Clinical characteristics and outcomes of Australian and Indian ST-segment elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PCI).

INTRODUCTION: The incidence of STEMI and subsequent mortality has been reported to be higher in Indian populations compared to developed countries. However, there is limited data directly comparing contemporary primary percutaneous coronary intervention (pPCI) treatment strategies and clinical outcomes for STEMI patients between developed and developing countries. MATERIALS AND METHODS: We compared population demographics, procedural characteristics, times to reperfusion and mortality in STEMI patients treated with pPCI between two tertiary referral centers in India and Australia respectively over a 3-year period (1st Jan 2017-31st Dec 2019). RESULTS: A total of 1293 STEMI presentations (896 Indian vs 397 Australian) were included. On average, Indian patients had lower median BMI than Australian patients (BMI 25.4 vs 27.8; p < 0.001), were significantly younger (mean age 56.0 vs 63.2 years; p < 0.001), more likely male (84 % vs 80 %; p = 0.046) and diabetic (48 % vs 18 %); p < 0.001). Radial access (50 % vs 88 %; p < 0.001) and TIMI III flow post PCI was also significantly lower (85 % vs 96 %; p < 0.001) with median door-to-balloon time significantly shorter in the Indian cohort (20mins vs 43mins; p < 0.001); however, median symptom to balloon time was significantly longer (245mins vs 160mins; p < 0.001). No significant differences in 30-day mortality (4.0 % vs 2.8 % Australian; p = 0.209) or 1-year mortality (6.5 % vs 4.3 %; p = 0.120) were observed. CONCLUSION: Significant differences in demographics and presentation characteristics exist between Indian and Australian STEMI patients treated with pPCI. Indian patients had significantly longer pre-hospital delays and lower achievement of TIMI III flow post PCI, yet shorter in-hospital time to treatment.

Spontaneous coronary artery dissection (SCAD): A contemporary review.

Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of myocardial infarction that most frequently affects younger women, making it an important cause of morbidity and mortality within these demographics. The evolution of intracoronary imaging, improved diagnosis with coronary angiography, and ongoing research efforts and attention via social media, has led to increasing recognition of this previously underdiagnosed condition. In this review, we provide a summary of the current body of knowledge, as well as focused updates on the pathogenesis of SCAD, insights on genetic susceptibility, contemporary diagnostic tools, and immediate, short- and long-term management.

Trends and impact of intravascular ultrasound and optical coherence tomography on percutaneous coronary intervention for myocardial infarction.

Background: Intravascular imaging with either intravascular ultrasound (IVUS) or optical coherence tomography (OCT) during percutaneous coronary intervention (PCI) is associated with improved outcomes, but these techniques have previously been underutilized in the real world. We aimed to examine the change in utilization of intravascular imaging-guided PCI over the past decade in the United States and assess the association between intravascular imaging and clinical outcomes following PCI for myocardial infarction (MI). Methods: We surveyed the National Inpatient Sample from 2008 to 2019 to calculate the number of PCIs for MI guided by IVUS or OCT. Temporal trends were analyzed using Cochran-Armitage trend test or simple linear regression for categorical or continuous outcomes, respectively. Multivariable logistic regression was used to compare outcomes following PCI with and without intravascular imaging. Results: A total of 2,881,746 PCIs were performed for MI. The number of IVUS-guided PCIs increased by 309.9 % from 6,180 in 2008 to 25,330 in 2019 (P-trend < 0.001). The percentage of IVUS use in PCIs increased from 3.4 % in 2008 to 8.7 % in 2019 (P-trend < 0.001). The number of OCT-guided PCIs increased 548.4 % from 246 in 2011 to 1,595 in 2019 (P-trend < 0.001). The percentage of OCT guidance in all PCIs increased from 0.0 % in 2008 to 0.6 % in 2019 (P-trend < 0.001). Intravascular imaging-guided PCI was associated with lower odds of in-hospital mortality (adjusted odds ratio 0.66, 95 % confidence interval 0.60-0.72, p < 0.001). Conclusions: Although the number of intravascular imaging-guided PCIs have been increasing, adoption of intravascular imaging remains poor despite an association with lower mortality.

STEMI: Considerations for Left Main Culprit Lesions.

PURPOSE OF REVIEW: There is a paucity of data regarding the prevalence, clinical characteristics, and outcomes of patients presenting with ST elevation myocardial infarction (STEMI) due to left main (LM) culprit vessel. RECENT FINDINGS: LM culprit STEMI (LMCSTEMI) is an uncommon, but frequently catastrophic event. Prior meta-analyses and registries have described a varying prevalence of LMCSTEMI, associated cardiogenic shock, and in-hospital mortality among those surviving to hospital presentation. These observed clinical discrepancies may be partially attributable to diverse clinical and angiographical subsets among this STEMI population. STEMI due to LM culprit artery disease represents a clinically high-risk subset of patients with substantial in-hospital mortality. In this paper, we summarize the available clinical data pertaining to STEMI with LM culprit, discuss unique ECG characteristics, and discuss contemporary revascularization therapy. We also report the preliminary findings from a contemporary, STEMI database describing clinical characteristics and angiographically defined subsets of LM culprit STEMI.

Targeting the Inflammasome in Cardiovascular Disease.

The pathogenesis of cardiovascular disease (CVD) is complex and multifactorial, and inflammation plays a central role. Inflammasomes are multimeric protein complexes that are activated in a 2-step manner in response to infection or tissue damage. Upon activation the proinflammatory cytokines, interleukins-1ß and -18 are released. In the last decade, the evidence that inflammasome activation plays an important role in CVD development became stronger. We discuss the role of different inflammasomes in the pathogenesis of CVD, focusing on atherosclerosis and heart failure. This review also provides an overview of existing experimental studies and clinical trials on inflammasome inhibition as a therapeutic target in these disorders.

Referral and participation in cardiac rehabilitation of patients following acute coronary syndrome; lessons learned.

PURPOSE: Cardiac rehabilitation (CR) after hospitalization for acute coronary syndrome (ACS) has shown to reduce mortality, readmissions, and improve quality of life. CR is recommended by international guidelines but previous studies have shown low participation rates. Systematic CR referral might improve CR participation. METHODS: The present study evaluates CR referral and CR participation of patients hospitalized for ACS in 2017 and treated according to local protocol, which includes systematic CR referral. Participation rate was divided into a group that finished the CR program and drop outs. In addition, factors associated with CR referral and participation rate were evaluated. RESULTS: A total of 469 patients eligible for CR were included in the study, of which 377 (80%) were referred for CR and 353 (75%) participated in CR. Ninety percent of participants completed the CR program. Factors independently associated with CR referral included age (50-60 year vs. > 70 year: odds ratio [OR] 4.7, 95% confidence interval [CI] 1.98-11.2), diagnosis (ST-elevation myocardial infarction vs. unstable angina: OR 17.7, CI 7.59-41.7), previous cardiovascular disease (OR 0.4, CI 0.19-0.73) and left ventricular dysfunction vs. normal function (OR 2.2, CI 1.11-4.52). A larger distance to the CR center was associated with lower CR participation (<5km vs. > 20 km: OR 3.1, CI 1.20-7.72). CONCLUSIONS: Systematic CR referral in ACS patients results in high CR referral (80%) and participation (75%) rates. CR adherence might be further improved by increasing CR referral, especially in older patients and patients with NSTEMI or unstable angina.

Prognostic implications and outcomes of cardiac arrest among contemporary patients with STEMI treated with PCI.

BACKGROUND: Cardiac arrest (CA) complicating ST-elevation myocardial infarction (STEMI) is associated with a disproportionately higher risk of mortality. We described the contemporary presentation, management, and outcomes of CA patients in the era of primary percutaneous coronary intervention (PCI). METHODS: We reviewed 1,272 consecutive STEMI patients who underwent PCI between 1/1/2011-12/31/2016 and compared characteristics and outcomes between non-CA (N = 1,124) and CA patients (N = 148), defined per NCDR definitions as pulseless arrest requiring cardiopulmonary resuscitation and/or defibrillation within 24-hr of PCI. RESULTS: Male gender, cerebrovascular disease, chronic kidney disease, in-hospital STEMI, left main or left anterior descending culprit vessel, and initial TIMI 0 or 1 flow were independent predictors for CA. CA patients had longer door-to-balloon-time (106 [83,139] vs. 97 [74,121] minutes, p = 0.003) and greater incidence of cardiogenic shock (48.0% vs. 5.9%, p < 0.001), major bleeding (25.0% vs. 9.4%, p < 0.001), and 30-day mortality (16.2% vs. 4.1%, p < 0.001). Risk score for 30-day mortality based on presenting characteristics provided excellent prognostic accuracy (area under the curve = 0.902). However, over long-term follow-up of 4.5 ± 2.4 years among hospital survivors, CA did not portend any additional mortality risk (HR: 1.01, 95% CI: 0.56-1.82, p = 0.97). CONCLUSIONS: In a contemporary cohort of STEMI patients undergoing primary PCI, CA occurs in >10% of patients and is an important mechanism of mortality in patients with in-hospital STEMI. While CA is associated with adverse outcomes, it carries no additional risk of long-term mortality among survivors highlighting the need for strategies to improve the in-hospital care of STEMI patients with CA.

Coronary Artery Embolism Caused by BioGlue Surgical Adhesive After Type A Acute Aortic Dissection Repair.

Coronary artery embolism due to BioGlue surgical adhesive after repair of type A acute aortic dissection is a rare condition. We report a case of BioGlue coronary artery embolism after type A acute aortic dissection repair confirmed using intravascular ultrasound imaging and pathological examination. It was successfully treated with percutaneous coronary intervention. (Level of Difficulty: Advanced.).

Coronary lipid-rich plaque characteristics in Japanese patients with acute coronary syndrome and stable angina: A near infrared spectroscopy and intravascular ultrasound study.

BACKGROUND: Asians have a much lower incidence of adverse coronary events than Caucasians. We sought to evaluate the characteristics of coronary lipid-rich plaques (LRP) in Asian patients with acute coronary syndrome (ACS) and stable angina (SA). We also aimed to identify surrogate markers for the extent of LRP. METHODS: We evaluated 207 patients (ACS, n = 75; SA, n = 132) who underwent percutaneous coronary intervention under near infrared spectroscopy intravascular ultrasound (NIRS-IVUS). Plaque characteristics and the extent of LRP [defined as a long segment with a 4-mm maximum lipid-core burden index (maxLCBI4mm)] on NIRS in de-novo culprit and non-culprit segments were analyzed. RESULTS: The ACS culprit lesions had a significantly higher maxLCBI4mm (median [interquartile range (IQR)]: 533 [385-745] vs. 361 [174-527], p < 0.001) than the SA culprit lesions. On multivariate logistic analysis, a large LRP (defined as maxLCBI4mm ≥ 400) was the strongest independent predictor of the ACS culprit segment (odds ratio, 3.87; 95% confidence interval, 1.95-8.02). In non-culprit segments, 19.8% of patients had at least one large LRP without a small lumen. No significant correlation was found between the extent of LRP and systematic biomarkers (hs-CRP, IL-6, TNF-α), whereas the extent of LRP was positively correlated with IVUS plaque burden (r = 0.24, p < 0.001). CONCLUSIONS: We confirmed that NIRS-IVUS plaque assessment could be useful to differentiate ACS from SA culprit lesions, and that a threshold maxLCBI4mm ≥ 400 was clinically suitable in Japanese patients. No surrogate maker for a high-risk LRP was found; consequently, direct intravascular evaluation of plaque characteristics remains important.

Risk prediction of bleeding and MACCE by PRECISE-DAPT score post-PCI.

BACKGROUND: Guidelines recommend the PRECISE-DAPT (PD) score to adapt duration of dual antiplatelet therapy due to bleeding risk. However, there is first evidence that PD predicts mortality and ischemic events as well. METHODS: We investigated PD Score in 994 patients after percutaneous coronary intervention (PCI). PD was correlated with clinically frequently used scores. Major adverse cardiac and cerebrovascular events (MACCE) and Thrombolysis in Myocardial Infarction (TIMI) bleeding were assessed during one-year follow-up. RESULTS: 524 patients had PD < 25 and 470 patients PD ≥ 25 (47%). Rate of major and minor bleeding was higher in the PD ≥ 25 group (major bleeding: Hazard ratio [HR] 2.9, 95% confidence interval [Cl] 1.01-8.16, p = 0.049; minor bleeding: HR 3.94, 95% Cl 1.36-9.19, p = 0.0096). Rate of MACCE, death and myocardial infarction were higher as well (MACCE: HR 2.0, 95% Cl 1.52-2.71, p < 0.0001; death: HR 3.9, 95% Cl 2.12-5.68, p < 0.0001; MI: HR 2.1, 95% Cl 1.26-3.43, p = 0.0041). Rate of stroke/transient ischemic attack did not differ between groups. Discriminative potency to predict major and minor bleeding, MACCE, death and MI were high with nearly equal cut-off values calculated by Youden's index (YI) (major bleeding: Area under the curve [AUC] 0.66; p = 0.026; YI 32; minor bleeding: AUC 0.72; p = 0.001; YI 28; MACCE: AUC 0.62; p < 0.0001; YI 24). CONCLUSION: In our cohort, PD score predicted bleeding moderately in post-PCI patients. In this study, ischemic events were predicted as well. Adaption of antiplatelet therapy duration by PD score is accurate. Nevertheless, it should be well-balanced with patient-related risk for ischemic events.

Rescue transventricular off-pump mitral valve repair with artificial neochords for acute mitral regurgitation due to postinfarction papillary muscle rupture.

BACKGROUND: We report 3 cases of rescue transventricular off-pump mitral valve (MV) repair in high-risk patients with acute mitral regurgitation (MR) due to post-myocardial infarction (MI) papillary muscle rupture (PMR). METHODS: The 3 patients presented with acute inferior ST elevation myocardial infarction, cardiogenic shock, and pulmonary edema. Their preoperative peak troponin I levels were 1909 ng/L, 16,963 ng/L, and 8299 ng/L. All 3 patients underwent successful percutaneous intervention to the culprit coronary artery, and antiplatelet therapy was initiated. All patients required inotropic support and had an intra-aortic balloon pump inserted preoperatively. Transesophageal echocardiography (TEE) demonstrated severe eccentric MR due to the leaflet prolapse secondary to PMR. The patients' estimated EuroSCORE II scores were 16.03%, 16.68%, and 7.81%, and their Society of Thoracic Surgeons scores were 14.77%, 18.24%, and 9.8%, respectively. All 3 patients underwent urgent transventricular off-pump MV repair using artificial chords, with 2 or 3 three neochords implanted. The duration of operation was <2 hours, and intraoperative and postoperative drainage was minimal in all cases. MV function was assessed by qualitative and semiquantitative TEE. RESULTS: Intraoperative MR reduction to a mild level was achieved in all 3 patients. All patients had moderate MR at discharge, likely due to left ventricular remodeling. Severe MR recurred in all patients, at 5, 4, and 2 months of follow-up, respectively. All 3 patients underwent an elective MV reoperation via conventional approach. CONCLUSIONS: Off-pump transventricular MV repair may offer a safe and feasible alternative to stabilize high-risk patients with acute MR due to post-MI PMR. Although early MR recurrence is concerning, urgent transventricular MV repair may serve as a bridge to conventional surgery in such unstable patients.

Impact of aortic stiffness by velocity-encoded magnetic resonance imaging on late gadolinium enhancement to predict cardiovascular events.

BACKGROUND: Increased aortic stiffness has been established as a marker in various cardiovascular diseases. Previous reports revealed a significant correlation between aortic stiffness and myocardial scarring using the late gadolinium enhancement cardiovascular magnetic resonance (LGE-CMR). However, prognostic data concerning aortic stiffness combining myocardial scarring remains limited. METHOD: A total of 402 patients who had undergone clinical CMR for the evaluation of cardiac function, LGE, and aortic pulse wave velocity (PWV) using velocity encoded-CMR (VE-CMR) were included. Patients were classified into 4 groups using mean PWV and the presence of LGE as elevated or non-elevated PWV and positive or negative LGE. Patients received follow-up for major adverse cardiovascular events (MACE) comprising cardiovascular death, non-fatal myocardial infarction, hospitalization for heart failure, coronary revascularization, and ischemic stroke. Predictors of MACE and hard cardiac events (cardiovascular death or non-fatal myocardial infarction) were evaluated. RESULTS: During the average follow-up period of 47.7 months, 58 MACE occurred. Patients who had elevated PWV and positive LGE experienced the highest rate of MACE compared to the group with non-elevated PWV and negative LGE (HR 11.90, p < 0.001). Among patients who had LGE, those who had elevated PWV experienced a 2.4-times higher rate of MACE compared to those who had non-elevated PWV. Multivariate analysis showed that PWV and LGE were independent predictors of MACE and hard cardiac events. PWV had excellent intra- and inter-observer reproducibility (intra-: ICC = 0.98, p < 0.001, inter-: ICC = 0.97, p < 0.001). CONCLUSION: Aortic stiffness using VE-CMR had prognostic value to predict cardiovascular events, with the added benefits of LGE.

The Cone Flare Crush Modified-T (CFCT) stenting technique for coronary artery bifurcation lesions.

BACKGROUND: The present study is a prospective observational single arm clinical investigation, with parallel bench test interrogation, aimed at investigating the technical feasibility, safety and clinical outcomes with the cone flare crush modified-T (CFCT) bifurcation stenting technique. Bifurcation percutaneous coronary intervention (PCI) remains an area of ongoing procedural evolution. More widely applicable and reproducible techniques are required. METHODS: From April 2018 until March 2019, 20 consecutive patients underwent bifurcation PCI using the CFCT technique with a Pt-Cr everolimus drug-eluting stent with a bioresorbable polymer. Exercise stress echocardiography was performed at 12-month follow-up. The primary outcome was a composite of cardiac related mortality, myocardial infarction, target lesion/vessel revascularization and stroke. Safety secondary endpoints included bleeding, all-cause mortality and stent thrombosis. RESULTS: All patients underwent a successful CFCT bifurcation procedure with no complications to 30-day follow-up. One patient met the primary endpoint requiring target lesion revascularization at 9 months for stable angina. There were no other primary or secondary outcome events in the cohort. There were no strokes, deaths, stent thrombosis or myocardial infarction during the follow-up period. The mean CCS score improved from 2.25 to 0.25 (p < 0.0001). Optical coherence tomography (OCT) and bench test findings indicated optimal side branch ostial coverage and minimal redundant strut material crowding the neo-carina. CONCLUSIONS: The CFCT technique appears to be a safe, efficacious and feasible strategy for managing coronary artery bifurcation disease. Expanded and randomized datasets with longer term follow-up are required to further explore confirm this feasibility data. (ANZCTR ID: ACTRN12618001145291).

Misdiagnosis in the COVID-19 Era: When Zebras Are Everywhere, Don't Forget the Horses.

We describe a patient who presented with respiratory failure, chest pain, and fever. In the COVID-19 pandemic era, the focus was diverted to the coronavirus infection, and ST-segment elevation myocardial infarction was missed. Although we need to be vigilant in the diagnosis of COVID-19, we should not forget about the common disorders. (Level of Difficulty: Beginner.).

Ability of FFR-CT to detect the absence of hemodynamically significant lesions in patients with high-risk NSTE-ACS admitted in the emergency department with chest pain, study design and rationale.

BACKGROUND: In the era of High-sensitive troponin (hs-Tn), up to 50% of patients with a mild increase of hs-Tn will finally have a normal invasive coronary angiogram. Fractional Flow Reserve (FFR) derived from coronary computed tomographic angiography (FFR-CT) has never been used as a non-invasive tool for the diagnosis of coronary artery disease in patients with high-risk acute coronary syndrome without ST segment elevation (NSTE-ACS). AIMS: The study aims to determine the role of coronary CT angiography and FFR-CT in the setting of high-risk NSTE-ACS. METHODOLOGY: We will conduct a prospective trial, enrolling 250 patients admitted with high-risk NSTE-ACS who will rapidly undergo a coronary CT angiography and then a coronary angiography with FFR measurements. Results of coronary CT, FFR-CT and coronary angiography (± FFR) will be compared. POTENTIAL SIGNIFICANCE: In conclusion, non-invasive identification of patients with high-risk NSTE-ACS who could avoid coronary angiography would reduce procedure related risks and medical costs.

An IL-6-IL-8 score derived from principal component analysis is predictive of adverse outcome in acute myocardial infarction.

INTRODUCTION: Many studies have shown that elevated biomarkers of inflammation following acute myocardial infarction (AMI) are associated with major adverse cardiovascular events (MACE). However, the optimal way of measuring the complex inflammatory response following AMI has not been determined. In this study we explore the use of principal component analysis (PCA) utilising multiple inflammatory cytokines to generate a combined cytokine score that may be predictive of MACE post-AMI. METHODS: Thirteen inflammatory cytokines were measured in plasma of 317 AMI patients, drawn 48-72 h following symptom onset. Patients were followed-up for one year to determine the incidence of MACE. PCA was used to generate a combined score using six cytokines that were detectable in the majority of patients (IL-1ß, -6, -8, and -10; MCP-1; and RANTES), and using a subset of cytokines that were associated with MACE on univariate analysis. Multivariate models using baseline characteristics, elevated individual cytokines and PCA-derived scores determined independent predictors of MACE. RESULTS: IL-6 and IL-8 were significantly associated with MACE on univariate analysis and were combined using PCA into an IL-6-IL-8 score. The combined cytokine score and IL-6-IL-8 PCA-derived score were both significantly associated with MACE on univariate analysis. In multivariate models IL-6-IL-8 scores (OR = 2.77, p = 0.007) and IL-6 levels (OR = 2.18, p = 0.035) were found to be independent predictors of MACE. CONCLUSION: An IL-6-IL-8 score derived from PCA was found to independently predict MACE at one year and was a stronger predictor than any individual cytokine, which suggests this may be an appropriate strategy to quantify inflammation post-AMI. Further investigation is required to determine the optimal set of cytokines to measure in this context.

Clinical and Angiographic Predictors of Mortality in Sudden Cardiac Arrest Patients Having Cardiac Catheterisation: A Single Centre Registry.

BACKGROUND: Immediate cardiac catheterisation (CC) is recommended in ST-elevation myocardial infarction (STEMI) following sudden cardiac arrest (SCA). Guidelines advise urgent CC for SCA patients without-STEMI, at clinician discretion. We examined the clinical and angiographic factors predicting mortality in SCA patients having CC. METHODS: Consecutive SCA patients having CC at Liverpool Hospital, Sydney (January 2011-September 2015) were retrospectively analysed. Patient data were retrieved from hospital records, and angiographic SYNTAX scores (SS) were quantified online. Independent predictors of mortality were derived using multivariate logistic analysis. RESULTS: The study cohort comprised 104 SCA patients; mean age 61±12years, and 79% male. Immediate CC (<2hours post-SCA) was performed in 35% overall. Compared to the without-STEMI subgroup, STEMI patients had more ventricular fibrillation (91 vs 50%; p<0.0001), and higher mean peak serum high-sensitivity troponin-T (8.25±14.7 vs 1.97±6.13 ug/L; p=0.006); in the context of higher median SS (18 vs 6.5; p=0.002) and target-lesion SS (tSS, 10 vs 0; p<0.001). Percutaneous coronary intervention (PCI; 75 vs 23%; p<0.0001) and target vessel revascularisation (11 vs 0%; p=0.005) were more frequent for STEMI. All-cause mortality was 39%, at 1.3±1.5years follow-up. Independent mortality predictors were: delayed CC (HR 4.08), serum lactate >7mmol/L (HR 3.47), and tSS (HR 1.05). CONCLUSIONS: Elevated serum lactate, tSS, and delayed CC, were predictive of longer-term mortality in SCA patients having CC. Late CC in patients without-STEMI suggest scope for improvement in real-world systems of care. Closer scrutiny of target lesion complexity may aid prognostication in SCA survivors.

Difference in plaque characteristics of coronary culprit lesions in a cohort of Egyptian patients presented with acute coronary syndrome and stable coronary artery disease: An optical coherence tomography study.

AIMS: This study was designed to utilize frequency-domain optical coherence tomography (FD-OCT) for assessment of plaque characteristics and vulnerability in patients with acute coronary syndrome (ACS) compared to stable coronary artery disease (SCAD). METHODS AND RESULTS: We enrolled 48 patients; divided into an ACS-group (27 patients) and SCAD-group (21 patients) according to their clinical presentation. Hypertension and diabetes mellitus were more prevalent in SCAD group. Patients with ACS showed higher frequency of lipid-rich plaques (96.3% vs. 66.7%, P = .015), lower frequency of calcium plaques (7.4% vs. 57.1%, P < .001), and fibrous plaques (14.8% vs. 81%, P < .001) when compared with SCAD patients. The TCFA (defined as lipid-rich plaque with cap thickness <65 µm) identified more frequently (33.3% vs. 14.3%, P = .185), with a trend towards thinner median fibrous cap thickness (70 (50-180) µm vs. 100 (50-220) µm, P = .064) in ACS group. Rupture plaque (52% vs. 14.3%, P = .014), plaque erosion (18.5% vs. 0%, P = .059) and intracoronary thrombus (92.6% vs. 14.3%, P < .001) were observed more frequently in ACS group, while cholesterol crystals were identified frequently in patients with SCAD (0.0% vs. 33.3%, P = .002). CONCLUSION: The current FD-OCT study demonstrated the differences of plaque morphology and identified distinct lesion characteristics between patients with ACS and those with SCAD. These findings could explain the clinical presentation of patients in both groups.