quantifying coronary flow (Q) in mL/min. To account for variability of Q within the cardiac cycle, the trace is smoothened with a 2 s moving average filter. This can sometimes be ineffective due to significant heart rate variability, ventricular extrasystoles, and deep inspiration, resulting in a fluctuating temperature trace and ambiguity in the location of the "steady state". This study aims to assess whether a longer moving average filter would smoothen any fluctuations within the continuous thermodilution traces resulting in improved interpretability and reproducibility on a test-retest basis. Patients with ANOCA underwent repeat continuous thermodilution measurements. Analysis of traces were performed at averages of 10, 15, and 20 s to determine the maximum acceptable average. The maximum acceptable average was subsequently applied as a moving average filter and the traces were re-analysed to assess the practical consequences of a longer moving average. Reproducibility was then assessed and compared to a 2 s moving average. Of the averages tested, only 10 s met the criteria for acceptance. When the data was reanalysed with a 10 s moving average filter, there was no significant improvement in reproducibility, however, it resulted in a 12% diagnostic mismatch. Applying a longer moving average filter to continuous thermodilution data does not improve reproducibility. Furthermore, it results in a loss of fidelity on the traces, and a 12% diagnostic mismatch. Overall, current practice should be maintained.

Comparison of bolus versus continuous thermodilution derived indices of microvascular dysfunction in revascularized coronary syndromes.

Background: The assessment of coronary microvascular dysfunction (CMD) using invasive methods is a field of growing interest, however the preferred method remains debated. Bolus and continuous thermodilution are commonly used methods, but weak agreement has been observed in patients with angina with non-obstructive coronary arteries (ANOCA). This study examined their agreement in revascularized acute coronary syndromes (ACS) and chronic coronary syndromes (CCS) patients. Objective: To compare bolus thermodilution and continuous thermodilution indices of CMD in revascularized ACS and CCS patients and assess their diagnostic agreement at pre-defined cut-off points. Methods: Patients from two centers underwent paired bolus and continuous thermodilution assessments after revascularization. CMD indices were compared between the two methods and their agreements at binary cut-off points were assessed. Results: Ninety-six patients and 116 vessels were included. The mean age was 64 ± 11 years, and 20 (21 %) were female. Overall, weak correlations were observed between the Index of Microcirculatory Resistance (IMR) and continuous thermodilution microvascular resistance (Rµ) (rho = 0.30p = 0.001). The median coronary flow reserve (CFR) from continuous thermodilution (CFRcont) and bolus thermodilution (CFRbolus) were 2.19 (1.76-2.67) and 2.55 (1.50-3.58), respectively (p < 0.001). Weak correlation and agreement were observed between CFRcont and CFRbolus (rho = 0.37, p < 0.001, ICC 0.228 [0.055-0.389]). When assessed at CFR cut-off values of 2.0 and 2.5, the methods disagreed in 41 (35 %) and 45 (39 %) of cases, respectively. Conclusions: There is a significant difference and weak agreement between bolus and continuous thermodilution-derived indices, which must be considered when diagnosing CMD in ACS and CCS patients.

Invasive Detection of Coronary Microvascular Dysfunction: How It Began, and Where We Are Now.

The landscape of interventional cardiology is ever evolving. Contemporary practice has shifted from a stenosis-centred approach to the total characterisation of both the epicardial and microcirculatory vessels. Microcirculatory dysfunction plays an important role in the pathophysiology of acute and chronic coronary syndromes, and characterisation of the microcirculation has important clinical consequences. Accordingly, the invasive diagnosis of microcirculatory dysfunction is becoming a key feature of the interventional cardiologist's toolkit. This review focuses on the methodology underpinning the invasive diagnosis of microvascular dysfunction and highlights the indices that have arisen from these methodologies.

The challenges of a randomised placebo-controlled trial of CTO PCI vs. placebo with optimal medical therapy: The ORBITA-CTO pilot study design and protocol.

Background: Percutaneous coronary intervention (PCI) for coronary chronic total occlusion (CTO) has been performed for the improvement of symptoms and quality of life in patients with stable angina. The ORBITA study demonstrated the role of the placebo effect in contemporary PCI in non-CTO chronic coronary syndromes. However, the benefit of CTO PCI beyond that of a placebo has not been demonstrated. Aims: The ORBITA-CTO pilot study will be a double-blind, placebo-controlled study of CTO PCI randomising patients who have: (1) been accepted by a CTO operator for PCI; (2) experienced symptoms due to a CTO; (3) evidence of ischaemia; (4) evidence of viability within the CTO territory; and (5) a J-CTO score ≤3. Methods: Patients will undergo medication optimisation that will ensure they are on at least a minimum amount of anti-anginals and complete questionnaires. Patients will record their symptoms on an app daily throughout the study. Patients will undergo randomisation procedures, including an overnight stay, and be discharged the following day. All anti-anginals will be stopped after randomisation and re-initiated on a patient-led basis during the 6-month follow-up period. At follow-up, patients will undergo repeat questionnaires and unblinding, with a further 2-week unblinded follow-up. Results: The co-primary outcomes are feasibility (blinding) in this cohort and angina symptom score using an ordinal clinical outcome scale for angina. Secondary outcomes include changes in quality-of-life measures, Seattle Angina Questionnaire (SAQ), peak VO2, and anaerobic threshold on the cardiopulmonary exercise test. Conclusion: The feasibility of a placebo-controlled CTO PCI study will lead to future studies assessing efficacy. The impact of CTO PCI on angina measured using a novel daily symptom app may provide improved fidelity in assessing symptoms in patients with CTO's.

Changes in absolute flow, myocardial resistance and FFR after chronic total occlusion percutaneous coronary intervention.

BACKGROUND: Randomised studies of percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO) have shown inconsistent outcomes, suggesting incomplete understanding of this cohort and their coronary physiology. To address this shortcoming, we designed a prospective observational study to measure the recovery of absolute coronary blood flow following successful CTO PCI Aims: We sought to identify patient and procedural characteristics associated with a favourable physiological outcome after CTO PCI. METHODS: Consecutive patients with a CTO subtending viable myocardium underwent PCI utilising contemporary techniques and the hybrid algorithm. Immediately after PCI, and at 3-month follow-up, physiological measurements were performed utilising continuous thermodilution. RESULTS: A total of 81 patients were included with a mean age of 63.6±8.9 years, and 66 (81.5%) were male. Physiological measurements of absolute coronary blood flow in the CTO vessel increased by 30% (p<0.001) and microvascular resistance reduced by 16% (p<0.001) from immediately post-CTO PCI to follow-up assessment. Fractional flow reserve increased by 0.02 (p=0.015) in the same period. Prior coronary artery bypass graft (CABG) and a higher estimated glomerular filtration rate (eGFR) were associated with a larger change in absolute flow. An extraplaque strategy was associated with a smaller change in absolute flow. CONCLUSIONS: Post-CTO PCI, there is a continued augmentation in absolute coronary blood flow and reduction in microvascular resistance from baseline to follow-up at 3 months. Prior CABG and a higher baseline eGFR were predictors of a larger change in absolute coronary flow, whilst an extraplaque final wire path strategy predicted a smaller change. Lastly, the patient characteristics and comorbidities had a larger influence than procedural factors on the observed change in absolute flow.

British Cardiovascular Intervention Society Consensus Position Statement on Out-of-hospital Cardiac Arrest 2: Post-discharge Rehabilitation.

Out-of-hospital cardiac arrest (OHCA) is a major public health issue that poses significant challenges both in immediate management and long-term follow-up. Survivors of OHCA often experience a combination of complex medical, physical and psychological needs that have a significant impact on quality of life. Guidelines suggest a multi-dimensional follow-up to address both physical and non-physical domains for survivors. However, it is likely that there is substantial unwarranted variation in provision of services throughout the UK. Currently, there is no nationally agreed model for the follow-up of OHCA survivors and there is an urgent need for a set of standards and guidelines in order to ensure equal access for all. Accordingly, the British Cardiovascular Interventional Society established a multi-disciplinary working group to develop a position statement that summarises the most up-to-date evidence and provides guidance on essential and desirable services for a dedicated follow-up pathway for survivors of OHCA.

British Cardiovascular Interventional Society Consensus Position Statement on Out-of-Hospital Cardiac Arrest 1: Pathway of Care.

Out-of-hospital cardiac arrest (OHCA) affects 80,000 patients per year in the UK; despite improvements in care, survival to discharge remains lower than 10%. NHS England and several societies recommend all resuscitated OHCA patients be directly transferred to a cardiac arrest centre (CAC). However, evidence is limited that all patients benefit from transfer to a CAC, and there are significant organisational, logistic and financial implications associated with such change in policies. Furthermore, there is significant variability in interventional cardiovascular practices for OHCA. Accordingly, the British Cardiovascular Interventional Society established a multidisciplinary group to address variability in practice and provide recommendations for the development of cardiac networks. In this position statement, we recommend: the formal establishment of dedicated CACs; a pathway of conveyance to CACs; and interventional practice to standardise our approach. Further research is needed to understand the role of CACs and which interventions benefit patients with OHCA to support wide-scale changes in networks of care across the UK.

Biomarker Assays for Personalised Stroke Risk Assessment in Atrial Fibrillation.

BACKGROUND: Atrial fibrillation is a well-known independent risk factor for stroke yet there is no international consensus on guidelines regarding the introduction of anticoagulation in patients deemed at intermediate risk (e.g. CHA2DS2-VASc of 1). The evolution of cardiac biomarkers such as highly sensitive troponins and B-type natriuretic peptide as well as data on D-dimers, may offer incremental enhancements for personalized thromboembolism risk assessment. These markers provide prognostic data for risk of cardiovascular morbidities associated with atrial fibrillation and offer additional specificity for assessing stroke and thromboembolic risk. These assays may therefore enhance risk prognosis in atrial fibrillation alongside conventional stroke risk stratification tool patients. We seek to explore the application of personalised risk assessment using the biomarkers to aid the clinician treating the patient with atrial fibrillation deemed to be at intermediate risk of stroke. CONCLUSION: The stroke risk assessment of a patient with an intermediate risk of stroke (CHA2DS2- VASc score 1) may be improved by using cardiac biomarkers such as highly sensitive troponin, BNP and D-dimers. We explore the application of these biomarkers to provide personalised risk assessment to help a patient with AF decide on whether to commence anticoagulation.