Mechanisms of regional ischaemic changes during dipyridamole echocardiography in patients with severe aortic valve stenosis and normal coronary arteries

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.

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.

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.

Coronary Revascularization in Patients Undergoing Transcatheter Aortic Valve Replacement

Concomitant coronary artery disease (CAD) is highly prevalent among patients with severe aortic stenosis (AS). Historically, surgical aortic valve replacement with coronary artery bypass grafting was the only treatment option for patients with severe AS and significant CAD. The rapid expansion of transcatheter aortic valve replacement has led to significant paradigm shifts in the treatment of severe AS and has raised new questions regarding the optimal management of CAD in these patients. We review the evidence regarding management of concomitant CAD in severe AS patients, specifically focusing on issues surrounding transcatheter aortic valve replacement. In the absence of robust evidence supporting specific treatment strategies, decisions regarding coronary revascularization in severe AS should be individualized and made within the context of a multidisciplinary heart team.

[Coronary microvascular dysfunction and aortic stenosis: an update]

The coronary microcirculatory impairment is a key feature of the pathophysiology of aortic stenosis (AS), the most operated valvular disease over the world. Several studies showed this coronary microcirculatory impairment in AS, using different tools and protocols, in various patient population of AS. This article will review the impairment of the coronary microcirculation in AS underlining its multifactorial origin, its functional part related to the hemodynamic consequences of AS, its complex relationship with left ventricular hypertrophy, and its potential diagnostic and prognostic value.

Eight-Row Multidetector Computed Tomography Coronary Angiography Evaluation of Significant Coronary Artery Disease in Patients with Severe Aortic Valve Stenosis

BACKGROUND

The aim of this study was to evaluate whether 8-row multidetector computed tomography coronary angiography (MDCT-CA) could replace invasive conventional coronary angiography (CCA) in patients with acquired severe aortic valve stenosis (AS). Coronary artery disease (CAD) diagnosis should be obtained with a noninvasive method in patients with AS undergoing valvular replacement. We evaluated the diagnostic accuracy of MDCT-CA in detecting high-grade (> or =50%) stenoses in the main coronary arteries in patients with AS.

METHODS

Twenty-three patients with acquired severe AS underwent both CCA and MDCT-CA. We calculated the total and volumetric calcium scores and evaluated the image quality of each coronary segment as assessable or nonassessable for stenosis. The images of the arteries were evaluated for the occurrence of artifacts and the presence of high-grade stenoses (> or =50%) by visual estimation and comparison with that of CCA.

RESULTS

Of the 322 segments screened 224 were assessable for stenosis. Heavy calcium load rendered 37 (38%) of the 98 coronary segments nonassessable. Compared to CCA, MDCT-CA had a sensitivity of 63%, a specificity of 96%, a positive predictive value of 52%, and a negative predictive value of 98% for > or =50% stenoses in the main coronary arteries.

CONCLUSIONS

Eight-row MDCT-CA revealed a low sensitivity in detecting significant coronary artery disease in patients with acquired severe AS. High calcium burden decreased visualization of the lumen and complicated most often a correct assessment. In this patient group, CCA should still remain the primary pre-surgical test to rule out coronary lesions requiring revascularization.

Long-term survival of patients with chest pain syndrome and angiographically normal or near-normal coronary arteries: the additional prognostic value of dipyridamole echocardiography test (DET)

AIMS

Patients with normal coronary arteries have a heterogeneous prognosis. Aim of this study was to assess whether dipyridamole stress echocardiography positivity identifies a prognostically less benign subset.

METHODS AND RESULTS

We selected 457 patients (245 males; 56+/-10 years) who underwent stress high-dose dipyridamole echocardiography and had angiographically non-significant (<50% visually assessed) stenosis in any major vessel and preserved left ventricular function. All patients were followed up for a median of 7.1 years (first quartile 5 and third quartile 10.5). Dipyridamole echocardiography test (DET) positivity for regional dysfunction occurred in 43(9%) patients. Kaplan-Meier survival estimates showed a significant better outcome for those patients with negative dipyridamole echocardiography test compared with those with a positive test (90 vs. 75.7%, at 140 months of follow-up, P=0.0018). At multivariable analysis, mild or moderate irregularity on coronary arteriogram (HR=3.3, CI 95%=1.7-6.2), diabetes (HR=3.5, CI 95%=1.4-9.2), and wall motion score index at peak stress (HR=6.7, CI 95%=2.5-17.8) were independent predictors of all-cause death.

CONCLUSION

DET adds incremental value to the prognostic stratification achieved with clinical and angiographic data in the subset of patients with normal or near-normal coronary arteries.

Evaluation by Contrast-Enhanced Electron Beam Computed Tomography of Myocardial Perfusion and Tissue Characteristics in Congenital Aortic Stenosis

The evaluation of myocardial perfusion and tissue characteristics gives useful information regarding the indication for surgery. In the present study, two-phase contrast enhanced electron beam computed tomography (EBT) was used to quantitatively examine myocardial perfusion and the tissue characteristics of the left ventricular (LV) myocardium in congenital aortic stenosis (AS). The AS group comprised 15 patients and the control group had 14 non-AS patients. Myocardial ischemia and tissue characteristics were evaluated by the ratio of the incremental CT number of the myocardium (M) and the lumen (L) of the LV (M/L) in, the early phase with and without dipyridamole (Dp) loading and in the late phase after enhancement (respectively). In a comparison between the AS group and the controls, mean early M/Ls were significantly lower in the AS group than in the controls (20+/-5% vs 37+/-10%, p<0.01) and mean late M/Ls in the AS group were also significantly lower (47+/-11% vs 62+/-13%, p<0.01). In the AS patients, early M/Ls in the subendocardial and apical regions were especially lower than those of other segments, but the late M/Ls in these segments were inversely higher than those of other segments. These results suggest 2 things: (1) the existence of latent LV myocardial ischemia in AS patients, which is probably because of a hypertrophied LV wall, in turn caused by afterload, and (2) the presence of more myocardial ischemia and interstitial fibrosis in the subendocardial and apical regions of the AS heart. Using Dp loading for the AS patients increased the clarity of the contrast images. Contrast-enhanced EBT is useful for evaluating myocardial characteristics and perfusion in AS, and gives new insight into the LV wall characteristics in AS, as well as an indication for surgical correction of congenital AS.

SPECT dipyridamole scintigraphy for detecting coronary artery disease in patients with isolated severe aortic stenosis

BACKGROUND

The sensitivity and specificity of non-invasive methods--specifically single-photon emission computed tomography (SPECT) dipyridamole-thallium myocardial perfusion--for detecting coronary artery disease (CAD) in patients with severe aortic stenosis remains unclear. Occasionally, these patients present with atypical angina. Therefore, a CAD diagnosis must be excluded to prevent unnecessary cardiac catheterization.

METHODS

To determine the diagnostic value of SPECT dipyridamole-thallium imaging in this population, we compared the effectiveness of the imaging procedure with that of coronary angiography by prospectively analyzing patients who underwent both procedures. Group 1 included 59 patients who were asymptomatic or had atypical angina; group 2; 51 preoperative aged-matched patients with typical angina. SPECT acquisition was performed 15 min after 0.142 mg/kg/min of dipyridamole infusion completion, and redistribution images were performed 4 h after thallium injection. Two cut-off values of luminal diameter narrowing, >50 and >70%, defined significant CAD.

RESULTS

Coronary angiography with significant CAD (>50%) was present in 15 (25%) group 1 patients and in 16 (32%) group 2 patients (P=NS). The sensitivity was greater in group 2 than in group 1 (56 versus 26%; P=0.001). The specificity, positive and negative predictive value, and accuracy in the groups were similar. CAD of >70% luminal stenosis was present in 11 (19%) group 1 patients and in 12 (23%) group 2 patients (P=NS). The positive predictive value was greater in group 2 than in group 1 (75 versus 43%; P=0.001) but similar sensitivity, specificity, negative predictive value, and accuracy. The likelihood ratio for abnormal test increased in patients with CAD of >70%.

CONCLUSIONS

symptoms of typical angina had significant impact on test sensitivity, positive predictive value and likelihood ratio for abnormal test. Furthermore, SPECT dipyridamole-thallium imaging was a useful non-invasive method to exclude the diagnosis of significant CAD (high specificity) in asymptomatic and symptomatic patients with isolated severe aortic stenosis.

Stress echocardiography in valvular heart disease

Stress echocardiography has been widely accepted as an important diagnostic and prognostic tool in the assessment of known or suspected coronary artery disease. Its use in valvular heart disease, to date, has been more limited, but is continuing to grow as the technology and the understanding of valvular disorders progress. In this article, we will review the current literature regarding the use of both exercise and pharmacological stress testing in conjunction with echocardiography in the settings of native and prosthetic mitral and aortic valve disease. We will also discuss the limitations of this modality and touch upon possible future areas of investigation.

ECG in stress testing: child of a lesser diagnostic god?

When new technologies are added to the previously existing ones, the latter can be prematurely discarded and judged obsolete not only on the basis of rational scientific facts, but also on irrational trends. Old techniques, like electrocardiography, suffer from diagnostic ambiguities that can be solved by combination with a cardiac imaging technique, like stress echocardiography. ECG monitoring during all forms of stress testing can still offer surprising dividends for a better understanding of the complex physiology of coronary artery disease, a better clinical characterization of patients with microvascular angina, and may serve as an important adjunct marker to cardiac imaging techniques.