Can the QRS morphology of outflow tract ventricular arrhythmia change when right bundle branch block emerges during sinus rhythm?

BACKGROUND: QRS morphology can change during ventricular arrhythmias (VAs) with the appearance of bundle branch block (BBB). METHODS: We retrospectively investigated 195 consecutive patients who underwent an initial ablation of VA. The study inclusion criteria were VAs that were successfully ablated in the outflow tract (OT) and in whom right bundle branch block (RBBB) was induced by catheter manipulation close to the His bundle area during sinus rhythm, before any radiofrequency application. We analyzed the QRS morphology of the VAs with and without RBBB during sinus beats. RESULTS: Twenty-four patients (age 59 ± 17 years, female 14) developed RBBB at some point during their procedure. The successful ablation sites of the VAs were the right ventricular outflow tract (RVOT) in 12 patients, pulmonary artery in one, left coronary cusp in five, right coronary cusp in three, right-left cusp junction in two, and great cardiac vein in two. QRS-morphology change was observed in five (20%) cases. The successful ablation sites in that group were the left coronary cusp in three cases, right coronary cusp in one, and RVOT septum in one. The QRS duration of the VAs increased during RBBB. CONCLUSIONS: There are some cases of OT-VAs in which the QRS waveform changes with the appearance of catheter induced RBBB. We need to be aware that when QRS morphology changes during an OT-VA ablation, it does not necessarily mean that the origin or exit of the VA has changed.

Difference in radiofrequency ablation profile between during sinus rhythm and atrial fibrillation: Considerations in this era of high-power short-duration strategy.

Background: The concept of ablation index (AI) was introduced to evaluate radiofrequency (RF) ablation lesions. It is calculated from power, contact force (CF), and RF duration. However, other factors may also affect the quality of ablation lesions. To examine the difference in RF lesions made during sinus rhythm (SR) and atrial fibrillation (AF). Methods: Sixty patients underwent index pulmonary vein isolation during SR (n = 30, SR group) or AF (n = 30, AF group). All ablations were performed with a power of 50 W, a targeted CF of 5-15 g, and AI of 400-450 using Thermocool Smarttouch SF. The CF, AI, RF duration, temperature rise (Δtemp), impedance drop (Δimp), and the CF stability of each ablation point quantified as the standard deviation of the CF (CF-SD) were compared between the two groups. Results: A total of 3579 ablation points were analyzed, which included 1618 and 1961 points in the SR and the AF groups, respectively. Power, average CF, RF duration per point, and the resultant AI (389 ± 59 vs. 388 ± 57) were similar for the two rhythms. However, differences were seen in the CF-SD (3.5 ± 2.2 vs. 3.8 ± 2.1 g, p < .01), Δtemp (3.8 ± 1.3 vs. 4.0 ± 1.3°C, p < .005), and Δimp (10.3 ± 5.8 vs. 9.4 ± 5.4 Ω, p < .005). Conclusions: Despite similar AI, various RF parameters differed according to the underlying atrial rhythm. Ablation delivered during SR demonstrated less CF variability and temperature increase and greater impedance drop than during AF.

Conduction time around the mitral valve annulus has the potential to rule out postablation perimitral atrial tachycardia.

INTRODUCTION: It would be helpful in determining ablation strategy if the occurrence of perimitral atrial tachycardia (PMAT) could be predicted in advance. We investigated whether estimated perimitral conduction time (E-PMCT), namely, twice the time between coronary sinus (CS) pacing and the ensuing wave-front collision at the opposite side of the mitral annulus, correlated with the cycle length of PMAT and could predict future PMAT. METHODS AND RESULTS: We retrospectively (retrospective cohort) and prospectively (validation cohort) investigated atrial fibrillation patients who had received pulmonary vein isolation (PVI) and in whom left atrial maps had been created during CS pacing. We calculated their E-PMCT. PMAT was observed either by provocation or during follow-up in 25, AT other than PMAT was observed in 24 (non-PMAT AT group), and 53 patients never displayed any AT (no-AT group) in the retrospective cohort. In the PMAT group of the retrospective cohort, a strong positive correlation was observed between the PMAT CL and E-PMCT (r = .85, p < 0.001). PMAT was never induced nor observed in patients with E-PMCT less than 176 ms, and the best cut-off value for PMAT was 180 ms by receiver-operating characteristic curve analysis. In the validation cohort of 76 patients, the cut-off value of the E-PMAT less than 180 ms predicted noninducibility of PMAT, with a sensitivity of 78.6%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 25.0%. CONCLUSION: Short E-PMCT may predict noninducibility of PMAT and guide a less invasive ablation strategy.

Differences between typical and reverse typical atrial flutter identified by ultrahigh resolution mapping.

BACKGROUND: Although atrial flutter (AFL) is a common arrhythmia that is based on a macro-reentrant tachycardia around the tricuspid annulus, the factors giving rise to typical AFL (t-AFL) versus reverse typical AFL (rt-AFL) are unknown. To investigate the difference between t-AFL and rt-AFL circuits using ultrahigh resolution mapping of the right atrium. METHODS: We investigated 30 isthmus-dependent AFL patients (mean age 71, 28 male) who underwent first-time cavo-tricuspid isthmus (CTI) ablation guided by Boston Scientific's Rhythmia mapping system and divided them into two groups: t-AFL (22 patients) and rt-AFL (8 patients). We compared the anatomy and electrophysiology of their reentrant circuits. RESULTS: Baseline patient characteristics, use of antiarrhythmic drugs, prevalence of atrial fibrillation, AFL cycle length (227.1 ± 21.4 vs. 245.5 ± 36.0 ms, p = .10), and CTI length (31.9 ± 8.3 vs. 31.1 ± 5.2 mm, p = .80) did not differ between the two groups. Functional block was observed at the crista terminalis in 16 patients and at the sinus venosus in 11. No functional block was observed in three patients, all of whom belonged to the rt-AFL group. That is, functional block was observed in 100% of the t-AFL group as opposed to 5/8 (62.5%) of the rt-AFL (p < .05). Slow conduction zones were frequently observed at the intra-atrial septum in the t-AFL group and at the CTI in the rt-AFL group. CONCLUSION: Mapping with ultrahigh-resolution mapping showed differences between t-AFL and rt-AFL in conduction properties in the right atrium and around the tricuspid valve, which suggested directional mechanisms.

Synthesized 18-Lead Electrocardiogram in Diagnosing Posterior Stemi-Equivalent Acute Coronary Syndrome in Patients with NSTEMI.

Objective: To assess the clinical utility of synthesized V7-V9 ST-segment elevation (sV7-9 STE) in patients with 12-lead-electrocardiogram (ECG)-based non-STE myocardial infarction (NSTEMI) in diagnosing left circumflex artery (LCx) STEMI-equivalent acute coronary syndrome (ACS). Background: The 12-lead-ECG is insufficient for diagnosing patients with ACS, especially those with an LCx culprit. Methods: We retrospectively examined 219 patients with NSTEMI who underwent synthesized 18-lead ECG acquisition on admission and urgent catheterization. Associations between baseline variables, including sV7-9 STE and LCx STEMI-equivalent ACS, were analyzed using logistic regression models and receiver operating characteristics. LCx-culprit ACS was defined as thrombolysis in myocardial infarction (TIMI) 0-1 flow. The association between sV7-9 STE and myocardial damage was also assessed. Results: The mean (SD) age of the population was 68.8 (12.0) years, and 81.7% were men. LCx-culprit NSTEMI occurred in 58 (26.5%) patients and 15 (6.8%) were LCx STEMI-equivalent. SV7-9 STE was observed in 16 patients (7.9%). SV7-9 STE was the sole significant predictor of LCx STEMI-equivalent ACS with an odds ratio of 19.0 (95% CI: 5.6-63.9, p < 0.001), area under the curve of 0.71 (95% CI: 0.58-0.84), sensitivity of 46.7%, and specificity of 95.6%. After adjustment for confounders, sV7-9 STE was significantly associated with a 308% (95% CI: 78-834%) increase in peak high-sensitivity cardiac troponin I (p=0.001). Conclusions: SV7-9 STE had sole preprocedural diagnostic utility in detecting LCx STEMI-equivalent ACS with greater myocardial damage among patients with 12 ECG-based NSTEMI. The use of synthesized extra leads on admission may help identify patients with NSTEMI requiring primary revascularization.

Treatment of atrial tachycardia arising after superior transseptal approach mitral valve surgery: Insights from ultra-high-density mapping to prevent atrioventricular block.

INTRODUCTION: Mitral valve surgery employing a superior transseptal approach (STA) is associated with arrhythmogenicity and intra-atrial conduction delay, despite being optimal for visualization of the surgical field. It is sometimes difficult to treat atrial tachycardias (AT) that arise after STA. To investigate AT circuits that arise after STA in detail in order to identify the optimal ablation line, using ultra-high-resolution mapping (UHRM). METHODS: We retrospectively analyzed 12 AT from 10 patients (median age 70 years, nine males) who had undergone STA surgery. The tachycardias were mapped using the Rhythmia mapping system (Boston Scientific, Natick, Massachusetts). RESULTS: The 12 STA-related AT (STA-AT) circuits were classifiable as follows according to location of the optimal ablation line: (1) peri-septal incision STA-AT (n = 3), (2) cavotricuspid isthmus (CTI) dependent STA-AT (n = 7), and (3) biatrial tachycardia (n = 2). Radiofrequency (RF) application terminated 11 of the 12 STA-AT. We found that difference in STA-AT circuit type was due to characteristics of the septal incision line made for STA. UHRM was important in identifying optimal ablation sites that did not create additional conduction disturbances in the right atrium (RA). CONCLUSIONS: ATs after STA involve complex arrhythmia circuits due to multiple and long incision lines in the RA. Accurate understanding of the arrhythmia circuit and sinus conduction in the RA after STA is recommended for treating post-surgical tachycardia in a minimally invasive manner.

Perimitral atrial tachycardias dependent on residual nonligament of Marshall conduction.

INTRODUCTION: Catheter ablation for perimitral atrial tachycardia (PMAT) that persists despite lateral mitral isthmus (LMI) ablation is challenging. The aim of this study was to identify the role of the ligament of Marshall (LOM) in PMATs that persist after LMI conduction block has been created, and evaluate the validity of ethanol infusion into the vein of Marshall (VOM) as treatment. METHODS AND RESULTS: Sixteen consecutive PMATs in 13 patients that persisted despite apparent LMI conduction block, which was confirmed by ultrahigh-resolution mapping and entrainment pacing along the mitral annulus, were analyzed. PMATs were classified into two types based on the location of the endocardial breakthrough site: those utilizing the LOM (n = 13), which had a breakthrough site along with the LOM, and those not utilizing the LOM (n = 3), which had a breakthrough site at an anterior or posterior side of the LOM. Of the 16 PMATs, 5 PMATs (31%) were not suitable for ethanol infusion into the VOM because the LOM was not involved in the tachycardia circuit or because of the anatomy of the VOM. Fourteen PMATs (88%) were successfully terminated solely by breakthrough site ablation. At a mean follow-up period of 12 ± 9 months, 10 (77%) patients have remained free from atrial tachyarrhythmias. CONCLUSION: In cases of PMAT following LMI ablation, epicardial conduction over the LMI can occur independently of the LOM. Ethanol infusion into the VOM in such cases would not abolish residual epicardial conduction. The anatomy of the VOM can also preclude the use of this method.

Physiological significance of pericoronary inflammation in epicardial functional stenosis and global coronary flow reserve.

Both fractional flow reserve (FFR) and global coronary flow reserve (g-CFR) provide prognostic information in patients with stable coronary artery disease (CAD). Inflammation plays a vital role in impaired endothelial dysfunction and atherosclerotic progression, potentially predicting cardiovascular mortality. This study aimed to evaluate the physiological significance of pericoronary adipose tissue inflammation assessed by CT attenuation (PCATA) in epicardial functional stenosis severity and g-CFR in patients with CAD. A total of 131 CAD patients with a single de novo epicardial coronary stenosis who underwent coronary CT-angiography (CCTA), phase-contrast cine-magnetic resonance imaging (PC-CMR) and FFR measurement were studied. PCATA was assessed using the mean CT attenuation value. G-CFR was obtained by quantifying absolute coronary sinus flow (ml/min/g) by PC-CMR at rest and during maximum hyperemia. Median FFR, g-CFR, and PCATA values were 0.75, 2.59, and - 71.3, respectively. Serum creatinine, NT-proBNP, left ventricular end-diastolic volume, and PCATA were independently associated with g-CFR. PCATA showed a significant incremental predictive efficacy for impaired g-CFR (< 2.0) when added to the clinical risk model. PCATA was significantly associated with g-CFR, independent of FFR. Our results suggest the pathophysiological mechanisms linking perivascular inflammation with g-CFR in CAD patients.

Association between pericoronary adipose tissue attenuation and outcome after second-generation cryoballoon ablation for atrial fibrillation.

OBJECTIVES: Previous studies reported the association between inflammation and atrial fibrillation (AF). Pericoronary adipose tissue (PCAT) attenuation, PCATA, on cardiac CT angiography (CTA) reflects pericoronary inflammation. We hypothesized that the PCATA predicts AF recurrence after cryoballoon ablation (CBA) for paroxysmal and persistent AF. METHODS: We studied 364 patients (median age, 65 years) with persistent (n = 41) and paroxysmal (n = 323) AF undergoing successful first-session second-generation CBA with pre-ablation cardiac CTA. Three-vessel (3V)-PCATA was defined as the mean CT attenuation value of PCAT of all three major coronary arteries. Predictors of AF recurrence during follow-up were evaluated. RESULTS: AF recurrence after the 3-month blanking period was detected in 90 patients (24.7%) during the median follow-up of 26 (interquartile range, 19-42) months. AF recurrence was associated with prior stroke and statin use, NT-proBNP and high-sensitivity cardiac troponin-I levels, left ventricular dimension, left atrial volume index (LAVI), 3V-PCATA, and early AF recurrence during the blanking period. On multivariable Cox proportional hazard analysis, prior stroke (hazard ratio [HR], 2.208, 95% confidence interval [CI], 1.166-4.180, p = 0.015), LAVI (HR, 1.030, 95% CI, 1.010-1.051, p = 0.003), 3V-PCATA (HR, 1.034, 95% CI, 1.001-1.069, p = 0.046), and early AF recurrence (HR, 2.858, 95% CI, 1.855-4.405, p < 0.001) remained statistically significant. CONCLUSION: Pre-ablation CTA-derived 3V-PCATA, representing pericoronary inflammation, was an independent predictor of recurrence after first-session AF ablation using a second-generation cryoballoon. ADVANCES IN KNOWLEDGE: Assessment of 3V-PCATA may identify patients at high risk of AF recurrence after CBA for AF.

Impact of pericoronary adipose tissue inflammation on left ventricular hypertrophy and regional physiological indices in stable coronary artery disease patients with preserved systolic function.

Systemic low-grade inflammation has been shown to be associated with left ventricular hypertrophy (LVH). However, the relationship between pericoronary adipose tissue attenuation (PCATA) and both LVH and regional physiological indices remains unknown. This study aimed to evaluate the association of PCATA with LVH and regional physiological indices in stable coronary artery disease (CAD) patients with preserved systolic function. A total of 114 CAD patients who underwent coronary CT angiography (CTA) and invasive physiological tests showing ischemia due to a single de novo lesion were included in the study. On proximal 40-mm segments of all three major coronary vessels on CTA, PCATA was assessed by the crude analysis of the mean CT attenuation value [- 190 to - 30 Hounsfield units [HU)] and the culprit vessel PCATA was used for the analysis. Regional physiological indices were invasively obtained by pressure-temperature sensor-tipped wire. The patients were divided into three groups by culprit vessel PCATA tertiles, and clinical, CTA-derived, and physiological indices were compared. Univariable and multivariable analyses were further performed to determine the predictors of LVH. Angiographic stenosis severity, culprit lesion locations, culprit vessel fractional flow reserve, coronary flow reserve, index of microcirculatory resistance, total and target vessel coronary calcium score, and biomarkers including high-sensitivity C-reactive protein were not different among the groups. The left ventricular (LV) mass, LV mass index (LVMI), and LV mass at risk were all significantly different in the three groups with the greatest values in the highest tertile group (all, P < 0.05). On multivariable analysis, male gender, NT-proBNP, and PCATA were independent predictors of LVMI. Culprit vessel PCATA was significantly associated with LVMI, but not with regional physiology in CAD patients with functionally significant lesions and preserved systolic function. Our results may offer insight into the pathophysiological mechanisms linking pericoronary inflammation and LVH to worse prognosis.

Determinants of Pericoronary Adipose Tissue Attenuation on Computed Tomography Angiography in Coronary Artery Disease.

Background Recent studies have reported the association between pericoronary inflammation assessed by pericoronary adipose tissue attenuation (PCATA) on computed tomography angiography and worse outcomes in patients with coronary artery disease. We investigated the determinants predicting increased PCATA in patients with known or suspected coronary artery disease. Methods and Results A total of 540 patients who underwent computed tomography angiography and invasive coronary angiography were studied. Mean computed tomography attenuation values of PCAT (-190 to -30 Hounsfield units) (PCATA) were assessed at the proximal 40-mm segments of all 3 major coronary arteries by crude analysis. Univariable and multivariable analyses were performed to determine the predictors of increased PCATA surrounding the proximal right coronary artery. Mean right coronary artery-PCATA was -72.22±8.47 Hounsfield units and the average of 3-vessel PCATA was -70.24±6.60 Hounsfield units. Multivariable linear regression analysis revealed that the independent determinants of right coronary artery-PCATA were male (ß coefficient=4.965, P<0.001), left ventricular mass index (ß coefficient=0.040, P=0.025), and angiographically significant stenosis (diameter stenosis >50%) (ß coefficient=2.418, P=0.008). Sex-related determinants were NT-proBNP level (N-terminal pro-B-type natriuretic peptide; ß coefficient <0.001, P=0.026), Agatston score (ß coefficient=-0.002, P=0.010), left ventricular mass index (ß coefficient=0.041, P=0.028), and significant stenosis (ß coefficient=4.006, P<0.001) in male patients and left ventricular ejection fraction (ß coefficient=-0.217, P=0.010) and significant stenosis (ß coefficient=3.835, P=0.023) in female patients. Conclusions Right coronary artery-PCATA was associated with multiple clinical characteristics, established risk factors, and the presence of significant stenosis. Our results suggest that clinically significant factors such as sex, left ventricular hypertrophy, ejection fraction, calcification, and epicardial stenosis should be taken into account in the assessment of pericoronary inflammation using computed tomography angiography.

Pre-percutaneous Coronary Intervention Pericoronary Adipose Tissue Attenuation Evaluated by Computed Tomography Predicts Global Coronary Flow Reserve After Urgent Revascularization in Patients With Non-ST-Segment-Elevation Acute Coronary Syndrome.

Background Impaired global coronary flow reserve (g-CFR) is related to worse outcomes. Inflammation has been postulated to play a role in atherosclerosis. This study aimed to evaluate the relationship between pre-procedural pericoronary adipose tissue inflammation and g-CFR after the urgent percutaneous coronary intervention in patients with first non-ST-segment-elevation acute coronary syndrome. Methods and Results Phase-contrast cine-magnetic resonance imaging was performed to obtain g-CFR by quantifying coronary sinus flow at 1 month after percutaneous coronary intervention in a total of 116 first non-ST-segment-elevation acute coronary syndrome patients who underwent pre-percutaneous coronary intervention computed tomography angiography. On proximal 40-mm segments of 3 major coronary vessels on computed tomography angiography, pericoronary adipose tissue attenuation was assessed by the crude analysis of mean computed tomography attenuation value. The patients were divided into 2 groups with and without impaired g-CFR divided by the g-CFR value of 1.8. There were significant differences in age, culprit lesion location, N-terminal pro-B-type natriuretic peptide levels, high-sensitivity C-reactive protein (hs-CRP) levels, mean pericoronary adipose tissue attenuation between patients with impaired g-CFR and those without (g-CFR, 1.47 [1.16, 1.68] versus 2.66 [2.22, 3.28]; P<0.001). Multivariable logistic regression analysis revealed that age (odds ratio [OR], 1.060; 95% CI, 1.012-1.111, P=0.015) and mean pericoronary adipose tissue attenuation (OR, 1.108; 95% CI, 1.026-1.197, P=0.009) were independent predictors of impaired g-CFR (g-CFR <1.8). Conclusions Mean pericoronary adipose tissue attenuation, a marker of perivascular inflammation, obtained by computed tomography angiography performed before urgent percutaneous coronary intervention, but not hs-CRP, a marker of systemic inflammation was significantly associated with g-CFR at 1-month after revascularization. Our results may suggest the pathophysiological mechanisms linking perivascular inflammation and g-CFR in patients with non-ST-segment-elevation acute coronary syndrome.

All Resting Physiological Indices May Not Be Equivalent　- Comparison Between the Diastolic Pressure Ratio and Resting Full-Cycle Ratio.

BACKGROUND: Differences between resting full-cycle ratio (RFR) and diastolic pressure ratio (dPR) have not been sufficiently discussed. This study aimed to investigate if there is a difference in diagnostic performance between RFR and dPR for the functional lesion assessment and to assess if there are specific characteristics for discordant revascularization decision-makings between RFR and dPR.Methods and Results:A total of 936 intermediate lesions in 776 patients who underwent measurements of fractional flow reserve (FFR), coronary flow reserve (CFR), and the index of microcirculatory resistance (IMR) were retrospectively studied. Physiological indices were measured from anonymized pressure recordings at an independent core laboratory. Both RFR and dPR measures were highly correlated (r=0.997, P<0.001), with equivalent diagnostic performance relative to FFR-based decision-makings measured by using a dichotomous threshold of 0.80 (accuracy, 79.7% vs. 80.1%, respectively, P=0.960). The rate of diagnostic discordance was 4.7% (44/936), with no RFR-/dPR+ lesions observed. An overall significant difference in FFR and CFR values were detected among RFR/dPR-based classifications. The prevalence of positive studies was significantly higher for RFR than dPR (54.3% vs. 49.6%, respectively, P=0.047) when using the cut-off value of 0.89. CONCLUSIONS: Both RFR and dPR were highly correlated, but the prevalence of positive studies was significantly different. The revascularization rate may differ significantly according to the resting index used.

Sex Differences in Long-Term Outcomes in Patients With Deferred Revascularization Following Fractional Flow Reserve Assessment: International Collaboration Registry of Comprehensive Physiologic Evaluation.

Background Sex-specific differences may influence prognosis after deferred revascularization following fractional flow reserve (FFR) measurement. This study sought to investigate the sex differences in long-term prognosis of patients with deferred revascularization following FFR assessment. Methods and Results A total of 879 patients (879 vessels) with deferred revascularization with FFR >0.75 who underwent FFR and coronary flow reserve measurements were enrolled from 3 countries (Korea, Japan, and Spain). Long-term outcomes were assessed in 649 men and 230 women by the patient-oriented composite outcome (POCO, a composite of any death, any myocardial infarction, and any revascularization). We applied inverse-probability weighting based on propensity scores to account for differences at baseline between women and men (age, hyperlipidemia, diabetes mellitus, diameter stenosis, lesion length, multivessel disease, FFR, coronary flow reserve. The median follow-up duration was 1855 days (745-1855 days). Median FFR values were 0.88 (0.83-0.93) in men and 0.89 (0.85-0.94) in women, respectively. The occurrences of POCO were significantly high in men compared with that in women (10.5% versus 4.2%, P=0.007). Kaplan-Meier analysis revealed that women had a significantly lower risk of POCO (χ2=7.2, P=0.007). Multivariate COX proportional hazards regression analysis revealed that age, male, diabetes mellitus, diameter stenosis, lesion length, and coronary flow reserve were independent predictors of POCO. After applying IPW, the hazard ratio of males for POCO was 2.07 (95% CI, 1.07-4.04, P=0.032). Conclusions This large multinational study reveals that long-term outcome differs between women and men in favor of women after FFR-guided revascularization deferral. Clinical Trial Registration URL: http://www.ClinicalTrials.gov. Unique identifier: NCT02186093.

Prognostic implication of global myocardial blood flow in patients with ST-segment elevation myocardial infarction.

The prognostic implications of cardiovascular magnetic resonance imaging (CMR)-derived hyperemic myocardial blood flow (MBF) in patients with ST-elevation myocardial infarction (STEMI) are unknown. This study sought to investigate the incremental prognostic value of hyperemic MBF over conventional CMR markers to identify patients with high risk of future incidence of patient-oriented composite outcomes (POCO) and major adverse cardiac events (MACE) after STEMI. A total of 237 patients who presented with STEMI were prospectively enrolled. The CMR protocol included left-ventricular ejection fraction (LVEF), late gadolinium enhancement (LGE) and microvascular obstruction (MVO) measurement, and volumetric MBF assessment. During a median follow-up of 2.6 years, 47 patients experienced POCO (primary outcome) and 21 patients had MACE. In a multivariable model, multivessel disease, LGE, MVO, and hyperemic MBF were independently associated with POCO. Addition of hyperemic MBF to the model consisting of GRACE score, multivessel disease, LVEF, LGE, and MVO significantly improved the predictive efficacy (integrated discrimination improvement 0.020, p = 0.021). Patients with low hyperemic MBF had significantly higher incidence of MACE compared to those with high hyperemic MBF in propensity score matching analysis (p = 0.018). In conclusion, CMR-derived hyperemic MBF could provide independent and incremental prognostic value over LVEF, LGE, and MVO in patients with STEMI.

Plaque morphology assessed by optical coherence tomography in the culprit lesions of the first episode of acute myocardial infarction in patients with low low-density lipoprotein cholesterol level.

BACKGROUND: There remains a residual risk for acute myocardial infarction (AMI) even with low low-density lipoprotein cholesterol (LDL-C) levels. This study aimed to characterize the culprit lesion morphology of AMI by optical coherence tomography (OCT) in patients with low LDL-C. METHODS: Four-hundred and nine culprit lesions of 409 patients with their first presentation of AMI imaged by OCT were investigated. OCT analysis included the presence of plaque rupture and thin-capped fibroatheroma (TCFA). Fibrous cap thickness and lipid length were also measured. Intravascular ultrasound (IVUS) was performed in 368 (90.0%) patients. OCT and IVUS findings were compared between patients with LDL-C < 100 mg/dl (lower-LDL group) and those with LDL ≥ 100 mg/dl (higher-LDL group). RESULTS: Lower-LDL group included 93 (22.7%) patients. Plaque rupture (54.8% vs. 68.7%, p = 0.018) and TCFA (39.8% vs. 54.6%, p = 0.013) were less frequently observed in lower-LDL than in higher-LDL. Fibrous cap was thicker [73 (59-109) µm vs. 63 (57-83) µm, p = 0.028] and lipid length was smaller [5.4 (2.3-9.9) mm vs. 7.1 (4.1-10.5) mm, p = 0.012] in lower-LDL than in higher-LDL. There were no significant differences in IVUS parameters including plaque burden or remodeling index between the two groups. CONCLUSIONS: Patients with lower LDL-C showed more prevalent intact fibrous cap and less vulnerable features in the culprit lesions, which may suggest the need for exploring a specific strategy for the prevention of plaque erosion in low LDL-C subjects.

Functional classification discordance in intermediate coronary stenoses between fractional flow reserve and angiography-based quantitative flow ratio.

Background: Measurement of the contrast-flow quantitative flow ratio (cQFR) is a novel method for rapid computational estimation of fractional flow reserve (FFR). Discordance between FFR and cQFR has not been completely characterised. Methods: We performed a post-hoc analysis of 504 vessels with angiographically intermediate stenosis in 504 patients who underwent measurement of FFR, coronary flow reserve (CFR), the index of microcirculatory resistance (IMR) and Duke jeopardy score. Results: In total, 396 (78.6%) and 108 (21.4%) lesions showed concordant and discordant FFR and cQFR functional classifications, respectively. Among lesions with a reduced FFR (FFR+), those with a preserved cQFR (cQFR-) showed significantly lower IMR, shorter mean transit time (Tmn), shorter lesion length (all, p<0.01) and similar CFR and Duke jeopardy scores compared with lesions showing a reduced cQFR (cQFR+). Furthermore, lesions with FFR+ and cQFR- had significantly lower IMR and shorter Tmn compared with lesions showing a preserved FFR (FFR-) and cQFR+. Of note, in cQFR+ lesions, higher IMR lesions were associated with decreased diagnostic accuracy (high-IMR; 63.0% and low-IMR; 75.8%, p<0.01). In contrast, in cQFR- lesions, lower IMR lesions was associated with decreased diagnostic accuracy (high-IMR group; 96.8% and low-IMR group; 80.0%, p<0.01). Notably, in total, 31 territories (6.2%; 'jump out' group) had an FFR above the upper limit of the grey zone (>0.80) and a cQFR below the lower limit (≤0.75). In contrast, five territories (1.0%; 'jump in' group) exhibited opposite results (FFR of ≤0.75 and cQFR of >0.80). The 'jump out' territories showed significantly higher IMR values than 'jump in' territories (p<0.01). Conclusions: FFR- with cQFR+ is associated with increased microvascular resistance, and FFR+ with cQFR- showed preservation of microvascular function with high coronary flow. Microvascular function affected diagnostic performance of cQFR in relation to functional stenosis significance.