Impact of Aortic Valve Stenosis on Coronary Hemodynamics and the Instantaneous Effect of Transcatheter Aortic Valve Implantation

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.

Fractional flow reserve in patients with coronary artery disease undergoing TAVI: a prospective analysis

OBJECTIVES

To determine the true prevalence of CAD in AS patients, to detect changes of the hemodynamic significance of coronary lesions following TAVI, to explore to what extent FFR-positive CAD might influence outcome and finally to develop a management algorithm for this patient subset.

METHODS

From May 2016 to March 2018, diagnostic coronary angiography was performed in 246 patients before TAVI. In the presence of coronary lesions with a diameter stenosis ≥ 50%, FFR was measured. In patients with positive FFR ≤ 0.80, a control angiography was performed 6-8 weeks after TAVI.

RESULTS

The study cohort was 81.0 ± 6.1 years old, 48.4% of the patients were male. 53.3% had concomitant CAD. 35.9% of these patients underwent PCI before TAVI due to functionally significant left main CAD and/or severe stenosis ≥ 90%. 31 patients underwent FFR measurements in cumulative 38 coronary lesions. Prior to TAVI, a negative FFR could be detected in 18 lesions, whereas a positive FFR was found in entirely 20 lesions. A control angiography and FFR measurement was performed in cumulative 13 lesions. Comparing the FFR values, there was no significant difference (0.77 ± 0.04 vs. 0.76 ± 0.08; p = 0.11).

CONCLUSION

Concomitant CAD was diagnosed in 53.3% of TAVI patients. FFR did not significantly change after TAVI, confirming the validity of FFR to evaluate coronary lesions in this specific clinical setting. Given the low rates of cardiac adverse events, it might therefore be considered to treat coronary stenoses not involving left main and those with a diameter stenosis < 90% after TAVI.

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.

Coronary Microcirculation in Aortic Stenosis

Aortic stenosis is a heterogeneous disorder. Variations in the pathological and physiological responses to pressure overload are incompletely understood and generate a range of flow and pressure gradient patterns, which ultimately cause varying microvascular effects. The impact of cardiac-coronary coupling depends on these pressure and flow effects. In this article, we explore important concepts concerning cardiac physiology and the coronary microcirculation in aortic stenosis and their impact on myocardial remodeling, aortic valve flow patterns, and clinical progression.

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

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

Left ventricular afterload reduction by transcatheter aortic valve implantation in severe aortic stenosis and its prompt effects on comprehensive coronary haemodynamics

AIMS

In this study we aimed to test the hypothesis that left ventricular (LV) afterload reduction in severe aortic valve stenosis (AS) by transcatheter aortic valve implantation (TAVI) acutely improves coronary haemodynamics.

METHODS AND RESULTS

This was a prospective, pathophysiologic study in 40 patients with severe AS undergoing TAVI. Endpoints were determined invasively immediately before and after TAVI without altering coronary stenotic lesions if present. Myocardial hyperaemia was induced by intravenous adenosine. The primary study endpoints were coronary flow reserve (thermodilution-derived CFR), and fractional flow reserve (FFR). The secondary study endpoint was coronary collateral flow index (CFI) as obtained during a one-minute coronary balloon occlusion. CFR was 1.9±0.9 before TAVI and 2.0±1.0 after TAVI (p=0.72). FFR was 0.90±0.08 before TAVI and 0.93±0.08 after TAVI (p=0.0021). The TAVI-induced increase in FFR was related to a significant decrease in hyperaemic mean aortic pressure from 71±16 mmHg before TAVI to 67±15 mmHg after TAVI (p=0.0099). Hyperaemic CFI increased from 0.127±0.083 before to 0.146±0.090 after TAVI (p=0.0508).

CONCLUSIONS

CFR appears not to be acutely affected by LV afterload reduction among patients with severe AS in response to TAVI. However, it acutely improves FFR; this occurs via lowering of mean aortic pressure. Hyperaemic coronary collateral flow index tends to augment in response to TAVI.

Late coronary ischemıc syndromes assocıated wıth transcatheter aortıc valve ımplantatıon: A revıew of mechanıstıc and clınıcal aspects

In the past years, transcatheter aortic valve implantation (TAVI) has emerged as a promising option for the treatment of aortic valve pathologies particularly in the the presence of surgically high-risk situations. Importantly, a variety of specific procedural complications including acute coronary osteal occlusion, though very rare, has been reported in major clinical studies. However, little is known about the late impact of TAVI on coronary system at the macro and microvascular levels.

On the other hand, clinical studies as well as real life experiences have shown variable rates of acute coronary syndrome (ACS) readmissions among TAVI recipients in the short and long terms. Within this context, it may be suggested that even though late coronary ischemic events arising after TAVI, to some extent, appears to be spontaneous or attributable to certain stressors, TAVI may also have the potential to directly account for, accelerate or contribute to the evolution of these ischemic events on follow-up. Accordingly, the present review primarily focuses on potential association of TAVI with late coronary ischemic syndromes along with a particular emphasis on its mechanistic basis and clinical implications among TAVI recipients.

Regression of left ventricular hypertrophy provides an additive physiological benefit following treatment of aortic stenosis: Insights from serial coronary wave intensity analysis

AIM

Severe aortic stenosis frequently involves the development of left ventricular hypertrophy (LVH) creating a dichotomous haemodynamic state within the coronary circulation. Whilst the increased force of ventricular contraction enhances its resultant relaxation and thus increases the distal diastolic coronary "suction" force, the presence of LVH has a potentially opposing effect on ventricular-coronary interplay. The aim of this study was to use non-invasive coronary wave intensity analysis (WIA) to separate and measure the sequential effects of outflow tract obstruction relief and then LVH regression following intervention for aortic stenosis.

METHODS

Fifteen patients with unobstructed coronary arteries undergoing aortic valve intervention (11 surgical aortic valve replacement [SAVR], 4 TAVI) were successfully assessed before and after intervention, and at 6 and 12 months post-procedure. Coronary WIA was constructed from simultaneously acquired coronary flow from transthoracic echo and pressure from an oscillometric brachial cuff system.

RESULTS

Immediately following intervention, a decline in the backward decompression wave (BDW) was noted (9.7 ± 5.7 vs 5.1 ± 3.6 × 10³  W/m² /s, P < 0.01). Over 12 months, LV mass index fell from 114 ± 19 to 82 ± 17 kg/m² . Accompanying this, the BDW fraction increased to 32.8 ± 7.2% at 6 months (P = 0.01 vs post-procedure) and 34.7 ± 6.7% at 12 months (P < 0.001 vs post-procedure).

CONCLUSION

In aortic stenosis, both the outflow tract gradient and the presence of LVH impact significantly on coronary haemodynamics that cannot be appreciated by examining resting coronary flow rates alone. An immediate change in coronary wave intensity occurs following intervention with further effects appreciable with hypertrophy regression. The improvement in prognosis with treatment is likely to be attributable to both features.

Coronary Hemodynamics in Patients With Severe Aortic Stenosis and Coronary Artery Disease Undergoing Transcatheter Aortic Valve Replacement: Implications for Clinical Indices of Coronary Stenosis Severity

OBJECTIVES

In this study, a systematic analysis was conducted of phasic intracoronary pressure and flow velocity in patients with severe aortic stenosis (AS) and coronary artery disease, undergoing transcatheter aortic valve replacement (TAVR), to determine how AS affects: 1) phasic coronary flow; 2) hyperemic coronary flow; and 3) the most common clinically used indices of coronary stenosis severity, instantaneous wave-free ratio and fractional flow reserve.

BACKGROUND

A significant proportion of patients with severe aortic stenosis (AS) have concomitant coronary artery disease. The effect of the valve on coronary pressure, flow, and the established invasive clinical indices of stenosis severity have not been studied.

METHODS

Twenty-eight patients (30 lesions, 50.0% men, mean age 82.1 ± 6.5 years) with severe AS and coronary artery disease were included. Intracoronary pressure and flow assessments were performed at rest and during hyperemia immediately before and after TAVR.

RESULTS

Flow during the wave-free period of diastole did not change post-TAVR (29.78 ± 14.9 cm/s vs. 30.81 ± 19.6 cm/s; p = 0.64). Whole-cycle hyperemic flow increased significantly post-TAVR (33.44 ± 13.4 cm/s pre-TAVR vs. 40.33 ± 17.4 cm/s post-TAVR; p = 0.006); this was secondary to significant increases in systolic hyperemic flow post-TAVR (27.67 ± 12.1 cm/s pre-TAVR vs. 34.15 ± 17.5 cm/s post-TAVR; p = 0.02). Instantaneous wave-free ratio values did not change post-TAVR (0.88 ± 0.09 pre-TAVR vs. 0.88 ± 0.09 post-TAVR; p = 0.73), whereas fractional flow reserve decreased significantly post-TAVR (0.87 ± 0.08 pre-TAVR vs. 0.85 ± 0.09 post-TAVR; p = 0.001).

CONCLUSIONS

Systolic and hyperemic coronary flow increased significantly post-TAVR; consequently, hyperemic indices that include systole underestimated coronary stenosis severity in patients with severe AS. Flow during the wave-free period of diastole did not change post-TAVR, suggesting that indices calculated during this period are not vulnerable to the confounding effect of the stenotic aortic valve.

Coronary Revascularisation in Transcatheter Aortic Valve Implantation Candidates: Why, Who, When?

Coronary artery disease (CAD) and aortic stenosis (AS) frequently coexist. The presence of CAD has been consistently associated with an impaired prognosis in patients undergoing surgical aortic valve replacement during short- and long-term follow-up. Accordingly, current guidelines recommend coronary revascularisation of all significant stenoses in patients undergoing surgical aortic valve replacement. Conversely, the management of concomitant CAD in patients with severe AS undergoing transcatheter aortic valve implantation (TAVI) is still a matter of debate. The aim of this review article is to provide an overview on the role of coronary revascularisation in TAVI patients.

Quantitative Assessment of Coronary Microvascular Function: Dynamic Single-Photon Emission Computed Tomography, Positron Emission Tomography, Ultrasound, Computed Tomography, and Magnetic Resonance Imaging

A healthy, functional microcirculation in combination with nonobstructed epicardial coronary arteries is the prerequisite of normal myocardial perfusion. Quantitative assessment in myocardial perfusion and determination of absolute myocardial blood flow can be achieved noninvasively using dynamic imaging with multiple imaging modalities. Extensive evidence supports the clinical value of noninvasively assessing indices of coronary flow for diagnosing coronary microvascular dysfunction; in certain diseases, the degree of coronary microvascular impairment carries important prognostic relevance. Although, currently positron emission tomography is the most commonly used tool for the quantification of myocardial blood flow, other modalities, including single-photon emission computed tomography, computed tomography, magnetic resonance imaging, and myocardial contrast echocardiography, have emerged as techniques with great promise for determination of coronary microvascular dysfunction. The following review will describe basic concepts of coronary and microvascular physiology, review available modalities for dynamic imaging for quantitative assessment of coronary perfusion and myocardial blood flow, and discuss their application in distinct forms of coronary microvascular dysfunction.

Transcatheter Aortic Valve Implantation With or Without Percutaneous Coronary Artery Revascularization Strategy: A Systematic Review and Meta-Analysis

BACKGROUND

Recent recommendations suggest that in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation and coexistent significant coronary artery disease, the latter should be treated before the index procedure; however, the evidence basis for such an approach remains limited. We performed a systematic review and meta-analysis to study the clinical outcomes of patients with coronary artery disease who did or did not undergo revascularization prior to transcatheter aortic valve implantation.

METHODS AND RESULTS

We conducted a search of Medline and Embase to identify studies evaluating patients who underwent transcatheter aortic valve implantation with or without percutaneous coronary intervention. Random-effects meta-analyses with the inverse variance method were used to estimate the rate and risk of adverse outcomes. Nine studies involving 3858 participants were included in the meta-analysis. Patients who underwent revascularization with percutaneous coronary intervention had a higher rate of major vascular complications (odd ratio [OR]: 1.86; 95% confidence interval [CI], 1.33-2.60; P=0.0003) and higher 30-day mortality (OR: 1.42; 95% CI, 1.08-1.87; P=0.01). There were no differences in effect estimates for 30-day cardiovascular mortality (OR: 1.03; 95% CI, 0.35-2.99), myocardial infarction (OR: 0.86; 95% CI, 0.14-5.28), acute kidney injury (OR: 0.89; 95% CI, 0.42-1.88), stroke (OR: 1.07; 95% CI, 0.38-2.97), or 1-year mortality (OR: 1.05; 95% CI, 0.71-1.56). The timing of percutaneous coronary intervention (same setting versus a priori) did not negatively influence outcomes.

CONCLUSIONS

Our analysis suggests that revascularization before transcatheter aortic valve implantation confers no clinical advantage with respect to several patient-important clinical outcomes and may be associated with an increased risk of major vascular complications and 30-day mortality. In the absence of definitive evidence, careful evaluation of patients on an individual basis is of paramount importance to identify patients who might benefit from elective revascularization.

Functional Assessment of Coronary Artery Disease in Patients Undergoing Transcatheter Aortic Valve Implantation

Background—

Aortic valve stenosis may influence fractional flow reserve (FFR) of concomitant coronary artery disease by causing hypertrophy and reducing the vasodilatory reserve of the coronary circulation. We sought to investigate whether FFR values might change after valve replacement.

Methods and Results—

The functional relevance of 133 coronary lesions was assessed by FFR in 54 patients with severe aortic valve stenosis before and after transcatheter aortic valve implantation (TAVI) during the same procedure. A linear mixed model was used to verify the interaction of TAVI effect with the FFR values. No significant overall change in FFR values was found before and after the aortic valve stenosis removal (0.89±0.10 versus 0.89±0.13; P =0.73). A different trend in FFR groups (positive if ≤0.8; negative if >0.8) was found after TAVI ( P for interaction <0.001). Positive FFR values worsened after TAVI (0.71±0.11 versus 0.66±0.14). Conversely, negative FFR values improved after TAVI (0.92±0.06 versus 0.93±0.07). Similarly, FFR values in coronary arteries with lesions presenting percent diameter stenosis >50 worsened after TAVI (0.84±0.12 versus 0.82±0.16; P =0.02), whereas FFR values in arteries with mild lesions (percent diameter stenosis <50) tended toward improvement after TAVI (0.90±0.07 versus 0.91±0.09; P =0.69). Functional FFR variations after TAVI changed the indication to treat the coronary stenosis in 8 of 133 (6%) lesions.

Conclusions—

Coronary hemodynamics are influenced by aortic valve stenosis removal. Nevertheless, FFR variations after TAVI are minor and crossed the diagnostic cutoff of 0.8 in a small number of patients after valve replacement. Borderline coronary lesions might become functionally significant after valve replacement, although FFR-guided interventions were infrequent even in patients with angiographically significant lesions.