Absolute coronary flow and microvascular resistance before and after transcatheter aortic valve implantation

BACKGROUND

Severe aortic stenosis (AS) is associated with left ventricular (LV) remodelling, likely causing alterations in coronary blood flow and microvascular resistance.

AIMS

We aimed to evaluate changes in absolute coronary flow and microvascular resistance in patients with AS undergoing transcatheter aortic valve implantation (TAVI).

METHODS

Consecutive patients with AS undergoing TAVI with non-obstructive coronary artery disease in the left anterior descending artery (LAD) were included. Absolute coronary flow (Q) and microvascular resistance (Rμ) were measured in the LAD using continuous intracoronary thermodilution at rest and during hyperaemia before and after TAVI, and at 6-month follow-up. Total myocardial mass and LAD-specific mass were quantified by echocardiography and cardiac computed tomography. Regional myocardial perfusion (QN) was calculated by dividing absolute flow by the subtended myocardial mass.

RESULTS

In 51 patients, Q and R were measured at rest and during hyperaemia before and after TAVI; in 20 (39%) patients, measurements were also obtained 6 months after TAVI. No changes occurred in resting and hyperaemic flow and resistance before and after TAVI nor after 6 months. However, at 6-month follow-up, a notable reverse LV remodelling resulted in a significant increase in hyperaemic perfusion (QN,hyper: 0.86 [interquartile range {IQR} 0.691.06] vs 1.20 [IQR 0.99-1.32] mL/min/g; p=0.008; pre-TAVI and follow-up, respectively) but not in resting perfusion (QN,rest: 0.34 [IQR 0.30-0.48] vs 0.47 [IQR 0.36-0.67] mL/min/g; p=0.06).

CONCLUSIONS

Immediately after TAVI, no changes occurred in absolute coronary flow or coronary flow reserve. Over time, the remodelling of the left ventricle is associated with increased hyperaemic perfusion.

Coronary artery disease and its management in TAVI

OBJECTIVE

Aortic stenosis and coronary artery disease (CAD) are frequently associated. The preprocedural evaluation and indications for treatment in patients undergoing transcatheter aortic valve intervention (TAVI) remain controversial. This study sought to 1) determine the prevalence and angiographic characteristics of CAD in TAVI candidates, along with revascularization patterns, and 2) to evaluate the impact of the presence and complexity of CAD, as well as angiography-guided percutaneous coronary intervention, on prognosis after TAVI.

METHODS

Single-center retrospective study from a prospectively collected institutional registry that included all patients that underwent TAVI between 2009 and 2018 and pre TAVI coronary angiography (CA) in our institution in the context of pre-procedure work-up. A multivariate analysis was performed to determine the effect of CAD and PCI on 2-year mortality.

RESULTS

A total of 379 patients were included: 55 patients (14.5%) presented with normal coronary arteries, 120 (31.6%) with non-obstructive CAD, and 204 (53.8%) with obstructive CAD (the mean SxS was 8.2). Ultimately, 110 patients (29%) underwent PCI. Two-year survival after TAVI was decreased in patients with complex coronary lesions (SS > 22), while it was not affected by the overall presence of non-obstructive CAD, obstructive CAD, residual SxS, or pre-TAVI PCI of angiographically significant lesions (OR 0.631, 95%CI 0.192-1.406).

CONCLUSION

In our population, the overall presence and management of obstructive CAD did not appear to impact mortality at 2 years after TAVI. Survival was decreased in patients with baseline complex coronary anatomies.

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.

Evaluation of Instantaneous Wave-Free Ratio and Fractional Flow Reserve in Severe Aortic Valve Stenosis

BACKGROUND

The optimal functional evaluation of coronary artery stenosis in patients with severe aortic stenosis (AS) has not been established. The objective of the study was to evaluate the instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) in patients with and without severe AS.

METHODS

We retrospectively investigated 395 lesions in 293 patients with severe AS and 2257 lesions in 1882 patients without severe AS between 2010 and 2022 from a subgroup of the Interventional Cardiology Research In-Cooperation Society FFR Registry. All patients had FFR values, and iFR was analyzed post hoc using dedicated software only in lesions with adequate resting pressure curves (311 lesions in patients with severe AS and 2257 lesions in patients with nonsevere AS).

RESULTS

The incidence of iFR ≤0.89 was 66.6% and 31.8% (P<0.001), while the incidence of FFR ≤0.80 was 45.3% and 43.9% (P=0.60) in the severe AS group and the nonsevere AS group, respectively. In the severe AS group, most lesions (95.2%) with iFR >0.89 had FFR >0.80, while 36.2% of lesions with iFR ≤0.89 had FFR >0.80. During a median follow-up of 2 years, FFR ≤0.80 was significantly associated with deferred lesion failure (adjusted hazard ratio, 2.71 [95% CI, 1.08-6.80]; P=0.034), while iFR ≤0.89 showed no prognostic value (adjusted hazard ratio, 1.31 [95% CI, 0.47-3.60]; P=0.60) in the severe AS group. Lesions with iFR ≤0.89 and FFR >0.80, in particular, were not associated with a higher rate of deferred lesion failure at 3 years compared with lesions with iFR >0.89 (15.4% versus 17.0%; P=0.58).

CONCLUSIONS

This study suggested that FFR appears to be less affected by the presence of severe AS and is more associated with prognosis. iFR may overestimate the functional severity of coronary artery disease without prognostic significance, yet it can be useful for excluding significant stenosis in patients with severe AS.

Is Coronary Physiology Assessment Valid in Special Circumstances?: Aortic Stenosis, Atrial Fibrillation, Left Ventricular Hypertrophy, and Other

Fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs) provide an important clinical tool to evaluate the hemodynamic significance of coronary lesions. However, these indices have major limitations. As these indices are meant to be surrogates of coronary flow, clinical scenarios such as aortic stenosis (with increased end-systolic and end-diastolic pressures) or atrial fibrillation (with significant beat-to-beat cardiac output variability) can have significant effect on the accuracy and reliability of these hemodynamic indices. Here, we provide a comprehensive evaluation of the pitfalls, limitations, and strengths of FFR and NHPRs in common clinical scenarios paired with coronary artery disease.

Practical Application of Coronary Physiologic Assessment: Asia-Pacific Expert Consensus Document: Part 2

Coronary physiologic assessment is performed to measure coronary pressure, flow, and resistance or their surrogates to enable the selection of appropriate management strategy and its optimization for patients with coronary artery disease. The value of physiologic assessment is supported by a large body of clinical data that has led to major recommendations in all practice guidelines. This expert consensus document aims to convey practical and balanced recommendations and future perspectives for coronary physiologic assessment for physicians and patients in the Asia-Pacific region, based on updated information in the field that includes both wire- and image-based physiologic assessment. This is Part 2 of the whole consensus document, which provides theoretical and practical information on physiologic indexes for specific clinical conditions and patient statuses.

Near-infrared spectroscopy-intravascular ultrasound to improve assessment of coronary artery disease severity in patients referred for transcatheter aortic valve implantation (The IMPACTavi registry): Design and rationale

BACKGROUND

Transcatheter aortic valve implantation (TAVI) was established as a standard treatment for high-operative risk patients with severe aortic stenosis (AS). Although coronary artery disease (CAD) often coexists with AS, clinical and angiographic evaluations of stenosis severity are unreliable in this specific setting. To provide precise risk stratification of coronary lesions, combined near-infrared spectroscopy and intravascular ultrasound (NIRS-IVUS) was developed to integrate morphological and molecular information on plaque composition. However, there is a lack of evidence on the association between NIRS-IVUS derived findings such as maximum 4mm lipid core burden index (maxLCBI4mm) and clinical outcomes in AS patients undergoing TAVI. This registry aims to assess feasibility and safety of NIRS-IVUS imaging in the setting of routine pre-TAVI coronary angiography to improve assessment of CAD severity.

METHODS

The registry is designed as a non-randomized, prospective, observational, multicenter cohort registry. Patients referred for TAVI with angiographic evidence of CAD receive NIRS-IVUS imaging and are followed up to 24 months. Enrolled patients are classified as NIRS-IVUS positive and NIRS-IVUS negative, respectively, based on their maxLCBI4mm to compare their clinical outcomes. The primary endpoint of the registry is major adverse cardiovascular events over a 24-month follow-up period.

CONCLUSIONS

Identification of patients likely or unlikely to benefit from revascularization prior to TAVI represents an important unmet clinical need. This registry is designed to investigate whether NIRS-IVUS-derived atherosclerotic plaque characteristics can identify patients and lesions at risk for future adverse cardiovascular events after TAVI, in order to refine interventional decision-making in this challenging patient population.

Integrated Assessment of Computational Coronary Physiology From a Single Angiographic View in Patients Undergoing TAVI

BACKGROUND

Angiography-derived computational physiology is an appealing alternative to pressure-wire coronary physiology assessment. However, little is known about its reliability in the setting of severe aortic stenosis. This study sought to provide an integrated assessment of epicardial and microvascular coronary circulation by means of single-view angiography-derived physiology in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI).

METHODS

Pre-TAVI angiographic projections of 198 stenotic coronary arteries (123 patients) were analyzed by means of Murray's law-based quantitative flow ratio and angiography microvascular resistance. Wire-based reference measurements were available for comparison: fractional flow reserve (FFR) in all cases, instantaneous wave-free ratio in 148, and index of microvascular resistance in 42 arteries.

RESULTS

No difference in terms of the number of ischemia-causing stenoses was detected between FFR ≤0.80 and Murray's law-based quantitative flow ratio ≤0.80 (19.7% versus 19.2%; P=0.899), while this was significantly higher when instantaneous wave-free ratio ≤0.89 (44.6%; P=0.001) was used. The accuracy of Murray's law-based quantitative flow ratio ≤0.80 in predicting pre-TAVI FFR ≤0.80 was significantly higher than the accuracy of instantaneous wave-free ratio ≤0.89 (93.4% versus 77.0%; P=0.001), driven by a higher positive predictive value (86.9% versus 50%). Similar findings were observed when considering post-TAVI FFR ≤0.80 as reference. In 82 cases with post-TAVI angiographic projections, Murray's law-based quantitative flow ratio values remained stable, with a low rate of reclassification of stenosis significance (9.9%), similar to FFR and instantaneous wave-free ratio. Angiography microvascular resistance demonstrated a significant correlation (Rho=0.458; P=0.002) with index of microvascular resistance, showing an area under the curve of 0.887 (95% CI, 0.752-0.964) in predicting index of microvascular resistance ≥25.

CONCLUSIONS

Angiography-derived physiology provides a valid, reliable, and systematic assessment of the coronary circulation in a complex scenario, such as severe aortic stenosis.

Comparison of different percutaneous revascularisation timing strategies in patients undergoing transcatheter aortic valve implantation

BACKGROUND

The optimal timing to perform percutaneous coronary interventions (PCI) in transcatheter aortic valve implantation (TAVI) patients remains unknown.

AIMS

We sought to compare different PCI timing strategies in TAVI patients.

METHODS

The REVASC-TAVI registry is an international registry including patients undergoing TAVI with significant, stable coronary artery disease (CAD) at preprocedural workup. In this analysis, patients scheduled to undergo PCI before, after or concomitantly with TAVI were included. The main endpoints were all-cause death and a composite of all-cause death, stroke, myocardial infarction (MI) or rehospitalisation for congestive heart failure (CHF) at 2 years. Outcomes were adjusted using the inverse probability treatment weighting (IPTW) method.

RESULTS

A total of 1,603 patients were included. PCI was performed before, after or concomitantly with TAVI in 65.6% (n=1,052), 9.8% (n=157) or 24.6% (n=394), respectively. At 2 years, all-cause death was significantly lower in patients undergoing PCI after TAVI as compared with PCI before or concomitantly with TAVI (6.8% vs 20.1% vs 20.6%; p<0.001). Likewise, the composite endpoint was significantly lower in patients undergoing PCI after TAVI as compared with PCI before or concomitantly with TAVI (17.4% vs 30.4% vs 30.0%; p=0.003). Results were confirmed at landmark analyses considering events from 0 to 30 days and from 31 to 720 days.

CONCLUSIONS

In patients with severe aortic stenosis and stable coronary artery disease scheduled for TAVI, performance of PCI after TAVI seems to be associated with improved 2-year clinical outcomes compared with other revascularisation timing strategies. These results need to be confirmed in randomised clinical trials.

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.

Discordance between fractional flow reserve and instantaneous wave-free ratio in patients with severe aortic stenosis: A retrospective cohort study

BACKGROUND

Discordance between fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) occurs in approximately 20 % of cases. However, no studies have reported the discordance in patients with severe aortic stenosis (AS). We aimed to evaluate the diagnostic discordance between FFR and iFR in patients with severe AS.

METHODS

We examined 140 consecutive patients with severe AS (164 intermediate coronary artery stenosis vessels). FFR and iFR were calculated in four quadrants based on threshold FFR and iFR values of ≤0.8 and ≤0.89, respectively (Group 1: iFR >0.89, FFR >0.80; Group 2: iFR ≤0.89, FFR >0.80; Group 3: iFR >0.89, FFR ≤0.80; and Group 4: iFR ≤0.89, FFR ≤0.80). Concordant groups were Groups 1 and 4, and discordant groups were Groups 2 and 3. Positive and negative discordant groups were Groups 3 and 2, respectively.

RESULTS

The median (Q1, Q3) FFR and iFR were 0.84 (0.76, 0.88) and 0.85 (0.76, 0.91), respectively. Discordance was observed in 48 vessels (29.3 %). In the discordant group, negative discordance (Group 2: iFR ≤0.89 and FFR >0.80) was predominant (45 cases, 93.6 %). Multivariate analysis showed that the left anterior descending artery [odds ratio (OR), 3.88; 95 % confidence interval (CI): 1.54-9.79, p = 0.004] and peak velocity ≥5.0 m/s (OR, 3.21; 95%CI: 1.36-7.57, p = 0.008) were independently associated with negative discordance (FFR >0.8 and iFR ≤0.89).

CONCLUSIONS

In patients with severe AS, discordance between FFR and iFR was predominantly negative and observed in 29.3 % of vessels. The left anterior descending artery and peak velocity ≥5.0 m/s were independently associated with negative discordance.

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.

Is Coronary Physiology Assessment Valid in Special Circumstances?: Aortic Stenosis, Atrial Fibrillation, Left Ventricular Hypertrophy, and Other

Fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs) provide an important clinical tool to evaluate the hemodynamic significance of coronary lesions. However, these indices have major limitations. As these indices are meant to be surrogates of coronary flow, clinical scenarios such as aortic stenosis (with increased end-systolic and end-diastolic pressures) or atrial fibrillation (with significant beat-to-beat cardiac output variability) can have significant effect on the accuracy and reliability of these hemodynamic indices. Here, we provide a comprehensive evaluation of the pitfalls, limitations, and strengths of FFR and NHPRs in common clinical scenarios paired with coronary artery disease.

Management of Myocardial Revascularization in Patients With Stable Coronary Artery Disease Undergoing Transcatheter Aortic Valve Implantation

BACKGROUND

The best management of stable coronary artery disease (CAD) in patients undergoing transcatheter aortic valve implantation (TAVI) is still unclear due to the marked inconsistency of the available evidence.

METHODS

The REVASC-TAVI registry (Management of Myocardial Revascularization in Patients Undergoing Transcatheter Aortic Valve Implantation With Coronary Artery Disease) collected data from 30 centers worldwide on patients undergoing TAVI who had significant, stable CAD at preprocedural work-up. For the purposes of this analysis, patients with either complete or incomplete myocardial revascularization were compared in a propensity score matched analysis, to take into account of baseline confounders. The primary and co-primary outcomes were all-cause death and the composite of all-cause death, stroke, myocardial infarction, and rehospitalization for heart failure, respectively, at 2 years.

RESULTS

Among 2407 patients enrolled, 675 pairs of patients achieving complete or incomplete myocardial revascularization were matched. The primary (21.6% versus 18.2%, hazard ratio' 0.88 [95% CI, 0.66-1.18]; P=0.38) and co-primary composite (29.0% versus 27.1%, hazard ratio' 0.97 [95% CI, 0.76-1.24]; P=0.83) outcome did not differ between patients achieving complete or incomplete myocardial revascularization, respectively. These results were consistent across different prespecified subgroups of patients (< or >75 years of age, Society of Thoracic Surgeons score > or <4%, angina at baseline, diabetes, left ventricular ejection fraction > or <40%, New York Heart Association class I/II or III/IV, renal failure, proximal CAD, multivessel CAD, and left main/proximal anterior descending artery CAD; all P values for interaction >0.10).

CONCLUSIONS

The present analysis of the REVASC-TAVI registry showed that, among TAVI patients with significant stable CAD found during the TAVI work-up, completeness of myocardial revascularization achieved either staged or concomitantly with TAVI was similar to a strategy of incomplete revascularization in reducing the risk of all cause death, as well as the risk of death, stroke, myocardial infarction, and rehospitalization for heart failure at 2 years, regardless of the clinical and anatomical situations.

Assessment of left main coronary artery disease: a comparison between invasive and noninvasive

Left main coronary artery disease has significant therapeutic as well as prognostic implications. The presence of left main coronary artery stenosis is strongly associated with poor short- and long-term prognoses. Accurate identification of left main stenosis is extremely important since it would be the main factor to guide management. There are several modalities used to determine the presence of atherosclerosis and the degree of stenosis in a left main coronary artery. Newer modalities allow for an accurate evaluation of left main stenosis and atherosclerosis. In this review, we go through different invasive and noninvasive modalities to diagnose left main stenosis, shedding more light into coronary computed tomography angiography, and its accuracy in this specific diagnosis.

Quantitative flow ratio for evaluation of borderline coronary lesions in patients with severe aortic stenosis

INTRODUCTION AND OBJECTIVES

Quantitative flow ratio (QFR) is a novel noninvasive method for evaluating coronary physiology. However, data on the QFR in patients with aortic stenosis (AS) and coronary artery disease are scarce. Thus, we compared the diagnostic performance of the QFR with that of the resting distal to aortic coronary pressure (Pd/Pa) ratio, fractional flow reserve (FFR), and instantaneous wave-free ratio (iFR), as well as angiographic indices.

METHODS

A total of 221 AS patients with 416 vessels undergoing FFR/iFR measurements were enrolled in the study.

RESULTS

The mean percent diameter stenosis (%DS) was 58.6%±13.4% and the mean Pd/Pa ratio, FFR, iFR, and QFR were 0.95±0.03, 0.85±0.07, 0.90±0.04, and 0.84±0.07, respectively. A FFR ≤ 0.80 was noted in 26.0% of interrogated vessels, as well as an iFR ≤ 0.89 in 33.2% and QFR ≤ 0.80 in 31.7%. The QFR had better agreement with FFR (intraclass correlation coefficient [ICC], 0.96; 95% confidence interval [95%CI], 0.95-0.96) than with the iFR (ICC, 0.79; 95%CI, 0.75-0.82) and Pd/Pa ratio (ICC, 0.52; 95%CI, 0.44-0.58). In addition, the QFR showed better diagnostic accuracy (98.6% vs 94.2%; P <.001) and discriminant function (area under the curve=0.996 vs 0.988; P <.001) when the iFR was used as the reference instead of FFR.

CONCLUSIONS

In patients with AS, the QFR has good agreement with both FFR and iFR. However, the agreement appears to be even better when the iFR is used as the reference, presumably due to the complex nature of the coronary physiology in the assessment of coronary artery disease in patients with severe AS.

Challenges in Diagnosis and Functional Assessment of Coronary Artery Disease in Patients With Severe Aortic Stenosis

More than half of patients with severe aortic stenosis (AS) over 70 years old have coronary artery disease (CAD). Exertional angina is often present in AS-patients, even in the absence of significant CAD, as a result of oxygen supply/demand mismatch and exercise-induced myocardial ischemia. Moreover, persistent myocardial ischemia leads to extensive myocardial fibrosis and subsequent coronary microvascular dysfunction (CMD) which is defined as reduced coronary vasodilatory capacity below ischemic threshold. Therefore, angina, as well as noninvasive stress tests, have a low specificity and positive predictive value (PPV) for the assessment of epicardial coronary stenosis severity in AS-patients. Moreover, in symptomatic patients with severe AS exercise testing is even contraindicated. Given the limitations of noninvasive stress tests, coronary angiography remains the standard examination for determining the presence and severity of CAD in AS-patients, although angiography alone has poor accuracy in the evaluation of its functional severity. To overcome this limitation, the well-established invasive indices for the assessment of coronary stenosis severity, such as fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR), are now in focus, especially in the contemporary era with the rapid increment of transcatheter aortic valve replacement (TAVR) for the treatment of AS-patients. TAVR induces an immediate decrease in hyperemic microcirculatory resistance and a concomitant increase in hyperemic flow velocity, whereas resting coronary hemodynamics remain unaltered. These findings suggest that FFR may underestimate coronary stenosis severity in AS-patients, whereas iFR as the non-hyperemic index is independent of the AS severity. However, because resting coronary hemodynamics do not improve immediately after TAVR, the coronary vasodilatory capacity in AS-patients treated by TAVR remain impaired, and thus the iFR may overestimate coronary stenosis severity in these patients. The optimal method for evaluating myocardial ischemia in patients with AS and co-existing CAD has not yet been fully established, and this important issue is under further investigation. This review is focused on challenges, limitations, and future perspectives in the functional assessment of coronary stenosis severity in these patients, bearing in mind the complexity of coronary physiology in the presence of this valvular heart disease.

Combined Coronary CT-Angiography and TAVI Planning: Utility of CT-FFR in Patients with Morphologically Ruled-Out Obstructive Coronary Artery Disease

Background: Coronary artery disease (CAD) is a frequent comorbidity in patients undergoing transcatheter aortic valve implantation (TAVI). If significant CAD can be excluded on coronary CT-angiography (cCTA), invasive coronary angiography (ICA) may be avoided. However, a high plaque burden may make the exclusion of CAD challenging, particularly for less experienced readers. The objective was to analyze the ability of machine learning (ML)-based CT-derived fractional flow reserve (CT-FFR) to correctly categorize cCTA studies without obstructive CAD acquired during pre-TAVI evaluation and to correlate recategorization to image quality and coronary artery calcium score (CAC). Methods: In total, 116 patients without significant stenosis (≥50% diameter) on cCTA as part of pre-TAVI CT were included. Patients were examined with an electrocardiogram-gated CT scan of the heart and high-pitch scan of the torso. Patients were re-evaluated with ML-based CT-FFR (threshold = 0.80). The standard of reference was ICA. Image quality was assessed quantitatively and qualitatively. Results: ML-based CT-FFR was successfully performed in 94.0% (109/116) of patients, including 436 vessels. With CT-FFR, 76/109 patients and 126/436 vessels were falsely categorized as having significant CAD. With CT-FFR 2/2 patients but no vessels initially falsely classified by cCTA were correctly recategorized as having significant CAD. Reclassification occurred predominantly in distal segments. Virtually no correlation was found between image quality or CAC. Conclusions: Unselectively applied, CT-FFR may vastly increase the number of false positive ratings of CAD compared to morphological scoring. Recategorization was virtually independently from image quality or CAC and occurred predominantly in distal segments. It is unclear whether or not the reduced CT-FFR represent true pressure ratios and potentially signifies pathophysiology in patients with severe aortic stenosis.

Coronary Artery Disease in Patients Undergoing Transvalvular Aortic Valve Implantation

Coronary artery disease (CAD) is common in patients with severe aortic stenosis. With the advent of transcatheter aortic valve implantation (TAVI) as a therapeutic option, management of CAD in such patients has undergone a revolution. Younger patients are now candidates for treatment, and have a greater life-time probability of requiring post-TAVI coronary access. Considerations include pre-procedural assessment and revascularisation, procedural planning to avoid coronary obstruction as well as optimisation of post-procedural coronary access. The authors review the challenges of managing CAD in TAVI patients, shed light on the evidence base, and provide guidance on how to optimise management.

The coronary and microcirculatory measurements in patients with aortic valve stenosis study: rationale and design

Although concomitant coronary artery disease (CAD) is frequent in patients with severe aortic stenosis (AS), hemodynamic assessment of CAD severity in patients undergoing valve replacement for severe AS is challenging. Myocardial hypertrophic remodeling interferes with coronary blood flow and may influence the values of fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs). The aim of the current study is to investigate the effect of the AS and its treatment on current indices used for evaluation of CAD. We will compare intracoronary hemodynamics before, immediately after, and 6 mo after aortic valve replacement (AVR) when it is expected that microvascular function has improved. Furthermore, we will compare FFR and resting full-cycle ratio (RFR) with myocardial perfusion single-photon emission-computed tomography (SPECT) as indicators of myocardial ischemia in patients with AS and CAD. One-hundred consecutive patients with AS and intermediate CAD will be prospectively included. Patients will undergo pre-AVR SPECT and intracoronary hemodynamic assessment at baseline, immediately after valve replacement [if transcatheter AVR (TAVR) is chosen], and 6 mo after AVR. The primary end point is the change in FFR 6 mo after AVR. Secondary end points include the acute change of FFR after TAVR, the diagnostic accuracy of FFR versus RFR compared with SPECT for the assessment of ischemia, changes in microvascular function as assessed by the index of microcirculatory resistance (IMR), and the effect of these changes on FFR. The present study will evaluate intracoronary hemodynamic parameters before, immediately after, and 6 mo after AVR in patients with AS and intermediate coronary stenosis. The understanding of the impact of AVR on the assessment of FFR, NHPR, and microvascular function may help guide the need for revascularization in patients with AS and CAD planned for AVR.

Combined Coronary CT-Angiography and TAVR Planning for Ruling Out Significant Coronary Artery Disease: Added Value of Machine-Learning-Based CT-FFR

OBJECTIVES

To analyze the ability of machine-learning (ML)-based computed tomography (CT)-derived fractional flow reserve (CT-FFR) to further improve the diagnostic performance of coronary CT angiography (cCTA) for ruling out significant coronary artery disease (CAD) during pre-transcatheter aortic valve replacement (TAVR) evaluation in patients with a high pre-test probability for CAD.

BACKGROUND

CAD is a frequent comorbidity in patients undergoing TAVR. Current guidelines recommend its assessment before TAVR. If significant CAD can be excluded on cCTA, invasive coronary angiography (ICA) may be avoided. Although cCTA is a very sensitive test, it is limited by relatively low specificity and positive predictive value, particularly in high-risk patients.

METHODS

Overall, 460 patients (79.6 ± 7.4 years) undergoing pre-TAVR CT were included and examined with an electrocardiogram-gated CT scan of the heart and high-pitch scan of the vascular access route. Images were evaluated for significant CAD. Patients routinely underwent ICA (388/460), which was omitted at the discretion of the local Heart Team if CAD could be effectively ruled out on cCTA (72/460). CT examinations in which CAD could not be ruled out (CAD⁺) (n = 272) underwent additional ML-based CT-FFR.

RESULTS

ML-based CT-FFR was successfully performed in 79.4% (216/272) of all CAD⁺ patients and correctly reclassified 17 patients as CAD negative. CT-FFR was not feasible in 20.6% because of reduced image quality (37/56) or anatomic variants (19/56). Sensitivity, specificity, positive predictive value, and negative predictive value were 94.9%, 52.0%, 52.2%, and 94.9%, respectively. The additional evaluation with ML-based CT-FFR increased accuracy by Δ+3.4% (CAD⁺: Δ+6.0%) and raised the total number of examinations negative for CAD to 43.9% (202/460).

CONCLUSIONS

ML-based CT-FFR may further improve the diagnostic performance of cCTA by correctly reclassifying a considerable proportion of patients with morphological signs of obstructive CAD on cCTA during pre-TAVR evaluation. Thereby, CT-FFR has the potential to further reduce the need for ICA in this challenging elderly group of patients before TAVR.

Revascularization in the Transcatheter Aortic Valve Replacement Population

Transcatheter aortic valve replacement (TAVR) is a standard treatment option for patients with severe aortic stenosis. Management of concomitant coronary artery disease (CAD) in these patients remains controversial with no randomized clinical trials to guide decision making in this cohort. The role of CAD in TAVR has been difficult to evaluate given the current heterogeneity in defining CAD, and the used methods to assess CAD. Subsequently, the role of coronary revascularization remains individualized and assessed on a case-by-case basis by the heart team. In this article, the authors discuss the rationale and prognostic role of CAD in patients undergoing TAVR.

Hyperemic versus non-hyperemic indexes for coronary physiology assessment in patients with severe aortic stenosis

PURPOSE

Recent data suggests that fractional flow reserve (FFR) may underestimate intermediate coronary stenosis in the presence of severe aortic stenosis (AS), whereas instantaneous wave-free ratio (iFR) values may remain similar after treatment of AS, yet the evidence still lacks to use iFR as the reference. We aimed to compare FFR/iFR values in the AS setting.

MATERIALS AND METHODS

The functional significance of 416 coronary lesions in 221 patients with severe AS was investigated with iFR and FFR.

RESULTS

The diagnostic agreement between iFR and FFR has been tested, using the cut-off value of 0.89 for iFR and 0.80 for FFR. The mean diameter stenosis was 58.6 ​± ​13.4% with FFR of 0.85 ​± ​0.07 and iFR of 0.90 ​± ​0.04. FFR ≤0.80 was identified in 26.0% and iFR≤0.89 in 33.2% of interrogated vessels. Good agreement between iFR and FFR was confirmed (Intraclass Correlation Coefficient 0.83 [95%CI 0.79-0.85]). The overall diagnostic accuracy (AUC in ROC analysis) of FFR in detecting iFR≤0.89 was 0.997 (95%CI 0.986 to 1.000; p<0.001) and of iFR in detecting FFR≤0.80 was 0.995 (95%CI 0.983 to 0.999; p<0.001). The optimal cut-off value for FFR to detect iFR≤0.89 was 0.82 with sensitivity, specificity, and accuracy of 97.1%, 98.9%, and 97.7%, respectively, and for IFR to detect FFR≤0.80 was 0.88 with sensitivity, specificity, and accuracy of 99.1%, 95.8%, and 97.4%, respectively.

CONCLUSION

In the presence of AS, FFR has good agreement with iFR. However, the optimal FFR/iFR threshold to identify iFR≤0.89/FFR≤0.80 may be different from the standard thresholds of ischemia.

Pathophysiology, Diagnosis, and Treatment of Patients with Concomitant Severe Aortic Stenosis and Coronary Artery Disease: A Closer Look to the Unresolved Perplexity

Degenerative aortic stenosis (AS) and coronary artery disease (CAD) are the most prevalent cardiovascular diseases in developed countries, and they coexist in up to 50% of patients. The pathophysiological rationale behind concomitant AS and CAD is discussed in detail in this review, together with prognostic implications. Detecting CAD in patients with AS may be challenging, as AS may mask the existence and symptoms of CAD. The safety and reliability of invasive and non-invasive physiological assessment for epicardial coronary disease are also a matter of debate. Finally, the selection and timing of optimal treatment of CAD in patients with severe AS are still unclear. Given the aging of the population, the increase in the prevalence of AS, and the ongoing paradigm shift in its treatment, controversies in the diagnosis and treatment of CAD in the setting of AS are deemed to grow in importance. In this paper, we present contemporary issues in the diagnosis and management of CAD in patients with severe AS who are transcatheter aortic valve implantation (TAVI) candidates and provide perspective on the treatment approach.

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.

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.

Coronary Microcirculation in Aortic Stenosis: Pathophysiology, Invasive Assessment, and Future Directions

With the increasing prevalence of aortic stenosis (AS) due to a growing elderly population, a proper understanding of its physiology is paramount to guide therapy and define severity. A better understanding of the microvasculature in AS could improve clinical care by predicting left ventricular remodeling or anticipate the interplay between epicardial stenosis and myocardial dysfunction. In this review, we combine five decades of literature regarding microvascular, coronary, and aortic valve physiology with emerging insights from newly developed invasive tools for quantifying microcirculatory function. Furthermore, we describe the coupling between microcirculation and epicardial stenosis, which is currently under investigation in several randomized trials enrolling subjects with concomitant AS and coronary disease. To clarify the physiology explained previously, we present two instructive cases with invasive pressure measurements quantifying coexisting valve and coronary stenoses. Finally, we pose open clinical and research questions whose answers would further expand our knowledge of microvascular dysfunction in AS. These trials were registered with NCT03042104, NCT03094143, and NCT02436655.

Assessment and management of coronary artery disease in patients undergoing transcatheter aortic valve replacement

PURPOSE OF REVIEW

Coronary artery disease (CAD) is commonly observed in patients undergoing transcatheter aortic valve replacement (TAVR). Significant variability exists across institutions for strategies used for CAD diagnosis and its management. The heart team often relies upon traditional practice patterns and the decision for revascularization by percutaneous coronary intervention (PCI) is influenced by patient, angiographic, operator, and system-related factors.

RECENT FINDINGS

Contemporary coronary tomography angiography (CTA) shows significant promise for detection of clinically important CAD and preliminary data support CTA use for TAVR patients. The prognostic implications of CAD in a TAVR population remain unclear with studies showing conflicting data for the benefits of PCI. Recent trials show that medical management is an effective initial treatment strategy for stable CAD, a finding likely also applicable for asymptomatic and stable TAVR patients. In addition, PCI performed pre-TAVR, concomitant with TAVR or after TAVR has been shown to produce similar outcomes. Dual antiplatelet therapy (DAPT) is mandated after PCI but associated with increased risk of bleeding in TAVR population with accumulating evidence for single antiplatelet therapy (SAPT) post-TAVR unless DAPT or anticoagulation is indicated for another reason.

SUMMARY

Although coronary angiography remains the predominant modality for CAD assessment, CTA is increasingly being used in TAVR patients. There is limited evidence to guide CAD management in TAVR patients with significant variability in practice patterns. Medical therapy is recommended for asymptomatic and stable CAD patients with applicability for TAVR population. Despite prior concerns, recent studies suggest successful coronary access post-TAVR and similar outcomes for PCI offered pre-TAVR, concomitant with TAVR and post-TAVR settings. Safety of DAPT should be an important consideration for PCI in TAVR patients. Ongoing studies will determine the preferred testing for CAD diagnosis, benefit of revascularization, timing of PCI, and optimum antithrombotic therapy for TAVR populations.

Long-term variations of FFR and iFR after transcatheter aortic valve implantation

Long-term variations of fractional flow reserve (FFR) and instantaneous wave-free-ratio (iFR) after transcatheter aortic valve implantation (TAVI) have not been previously assessed. A total of 23 coronary lesions in 14 patients with aortic stenosis (AS) underwent physiology assessment at baseline, immediately after TAVI and at 14(7-29) months of follow-up. The angiographic severity of the lesions did not progress at follow-up (54[45-64] vs 54[49-63], p = .53). Overall, FFR (0.87[0.85-0.92] vs 0.88[0.82-0.92], p = .45) and iFR (0.88[0.85-0.96] vs 0.91[0.86-0.97], p = .30) did not change significantly compared with the baseline. FFR decreased in 3(13%) lesions with abnormal baseline value, whereas it remained stable in lesions with FFR > 0.80. Conversely, iFR did not show a systematic trend at long-term after TAVI. However, iFR demonstrated a higher reclassification rate at follow-up compared with FFR (p = .02). In conclusions, in this exploratory study, only minor variations of coronary physiology indices were observed at long-term after TAVI. Nevertheless, caution should be exercised in the interpretation of borderline FFR and iFR values in severe AS.

Coronary Artery Disease and Transcatheter Aortic Valve Replacement: JACC State-of-the-Art Review

About one-half of transcatheter aortic valve replacement (TAVR) candidates have coronary artery disease (CAD), and controversial results have been reported regarding the effect of the presence and severity of CAD on clinical outcomes post-TAVR. In addition to coronary angiography, promising data has been recently reported on both the use of computed tomography angiography and the functional invasive assessment of coronary lesions in the work-up pre-TAVR. While waiting for the results of ongoing randomized trials, percutaneous revascularization of significant coronary lesions has been the routine strategy in TAVR candidates with CAD. Also, scarce data exists on the incidence, characteristics, and management of coronary events post-TAVR, and increasing interest exist on potential coronary access challenges in patients requiring coronary angiography/intervention post-TAVR. This review provides an updated overview of the current landscape of CAD in TAVR recipients, focusing on its prevalence, clinical impact, pre- and post-procedural evaluation and management, unresolved issues and future perspectives.

Comparison of Instantaneous Wave-Free Ratio (iFR) and Fractional Flow Reserve (FFR) with respect to Their Sensitivities to Cardiovascular Factors: A Computational Model-Based Study

While coronary revascularization strategies guided by instantaneous wave-free ratio (iFR) are, in general, noninferior to those guided by fractional flow reserve (FFR) with respect to the rate of major adverse cardiac events at one-year follow-up in patients with stable angina or an acute coronary syndrome, the overall accuracy of diagnosis with iFR in large patient cohorts is about 80% compared with the diagnosis with FFR. So far, it remains incompletely understood what factors contribute to the discordant diagnosis between iFR and FFR. In this study, a computational method was used to systemically investigate the respective effects of various cardiovascular factors on FFR and iFR. The results showed that deterioration in aortic valve disease (e.g., regurgitation or stenosis) led to a marked decrease in iFR and a mild increase in FFR given fixed severity of coronary artery stenosis and that increasing coronary microvascular resistance caused a considerable increase in both iFR and FFR, but the degree of increase in iFR was lower than that in FFR. These findings suggest that there is a high probability of discordant diagnosis between iFR and FFR in patients with severe aortic valve disease or coronary microcirculation dysfunction.

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.

Long-Term Effects of Transcatheter Aortic Valve Implantation on Coronary Hemodynamics in Patients With Concomitant Coronary Artery Disease and Severe Aortic Stenosis

Background As younger patients are being considered for transcatheter aortic valve implantation (TAVI), the assessment and treatment of concomitant coronary artery disease is taking on increased importance. Methods and Results Thirteen contemporary lower-risk patients with TAVI with severe aortic stenosis (AS) and moderate-severe coronary lesions were included. Patients underwent assessment of coronary hemodynamics in the presence of severe AS (pre-TAVI), in the absence of severe AS (immediately post-TAVI), and at longer-term follow-up (6 months post-TAVI). Fractional flow reserve decreased from 0.85 (0.76-0.88) pre-TAVI to 0.79 (0.74-0.83) post-TAVI, and then to 0.71 (0.65-0.77) at 6-month follow-up (P<0.001 for all comparisons). Conversely, instantaneous wave-free ratio was not significantly different: 0.82 (0.80-0.90) pre-TAVI, 0.83 (0.77-0.88) post-TAVI, and 0.83 (0.73-0.89) at 6 months (P=0.735). These changes are explained by the underlying coronary flow. Hyperemic whole-cycle coronary flow (fractional flow reserve flow) increased from 26.36 cm/s (23.82-31.82 cm/s) pre-TAVI to 30.78 cm/s (29.70-34.68 cm/s) post-TAVI (P=0.012), to 40.20 cm/s (32.14-50.00 cm/s) at 6-month follow-up (P<0.001 for both comparisons). Resting flow during the wave-free period of diastole was not significantly different: 25.48 cm/s (21.12-33.65 cm/s) pre-TAVI, 24.54 cm/s (20.74-27.88 cm/s) post-TAVI, and 25.89 cm/s (22.57-28.96 cm/s) at 6 months (P=0.500). Conclusions TAVI acutely improves whole-cycle hyperemic coronary flow, with ongoing sustained improvements at longer-term follow-up. This enhanced response to hyperemic stimuli appears to make fractional flow reserve assessment less suitable for patients with severe AS. Conversely, resting diastolic flow is not significantly influenced by the presence of severe AS. Resting indices of coronary stenosis severity, therefore, appear to be more appropriate for this patient population, although large-scale prospective randomized trials will be required to determine the role of coronary physiology in patients with severe AS.

Physiological Assessment of Coronary Lesions in 2020

PURPOSE OF REVIEW

Physiological assessment of coronary artery disease (CAD) is an essential component of the interventional cardiology toolbox. However, despite long-term data demonstrating improved outcomes, physiology-guided percutaneous coronary intervention (PCI) remains underutilized in current practice. This review outlines the indications and technical aspects involved in evaluating coronary stenosis physiology, focusing on the latest developments in the field.

RECENT FINDINGS

Beyond fractional flow reserve (FFR), non-hyperemic pressure ratios (NHPR) that assess coronary physiology at rest without hyperemia now abound. Additional advances in other alternative FFR approaches, including non-invasive coronary CT (FFR_CT), invasive angiography (FFR_angio), and optical coherence tomography (FFR_OCT), are being realized. Artificial intelligence algorithms and robust tools that enable detailed pre-procedure "virtual" intervention are also emerging. The benefits of coronary physiological assessment to determine lesion functional significance are well established. In addition to stable CAD, coronary physiology can be especially helpful in clinical scenarios such as left main and multivessel CAD, serial lesions, non-infarct-related arteries in acute coronary syndromes, and residual ischemia post-PCI. Today, coronary physiological assessment remains an indispensable tool in the catheterization laboratory, with an exciting technological future that will further refine clinical practice and improve patient care.

Determining the Predominant Lesion in Patients With Severe Aortic Stenosis and Coronary Stenoses: A Multicenter Study Using Intracoronary Pressure and Flow

Patients with severe aortic stenosis (AS) often have coronary artery disease. Both the aortic valve and the coronary disease influence the blood flow to the myocardium and its ability to respond to stress; leading to exertional symptoms. In this study, we aim to quantify the effect of severe AS on the coronary microcirculation and determine if this is influenced by any concomitant coronary disease. We then compare this to the effect of coronary stenoses on the coronary microcirculation.

Physiological Versus Angiographic Guidance for Myocardial Revascularization in Patients Undergoing Transcatheter Aortic Valve Implantation

Background Management of coronary artery disease in patients undergoing transcatheter aortic valve implantation is uncertain. Fractional flow reserve (FFR) has never been clinically validated in aortic stenosis. The study aim was to analyze the clinical outcome of FFR-guided revascularization in patients undergoing transcatheter aortic valve implantation. Methods and Results Patients with severe aortic stenosis and coronary artery disease at coronary angiography were included in this retrospective analysis and divided in 2 groups: angiography guided (122/216; 56.5%) versus FFR-guided revascularization (94/216; 43.5%). Patients were clinically followed up and evaluated for the occurrence of major adverse cardiac and cerebrovascular events at 2-year follow-up. Most lesions in the FFR group resulted negative according to the conventional 0.80 cutoff value (111/142; 78.2%) and were deferred. The FFR-guided group showed a better major adverse cardiac and cerebrovascular event-free survival compared with the angio-guided group (92.6% versus 82.0%; hazard ratio, 0.4; 95% CI, 0.2-1.0; P=0.035). Patients with deferred lesions based on FFR presented better outcome compared with patients who underwent angio-guided percutaneous coronary intervention (91.4% versus 68.1%; hazard ratio, 0.3; 95% CI, 0.1-0.6; P=0.001). Conclusions FFR guidance was associated with favorable outcome in this observational study in patients undergoing transcatheter aortic valve implantation. Randomized trials are needed to investigate the long-term effects of FFR-guided revascularization against angiographic guidance alone in patients with aortic stenosis.

Pathophysiological coronary and microcirculatory flow alterations in aortic stenosis

Regulation of coronary blood flow is maintained through a delicate balance of ventriculoarterial and neurohumoral mechanisms. The aortic valve is integral to the functions of these systems, and disease states that compromise aortic valve integrity have the potential to seriously disrupt coronary blood flow. Aortic stenosis (AS) is the most common cause of valvular heart disease requiring medical intervention, and the prevalence and associated socio-economic burden of AS are set to increase with population ageing. Valvular stenosis precipitates a cascade of structural, microcirculatory, and neurohumoral changes, which all lead to impairment of coronary flow reserve and myocardial ischaemia even in the absence of notable coronary stenosis. Coronary physiology can potentially be normalized through interventions that relieve severe AS, but normality is often not immediately achievable and probably requires continued adaptation. Finally, the physiological assessment of coronary artery disease in patients with AS represents an ongoing challenge, as the invasive physiological measures used in current cardiology practice are yet to be validated in this population. This Review discusses the key concepts of coronary pathophysiology in patients with AS through presentation of contemporary basic science and data from animal and human studies.

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.