Pathophysiological coronary and microcirculatory flow alterations in aortic stenosis

Differential Effect of Aortic Valve Replacement for Severe Aortic Stenosis on Hyperemic and Resting Epicardial Coronary Pressure Indices

BACKGROUND

Coronary pressure indices to assess coronary artery disease are currently underused in patients with aortic stenosis due to many potential physiological effects that might hinder their interpretation. Studies with varying sample sizes have provided us with conflicting results on the effect of transcatheter aortic valve replacement (TAVR) on these indices. The aim of this meta-analysis was to study immediate and long-term effects of TAVR on fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs).

METHODS AND RESULTS

Lesion-specific coronary pressure data were extracted from 6 studies, resulting in 147 lesions for immediate change in FFR analysis and 105 for NHPR analysis. To investigate the long-term changes, 93 lesions for FFR analysis and 68 for NHPR analysis were found. Lesion data were pooled and compared with paired t tests. Immediately after TAVR, FFR decreased significantly (-0.0130±0.0406 SD, P: 0.0002) while NHPR remained stable (0.0003±0.0675, P: 0.9675). Long-term after TAVR, FFR decreased significantly (-0.0230±0.0747, P: 0.0038) while NHPR increased nonsignificantly (0.0166±0.0699, P: 0.0543). When only borderline NHPR lesions were considered, this increase became significant (0.0249±0.0441, P: 0.0015). Sensitivity analysis confirmed our results in borderline lesions.

CONCLUSIONS

TAVR resulted in small significant, but opposite, changes in FFR and NHPR. Using the standard cut-offs in patients with severe aortic stenosis, FFR might underestimate the physiological significance of a coronary lesion while NHPRs might overestimate its significance. The described changes only play a clinically relevant role in borderline lesions. Therefore, even in patients with aortic stenosis, an overtly positive or negative physiological assessment can be trusted.

Coronary Artery Disease Assessment via On-Site CT Fractional Flow Reserve in Patients Undergoing Transcatheter Aortic Valve Replacement

Purpose To examine the clinical feasibility of workstation-based CT fractional flow reserve (CT-FFR) for coronary artery disease (CAD) evaluation during preprocedural planning in patients undergoing transcatheter aortic valve replacement (TAVR). Materials and Methods In this retrospective single-center study, 434 patients scheduled for TAVR between 2018 and 2020 were screened for study inclusion; a relevant proportion of patients (35.0% [152 of 434]) was not suitable for evaluation due to insufficient imaging properties. A total of 112 patients (mean age, 82.1 years ± 6.7 [SD]; 58 [52%] men) were included in the study. Invasive angiography findings, coronary CT angiography results, and Agatston score were acquired and compared with on-site CT-FFR computation for evaluation of CAD and prediction of major adverse cardiovascular events (MACE) within a 24-month follow-up. Results Hemodynamic relevant CAD, as suggested by CT-FFR of 0.80 or less, was found in 41 of 70 (59%) patients with stenosis of 50% or more. MACE occurred in 23 of 112 (20.5%) patients, from which 14 of 23 had stenoses with CT-FFR of 0.80 or less (hazard ratio [HR], 3.33; 95% CI: 1.56, 7.10; P = .002). CT-FFR remained a significant predictor of MACE after inclusion in a multivariable model with relevant covariables (HR, 2.89; 95% CI: 1.22, 6.86; P = .02). An Agatston score of 1000 Agatston units or more (HR, 2.25; 95% CI: 0.98, 5.21; P = .06) and stenoses of 50% or more determined via invasive angiography (HR, 0.94; 95% CI: 0.41, 2.17; P = .88) were not significant predictors of MACE. Conclusion Compared with conventional CAD markers, CT-FFR better predicted adverse outcomes after TAVR. A relevant portion of the screened cohort, however, was not suitable for CT-based CAD evaluation. Keywords: CT, Transcatheter Aortic Valve Implantation/Replacement (TAVI/TAVR), Cardiac, Coronary Arteries, Outcomes Analysis © RSNA, 2024 See also the commentary by Weir-McCall and Pugliese in this issue.

Coronary microvascular dysfunction in patients undergoing transcatheter aortic valve implantation

OBJECTIVES

This study aimed to evaluate the prognostic value of coronary microvascular dysfunction (CMD) at long term after transcatheter aortic valve implantation (TAVI) and to explore its relationship with extravalvular cardiac damage (EVCD). Moreover, we sought to test the correlation between angiography-derived index of microcirculatory resistance (IMRangio) and invasive IMR in patients with aortic stenosis (AS).

METHODS

This was a retrospective analysis of the Verona Valvular Heart Disease Registry (Italy) including 250 patients (83 (80-86) years, 53% female) with severe AS who underwent TAVI between 2019 and 2021. IMRangio was calculated offline using a computational flow model applied to coronary angiography obtained during the TAVI workup. CMD was defined as IMRangio ≥30 units.The primary endpoint was the composite of cardiovascular death and rehospitalisation for heart failure (HF). Advanced EVCD was defined as pulmonary circulation impairment, severe tricuspid regurgitation or right ventricular dysfunction.The correlation between IMR and IMRangio was prospectively assessed in 31 patients undergoing TAVI.

RESULTS

The primary endpoint occurred in 28 (11.2%) patients at a median follow-up of 22 (IQR 12-30) months. Patients with CMD met the primary endpoint more frequently than those without CMD (22.9% vs 2.8%, p<0.0001). Patients with CMD were more frequently characterised by advanced EVCD (33 (31.4%) vs 27 (18.6%), p=0.024). CMD was an independent predictor of adverse outcomes (adjusted HR 6.672 (2.251 to 19.778), p=0.001) and provided incremental prognostic value compared with conventional clinical and imaging variables. IMRangio demonstrated fair correlation with IMR.

CONCLUSIONS

CMD is an independent predictor of cardiovascular mortality and HF after TAVI.

Coronary microvascular dysfunction and myocardial infarction with non-obstructive coronary arteries: Where do we stand?

In the past decade, scientific and clinical research has provided a translational perspective on myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA). MINOCA is characterized by clinical documentation of an acute MI but angiography shows no significant coronary artery obstruction (stenosis <50%). The prevalence of MINOCA is estimated to range from approximately 6 to 10% among MI patients, and those with this condition have a poor prognosis, experiencing high rates of mortality, rehospitalization, and socioeconomic burden. MINOCA represents a major unmet need in cardiovascular medicine, with uncertain clinical management. It is a complex condition that can be caused by various factors, including atherosclerosis, plaque rupture, coronary vasospasm, and microvascular dysfunction. Effective management of MINOCA depends on identifying the underlying mechanism of the infarction, thus a systematic diagnostic approach is recommended. Contemporary data shows that a significant number of patients exhibit structural and functional abnormalities in coronary microcirculation, which is referred to as coronary microvascular dysfunction (CMD). CMD plays a crucial role in patients with signs and symptoms of myocardial ischemia and non-obstructive coronary artery stenosis, including MINOCA. Furthermore, conducting a thorough evaluation of coronary function can have significant prognostic and therapeutic implications, since personalized patient management strategies based on this assessment have been shown to improve symptoms and prognosis. Therefore, an accurate and timely diagnosis of CMD is essential for effective patient management, which can be achieved through various invasive and non-invasive methods. This review will discuss the pathophysiological understanding, current diagnostic techniques, and management strategies of patients with MINOCA and CMD.

Management of coronary artery disease in patients undergoing transcatheter aortic valve implantation. A clinical consensus statement from the European Association of Percutaneous Cardiovascular Interventions in collaboration with the ESC Working Group on Cardiovascular Surgery

Significant coronary artery disease (CAD) is a frequent finding in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI), and the management of these two conditions becomes of particular importance with the extension of the procedure to younger and lower-risk patients. Yet, the preprocedural diagnostic evaluation and the indications for treatment of significant CAD in TAVI candidates remain a matter of debate. In this clinical consensus statement, a group of experts from the European Association of Percutaneous Cardiovascular Interventions (EAPCI) in collaboration with the European Society of Cardiology (ESC) Working Group on Cardiovascular Surgery aims to review the available evidence on the topic and proposes a rationale for the diagnostic evaluation and indications for percutaneous revascularisation of CAD in patients with severe aortic stenosis undergoing transcatheter treatment. Moreover, it also focuses on commissural alignment of transcatheter heart valves and coronary re-access after TAVI and redo-TAVI.

Coronary Obstruction during Valve-in-Valve Transcatheter Aortic Valve Replacement: Pre-Procedural Risk Evaluation, Intra-Procedural Monitoring, and Follow-Up

Valve-in-valve (ViV) transcatheter aortic valve replacement (TAVR) is emerging as an effective treatment for patients with symptomatically failing bioprosthetic valves and a high prohibitive surgical risk; a longer life expectancy has led to a higher demand for these valve reinterventions due to the increased possibilities of outliving the bioprosthetic valve's durability. Coronary obstruction is the most feared complication of valve-in-valve (ViV) TAVR; it is a rare but life-threatening complication and occurs most frequently at the left coronary artery ostium. Accurate pre-procedural planning, mainly based on cardiac computed tomography, is crucial to determining the feasibility of a ViV TAVR and to assessing the anticipated risk of a coronary obstruction and the eventual need for coronary protection measures. Intraprocedurally, the aortic root and a selective coronary angiography are useful for evaluating the anatomic relationship between the aortic valve and coronary ostia; transesophageal echocardiographic real-time monitoring of the coronary flow with a color Doppler and pulsed-wave Doppler is a valuable tool that allows for a determination of real-time coronary patency and the detection of asymptomatic coronary obstructions. Because of the risk of developing a delayed coronary obstruction, the close postprocedural monitoring of patients at a high risk of developing coronary obstructions is advisable. CT simulations of ViV TAVR, 3D printing models, and fusion imaging represent the future directions that may help provide a personalized lifetime strategy and tailored approach for each patient, potentially minimizing complications and improving outcomes.

Management of coronary artery disease in patients with aortic stenosis

Aortic stenosis (AS) is the most common valvular heart disorder in the elderly population. As a result of the shared pathophysiological processes, AS frequently coexists with coronary artery disease (CAD). These patients have traditionally been managed through surgical aortic valve replacement (SAVR) and coronary artery bypass grafting. However, increasing body of evidence supports transcatheter aortic valve implantation (TAVI) as an alternative treatment for severe AS across the spectrum of operative risk. This has created the potential for treating AS and concurrent CAD completely percutaneously. In this review we consider the evidence guiding the optimal management of patients with severe AS and CAD. While invasive coronary angiography plays a central role in detecting CAD in patients with AS undergoing surgery or TAVI, the benefits of complementary functional assessment of coronary stenosis in the context of AS have not been fully established. Although the indications for revascularisation of significant proximal CAD in SAVR patients have not recently changed, routine revascularisation of all significant CAD before TAVI in patients with minimal angina is not supported by the latest evidence. Several ongoing trials will provide new insights into physiology-guided revascularisation in TAVI recipients. The role of the heart team remains essential in this complex patient group, and if revascularisation is being considered careful evaluation of clinical, anatomical and procedural factors is essential for individualised decision-making.

The Importance of Integrated Regulation Mechanism of Coronary Microvascular Function for Maintaining the Stability of Coronary Microcirculation: An Easily Overlooked Perspective

Coronary microvascular dysfunction (CMD) refers to a group of disorders affecting the structure and function of coronary microcirculation and is associated with an increased risk of major adverse cardiovascular events. At present, great progress has been made in the diagnosis of CMD, but there is no specific treatment for it because of the complexity of CMD pathogenesis. Vascular dysfunction is one of the important causes of CMD, but previous reviews mostly considered microvascular dysfunction as a whole abnormality so the obtained conclusions are skewed. The coronary microvascular function is co-regulated by multiple mechanisms, and the mechanisms by which microvessels of different luminal diameters are regulated vary. The main purpose of this review is to revisit the mechanisms by which coronary microvessels at different diameters regulate coronary microcirculation through integrated sequential activation and briefly discuss the pathogenesis, diagnosis, and treatment progress of CMD from this perspective.

Association between periprocedural myocardial injury and long-term all-cause mortality in patients undergoing transcatheter aortic valve replacement: a systematic review and meta-analysis

Objective. The purpose of this meta-analysis was to investigate the effect of periprocedural myocardial injury (PPMI) on long-term all-cause mortality in patients undergoing transcatheter aortic valve replacement (TAVR) and to explore potential factors associated with mortality risk. Design. The PubMed, Embase, and Cochrane Library databases were searched up to April 2022. Studies reporting the effect of PPMI on the risk of long-term all-cause mortality were included. The summary odds ratio (OR) was calculated using a random effects model. Additionally, meta-regression and subgroup analyses were conducted according to specific research characteristics to explore sources of heterogeneity. Results. Fourteen studies involving 6,415 patients who underwent TAVR showed that the occurrence of PPMI was associated with a higher risk of long-term mortality. Subgroup analysis showed that in the group of aged ≥82 years, men accounted for less than 50%, coronary artery disease patients accounted for more than 50%, and the proportion of patients with chronic kidney disease accounted for more than 60%, the proportion of patients with atria fibrillation accounted for less than 30%, and the Society of Thoracic Surgeons predicted risk of mortality score was >8 points, patients with PPMI had higher long-term all-cause mortality than those without PPMI. Conclusions. Among the patients who underwent TAVR, those who developed PPMI had higher long-term all-cause mortality.

Coronary physiology to guide treatment of coronary artery disease in a patient with severe aortic valve stenosis: friend or foe? A case report

Background

Severe aortic valve stenosis (AS) is the most frequent valve pathology in the developed world requiring intervention. Due to common factors in pathogenesis, patients with AS frequently have concomitant coronary artery disease (CAD). Determining the relative contribution of each component to the disease state is not easy as there is much overlap in complaints. Moreover, severe AS interferes with the haemodynamic assessment of intermediate coronary lesions.

Case summary

In this case report we describe the presentation and management of an 84-year-old patient, with a severely degenerated aortic valve bioprosthesis and an intermediate coronary artery lesion, presenting with acute decompensated heart failure and chest pain. Initial invasive haemodynamic assessment of the coronary lesion provided challenging findings and a second catheterization and intervention was needed to free the patient from his chest pain.

Discussion

Optimal assessment and treatment of CAD before valve replacement are controversial. Aortic valve stenosis on itself can lead to subendocardial ischaemia with subsequent angina pectoris. Simultaneously, AS can significantly affect coronary haemodynamics, hereby interfering with intra-coronary haemodynamic assessment of co-existing coronary lesions. Currently used coronary physiological indices are not validated in the AS population and valve replacement has variable effects on the fractional flow reserve and commonly used resting indices, such as the resting full-cycle ratio. Further research on this topic is needed and an overview of currently running studies that will advance this field significantly is provided.

Coronary to pulmonary artery fistula associated with significant coronary atherosclerosis and severe aortic valve stenosis: A Case Report

Coronary artery fistulas are anomalous connections between one or two coronary arteries with either a cardiac chamber or any major blood vessels (coronary sinus, superior vena cava, pulmonary veins and pulmonary artery). It is rarely reported, occurring only in 0.1%-0.2% of patients who undergo coronary angiography. We report a very rare case where myocardial ischaemia may have resulted from the presence of coronary artery fistula, significant coronary artery stenosis and severe aortic valve stenosis. Transthoracic echocardiography showed severe aortic stenosis, while coronary angiography showed a tortuous coronary artery fistula originating from the proximal left anterior descending artery, with a single opening in the main pulmonary artery. Angiography also showed significant stenosis in the middle of the left anterior descending artery. Coronary artery fistula with concomitant significant coronary atherosclerosis and severe aortic stenosis requires optimal therapeutic planning.

Digital Subtraction Angiography Image Features under the Deep Learning Algorithm in Cardiovascular Interventional Treatment and Nursing for Vascular Restenosis

The objective of this study was to explore the application value of digital subtraction angiography (DSA) images optimized by deep learning algorithms in vascular restenosis patients undergoing cardiovascular intervention and their nursing efficacy. In this study, a network model for removing artifacts was constructed based on a deep algorithm. 60 patients with coronary artery restenosis were selected as the research objects, and they were randomly divided into the CTA group guided by CT angiography (CTA) and digital subtraction angiography (DSA) group, with 30 cases in each group. The antiartifact network model constructed based on the depth algorithm was applied to the images of CTA and DSA for experiments. After cardiovascular intervention and clinical pathway nursing intervention, it was found that the diameter stenosis rate in the DSA group decreased from 65.82 ± 12.9% to 4.7 ± 1.3%, and the area stenosis rate decreased from 88.4 ± 14.3% to 5.4 ± 1.7%. During the follow-up period of 3-24 months, 3 out of 46 lesions in the DSA group showed restenosis, so the restenosis rate was 6.5%, which was significantly lower than the 18.4% in the CTA group (P < 0.05). In the DSA group, there was 1 case of bleeding, 0 case of hematoma, 2 cases of urinary retention, and 0 case of hypotension, so the total incidence of adverse reactions was 10%, which was significantly lower than the 30% of the CTA group (P < 0.05). The high-sensitivity C-reactive protein (hs-CRP) levels of the two groups of patients were 3.58 ± 2.02 mg/L and 4.36 ± 3.11 mg/L before surgery and 3.49 ± 2.18 mg/L and 4.57 ± 3.4 mg/L after the surgery. The postoperative hs-CRP level in the CTA group was slightly lower than that before the surgery and the postoperative hs-CRP level in the DSA group was slightly higher than that before the surgery, but they were not statistically significant (P > 0.05). The hs-CRP level of the DSA group before and after the surgery was slightly higher than that of the CTA group, but there was no significant difference (P > 0.05). In summary, the network model based on the deep learning algorithm can remove the artifacts in DSA images and present high-quality clear images, and convolutional neural network (CNN) algorithms had a strong ability to automatically learn features in the field of medical image processing and were worthy of being widely used and popularized. In addition, the DSA-guided intervention can reduce the rate of vascular stenosis in patients, showing low probability of postoperative restenosis and adverse reactions and a good clinical effect.

Multiparametric MRI identifies subtle adaptations for demarcation of disease transition in murine aortic valve stenosis

Aortic valve stenosis (AS) is the most frequent valve disease with relevant prognostic impact. Experimental model systems for AS are scarce and comprehensive imaging techniques to simultaneously quantify function and morphology in disease progression are lacking. Therefore, we refined an acute murine AS model to closely mimic human disease characteristics and developed a high-resolution magnetic resonance imaging (MRI) approach for simultaneous in-depth analysis of valvular, myocardial as well as aortic morphology/pathophysiology to identify early changes in tissue texture and critical transition points in the adaptive process to AS. AS was induced by wire injury of the aortic valve. Four weeks after surgery, cine loops, velocity, and relaxometry maps were acquired at 9.4 T to monitor structural/functional alterations in valve, aorta, and left ventricle (LV). In vivo MRI data were subsequently validated by histology and compared to echocardiography. AS mice exhibited impaired valve opening accompanied by significant valve thickening due to fibrotic remodelling. While control mice showed bell-shaped flow profiles, AS resulted not only in higher peak flow velocities, but also in fragmented turbulent flow patterns associated with enhanced circumferential strain and an increase in wall thickness of the aortic root. AS mice presented with a mild hypertrophy but unaffected global LV function. Cardiac MR relaxometry revealed reduced values for both T1 and T2 in AS reflecting subtle myocardial tissue remodelling with early alterations in mitochondrial function in response to the enhanced afterload. Concomitantly, incipient impairments of coronary flow reserve and myocardial tissue integrity get apparent accompanied by early troponin release. With this, we identified a premature transition point with still compensated cardiac function but beginning textural changes. This will allow interventional studies to explore early disease pathophysiology and novel therapeutic targets.

Coronary CT Fractional Flow Reserve before Transcatheter Aortic Valve Replacement: Clinical Outcomes

Background The role of CT angiography-derived fractional flow reserve (CT-FFR) in pre-transcatheter aortic valve replacement (TAVR) assessment is uncertain. Purpose To evaluate the predictive value of on-site machine learning-based CT-FFR for adverse clinical outcomes in candidates for TAVR. Materials and Methods This observational retrospective study included patients with severe aortic stenosis referred to TAVR after coronary CT angiography (CCTA) between September 2014 and December 2019. Clinical end points comprised major adverse cardiac events (MACE) (nonfatal myocardial infarction, unstable angina, cardiac death, or heart failure admission) and all-cause mortality. CT-FFR was obtained semiautomatically using an on-site machine learning algorithm. The ability of CT-FFR (abnormal if ≤0.75) to predict outcomes and improve the predictive value of the current noninvasive work-up was assessed. Survival analysis was performed, and the C-index was used to assess the performance of each predictive model. To compare nested models, the likelihood ratio χ² test was performed. Results A total of 196 patients (mean age ± standard deviation, 75 years ± 11; 110 women [56%]) were included; the median time of follow-up was 18 months. MACE occurred in 16% (31 of 196 patients) and all-cause mortality in 19% (38 of 196 patients). Univariable analysis revealed CT-FFR was predictive of MACE (hazard ratio [HR], 4.1; 95% CI: 1.6, 10.8; P = .01) but not all-cause mortality (HR, 1.2; 95% CI: 0.6, 2.2; P = .63). CT-FFR was independently associated with MACE (HR, 4.0; 95% CI: 1.5, 10.5; P = .01) when adjusting for potential confounders. Adding CT-FFR as a predictor to models that include CCTA and clinical data improved their predictive value for MACE (P = .002) but not all-cause mortality (P = .67), and it showed good discriminative ability for MACE (C-index, 0.71). Conclusion CT angiography-derived fractional flow reserve was associated with major adverse cardiac events in candidates for transcatheter aortic valve replacement and improved the predictive value of coronary CT angiography assessment. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Choe in this issue.

Long term effects of surgical and transcatheter aortic valve replacement on FFRCT in patients with severe aortic valve stenosis

The long-term variations of fractional flow reserve derived from coronary computed tomography (FFR_CT) after surgical (SAVR) or transcatheter (TAVR) aortic valve replacement in patients with severe aortic valve stenosis (AS) have not been investigated. A total of 25 patients with isolated, severe AS underwent coronary computed tomography with 3-vessel FFR_CT analysis (Heartflow Inc.-Redwood City, California, USA) and measurement of total coronary volume (V), left ventricular mass (M) and their ratio (V/M) before and 6 months after SAVR or TAVR. A significant increase in V/M due to a decrease in left ventricular mass 6 months after intervention was observed, whereas total coronary volume did not change (coronary volume pre: 2924.5 ± 867.9 mm³, coronary volume post: 2844.2 ± 792.8 mm³, P = 0.158; LV mass pre: 151.7 ± 40.7 g, LV mass post: 127.3 ± 34.7 g, P < 0.001; V/M pre: 19.5 ± 4.1 mm³/g, V/M post: 22.7 ± 4.28 mm³/g, P = 0.002). FFR_CT (expressed as area under the virtual pullback curve) remained constant. This proof-of-concept study showed that FFR_CT was not subject to the confounding effect of left ventricular mass regression after SAVR or TAVR. Despite significant left ventricular remodeling at 6 months after AS treatment, FFR_CT values remained constant. Further studies are needed comparing the performance of the different invasive and non-invasive coronary physiological indices in this patient cohort.

Asymmetric multiscale multifractal analysis (AMMA) of heart rate variability

Objective.The physiological activity of the heart is controlled and modulated mostly by the parasympathetic and sympathetic nervous systems. Heart rate variability (HRV) analysis is therefore used to observe fluctuations that reflect changes in the activity in these two branches. Knowing that acceleration and deceleration patterns in heart rate fluctuations are asymmetrically distributed, the ability to analyze HRV asymmetry was introduced into MMA.Approach. The new method is called asymmetric multiscale multifractal analysis (AMMA) and the analysis involved six groups: 36 healthy persons, 103 cases with aortic valve stenosis, 36 with hypertrophic cardiomyopathy, 32 with atrial fibrillation, 59 patients with coronary artery disease (CAD) and 13 with congestive heart failure.Main results. Analyzing the results obtained for the 6 groups of patients based on the AMMA method, i.e. comparing the Hurst surfaces for heart rate decelerations and accelerations, it was noticed that these surfaces differ significantly. And the differences occur in most groups for large fluctuations (multifractal parameterq > 0). In addition, a similarity was found for all groups for the AMMA Hurst surface for decelerations to the MMA Hurst surface-heart rate decelerations (lengthening of the RR intervals) appears to be the main factor determining the shape of the complete Hurst surface and so the multifractal properties of HRV. The differences between the groups, especially for CAD, hypertrophic cardiomyopathy and aortic valve stenosis, are more visible if the Hurst surfaces are analyzed separately for accelerations and decelerations.Significance. The AMMA results presented here may provide additional input for HRV analysis and create a new paradigm for future medical screening. Note that the HRV analysis using MMA (without distinguishing accelerations from decelerations) gave satisfactory screening statistics in our previous studies.

Variation of computed tomographic angiography-based fractional flow reserve after transcatheter aortic valve implantation

OBJECTIVES

We sought to identify the impact of transcatheter aortic valve implantation (TAVI) on changes of fractional flow reserve computed tomography (FFR_CT) values and the associated clinical impact.

METHODS

A retrospective analysis was done with CT obtained pre-TAVI, prior to hospital discharge and at 1-year follow-up, which provided imaging sources for the calculation of FFR_CT values based on an online platform.

RESULTS

A total of 190 patients were enrolled. Patients with pre-procedural FFR_CT value > 0.80 (i.e., negative) and ≤ 0.80 (i.e., positive) demonstrated a significantly opposite change in the value after TAVI (0.8798 vs. 0.8718, p < 0.001 and 0.7634 vs. 0.8222, p < 0.001, respectively). The history of coronary artery disease (CAD) was identified as an independent predictor for FFR_CT changing from negative to positive after TAVI (odds ratio [OR] 2.927, 95% confidence interval [CI] 1.130-7.587, p = 0.027), with lesions more severely stenosed (OR 1.039, 95% CI 1.003-1.076, p = 0.034) and in left anterior descending coronary artery (LAD) (OR 3.939, 95% CI 1.060-14.637, p = 0.041) being prone to change.

CONCLUSIONS

TAVI directly brings improvement in FFR_CT values in patients with compromised coronary flow. Patients with a history of CAD, especially with lesions more severely stenosed and in LAD, were under risk of FFR_CT changing from negative to positive after TAVI.

KEY POINTS

•The effect of TAVI on coronary hemodynamics might be influenced by different ischemic severity and coronary territories reflected by FFR_CT values. •As different FFR_CT variations did not impact outcomes of TAVI patients, AS, but not coronary issues, may be the primary problem to affect, which needs further validation.

Patients with aortic stenosis exhibit early improved endothelial function following transcatheter aortic valve replacement: The eFAST study

BACKGROUND

Patients with severe aortic stenosis (AS) exhibit systemic endothelial dysfunction, which can be associated with myocardial ischaemia in absence of obstructive coronary disease. Transcatheter aortic valve replacement (TAVR) is used to treat severe AS in patients with high or prohibitive surgical risk. However, it remains unknown whether endothelial function recovers post-TAVR. We therefore sought to assess the early and late changes in flow-mediated dilation (FMD), a measure of endothelial function, following TAVR.

METHODS

Patients undergoing TAVR for severe AS had ultrasound assessment of brachial endothelial-independent and -dependent FMD. Measurements were performed pre-TAVR, at early follow-up (<48 h post-TAVR) and late follow-up (4-6 weeks post-TAVR).

RESULTS

27 patients (mean age 82.0 ± 7.0; 33.3% female) were recruited; 37.0% had diabetes mellitus and 59.3% had hypertension. Brachial artery FMD increased from 4.2 ± 1.6% (pre-TAVR) to 9.7 ± 3.5% at early follow-up (p < 0.0001). At late follow-up, improvement compared with early follow-up was sustained (8.7 ± 1.9%, p = 0.27). Resting brachial arterial flow velocities decreased significantly at late follow-up (11.24 ± 5.16 vs. 7.73 ± 2.79 cm/s, p = 0.003). Concordantly, at late follow-up, there was decrease in resting wall shear stress (WSS; 14.8 ± 7.8 vs. 10.6 ± 4.8dyne/cm2, p = 0.01), peak WSS (73.1 ± 34.1 vs. 58.8 ± 27.8dyne/cm2, p = 0.03) and cumulative WSS (3543 ± 1852 vs. 2504 ± 1089dyne·s/cm², p = 0.002). Additionally, a favourable inverse correlation between cumulative WSS and FMD was restored at late follow-up (r = -0.21 vs. r = 0.49).

CONCLUSION

Endothelial function in patients with AS improves early post-TAVR and this improvement is sustained. This likely occurs as a result of improved arterial haemodynamics, leading to lower localised WSS and release of vasoactive mediators that may also alleviate myocardial ischaemia.

The Combined Contribution of Vascular Endothelial Cell Migration and Adhesion to Stent Re-endothelialization

Coronary stent placement inevitably causes mechanical damage to the endothelium, leading to endothelial denudation and in-stent restenosis (ISR). Re-endothelialization depends mainly on the migration of vascular endothelial cells (VECs) adjacent to the damaged intima, as well as the mobilization and adhesion of circulating VECs. To evaluate the combined contribution of VEC migration and adhesion to re-endothelialization under flow and the influence of stent, in vitro models were constructed to simulate various endothelial denudation scales (2 mm/5 mm/10 mm) and stent deployment depths (flat/groove/bulge). Our results showed that (1) in 2 mm flat/groove/bulge models, both VEC migration and adhesion combined completed the percentage of endothelial recovery about 27, 16, and 12%, and migration accounted for about 21, 15, and 7%, respectively. It was suggested that the flat and groove models were in favor of VEC migration. (2) With the augmentation of the injury scales (5 and 10 mm), the contribution of circulating VEC adhesion on endothelial repair increased. Taken together, endothelial restoration mainly depended on the migration of adjacent VECs when the injury scale was 2 mm. The adhered cells contributed to re-endothelialization in an injury scale-dependent way. This study is helpful to provide new enlightenment for surface modification of cardiovascular implants.

Feasibility and Validity of Computed Tomography-Derived Fractional Flow Reserve in Patients With Severe Aortic Stenosis: The CAST-FFR Study

BACKGROUND

Coronary artery disease is common in patients with severe aortic stenosis. Computed tomography-derived fractional flow reserve (CT-FFR) is a clinically used modality for assessing coronary artery disease, however, its use has not been validated in patients with severe aortic stenosis. This study assesses the safety, feasibility, and validity of CT-FFR in patients with severe aortic stenosis.

METHODS

Prospectively recruited patients underwent standard-protocol invasive FFR and coronary CT angiography (CTA). CTA images were analyzed by central core laboratory (HeartFlow, Inc) for independent evaluation of CT-FFR. CT-FFR data were compared with FFR (ischemia defined as FFR ≤0.80).

RESULTS

Forty-two patients (68 vessels) underwent FFR and CTA; 39 patients (92.3%) and 60 vessels (88.2%) had interpretable CTA enabling CT-FFR computation. Mean age was 76.2±6.7 years (71.8% male). No patients incurred complications relating to premedication, CTA, or FFR protocol. Mean FFR and CT-FFR were 0.83±0.10 and 0.77±0.14, respectively. CT calcium score was 1373.3±1392.9 Agatston units. On per vessel analysis, there was positive correlation between FFR and CT-FFR (Pearson correlation coefficient, R=0.64, P<0.0001). Sensitivity, specificity, positive predictive value, and negative predictive values were 73.9%, 78.4%, 68.0%, and 82.9%, respectively, with 76.7% diagnostic accuracy. The area under the receiver-operating characteristic curve for CT-FFR was 0.83 (0.72-0.93, P<0.0001), which was higher than that of CTA and quantitative coronary angiography (P=0.01 and P<0.001, respectively). Bland-Altman plot showed mean bias between FFR and CT-FFR as 0.059±0.110. On per patient analysis, the sensitivity, specificity, positive predictive, and negative predictive values were 76.5%, 77.3%, 72.2%, and 81.0% with 76.9% diagnostic accuracy. The per patient area under the receiver-operating characteristic curve analysis was 0.81 (0.67-0.95, P<0.0001).

CONCLUSIONS

CT-FFR is safe and feasible in patients with severe aortic stenosis. Our data suggests that the diagnostic accuracy of CT-FFR in this cohort potentially enables its use in clinical practice and provides the foundation for future research into the use of CT-FFR for coronary evaluation pre-aortic valve replacement.

Cardiac Imaging of Aortic Valve Area From 34 287 UK Biobank Participants Reveals Novel Genetic Associations and Shared Genetic Comorbidity With Multiple Disease Phenotypes

Background:

The aortic valve is an important determinant of cardiovascular physiology and anatomic location of common human diseases.

Methods:

From a sample of 34 287 white British ancestry participants, we estimated functional aortic valve area by planimetry from prospectively obtained cardiac magnetic resonance imaging sequences of the aortic valve. Aortic valve area measurements were submitted to genome-wide association testing, followed by polygenic risk scoring and phenome-wide screening, to identify genetic comorbidities.

Results:

A genome-wide association study of aortic valve area in these UK Biobank participants showed 3 significant associations, indexed by rs71190365 (chr13:50764607, DLEU1 , P =1.8×10 −9 ), rs35991305 (chr12:94191968, CRADD , P =3.4×10 −8 ), and chr17:45013271:C:T ( GOSR2 , P =5.6×10 −8 ). Replication on an independent set of 8145 unrelated European ancestry participants showed consistent effect sizes in all 3 loci, although rs35991305 did not meet nominal significance. We constructed a polygenic risk score for aortic valve area, which in a separate cohort of 311 728 individuals without imaging demonstrated that smaller aortic valve area is predictive of increased risk for aortic valve disease (odds ratio, 1.14; P =2.3×10 −6 ). After excluding subjects with a medical diagnosis of aortic valve stenosis (remaining n=308 683 individuals), phenome-wide association of >10 000 traits showed multiple links between the polygenic score for aortic valve disease and key health-related comorbidities involving the cardiovascular system and autoimmune disease. Genetic correlation analysis supports a shared genetic etiology with between aortic valve area and birth weight along with other cardiovascular conditions.

Conclusions:

These results illustrate the use of automated phenotyping of cardiac imaging data from the general population to investigate the genetic etiology of aortic valve disease, perform clinical prediction, and uncover new clinical and genetic correlates of cardiac anatomy.

Fluid structure interaction modelling of aortic valve stenosis: Effects of valve calcification on coronary artery flow and aortic root hemodynamics

BACKGROUND AND OBJECTIVE

Coronary artery diseases and aortic valve stenosis are two of the main causes of mortality and morbidity worldwide. Stenosis of the aortic valve develops due to calcium deposition on the aortic valve leaflets during the cardiac cycle. Clinical investigations have demonstrated that aortic valve stenosis not only affects hemodynamic parameters inside the aortic root but also has a significant influence on the coronary artery hemodynamics and leads to the initiation of coronary artery disease. The aim of this study is to investigate the effect of calcification of the aortic valve on the variation of hemodynamic parameters in the aortic root and coronary arteries in order to find potential locations for initiation of the coronary stenoses.

METHODS

Fluid structure interaction modelling methodology was used to simulate aortic valve hemodynamics in the presence of coronary artery flow. A 2-D model of the aortic valve leaflets was developed in ANSYS Fluent based on the available echocardiography images in literature. The k-ω SST turbulence model was utilised to model the turbulent flow downstream of the leaflets.

RESULTS

The effects of calcification of the aortic valve on aortic root hemodynamics including transvalvular pressure gradient, valve orifice dimeter, vorticity magnitude in the sinuses and wall shear stress on the ventricularis and fibrosa layers of the leaflets were studied. Results revealed that the transvalvular pressure gradient increases from 792 Pa (∼ 6 mmHg) for a healthy aortic valve to 2885 Pa (∼ 22 mmHg) for a severely calcified one. Furthermore, the influence of the calcification of the aortic valve leaflets on the velocity profile and the wall shear stress in the coronary arteries was investigated and used for identification of potential locations of initiation of the coronary stenoses. Obtained results show that the maximum velocity inside the coronary arteries at early diastole decreases from 1 m/s for the healthy valve to 0.45 m/s for the severely calcified case.

CONCLUSIONS

Calcification significantly decreases the wall shear stress of the coronary arteries. This reduction in the wall shear stress can be a main reason for initiation of the coronary atherosclerosis process and eventually results in coronary stenoses.

Non-hyperaemic pressure ratios to guide percutaneous coronary intervention

The use of fractional flow reserve (FFR) in guiding revascularisation improves patient outcomes and has been well-established in clinical guidelines. Despite this, the uptake of FFR has been limited, likely attributable to the perceived increase in procedural time and use of hyperaemic agents that can cause patient discomfort. This has led to the development of instantaneous wave-free ratio (iFR), an alternative non-hyperaemic pressure ratio (NHPR). Since its inception, the use of iFR has been supported by an increasing body of evidence and is now guideline recommended. More recently, other commercially available NHPRs including diastolic hyperaemia-free ratio and resting full-cycle ratio have emerged. Studies have demonstrated that these indices, in addition to mean distal coronary artery pressure to mean aortic pressure ratio, are mathematically analogous (with specific nuances) to iFR. Additionally, there is increasing data demonstrating the equivalent diagnostic performance of alternative NHPRs in comparison with iFR and FFR. These NHPRs are now integral within most current pressure wire systems and are commonly available in the catheter laboratory. It is therefore key to understand the fundamental differences and evidence for NHPRs to guide appropriate clinical decision-making.

Peripheral Blood Mononuclear Cells Expression Levels of miR-196a and miR-100 in Coronary Artery Disease Patients

As a chronic inflammatory disease, coronary artery disease (CAD) is a common cause of death worldwide. Dysregulation of microRNA expression levels in peripheral blood mononuclear cells (PBMCs) may contribute to CAD and serve as a potential diagnostic biomarker. Here, we evaluated PBMC expression of two CAD-related inflammatory miRNAs, miR-196a and miR-100, in PBMCs of CAD patients with significant stenosis (CAD, n: 72), patients with insignificant coronary stenosis (ICAD, n: 30), and controls (n: 74) and checked whether they can segregate study groups. MiRNA expression was evaluated using the standard stem-loop RT-qPCR method. MiR-196a expression was downregulated in ICAD compared to CADs and healthy groups. MiR100 expression levels were not different between groups. The receiver operating characteristic (ROC) curve analysis acquainted that miR-196a expression levels in PBMC could segregate CAD individuals or any of its clinical manifestations (i.e. unstable angina, stable angina, acute myocardial infarction) from ICADs. In conclusion, this study reported a distinct miR-196a expression pattern in PBMCs of all patient groups and recommended a biomarker potential for miR-196a in discriminating ICADs from CADs or healthy controls.

Angiographic Functional Scoring of Coronary Artery Disease Predicts Mortality in Patients With Severe Aortic Stenosis Undergoing TAVR

BACKGROUND/PURPOSE

Coronary artery disease (CAD) is common in patients undergoing transcatheter aortic valve replacement (TAVR), although its prognostic significance is questionable. Significant CAD stratified using SYNTAX score (SS) has been associated with greater mortality, yet it is unknown whether the functional impact of CAD also impacts outcomes in this cohort. DILEMMA score (DS) is a validated angiographic functional scoring tool that correlates with fractional flow reserve and instantaneous wave-free ratio. This study sought to assess the functional impact of CAD on outcomes in patients undergoing TAVR for severe aortic stenosis (AS).

METHODS/MATERIALS

229 patients were included in this analysis. Patients underwent angiographic DS and SS and were classified using predefined values. The primary endpoint was one-year all-cause mortality, with secondary endpoints of 30-day major adverse cardiac and cerebrovascular events (MACCE).

RESULTS

The mean age was 83.9 ± 0.5 years (55.0% female), with 11.8% all-cause mortality. CAD defined by ≥30% stenosis in any vessel was not associated with adverse outcomes (HR = 1.08, p = 0.84). However, the risk of one-year mortality was greater in patients with either SS > 9 (20.8% vs. 9.4%, HR 2.34, p = 0.03) or DS > 2 (18.4% vs. 8.5%, HR = 2.28, p = 0.03). Both scoring systems were also associated with 30-day MACCE (both p < 0.05). After multivariate adjustment, independent predictors of one-year mortality were DS > 2 (HR = 2.29, p = 0.04), left ventricular ejection fraction <50% (HR 2.66, p = 0.04) and COPD (HR 2.43, p = 0.04).

CONCLUSION

Our results demonstrate that angiographic functional scoring is independently predictive of both 12-month mortality and 30-day MACCE following TAVR.

Acute Effects of Transcatheter Aortic Valve Replacement on Central Aortic Hemodynamics in Patients With Severe Aortic Stenosis

Severe aortic stenosis induces abnormalities in central aortic pressure, with consequent impaired organ and tissue perfusion. Relief of aortic stenosis by transcatheter aortic valve replacement (TAVR) is associated with both a short- and long-term hypertensive response. Counterintuitively, patients who are long-term normotensive post-TAVR have a worsened prognosis compared with patients with hypertension, yet the underlying mechanisms are not understood. We investigated immediate changes in invasively measured left ventricular and central aortic pressure post-TAVR in patients with severe aortic stenosis using aortic reservoir pressure, wave intensity analysis, and indices of aortic function. Fifty-four patients (mean age 83.6±6.2 years, 50.0% female) undergoing TAVR were included. We performed reservoir pressure and wave intensity analysis on invasively acquired pressure waveforms from the ascending aorta and left ventricle immediately pre- and post-TAVR. Following TAVR, there were increases in systolic, diastolic, mean, and pulse aortic pressures (all P<0.05). Post-TAVR reservoir pressure was unchanged (54.5±12.4 versus 56.6±14.0 mm Hg, P=0.30) whereas excess pressure increased 47% (29.0±10.9 versus 42.6±15.5 mm Hg, P<0.001). Wave intensity analysis (arbitrary units, au) demonstrated increased forward compression wave (64.9±35.5 versus 124.4±58.9, ×10³ au, P<0.001), backward compression wave (11.6±5.5 versus 14.4±6.9, ×10³ au, P=0.01) and forward expansion wave energies (43.2±27.3 versus 82.8±53.1, ×10³ au, P<0.001). Subendocardial viability ratio improved with aortic function effectively unchanged post-TAVR. Increased central aortic pressure following TAVR relates to increased transmitted power and energy to the proximal aorta with increased excess pressure but unchanged reservoir pressure. These changes provide a potential mechanism for the improved prognosis associated with relative hypertension post-TAVR.

Evaluation of cardiac hypertrophy in the setting of sudden cardiac death

Ventricular hypertrophy is a common pathological finding at autopsy that can act as a substrate for arrhythmogenesis. Pathologists grapple with the significance of ventricular hypertrophy when assessing the sudden and unexpected deaths of young people and what it could mean for surviving family members. The pathological spectrum of left ventricular hypertrophy (LVH) is reviewed herein. This article is oriented to the practicing autopsy pathologist to help make sense of various patterns of increased heart muscle, particularly those that are not clearly cardiomyopathic, yet present in the setting of sudden cardiac death. The article also reviews factors influencing arrhythmogenesis as well as genetic mutations most commonly associated with ventricular hypertrophy, especially those associated with hypertrophic cardiomyopathy (HCM).

Coronary arterial vasculature in the pathophysiology of hypertrophic cardiomyopathy

Alterations in the coronary vascular system are likely associated with a mismatch between energy demand and energy supply and critical in triggering the cascade of events that leads to symptomatic hypertrophic cardiomyopathy. Targeting the early events, particularly vascular remodeling, may be a key approach to developing effective treatments. Improvement in our understanding of hypertrophic cardiomyopathy began with the results of early biophysical studies, proceeded to genetic analyses pinpointing the mutational origin, and now pertains to imaging of the metabolic and flow-related consequences of such mutations. Microvascular dysfunction has been an ongoing hot topic in the imaging of genetic cardiomyopathies marked by its histologically significant remodeling and has proven to be a powerful asset in determining prognosis for these patients as well as enlightening scientists on a potential pathophysiological cascade that may begin early during the developmental process. Here, we discuss questions that continue to remain on the mechanistic processes leading to microvascular dysfunction, its correlation to the morphological changes in the vessels, and its contribution to disease progression.