Influence of Pathophysiological Patterns of Coronary Artery Disease on Immediate Percutaneous Coronary Intervention Outcomes.

BACKGROUND: Diffuse coronary artery disease (CAD) impacts the safety and efficacy of percutaneous coronary intervention (PCI). Pathophysiological CAD patterns can be quantified using fractional flow reserve (FFR) pullbacks incorporating the pullback pressure gradient (PPG) calculation. This study aimed to establish the capacity of PPG to predict optimal revascularisation and procedural outcomes. METHODS: This prospective, investigator-initiated, single-arm, multicentre study enrolled patients with at least one epicardial lesion with an FFR ≤ 0.80 scheduled for PCI. Manual FFR pullbacks were employed to calculate PPG. The primary outcome of optimal revascularisation was defined as a post-PCI FFR ≥ 0.88. RESULTS: 993 patients with 1044 vessels were included. The mean FFR was 0.68 ± 0.12, PPG 0.62 ± 0.17, and post-PCI FFR 0.87 ± 0.07. PPG was significantly correlated with the change in FFR after PCI (r=0.65, 95% CI 0.61-0.69, p<0.001) and demonstrated excellent predicted capacity for optimal revascularisation (AUC 0.82, 95% CI 0.79-0.84, p<0.001). Conversely, FFR alone did not predict revascularisation outcomes (AUC 0.54, 95% CI 0.50-0.57). PPG influenced treatment decisions in 14% of patients, redirecting them from PCI to alternative treatment modalities. Periprocedural myocardial infarction occurred more frequently in patients with low PPG (<0.62) compared to those with focal disease (OR 1.71, 95% CI: 1.00-2.97). CONCLUSIONS: Pathophysiological CAD patterns distinctly affect the safety and effectiveness of PCI. The PPG showed an excellent predictive capacity for optimal revascularisation and demonstrated added value compared to a FFR measurement.

Rationale and design of the pullback pressure gradient (PPG) global registry.

INTRODUCTION: Diffuse disease has been identified as one of the main reasons leading to low post-PCI fractional flow reserve (FFR) and residual angina after PCI. Coronary pressure pullbacks allow for the evaluation of hemodynamic coronary artery disease (CAD) patterns. The pullback pressure gradient (PPG) is a novel metric that quantifies the distribution and magnitude of pressure losses along the coronary artery in a focal-to-diffuse continuum. AIM: The primary objective is to determine the predictive capacity of the PPG for post-PCI FFR. METHODS: This prospective, large-scale, controlled, investigator-initiated, multicenter study is enrolling patients with at least 1 lesion in a major epicardial vessel with a distal FFR ≤ 0.80 intended to be treated by PCI. The study will include 982 subjects. A standardized physiological assessment will be performed pre-PCI, including the online calculation of PPG from FFR pullbacks performed manually. PPG quantifies the CAD pattern by combining several parameters from the FFR pullback curve. Post-PCI physiology will be recorded using a standardized protocol with FFR pullbacks. We hypothesize that PPG will predict optimal PCI results (post-PCI FFR ≥ 0.88) with an area under the ROC curve (AUC) ≥ 0.80. Secondary objectives include patient-reported and clinical outcomes in patients with focal vs. diffuse CAD defined by the PPG. Clinical follow-up will be collected for up to 36 months, and an independent clinical event committee will adjudicate events. RESULTS: Recruitment is ongoing and is expected to be completed in the second half of 2023. CONCLUSION: This international, large-scale, prospective study with pre-specified powered hypotheses will determine the ability of the preprocedural PPG index to predict optimal revascularization assessed by post-PCI FFR. In addition, it will evaluate the impact of PPG on treatment decisions and the predictive performance of PPG for angina relief and clinical outcomes.

The double injection technique to improve visualization of severe coronary lesions with optical coherence tomography.

BACKGROUND: Optical coherence tomography (OCT) is a high-resolution imaging modality that provides a precise evaluation of coronary anatomy. However, the presence of severe coronary lesions can prevent the required adequate distal contrast flushing resultting in inadequate blood clearance and poor image quality or complete blood shadowing of the underlying vessel wall. OBJECTIVES: The aim of this prospective study was to evaluate the feasibility and safety of a novel "double injection technique" (DIT) to overcome the limitations of the conventional technique (CT) in patients with severely stenotic lesions. METHODS: Twenty-three patients with severe angiographic lesions were sequentially imaged before intervention with OCT with the CT and then with DIT. A total of 5125 OCT frames were carefully matched and analyzed by an independent central core lab. A semiquantitative image quality score was used to grade the number of quadrants (0-4) with vessel wall visualization. RESULTS: Optimal OCT visualization (Grades 3-4) significantly improved by the DIT (68% vs. 38% of frames, p < 0.001). The DIT also improved the mean score (3.1 ± 0.6 vs. 2.0 ± 0.8; p < 0.05; mean improvement of 1.1 ± 0.5 per patient). There were no complications associated with the DIT. CONCLUSION: The DIT significantly improved preintervention image quality of OCT in severe coronary lesions.

Optical detection of atherosclerosis at molecular level by optical coherence tomography: An in vitro study.

There is an urgent need for contrast agents to detect the first inflammation stage of atherosclerosis by cardiovascular optical coherence tomography (CV-OCT), the imaging technique with the highest spatial resolution and sensitivity of those used during coronary interventions. Gold nanoshells (GNSs) provide the strongest signal by CV-OCT. GNSs are functionalized with the cLABL peptide that binds specifically to the ICAM-1 molecule upregulated in the first stage of atherosclerosis. Dark field microscopy and CV-OCT are used to evaluate the specific adhesion of these functionalized GNSs to activated endothelial cells. This adhesion is investigated under static and dynamic conditions, for shear stresses comparable to those of physiological conditions. An increase in the scattering signal given by the functionalized GNSs attached to activated cells is observed compared to non-activated cells. Thus, cLABL-functionalized GNSs behave as excellent contrast agents for CV-OCT and promise a novel strategy for clinical molecular imaging of atherosclerosis.

Thin-cap fibroatheroma predicts clinical events in diabetic patients with normal fractional flow reserve: the COMBINE OCT-FFR trial.

AIMS: The aim of this study was to understand the impact of optical coherence tomography (OCT)-detected thin-cap fibroatheroma (TCFA) on clinical outcomes of diabetes mellitus (DM) patients with fractional flow reserve (FFR)-negative lesions. METHODS AND RESULTS: COMBINE OCT-FFR study was a prospective, double-blind, international, natural history study. After FFR assessment, and revascularization of FFR-positive lesions, patients with ≥1 FFR-negative lesions (target lesions) were classified in two groups based on the presence or absence of ≥1 TCFA lesion. The primary endpoint compared FFR-negative TCFA-positive patients with FFR-negative TCFA-negative patients for a composite of cardiac mortality, target vessel myocardial infarction, clinically driven target lesion revascularization or unstable angina requiring hospitalization at 18 months. Among 550 patients enrolled, 390 (81%) patients had ≥1 FFR-negative lesions. Among FFR-negative patients, 98 (25%) were TCFA positive and 292 (75%) were TCFA negative. The incidence of the primary endpoint was 13.3% and 3.1% in TCFA-positive vs. TCFA-negative groups, respectively (hazard ratio 4.65; 95% confidence interval, 1.99-10.89; P < 0.001). The Cox regression multivariable analysis identified TCFA as the strongest predictor of major adverse clinical events (MACE) (hazard ratio 5.12; 95% confidence interval 2.12-12.34; P < 0.001). CONCLUSIONS: Among DM patients with ≥1 FFR-negative lesions, TCFA-positive patients represented 25% of this population and were associated with a five-fold higher rate of MACE despite the absence of ischaemia. This discrepancy between the impact of vulnerable plaque and ischaemia on future adverse events may represent a paradigm shift for coronary artery disease risk stratification in DM patients.

Severe coronary spasm in a COVID-19 patient.

Myocardial injury is frequently detected in coronavirus disease 2019 (COVID-19) patients. However, up to one-third of COVID-19 patients showing ST-segment elevation on the electrocardiogram have angiographically normal coronary arteries. We present a case of an acute coronary syndrome due to a coronary spasm in a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) patient. This pathophysiological mechanism was clearly demonstrated by intracoronary imaging techniques (optical coherence tomography) and invasive vasospasm test.

Role of optical coherence tomography for distal left main stem angioplasty.

OBJECTIVE: The objective is to analyze the acute and midterm angiographic outcome of percutaneous treatment of left main coronary stem (LM-PCI) guided by optical coherence tomography (OCT). BACKGROUND: LM-PCI is a complex procedure, and several anatomical factors may impair its outcome. Intravascular imaging is emerging as a useful tool to guide the procedure. METHODS: We conducted a retrospective analysis of patients undergoing LM-PCI at three European centers between 2014 and 2017 with a control angiography at 6-12 months. Patients were divided into two groups: OCT-guidance (pre- and post-PCI) and control group (standard angiographic guidance with/out intravascular ultrasound [IVUS]). A blinded core lab analyzed all angiographic images. Primary endpoint was late lumen loss (LLL) after 6 months. RESULTS: A total of 112 patients entered the study, 55 in the OCT group and 57 in the control group (10 IVUS). Baseline and procedural characteristics were similar between groups. Overall, reference vessel diameter of the LM was 3.98 ± 0.65 mm. OCT guidance detected four cases of stent underexpansion (7.2%) and six cases of acute malapposition (10.9%). After a median of 207 ± 23 days, LLL of LM tended to be lower in the OCT group (0.12 ± 0.41 vs. 0.26 ± 0.52 mm, p = .10), and was significantly reduced in the distal portion of the main vessel (0.03 ± 0.45 vs. 0.24 ± 0.53 mm, p = .025). Percent diameter stenosis was also lower (14 ± 9 vs. 19 ± 16%, p = .05). Adverse event rates were similar in the two groups. CONCLUSIONS: In this study, systematic OCT guidance during LM-PCI allowed a timely detection and correction of acute stent underexpansion and malapposition, and was associated with signs of improved angiographic outcome at midterm, compared to standard practice.

Prospective, randomized trial of bioresorbable scaffolds vs. everolimus-eluting stents in patients undergoing coronary stenting for myocardial infarction: the Intracoronary Scaffold Assessment a Randomized evaluation of Absorb in Myocardial Infarction (ISAR-Absorb MI) trial.

Aims: Bioresorbable scaffolds (BRS) provide short-term coronary artery scaffolding and drug delivery. Although prior trials showed a higher rate of device failure compared with conventional drug-eluting stents (DES), only a single trial investigated patients undergoing percutaneous coronary intervention (PCI) for acute myocardial infarction (MI). We aimed to compare outcomes with BRS vs. DES in patients undergoing PCI for MI. Methods and results: We did a prospective, randomized, multicentre, non-inferiority, clinical trial of everolimus-eluting BRS vs. durable polymer everolimus-eluting stents (EES) in patients with acute MI. Patients were eligible for enrolment if they presented with ST-elevation MI, or non-ST-elevation MI with thrombosis visual at angiography and were randomly allocated to treatment with BRS or EES in 2:1 proportion. Angiographic follow-up was scheduled at 6-8 months and clinical follow-up was done at 12 months. The primary endpoint was percentage diameter stenosis in-segment at follow-up. A total of 262 patients were enrolled and were allocated to BRS (n = 173) or EES (n = 89). Angiographic follow-up was available for 213 (81.3%) patients. Mean diameter stenosis was 24.6 ± 12.2% with BRS vs. 27.3 ± 11.7% with EES (mean difference -2.7%, upper limit of one-sided 97.5% confidence limit 0.7%, pre-specified margin of non-inferiority 5%, Pnon-inferiority <0.001). The rate of the device-oriented composite of cardiac death/target vessel MI/target lesion revascularization [BRS: 12 (7.0%) vs. EES: 6 (6.7%), hazard ratio (HR) 1.04, 95% confidence interval (CI) 0.39-2.78] and definite/probable stent thrombosis [3 (1.7%) vs. 2 (2.3%), HR 0.76, 95% CI 0.13-4.56] were comparable in both groups. Conclusion: In patients undergoing PCI for acute MI BRS were non-inferior to EES for percentage diameter stenosis at angiographic follow-up. Rates of clinical events were comparable between the treatment groups, although the study was not powered to detect differences in clinical outcomes. Clinical trial registration: The trial was registered at www.clinicaltrials.gov (NCT01942070).

Diagnostic accuracy of a hybrid approach of instantaneous wave-free ratio and fractional flow reserve using high-dose intracoronary adenosine to characterize intermediate coronary lesions: Results of the PALS (Practical Assessment of Lesion Severity) prospective study.

OBJECTIVES: We sought to investigate the diagnostic accuracy of instantaneous wave-free ratio (iFR) and high-dose intracoronary adenosine fractional flow reserve (IC-FFR) compared with classical intravenous adenosine fractional flow reserve (IV-FFR) to assess coronary stenosis severity. The usefulness of two hybrid strategies combining iFR and high-dose IC-FFR was also evaluated. BACKGROUND: Physiological assessment of intermediate coronary stenoses to guide revascularization is currently recommended. METHODS: Consecutive real-world patients with angiographically intermediate coronary stenosis (40-80% diameter stenosis) were prospectively included in the PALS (Practical Assessment of Lesion Severity) study. In every target lesion iFR, high-dose IC-FFR and IV-FFR were systematically measured to assess the accuracy of an hybrid sequential approach combining iFR and IC-FFR. RESULTS: A total of 106 patients with 121 intermediate coronary lesions were analyzed. Both, iFR and IC-FFR showed a significant correlation with IV-FFR (iFR: r = 0.60, 95%CI 0.48-0.70; IC-FFR: r = 0.88; 95%CI: 0.83-0.92). High-dose IC-FFR provided lower FFR values than IV-FFR (0.81 ± 0.08 vs. 0.82 ± 0.09, P = 0.25). Using a receiver-operating-characteristic curve an optimal iFR threshold of 0.91 for the screening test was identified. A sequential test strategy (initial iFR followed by IC-FFR only in lesions with iFR <0.91) yielded an excellent diagnostic accuracy (96.7%, 95%CI 96.7-99.1%) with a sensitivity, specificity, positive and negative predicted values of 100%, 94.7%, 91.8%, and 100%, respectively. A hybrid approach using the previously described iFR gray zone (0.85-0.94) also provided an excellent diagnostic accuracy (95%, 95%CI: 89.5-98.1%). CONCLUSIONS: In patients with intermediate coronary lesions a hybrid strategy by using a sequential approach of iFR and high-dose IC-FFR, provided a very good diagnostic performance to identify physiologically significant stenoses. © 2017 Wiley Periodicals, Inc.

Regulation of antigenic variation in Giardia lamblia.

Antigenic variation, a clonal phenotypic variation developed by microorganisms, involves the permanent switching of homologous, antigenically different cell surface molecules. In pathogenic microorganisms, antigenic variation is often described as a mechanism to evade the host immune system and therefore is responsible for the generation of chronic and/or recurrent infections. However, antigenic variation has also been involved in expanding host diversity and differential courses of the diseases. The intestinal protozoan parasite Giardia lamblia undergoes antigenic variation through the continuous exchange of approximately 200 variant-specific surface proteins. Here we review the principal issues regarding the significance of antigenic variation during Giardia infections, the particular features of the variant-specific surface proteins, and the current knowledge on the mechanisms that regulate this process, as well as the relevance of disrupting antigenic variation as a novel approach to design effective antiparasitic vaccines.

Spontaneous coronary artery dissection.

Spontaneous coronary artery dissection (SCAD) is a rare but challenging clinical entity of unknown etiology. From a pathophysiological standpoint, SCAD may occur in patients with a coronary intimal tear (presenting with the classic angiographic "flap" and multiple lumens), but also in patients without an intimal rupture (presenting as an intramural hematoma). Until now, available information on SCAD was largely based on multiple, small case-series studies but, recently, data from relatively large registries have cast a new light on this disease. Classically, SCAD was thought to present in young females without traditional atherosclerotic risk factors but recent reports suggest a broader clinical spectrum encompassing older patients with associated coronary artery disease. In this review, we concentrate on 3 main aspects of this unique disease: (1) the value of intracoronary diagnostic techniques (intravascular ultrasound and optical coherence tomography) to complement coronary angiography and to provide novel diagnostic insights on this elusive clinical condition; (2) the growing clinical evidence suggesting an association and potential causation between fibromuscular dysplasia and SCAD; and (3) the challenges of coronary revascularization in this adverse anatomic setting, together with recent data suggesting that a initial, conservative medical management may be preferable for the majority of patients with SCAD.

Antigenic variation in Giardia lamblia is regulated by RNA interference.

Giardia lamblia (also called Giardia intestinalis) is one of the most common intestinal parasites of humans. To evade the host's immune response, Giardia undergoes antigenic variation-a process that allows the parasite to develop chronic and recurrent infections. From a repertoire of approximately 190 variant-specific surface protein (VSP)-coding genes, Giardia expresses only one VSP on the surface of each parasite at a particular time, but spontaneously switches to a different VSP by unknown mechanisms. Here we show that regulation of VSP expression involves a system comprising RNA-dependent RNA polymerase, Dicer and Argonaute, known components of the RNA interference machinery. Clones expressing a single surface antigen efficiently transcribe several VSP genes but only accumulate transcripts encoding the VSP to be expressed. Detection of antisense RNAs corresponding to the silenced VSP genes and small RNAs from the silenced but not for the expressed vsp implicate the RNA interference pathway in antigenic variation. Remarkably, silencing of Dicer and RNA-dependent RNA polymerase leads to a change from single to multiple VSP expression in individual parasites.

Nonatherosclerotic causes of acute coronary syndrome: recognition and management.

Acute coronary syndromes (ACS) frequently result from the rupture or erosion of a vulnerable coronary plaque, with associated intracoronary thrombosis. ACS also may occur in patients with angiographically normal coronary arteries. Some of these patients, however, still have angiographically silent underlying coronary artery disease. In this setting, subtle atherosclerotic changes frequently associated with unstable morphologic features or residual intracoronary thrombus may be detected with intracoronary imaging techniques. Nevertheless, other patients develop ACS as a result of nonatherosclerotic coronary artery disease (NA-CAD). ACS in patients with NA-CAD may be the consequence of coronary spasm or transient coronary embolic phenomena. In these patients, after the initial ischemic insult, late coronary angiography usually reveals normal epicardial coronary vessels. Kounis syndrome is a type of ACS generated by allergic reactions. Takotsubo cardiomyopathy is characterized by normal coronary arteries with a distinct pattern of transient left ventricular wall motion abnormalities. ACS also may occur in young patients following illicit drug use. Finally, spontaneous coronary artery dissection and intramural hematoma represent other etiologies of NA-CAD. In this review, we discuss current evidence regarding diagnostic and treatment strategies in patients presenting with ACS as a result of NA-CAD.

Angiographic patterns in spontaneous coronary artery dissection: novel diagnostic insights.

INTRODUCTION: Spontaneous coronary artery dissection (SCAD) is a rare but well-recognized cause of acute coronary syndrome, especially important in women. Invasive coronary angiography (ICA) is the fundamental diagnostic technique for the confirmation of SCAD. Knowing the angiographic patterns suggestive of SCAD is essential for the correct identification of patients with this entity. AREAS COVERED: In this narrative review, the main angiographic characteristics of SCAD lesions as detected by ICA are presented and discussed. EXPERT OPINION: In addition to the specific angiographic classification of SCAD, several authors have described complementary angiographic patterns suggestive of SCAD. Knowledge and correct identification of these angiographic patterns is essential for the correct diagnosis of patients with clinical suspicion of SCAD.