Measuring Absolute Coronary Flow and Microvascular Resistance by Thermodilution: JACC Review Topic of the Week

Diagnosing coronary microvascular dysfunction remains challenging, primarily due to the lack of direct measurements of absolute coronary blood flow (Q) and microvascular resistance (Rμ). However, there has been recent progress with the development and validation of continuous intracoronary thermodilution, which offers a simplified and validated approach for clinical use. This technique enables direct quantification of Q and Rμ, leading to precise and accurate evaluation of the coronary microcirculation. To ensure consistent and reliable results, it is crucial to follow a standardized protocol when performing continuous intracoronary thermodilution measurements. This document aims to summarize the principles of thermodilution-derived absolute coronary flow measurements and propose a standardized method for conducting these assessments. The proposed standardization serves as a guide to ensure the best practice of the method, enhancing the clinical assessment of the coronary microcirculation.

Biomarkers of brain injury after cardiac arrest; a statistical analysis plan from the TTM2 trial biobank investigators

Background

Several biochemical markers in blood correlate with the magnitude of brain injury and may be used to predict neurological outcome after cardiac arrest. We present a protocol for the evaluation of prognostic accuracy of brain injury markers after cardiac arrest. The aim is to define the best predictive marker and to establish clinically useful cut-off levels for routine implementation.

Methods

Prospective international multicenter trial within the Targeted Hypothermia versus Targeted Normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial in collaboration with Roche Diagnostics International AG. Samples were collected 0, 24, 48, and 72 hours after randomisation (serum) and 0 and 48 hours after randomisation (plasma), and pre-analytically processed at each site before storage in a central biobank. Routine markers neuron-specific enolase (NSE) and S100B, and neurofilament light, total-tau and glial fibrillary acidic protein will be batch analysed using novel Elecsys® electrochemiluminescence immunoassays on a Cobas e601 instrument.

Results

Statistical analysis will be reported according to the Standards for Reporting Diagnostic accuracy studies (STARD) and will include comparisons for prediction of good versus poor functional outcome at six months post-arrest, by modified Rankin Scale (0-3 vs. 4-6), using logistic regression models and receiver operating characteristics curves, evaluation of mortality at six months according to biomarker levels and establishment of cut-off values for prediction of poor neurological outcome at 95-100% specificities.

Conclusions

This prospective trial may establish a standard methodology and clinically appropriate cut-off levels for the optimal biomarker of brain injury which predicts poor neurological outcome after cardiac arrest.

Exploring cognitive impairment in the early stages of an out-of-hospital cardiac arrest - a consecutive case series study

Cognitive deficits are common, although often mild, in out-of-hospital cardiac arrest patients. Prevalence and severity of cognitive deficits on discharge from acute hospital, however, are not systematically assessed in clinical practice, and not frequently reported in scientific literature, potentially hindering the development of appropriate follow-up care pathways for these patients. We hereby present data from a consecutive case series of 75 out-of-hospital cardiac arrest patients discharged from our hospital over a period of 16 months; for 46 of them we were able to obtain a cognitive profile around the time of discharge from hospital, with 37 of them experiencing cognitive deficits, ranging from mild to severe. Memory, verbal fluency and cognitive flexibility were the areas more frequently impaired. The patients we were able to assess did not differ for age, cerebral performance category score and time to return of spontaneous circulation from those we were unable to assess. Cognitive deficits were not associated with duration of "no blood flow" during cardiac arrest or with age. Our results suggest that cognitive deficits in the immediate aftermath of out-of-hospital cardiac arrest are common; however, these may be missed due to lack of systematic assessment and use of poorly sensitive cognitive tests.

Neuropsychological outcome after cardiac arrest: a prospective case control sub-study of the Targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest trial (TTM2)

BACKGROUND

This study is designed to provide detailed knowledge on cognitive impairment after out-of-hospital cardiac arrest (OHCA) and its relation to associated factors, and to validate the neurocognitive screening of the Targeted Hypothermia versus Targeted Normothermia after Out-of-Hospital Cardiac Arrest trial (TTM2-trial), assessing effectiveness of targeted temperature management after OHCA.

METHODS

This longitudinal multi-center clinical study is a sub-study of the TTM2-trial, in which a comprehensive neuropsychological examination is performed in addition to the main TTM2-trial neurocognitive screening. Approximately 7 and 24 months after OHCA, survivors at selected study sites are invited to a standardized assessment, including performance-based tests of cognition and questionnaires of emotional problems, fatigue, executive function and insomnia. At 1:1 ratio, a matched control group from a cohort of acute myocardial infarction (MI) patients is recruited to perform the same assessment. We aim to include 100 patients per group. Potential differences between the OHCA patients and the MI controls at 7 and 24 months will be analyzed with a linear regression, using composite z-scores per cognitive domain (verbal, visual/constructive, working memory, episodic memory, processing speed, executive functions) as primary outcome measures. Results from OHCA survivors on the main TTM2-trial neurocognitive screening battery will be compared with neuropsychological test results at 7 months, using sensitivity and specificity analyses.

DISCUSSION

In this study we collect detailed information on cognitive impairment after OHCA and compare this to a control group of patients with acute MI. The validation of the TTM2 neurocognitive screening battery could justify its inclusion in routine follow-up. Our results may have a potential to impact on the design of future follow-up strategies and interventions after OHCA.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03543371 . Registered 1 June 2018.

Eosinophil Deficiency Promotes Aberrant Repair and Adverse Remodeling Following Acute Myocardial Infarction

In ST-segment elevation myocardial infarction of both patients and mice, there was a decline in blood eosinophil count, with activated eosinophils recruited to the infarct zone. Eosinophil deficiency resulted in attenuated anti-inflammatory macrophage polarization, enhanced myocardial inflammation, increased scar size, and deterioration of myocardial structure and function. Adverse cardiac remodeling in the setting of eosinophil deficiency was prevented by interleukin-4 therapy.

Dobutamine Stress Echocardiography Ischemia as a Predictor of the Placebo-Controlled Efficacy of Percutaneous Coronary Intervention in Stable Coronary Artery Disease: The Stress Echocardiography-Stratified Analysis of ORBITA

BACKGROUND

Dobutamine stress echocardiography is widely used to test for ischemia in patients with stable coronary artery disease. In this analysis, we studied the ability of the prerandomization stress echocardiography score to predict the placebo-controlled efficacy of percutaneous coronary intervention (PCI) within the ORBITA trial (Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina).

METHODS

One hundred eighty-three patients underwent dobutamine stress echocardiography before randomization. The stress echocardiography score is broadly the number of segments abnormal at peak stress, with akinetic segments counting double and dyskinetic segments counting triple. The ability of prerandomization stress echocardiography to predict the placebo-controlled effect of PCI on response variables was tested by using regression modeling.

RESULTS

At prerandomization, the stress echocardiography score was 1.56±1.77 in the PCI arm (n=98) and 1.61±1.73 in the placebo arm (n=85). There was a detectable interaction between prerandomization stress echocardiography score and the effect of PCI on angina frequency score with a larger placebo-controlled effect in patients with the highest stress echocardiography score (P_interaction=0.031). With our sample size, we were unable to detect an interaction between stress echocardiography score and any other patient-reported response variables: freedom from angina (P_interaction=0.116), physical limitation (P_interaction=0.461), quality of life (P_interaction=0.689), EuroQOL 5 quality-of-life score (P_interaction=0.789), or between stress echocardiography score and physician-assessed Canadian Cardiovascular Society angina class (P_interaction=0.693), and treadmill exercise time (P_interaction=0.426).

CONCLUSIONS

The degree of ischemia assessed by dobutamine stress echocardiography predicts the placebo-controlled efficacy of PCI on patient-reported angina frequency. The greater the downstream stress echocardiography abnormality caused by a stenosis, the greater the reduction in symptoms from PCI.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02062593.

Fractional Flow Reserve and Instantaneous Wave-Free Ratio as Predictors of the Placebo-Controlled Response to Percutaneous Coronary Intervention in Stable Single-Vessel Coronary Artery Disease

BACKGROUND

There are no data on how fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are associated with the placebo-controlled efficacy of percutaneous coronary intervention (PCI) in stable single-vessel coronary artery disease.

METHODS

We report the association between prerandomization invasive physiology within ORBITA (Objective Randomised Blinded Investigation With Optimal Medical Therapy of Angioplasty in Stable Angina), a placebo-controlled trial of patients who have stable angina with angiographically severe single-vessel coronary disease clinically eligible for PCI. Patients underwent prerandomization research FFR and iFR assessment. The operator was blinded to these values. Assessment of response variables, treadmill exercise time, stress echocardiography score, symptom frequency, and angina severity were performed at prerandomization and blinded follow-up. Effects were calculated by analysis of covariance. The ability of FFR and iFR to predict placebo-controlled changes in response variables was tested by using regression modeling.

RESULTS

Invasive physiology data were available in 196 patients (103 PCI and 93 placebo). At prerandomization, the majority had Canadian Cardiovascular Society class II or III symptoms (150/196, 76.5%). Mean FFR and iFR were 0.69±0.16 and 0.76±0.22, respectively; 97% had ≥1 positive ischemia tests. The estimated effect of PCI on between-arm prerandomization-adjusted total exercise time was 20.7 s (95% confidence interval [CI], -4.0 to 45.5; P=0.100) with no interaction of FFR ( P_interaction=0.318) or iFR ( P_interaction=0.523). PCI improved stress echocardiography score more than placebo (1.07 segment units; 95% CI, 0.70-1.44; P<0.00001). The placebo-controlled effect of PCI on stress echocardiography score increased progressively with decreasing FFR ( P_interaction<0.00001) and decreasing iFR ( P_interaction<0.00001). PCI did not improve angina frequency score significantly more than placebo (odds ratio, 1.64; 95% CI, 0.96-2.80; P=0.072) with no detectable evidence of interaction with FFR ( P_interaction=0.849) or iFR ( P_interaction=0.783). However, PCI resulted in more patient-reported freedom from angina than placebo (49.5% versus 31.5%; odds ratio, 2.47; 95% CI, 1.30-4.72; P=0.006) but neither FFR ( P_interaction=0.693) nor iFR ( P_interaction=0.761) modified this effect.

CONCLUSIONS

In patients with stable angina and severe single-vessel disease, the blinded effect of PCI was more clearly seen by stress echocardiography score and freedom from angina than change in treadmill exercise time. Moreover, the lower the FFR or iFR, the greater the magnitude of stress echocardiographic improvement caused by PCI.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov . Unique identifier: NCT02062593.

Pre-Angioplasty Instantaneous Wave-Free Ratio Pullback Predicts Hemodynamic Outcome In Humans With Coronary Artery Disease: Primary Results of the International Multicenter iFR GRADIENT Registry

OBJECTIVES

The authors sought to evaluate the accuracy of instantaneous wave-Free Ratio (iFR) pullback measurements to predict post-percutaneous coronary intervention (PCI) physiological outcomes, and to quantify how often iFR pullback alters PCI strategy in real-world clinical settings.

BACKGROUND

In tandem and diffuse disease, offline analysis of continuous iFR pullback measurement has previously been demonstrated to accurately predict the physiological outcome of revascularization. However, the accuracy of the online analysis approach (iFR pullback) remains untested.

METHODS

Angiographically intermediate tandem and/or diffuse lesions were entered into the international, multicenter iFR GRADIENT (Single instantaneous wave-Free Ratio Pullback Pre-Angioplasty Predicts Hemodynamic Outcome Without Wedge Pressure in Human Coronary Artery Disease) registry. Operators were asked to submit their procedural strategy after angiography alone and then after iFR-pullback measurement incorporating virtual PCI and post-PCI iFR prediction. PCI was performed according to standard clinical practice. Following PCI, repeat iFR assessment was performed and the actual versus predicted post-PCI iFR values compared.

RESULTS

Mean age was 67 ± 12 years (81% male). Paired pre- and post-PCI iFR were measured in 128 patients (134 vessels). The predicted post-PCI iFR calculated online was 0.93 ± 0.05; observed actual iFR was 0.92 ± 0.06. iFR pullback predicted the post-PCI iFR outcome with 1.4 ± 0.5% error. In comparison to angiography-based decision making, after iFR pullback, decision making was changed in 52 (31%) of vessels; with a reduction in lesion number (-0.18 ± 0.05 lesion/vessel; p = 0.0001) and length (-4.4 ± 1.0 mm/vessel; p < 0.0001).

CONCLUSIONS

In tandem and diffuse coronary disease, iFR pullback predicted the physiological outcome of PCI with a high degree of accuracy. Compared with angiography alone, availability of iFR pullback altered revascularization procedural planning in nearly one-third of patients.

Percutaneous coronary intervention in stable angina (ORBITA): a double-blind, randomised controlled trial

BACKGROUND

Symptomatic relief is the primary goal of percutaneous coronary intervention (PCI) in stable angina and is commonly observed clinically. However, there is no evidence from blinded, placebo-controlled randomised trials to show its efficacy.

METHODS

ORBITA is a blinded, multicentre randomised trial of PCI versus a placebo procedure for angina relief that was done at five study sites in the UK. We enrolled patients with severe (≥70%) single-vessel stenoses. After enrolment, patients received 6 weeks of medication optimisation. Patients then had pre-randomisation assessments with cardiopulmonary exercise testing, symptom questionnaires, and dobutamine stress echocardiography. Patients were randomised 1:1 to undergo PCI or a placebo procedure by use of an automated online randomisation tool. After 6 weeks of follow-up, the assessments done before randomisation were repeated at the final assessment. The primary endpoint was difference in exercise time increment between groups. All analyses were based on the intention-to-treat principle and the study population contained all participants who underwent randomisation. This study is registered with ClinicalTrials.gov, number NCT02062593.

FINDINGS

ORBITA enrolled 230 patients with ischaemic symptoms. After the medication optimisation phase and between Jan 6, 2014, and Aug 11, 2017, 200 patients underwent randomisation, with 105 patients assigned PCI and 95 assigned the placebo procedure. Lesions had mean area stenosis of 84·4% (SD 10·2), fractional flow reserve of 0·69 (0·16), and instantaneous wave-free ratio of 0·76 (0·22). There was no significant difference in the primary endpoint of exercise time increment between groups (PCI minus placebo 16·6 s, 95% CI -8·9 to 42·0, p=0·200). There were no deaths. Serious adverse events included four pressure-wire related complications in the placebo group, which required PCI, and five major bleeding events, including two in the PCI group and three in the placebo group.

INTERPRETATION

In patients with medically treated angina and severe coronary stenosis, PCI did not increase exercise time by more than the effect of a placebo procedure. The efficacy of invasive procedures can be assessed with a placebo control, as is standard for pharmacotherapy.

FUNDING

NIHR Imperial Biomedical Research Centre, Foundation for Circulatory Health, Imperial College Healthcare Charity, Philips Volcano, NIHR Barts Biomedical Research Centre.

Feasibility of Left Atrial Appendage Occlusion Without Preprocedural Transesophageal Echocardiography or CT Scanning

OBJECTIVE

To assess the success rate and safety outcomes of left atrial appendage occlusion (LAAO) procedures in a cohort of patients who had not undergone preprocedural imaging.

BACKGROUND

LAAO patients usually undergo imaging with either transesophageal echocardiography (TEE) or computed tomography (CT) prior to the procedure itself. This preprocedural imaging may not be necessary.

METHODS

The procedural success and major complication rates were assessed in a cohort of 52 patients who underwent LAAO without preprocedural imaging.

RESULTS

Mean patient age was 75 ± 8 years. Median CHA2DS2-VASc score was 4 and median HASBLED score was 3. The LAAO procedure was successful in 51/52 cases (98.1%). In 1 case, the LAAO procedure did not proceed because the LAA was too large for the available occlusion devices. No patient had left atrial appendage thrombus, despite the fact that only 4 patients were taking oral anticoagulation therapy at the time. Major complications occurred in 2/52 cases (3.8%), both due to vascular injuries causing pseudoaneurysm formation.

CONCLUSION

LAAO in this series was not adversely affected by lack of preprocedural imaging. Omitting preprocedural imaging reduces risk attributable to the modality, reduces patient inconvenience and discomfort, reduces cost, and does not appear to significantly reduce the proportion of patients who can undergo a successful procedure. Further larger studies are warranted.

Functional coupling between the extracellular matrix and nuclear lamina by Wnt signaling in progeria

The segmental premature aging disease Hutchinson-Gilford Progeria (HGPS) is caused by a truncated and farnesylated form of Lamin A. In a mouse model for HGPS, a similar Lamin A variant causes the proliferative arrest and death of postnatal, but not embryonic, fibroblasts. Arrest is due to an inability to produce a functional extracellular matrix (ECM), because growth on normal ECM rescues proliferation. The defects are associated with inhibition of canonical Wnt signaling, due to reduced nuclear localization and transcriptional activity of Lef1, but not Tcf4, in both mouse and human progeric cells. Defective Wnt signaling, affecting ECM synthesis, may be critical to the etiology of HGPS because mice exhibit skeletal defects and apoptosis in major blood vessels proximal to the heart. These results establish a functional link between the nuclear envelope/lamina and the cell surface/ECM and may provide insights into the role of Wnt signaling and the ECM in aging.

Pulmonary cyst and cerebral arterial gas embolism in a hypobaric chamber: a case report

This is a report of an aircrew member who suffered a serious physiological incident in the form of pulmonary barotrauma and cerebral arterial gas embolism during hypobaric chamber training, and who subsequently was shown to have a cyst in the upper lobe of the left lung. The likely origin of the cyst is discussed, as well as the aeromedical disposition following thoracotomy and apical segmentectomy to remove the cyst.

Plasma antioxidants: evidence for a protective role against reactive oxygen species following cardiac surgery

Total plasma antioxidant status (TPAS), lipid peroxide concentration (LPX) and cardiac troponin T (cTnT) were measured in 24 patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). Samples were obtained preoperatively and at 1.5 h, 6 h, 24 h and 72 h after CPB. The absolute TPAS values were significantly lower at 1.5 h, 6 h, 24 h and 72 h after CPB than were preoperative values (P < 0.05). The LPX concentration was significantly elevated at 1.5 h after CPB (P < 0.05). Cardiac troponin T concentrations were significantly elevated at all time points postoperatively (P < 0.05). Preoperative TPAS values were significantly correlated with the magnitude of fall in TPAS at 1.5 h (P < 0.05). The greater the fall in TPAS between 0 and 1.5 h, the less LPX was formed between 0 and 1.5 h. The LPX at 1.5 h displayed a significant correlation with cTnT release from myocardial myocytes (P < 0.05). These data provide evidence for the first time that the consumption of antioxidants during CABG surgery with CPB protects against the production of reactive oxygen species and subsequent myocyte necrosis. Furthermore, the availability of protective antioxidants is dependent upon preoperative TPAS.

Efficacy and pharmacokinetics of a new controlled-release morphine sulfate 200-mg tablet

Nineteen of 25 patients (14 female) with advanced malignant disease completed a randomized controlled trial of a new high-dose (200 mg) tablet formulation of controlled-release morphine. Compared with the currently available 100-mg tablets there were no differences in pain severity or adverse effects with the new formulation. In four patients, full 12-hr plasma morphine concentration profiles at steady state were obtained and showed no significant differences between the same dose provided as 100-mg and 200-mg tablets in Cmax, tmax, or other pharmacokinetic indices.