Development of machine learning models for fractional flow reserve prediction in angiographically intermediate coronary lesions.

BACKGROUND: Fractional flow reserve (FFR) represents the gold standard in guiding the decision to proceed or not with coronary revascularization of angiographically intermediate coronary lesion (AICL). Optical coherence tomography (OCT) allows to carefully characterize coronary plaque morphology and lumen dimensions. OBJECTIVES: We sought to develop machine learning (ML) models based on clinical, angiographic and OCT variables for predicting FFR. METHODS: Data from a multicenter, international, pooled analysis of individual patient's level data from published studies assessing FFR and OCT on the same target AICL were collected through a dedicated database to train (n = 351) and validate (n = 151) six two-class supervised ML models employing 25 clinical, angiographic and OCT variables. RESULTS: A total of 502 coronary lesions in 489 patients were included. The AUC of the six ML models ranged from 0.71 to 0.78, whereas the measured F1 score was from 0.70 to 0.75. The ML algorithms showed moderate sensitivity (range: 0.68-0.77) and specificity (range: 0.59-0.69) in detecting patients with a positive or negative FFR. In the sensitivity analysis, using 0.75 as FFR cut-off, we found a higher AUC (0.78-0.86) and a similar F1 score (range: 0.63-0.76). Specifically, the six ML models showed a higher specificity (0.71-0.84), with a similar sensitivity (0.58-0.80) with respect to 0.80 cut-off. CONCLUSIONS: ML algorithms derived from clinical, angiographic, and OCT parameters can identify patients with a positive or negative FFR.

Angiography-derived versus invasively-determined index of microcirculatory resistance in the assessment of coronary microcirculation: A systematic review and meta-analysis.

BACKGROUND: The index of microvascular resistance (IMR) is an established tool to assess the status of coronary microcirculation. However, the need for a pressure wire and hyperemic agents have limited its routine use and have led to the development of angiography-derived pressure-wire-free methods (angiography-derived IMR [IMRAngio]). In this review and meta-analysis, we aim to assess the global diagnosis accuracy of IMRAngio versus IMR. METHODS: A systematic review of the literature was performed. Studies directly evaluating IMRAngio versus IMR were considered eligible. Pooled values of diagnostic test and summary receiver operator curve were calculated. RESULTS: Seven studies directly comparing IMRAngio versus IMR were included (687 patients; 807 vessels). Pooled sensitivity, specificity, +likelihood ratio (LR), and -LR were 82%, 83%, 4.5, and 0.26 respectively. Pooled accuracy was 83% while pooled positive predictive value and negative predictive value were 76% and 85%, respectively. Comparable results were obtained when analyzing by clinical scenario (acute and nonacute coronary syndromes). CONCLUSION: IMRAngio shows a good diagnostic performance for the prediction of abnormal IMR.

Volume of contrast to creatinine clearance ratio predicts early mortality and AKI after TAVI.

The volume of contrast to creatinine clearance ratio (CV/CrCl) is a useful indicator of the risk of acute kidney injury (AKI) in patients undergoing percutaneous interventional procedures. Association between CV/CrCl and adverse outcome after transcatheter aortic valve implantation (TAVI) was suggested but it is not well established. A large retrospective multicenter cohort of 1381 patients treated with TAVI was analyzed to assess the association between CV/CrCl and the risk of AKI and mortality at 90 days and 1 year after TAVI. Patients receiving renal replacement therapy at the time of TAVI were excluded. CV/CrCl ≥ 2.2 was associated with the risk of AKI and 90 days mortality after TAVI after adjustment for age, sex, diabetes, baseline left ventricular function, baseline chronic kidney disease (CKD), previous myocardial infarction and peripheral vascular disease (hazard ratio [HR]: 1.16, 95% confidence interval [CI]: 1.09-1.22, p < 0.0001). Importantly, CV/CrCl was associated with the adverse outcome independently from the presence of baseline CKD (p for interaction = 0.22). CV/CrCl was independently associated with the individual components of the composite primary outcome including AKI (odds ratio: 1.18, 95% CI: 1.08-1.28, p < 0.0001) and 90 days mortality (HR: 1.90, 95% CI: 1.01-3.60, p = 0.047) after TAVI. AKI (HR: 1.94, 95% CI: 1.21-3.11, p = 0.006) but not CV/CrCl was associated with the risk of 1-year mortality after TAVI. CV/CrCl is associated with excess renal damage and early mortality after TAVI. Procedural strategies to minimize the CV/CrCl during TAVI may improve early clinical outcomes in patients undergoing TAVI.

Transcatheter aortic valve replacement and percutaneous coronary intervention versus surgical aortic valve replacement and coronary artery bypass grafting in patients with severe aortic stenosis and concomitant coronary artery disease: A systematic review and meta-analysis.

OBJECTIVES: We performed a systematic review and meta-analysis to evaluate the early and midterm outcomes of patients who underwent surgical aortic valve replacement (SAVR) and coronary artery bypass grafting (CABG) against patients who had transcatheter aortic valve replacement (TAVR) and percutaneous coronary intervention (PCI). BACKGROUND: Contemporary guidelines suggest that surgical or percutaneous revascularization of significant coronary artery disease (CAD) in patients with severe aortic stenosis (AS) is a reasonable strategy. METHODS: We conducted a comprehensive search of Medline and Embase to identify studies comparing a percutaneous transcatheter versus a surgical approach. Random effects meta-analyses using the Mantel-Haenszel method were performed to estimate the effect of percutaneous compared surgical strategies using aggregate data. RESULTS: Six studies reporting on 1770 participants were included in the meta-analysis. There were no significant differences in effect estimates for early and midterm mortality (OR: 0.78; 95% CI, 0.50-1.20 and OR: 1.09; 95% CI, 0.80-1.49, respectively) or myocardial infarction (OR: 0.52; 95% CI, 0.20-1.33 and OR: 1.34; 95% CI, 0.67-2.65, respectively). No significant difference was shown for peri-procedural stroke (OR: 0.80; 95% CI, 0.35-1.87). A transcatheter approach had a higher rate of major vascular complications (OR: 14.44; 95% CI, 4.42-47.16), but a lower rate of acute kidney injury (OR: 0.41; 95% CI, 0.19-0.91). CONCLUSION: Our analysis suggests that a percutaneous transcatheter approach confers similar outcomes compared to a surgical approach in patients with severe AS and CAD. However, our findings are based on low quality studies and should serve as hypothesis generating. In the absence of adequately powered studies yielding high level evidence, individualized decision making should be based on surgical risk assessment.

Ultrasound guided vascular access site management and left ventricular pacing are associated with improved outcomes in contemporary transcatheter aortic valve replacement: Insights from the OxTAVI registry.

OBJECTIVES: To identify clinical and procedural practice predictors of avoidable complications during transcatheter aortic valve replacement (TAVR). BACKGROUND: TAVR is evolving as a viable strategy for treatment of aortic stenosis (AS). Vascular complications, major bleeding, or pericardial tamponade may be influenced by procedural practice. METHODS: The Oxford TAVR (OxTAVI) prospective registry was retrospectively analyzed to identify predictors of avoidable procedural complications in a contemporary cohort of transfemoral TAVR between January 2015 and September 2018. The primary endpoint was defined as a hierarchic composite of in-hospital mortality, pericardial effusion/cardiac tamponade, major bleeding, and vascular access complications. Individual components of the primary endpoint have been analyzed separately. RESULTS: Five-hundred-twenty-nine patients underwent transfemoral TAVR using contemporary techniques during the study period and were enrolled in the OxTAVI registry. Female sex and high frailty were associated with a higher risk of death, major bleeding, vascular complication or pericardial tamponade. The use of ultrasound (US) guidance for vascular access management was independently associated with a reduced composite primary endpoint (OR = 0.35, CI:0.14-0.86, p = .02) after adjustment for clinical confounders, largely driven by a threefold reduction in vascular access complication (OR = 0.29, CI:0.15-0.55, p < .001). Performing rapid pacing via the left ventricle guidewire (LV-GW) was associated with a significant decrease in the risk of cardiac tamponade/pericardial effusion (OR = 0.19, CI:0.05-0.66, p = .009). CONCLUSION: US-guided vascular access management and rapid pacing via the LV-GW are important determinants of reduced procedural complications during TAVR.

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

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

From anatomy to function and then back to anatomy: invasive assessment of myocardial ischemia in the catheterization laboratory based on anatomy-derived indices of coronary physiology.

For many decades, the severity of coronary artery disease (CAD) and the indication to proceed with either percutaneous coronary intervention (PCI) or surgical revascularization has been based on anatomically derived parameters of vessel stenosis, and typically on the percentage of lumen diameter stenosis (DS%) as determined by invasive coronary angiography (CA). However, it is currently a well-accepted concept that pre-specified thresholds of DS% have a weak correlation with the ischemic and functional potential of an epicardial coronary stenosis. In this regard, the introduction of fractional-flow reserve (FFR) has represented a paradigm-shift in the understanding, diagnosis, and treatment of CAD, but the adoption of FFR into the clinical practice remains surprisingly limited and sub-standard, probably because of the inherent drawbacks of pressure-wire-based technology such as additional costs, prolonged procedural time, invasive instrumentation of the target vessel, and use of vaso-dilatory agents causing side effects for patients. For this reason, new modalities are under development or validation to derive FFR from computational fluid dynamics (CFD) applied to a three-dimensional model (3D) of the target vessel obtained from CA, intravascular imaging, or coronary computed tomography angiography. The purpose of this review was to describe the technical details of these anatomy-derived indices of coronary physiology with a special focus on summarizing their workflow, available evidence, and future perspectives about their application in the clinical practice.

Aortic Valve Disease and Associated Complex CAD: The Interventional Approach.

Coronary artery disease (CAD) is highly prevalent in patients with severe aortic stenosis (AS). The management of CAD is a central aspect of the work-up of patients undergoing transcatheter aortic valve implantation (TAVI), but few data are available on this field and the best percutaneous coronary intervention (PCI) practice is yet to be determined. A major challenge is the ability to elucidate the severity of bystander coronary stenosis independently of the severity of aortic valve stenosis and subsequent impact on blood flow. The prognostic role of CAD in patients undergoing TAVI is being still debated and the benefits and the best timing of PCI in this context are currently under evaluation. Additionally, PCI in the setting of advanced AS poses some technical challenges, due to the complex anatomy, risk of hemodynamic instability, and the increased risk of bleeding complications. This review aims to provide a comprehensive synthesis of the available literature on myocardial revascularization in patients with severe AS undergoing TAVI. This work can assist the Heart Team in individualizing decisions about myocardial revascularization, taking into account available diagnostic tools as well as the risks and benefits.

The Impact of Blood Pressure Variability on Coronary Arterial Lumen Dimensions as Assessed by Optical Coherence Tomography in Patients with ST-Elevation Myocardial Infarction.

BACKGROUND: Patients with ST-elevation Myocardial Infarction treated by primary percutaneous coronary intervention (PPCI) experience drastic hemodynamic systemic changes (i.e., blood pressure) during the different phases of the procedure. Optical coherence tomography is often used to unveil the underlying cause of STEMI (pre-PCI) and to optimize stent implantation (post-PCI). The impact of blood pressure variability on coronary lumen remains uncertain. This study aimed to investigate the relationship between blood pressure variability, before and after PCI, and coronary arterial lumen dimensions of the infarct-related artery. METHODS: We measured systolic, diastolic and mean arterial blood pressure (SBP, DBP, and MAP; respectively) at pre- and post-PCI. Frequency-domain optical coherence tomography (FD-OCT) imaging was performed at the same time points. Offline quantitative image analyses were performed to assess the average and minimum lumen area (LA). Δ blood pressure (after and before the PCI) was then calculated. RESULTS: A total of 14 ST-segment elevation myocardial infarction (STEMI) patients were included. 84.2% of enrolled patients were male with a mean age of (58 ±â€¯10.7 years). Roughly two-thirds (57.8%) had hypertension. The mean SBP was (112.6 mm Hg ±â€¯16.1) and (117.2 mm Hg ±â€¯20.9), pre- and post-stenting, respectively; the range of the observed SBP differences (between pre- and post-PCI) went from -25 to +23 mm Hg. Pre- and post-stenting mean average LA were (7.1 ±â€¯2.5 mm2 and 6.8 ±â€¯2.3 mm2; respectively). There were poor correlations between ΔSBP and Δ mean minimum LA. A similar pattern was observed with ΔDBP and ΔMAP. CONCLUSION: Despite significant hemodynamic variability, the difference in lumen cross-sectional area, between pre- and post-coronary artery stenting was minimal. This study supports the use of OCT lumen areas to inform clinical decisions during PPCI.

Safety of Rotational Atherectomy Using the Radial Access in Patients With Severe Aortic Stenosis.

Despite frequent percutaneous coronary intervention (PCI) in calcified vessels of older patients, rotational atherectomy (RA) has not been endorsed in patients with severe aortic stenosis (AS) due to safety concerns and lack of data. We explored periprocedural safety and mortality in severe AS patients undergoing RA. Prospective anonymized clinical, echocardiographic, procedural and outcome data of patients undergoing RA PCI between January 2012 and July 2018 were retrospectively extracted from the institutional coronary database. Patients with severe AS undergoing RA PCI were 1:1 propensity matched with patients undergoing RA PCI in the absence of AS. Outcomes of interest were RA related periprocedural complications, 30-day and 1-year mortality. A prespecified subgroup analysis examined the influence of transcatheter aortic valve replacement on mortality following RA PCI. A total of 544 patients underwent RA PCI; 478 without AS and 66 with AS. Propensity matching yielded 35 matched pairs with improved balance in covariates of interest and no significant differences in baseline characteristics postmatching. In the matched cohort (n = 70) slow flow/no-reflow, coronary dissection, perforation, and hemodynamic instability were rare and not significantly different. Survival analyses revealed significantly higher 30-day (Log-Rank p = 0.02) and 1-year mortality (Log rank p = 0.02, HR 5.24 [95% CI 1.13 to 24.28]) in the severe AS group; driven by a fivefold increase in the hazard of death among patients who did not undergo transcatheter aortic valve replacement HR 4.98 [95% CI 1.03 to 24.1]. In conclusion, our study of 70 patients undergoing radial RA PCI suggests that it can be safely performed in patients with severe AS. Long-term outcomes after RA in patients with severe AS are determined by the presence of the valve disease and other co-morbidities.

The Influence of Aortic Valve Obstruction on the Hyperemic Intracoronary Physiology: Difference Between Resting Pd/Pa and FFR in Aortic Stenosis.

The reliability of fractional flow reserve (FFR) in aortic stenosis (AS) has been questioned because of the uncertain response to vasodilators. A retrospective multicenter cohort of 114 AS patients who underwent coronary physiology assessment was compared with 154 controls before and after propensity matching adjustment. The difference between resting distal coronary vs aortic pressure ratio (Pd/Pa) and FFR (ΔPd/Pa-FFR) was tested against the severity of AS. ΔPd/Pa-FFR was not influenced by the severity of AS in terms of aortic valve area (r = - 0.02, p = 0.83) and gradient (r = - 0.05, p = 0.64) or by the left ventricle hypertrophy (r = - 0.03, p = 0.88). Conversely, ΔPd/Pa-FFR was influenced by the presence of diabetes (r = - 0.24, p = 0.005), peripheral vascular disease (r = - 0.16, p = 0.047), and chronic kidney disease (r = - 0.19, p = 0.03). No significant difference was observed in the ΔPd/Pa-FFR between patients with AS and matched controls. Further studies are warranted to validate the FFR-guided revascularization in patients with AS.

The influence of coronary plaque morphology assessed by optical coherence tomography on final microvascular function after stenting in patients with ST-elevation myocardial infarction.

OBJECTIVES: The index of microcirculatory resistance (IMR) provides a reproducible assessment of the status of coronary microvasculature in patients with ST-elevation myocardial infarction (STEMI). Frequency-domain optical coherence tomography (FD-OCT) enables detailed assessment of the morphology of coronary plaque.We sought to determine the influence of the initial culprit coronary plaque anatomy within the infarct-related artery on IMR after stenting in STEMI. PATIENTS AND METHODS: In 25 STEMI patients IMR was measured immediately before and after stent implantation. FD-OCT imaging was performed at the same time points and atherothrombotic volume (ATV) before stenting, prolapsed+floating ATV after stenting and ΔATV was measured using three different strategies. RESULTS: There were no relationships between preprocedural IMR and FD-OCT parameters. Prestenting IMR was related only to pain to wire time (P: 0.02). Irrespective of the method adopted, the final IMR was related to prestenting ATV (ρ: 0.44, P: 0.03 for method I, ρ: 0.48, P: 0.02 for method II and ρ: 0.30, P: 0.06 for method III) and ΔATV (ρ: 0.41, P: 0.04 for method II and ρ: 0.44, P: 0.03 for method III). CONCLUSION: IMR measured before stenting is independent of the appearances of the culprit coronary plaque within the infarct-related artery. IMR after stenting, and more importantly, the change in IMR after stenting, reflect the degree of distal embolization during stent implantation.

Differential levels of circulating progenitor cells in acute coronary syndrome patients with a first event versus patients with recurring events.

OBJECTIVE: Pathophysiology of acute coronary syndromes in patients presenting with a first cardiac event (FCE) can be different from patients with a recurring cardiac event (RCE). We assessed inflammatory activation and circulating progenitor cells' (CPC) mobilisation in patients with a FCE versus those with RCE. METHODS: We recruited 41 patients: 18 with FCE and 23 with RCE. Peripheral blood samples were drawn at baseline and at 20 days to measure high sensitivity C-reactive protein (CRP) and to assess CD34+/133+ CPC and CD34+/KDR+ CPC by flow cytometry. RESULTS: CD34+/133+ cells (% number of cells per total number of cytometric events) were similar at baseline, being 0.25% (0.17-0.42%) in the FCE vs 0.23% (0.11-0.43%) in the RCE group, and increased at follow-up only in the FCE group to 0.41% (0.22-0.64%), while in the RCE group they were 0.27% (0.11-0.36%) (p=0.009 for the interaction, p=0.07 for the main effect of time). CD34+/KDR+ cells were similar at baseline in the two groups, did not significantly increase over time (p=0.2), and no differential effect of FCE vs RCE over time was seen (p=0.38). CRP levels, similar at baseline, were consistently reduced at 20 days after ACS (p=0.001), with no differential effect of FCE vs RCE pts (p=0.74). Variation from baseline to follow-up for both CD34+/133+ and CD34+/KDR+ did not correlate with either baseline CRP or delta CRP. CONCLUSIONS: Our data demonstrate a differential CPC mobilization behavior for FCE patients compared to RCE ones, independent of inflammatory activation.