Computed tomography to predict pacemaker need after transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) is preferred therapy for elderly patients with severe aortic stenosis (AS) and increasingly used in younger patient populations with good safety and efficacy outcomes. However, cardiac conduction abnormalities remain a frequent complication after TAVR ranging from relative benign interventriculair conduction delays to prognostically relevant left bundle branch block and complete atrio-ventricular (AV) block requiring permanent pacemaker implantation (PPI). Although clinical, procedural and electrocardiographic factors have been identified as predictors of this complication, there is a need for advanced strategies to control the burden of conduction defects particularly as TAVR shifts towards younger populations. This state of the art review highlights the value of ECG-synchronized computed tomographic angiography (CTA) evaluation of the aortic root to better understand and manage conduction problems post-TAVR. An update on CTA derived anatomic features related to conduction issues is provided and complemented with computational framework modelling. This CTA-derived 3-dimensional anatomical reconstruction tool generates patient-specific TAVR simulations enabling operators to adapt procedural strategy and implantation technique to mitigate conduction abnormality risks.

Cardiac Computed Tomography: Application in Valvular Heart Disease

The incidence and prevalence of valvular heart disease (VHD) is increasing and has been described as the next cardiac epidemic. Advances in imaging and therapeutics have revolutionized how we assess and treat patients with VHD. Although echocardiography continues to be the first-line imaging modality to assess the severity and the effects of VHD, advances in cardiac computed tomography (CT) now provide novel insights into VHD. Transcatheter valvular interventions rely heavily on CT guidance for procedural planning, predicting and detecting complications, and monitoring prosthesis. This review focuses on the current role and future prospects of CT in the assessment of aortic and mitral valves for transcatheter interventions, prosthetic valve complications such as thrombosis and endocarditis, and assessment of the myocardium.

Role of Multidetector Computed Tomography in Transcatheter Aortic Valve Implantation – from Pre-procedural Planning to Detection of Post-procedural Complications

Transcatheter aortic valve implantation (TAVI) is an effective treatment option for patients suffering from symptomatic, severe aortic valve stenosis. Previously, only patients with prohibitive or high surgical risk were TAVI candidates; however, current guidelines already recommend TAVI as a treatment alternative for patients with intermediate surgical risk. Multidetector computed tomography (MDCT) has gained great importance in the periprocedural assessment of patients who undergo TAVI. Due to the three-dimensional image visualization, MDCT allows the evaluation of anatomical structures in a more comprehensive manner compared to echocardiography, the traditional tool used in TAVI patient work-up. By providing accurate measurements of the aortic root, MDCT helps to avoid potential patient-prosthesis mismatch throughout transcatheter valve sizing. Moreover, MDCT is also a feasible tool for access route evaluation and to determine the optimal projection angles for the TAVI procedure. Although the routine MDCT follow-up of patients is currently not recommended in clinical practice, if performed, it could provide invaluable information about valve integrity and asymptomatic leaflet thrombosis. Post-procedural MDCT can provide details about the position of the prosthesis and complications such as leaflet-thrombosis, aortic regurgitation, coronary occlusion, and other vascular complications that can represent major cardiac emergencies. The aim of the current review is to overview the role of MDCT in the pre- and post-procedural assessment of TAVI patients. In the first part, the article presents the role of pre-TAVI imaging in the complex anatomical assessment of the aortic valve and the selection of the most appropriate device. The second part of the review describes the role of MDCT in patients who underwent TAVI to assess potential complications, some of them leading to a major cardiovascular emergency.

Computed Tomography of Cardiac Valves: Review

Valvular heart disease is a common clinical problem. Although echocardiography is the standard technique for the noninvasive evaluation of the valves, cardiac CT has evolved to become a useful tool in the evaluation of the cardiac structures as well. Importantly, CT allows for improved quantification of valvular calcification due to its superior spatial resolution. It may improve the detection of small valvular or perivalvular pathology or the characterization of valvular masses and vegetations. This review describes the assessment of normal and diseased heart valves by cardiac CT and discusses its strengths and weaknesses.

Complementary Role of the Computed Biomodelling through Finite Element Analysis and Computed Tomography for Diagnosis of Transcatheter Heart Valve Thrombosis

Introduction

The TAVR procedure is associated with a substantial risk of thrombosis. Current guidelines recommend catheter-based aortic valve implantation for prohibitive-high-risk patients with severe aortic valve stenosis but acknowledge that the aetiology and mechanism of thrombosis are unclear.

Methods

From 2015 to 2018, 607 patients with severe aortic valve stenosis underwent either self-expandable or balloon-expandable catheter-based aortic valve implantation at our institute. A complementary study was designed to support computed tomography as a predictor of complications using an advanced biomodelling process through finite element analysis (FEA). The primary evaluation of study was the thrombosis of the valve at 12 months.

Results

At 12 months, 546 patients had normal valvular function. 61 patients had THVT while 6 showed thrombosis and dislodgement with deterioration to NYHA Class IV requiring rehospitalization. The FEA biomodelling revealed a strong link between solid uncrushed calcifications, delayed dislodgement of TAVR and late thrombosis. We observed an interesting phenomenon of fibrosis/calcification originating at the level of the misplaced valve, which was the primary cause of coronary obstruction.

Conclusion

The use of cardiac CT and predictive biomodelling should be integrated into routine practice for the selection of TAVR candidates and as a predictor of negative outcomes given the lack of accurate investigations available. This would assist in effective decision-making and diagnosis especially in a high-risk cohort of patients.

Delayed prosthesis malposition after transcatheter aortic valve implantation causing coronaries obstruction

A case of delayed malposition of a CoreValve device causing obstruction of coronary ostia is described. Nine months after the original implant, the patient developed an acute coronary syndrome and was readmitted to hospital. Angiogram demonstrated an ostial stenosis of both the left main stem and the right coronary ostia, which were filled by a paravalvular leakage of the bioprosthesis. Gated computed tomography scan with 3D reconstruction showed valve malposition with cusps situated 14 mm above the ostium of the right coronary and the presence of fibrous and calcific agglomerations associated to one of the cusp causing a tight stenosis of the left ostium. Computed tomography scan is a crucial imaging technique in the transcatheter aortic valve replacement field and in this case enabled us to identify an interesting phenomenon of fibrosis/calcification originating at the level of the misplaced valve, which was actually the triggering cause of the coronary obstruction. Considering the reported need for more accurate investigations regarding the predictors of negative outcomes and the selection of transcatheter aortic valve replacement candidates, the use of cardiac-gated computed tomography should be stimulated and promoted as a valuable aid for the diagnosis and further clinical decision making in those patients.

Multidetector computed tomography evaluation of candidates for transcatheter aortic valve implantation

In transcatheter aortic valve implantation (TAVI), a biologic valve mounted in a stent is implanted without removing the native valve. This procedure was first done in humans by Alain Cribier in 2002 and was included in clinical guidelines after the multicenter PARTNER (Placement of AoRtic TraNscathetER) randomized clinical trial, which showed that TAVI obtained better outcomes than conservative medical treatment and is an alternative to surgery in patients with high surgical risk. Candidates for TAVI must be assessed to determine whether the procedure is feasible, because TAVI is not ideal for all patients who are considered inoperable. Multidetector computed tomography plays an important role in the anatomic evaluation of candidates and in guiding the procedure in those who are finally selected.

[Usefulness of multidetector computed tomography in transcatheter aortic valve implantation. Advantage of a tridimentional imaging modality]

Aortic stenosis is the most common valvular disorder in the United States and Europe. Nowadays, surgical aortic valve replacement remains the standard treatment for patients with severe aortic stenosis; however, transcatheter aortic valve implantation represents a less invasive treatment option for aortic stenosis patients considered as high-risk or not suitable for surgical management. Because of the lack of direct visualization of the operative field in transcatheter aortic valve implantation, there is an increased need for precise pre-operative assessment of vascular anatomy. Therefore, in order to improve outcome and avoid complications, multidetector tomography is part of the routine evaluation of patients considered for this treatment. The data obtained covering the aorta and iliac arteries, allows the physician a precise planning prior to the intervention. In this review, we described basic aspects of the procedure, and the clinical relevance of the multidetector tomography.

Recovery from anemia in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation--prevalence, predictors and clinical outcome

Introduction

Preoperative anemia is common in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) and has been linked to a poorer outcome – including a higher 1-year mortality. The aim of this study was to investigate the impact of successful TAVI on baseline anemia.

Methods

A total of 253 patients who survived at least 1 year following TAVI were included in this study. The prevalence, predictors and clinical outcome of hemoglobin (Hb)-recovery were assessed.

Results

The prevalence of baseline anemia was 49% (n = 124) – recovery from anemia occurred in 40% of the anemic patients (n = 49) at 1 year after TAVI with an increase in mean Hb-level of 1.35 g/dL from baseline. This increase was not related to an improvement in renal function. At multivariate analysis, a high peak gradient (OR 4.82, P = 0.003) was shown to be an independent predictor for Hb-recovery, while blood transfusion (OR 0.31, P = 0.038) and chronic kidney disease (CKD, OR 0.33, P = 0.043) were identified as negative predictors at, respectively, one and two years after TAVI. When compared to patients without baseline anemia, those anemic patients with Hb-recovery had a similar functional improvement (OR 0.98, P = 0.975), whereas those without Hb-recovery had a significantly lower likelihood of functional improvement with ≧2 NYHA classes (OR 0.49, P = 0.034) and a higher likelihood of re-hospitalization within the first year after TAVI (OR 1.91, P = 0.024).

Conclusion

Recovery from anemia occurs in 40% of anemic patients at 1 year after TAVI – mainly in those with a high gradient and without CKD. Blood transfusion was found to have a transient adverse effect on this Hb-recovery. Finally, anemic patients without Hb-recovery experience less functional improvement and have a higher re-hospitalization rate within the first year after TAVI.

Multidimensional MDCT angiography in the context of transcatheter aortic valve implantation

OBJECTIVE

Transcatheter aortic valve implantation has emerged as a viable treatment alternative for patients with severe aortic stenosis who are not surgical candidates. Multidimensional (3D and 4D) MDCT angiography plays a critical role in the safety, success, and outcome of an institutional transcatheter aortic valve implantation program.

CONCLUSION

Given the increasing therapeutic role of this innovative technique, an understanding of essential imaging concepts in its context is critical for appropriate image acquisition and interpretation.

New design of the Amplatzer membranous VSD occluder: a step forward?

Closure of perimembranous ventricular septal defects (PmVSDs) [4] with the original Amplatzer membranous VSD occluder (mVSD1) has been associated with an increased risk of complications, the most notable of which has been complete heart block. This has led to the introduction of a new device to close PmVSDs. The authors describe their experience with the new Amplatzer membranous VSD occluder (mVSD2) in two patients and critique the new device design and delivery system, comparing it with the mVSD1 occluder. Two patients underwent attempted closure of PmVSDs with the new mVSD2 device. One patient had successful closure of the defect with no residual shunt and no evidence of heart block at follow-up evaluation. Trace to mild aortic insufficiency was observed at the time of closure and at the last follow-up visit. The rhythm remained sinus. In the second patient, the device was placed but removed before release because of inability to orient the device in optimal position. Percutaneous closure of PmVSD is feasible with the new mVSD2 occluder. The change in the design may reduce the incidence of complete heart block. It remains to be seen whether the device will be suitable for smaller patients.

Clinical validation of dual-source dual-energy computed tomography (DECT) for coronary and valve imaging in patients undergoing trans-catheter aortic valve implantation (TAVI)

AIM

To assess the validity of virtual non-contrast (VNC) reconstructions for coronary artery calcium (CACS) and aortic valve calcium scoring (AVCS) in patients undergoing trans-catheter aortic valve implantation (TAVI).

MATERIALS AND METHODS

Twenty-three consecutive TAVI patients underwent a three-step computed tomography (CCT) acquisition: (1) traditional CACS; (2) dual-energy (DE) CT coronary angiogram (CTCA); and (3) DE whole-body angiogram. Linear regression was used to model calcium scores generated from VNC images with traditional scores to derive a conversion factor [2.2 (95% CI: 1.97-2.58)]. The effective radiation dose for the TAVI protocol was compared to a standard control group. Bland-Altman analysis and weighted k-statistic were used to assess inter-method agreement for absolute score and risk centiles.

RESULTS

CACS and AVCS from VNC reconstructions correlated well with traditional scores (r = 0.94 and r = 0.86; both p < 0.0001). There was excellent agreement between VNC and non-contrast coronary calcium scores [mean difference -71.8 (95% limits of agreement -588.7 to 445.1)], with excellent risk stratification into risk centiles (k = 0.99). However, the agreement was weaker for the aortic valve [mean difference -210.6 (95% limits of agreement -1233.2 to 812)]. Interobserver variability was excellent for VNC CACS [mean difference of 6 (95% limits of agreement 134.1-122.1)], and AVCS [mean difference of -16.4 (95% limits of agreement 576 to -608.7)]. The effective doses for the DE TAVI protocol was 16.4% higher than standard TAVI protocol (22.7 versus 19.5 mSv, respectively) accounted for by the DE CTCA dose being 47.8% higher than that for a standard CTCA [9.9 (5.6-14.35) versus 6.7 (1.17-13.72) mSv; p < 0.01).

CONCLUSIONS

CACS and AVCS can be accurately quantified, and patients can be risk stratified using DECT VNC reconstructions. However, the dose from DE CTCA is significantly greater than the standard single-energy CTCA precluding the use of this technology in routine clinical practice.

Imaging in Transcatheter Aortic Valve Replacement (TAVR): role of the radiologist

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is a novel technique developed in the last decade to treat severe aortic stenosis in patients who are non-surgical candidates because of multiple comorbidities.

METHODS

Since the technique is performed using a transvascular approach, pre-procedural assessment of the aortic valve apparatus, ascending aorta and vascular access is of paramount importance for both appropriate patient selection and correct device selection. This assessment is performed by a multi-disciplinary team with radiology being an integral and important part.

RESULTS

Among imaging modalities, there is growing scientific evidence supporting the crucial role of MDCT in the assessment of the aortic valve apparatus, suitability of the iliofemoral or alternative pathway, and determination of appropriate coaxial angles. MDCT also plays an important role in post-procedure imaging in the assessment of valve integrity and position.

CONCLUSION

This review outlines the principal aspects of TAVR, the multidisciplinary approach and utilisation of different imaging modalities, as well as a step-by-step approach to MDCT acquisition protocols, reconstruction techniques, pre-procedure measurements and post-procedure assessment.

TEACHING POINTS

• TAVR is a new technique to treat severe aortic stenosis in high-risk and nonsurgical candidates. • MDCT assessment of the aortic annulus is important for appropriate patient and device selection. • Multidisciplinary approach is required for patient selection, procedure planning and performance. • MDCT is required for assessment of the aortic root, iliofemoral or alternative vascular pathway.

Timing, Predictive Factors, and Prognostic Value of Cerebrovascular Events in a Large Cohort of Patients Undergoing Transcatheter Aortic Valve Implantation

Background—

The objective of this study was to evaluate the timing, predictive factors, and prognostic value of cerebrovascular events (CVEs) after transcatheter aortic valve implantation.

Methods and Results—

The study included 1061 consecutive patients who underwent transcatheter aortic valve implantation with a balloon-expandable (64%) or self-expandable (36%) valve. CVEs were classified as acute (≤24 hours), subacute (1–30 days), or late (>30 days). CVEs occurred in 54 patients (5.1%; stroke, 4.2%) within 30 days after transcatheter aortic valve implantation (acute in 54% of cases). The predictors of acute CVEs were balloon postdilation of the valve prosthesis (odds ratio, 2.46; 95% confidence interval,1.07–5.67) and valve dislodgment/embolization (odds ratio, 4.36; 95% CI, 1.21–15.69); new-onset atrial fibrillation (odds ratio, 2.76; 95% CI, 1.11–6.83) was a predictor of subacute CVEs. Late CVEs occurred in 35 patients (3.3%; stroke, 2.1%) at a median follow-up of 12 months (3–23 months). The predictors of late CVEs were chronic atrial fibrillation (2.84; 95% CI, 1.46–5.53), peripheral vascular disease (hazard ratio, 2.02; 95% CI, 1.02–3.97), and prior cerebrovascular disease (hazard ratio, 2.04; 95% CI, 1.01–4.15). Major stroke was associated with 30-day (odds ratio, 7.43; 95% CI, 2.45–22.53) and late (hazard ratio, 1.75; 95% CI, 1.01–3.04) mortality.

Conclusions—

In a large cohort of patients undergoing transcatheter aortic valve implantation, the rates of acute and subacute CVEs were 2.7% and 2.4%, respectively. While balloon postdilation and valve dislodgment/embolization were the predictors of acute CVEs, new-onset atrial fibrillation determined a higher risk for subacute events. Late events were determined mainly by a history of chronic atrial fibrillation and peripheral and cerebrovascular disease. The occurrence of major stroke was associated with increased early and late mortality. These results provide important insights for the implementation of preventive measures for CVEs after transcatheter aortic valve implantation.

SCCT expert consensus document on computed tomography imaging before transcatheter aortic valve implantation (TAVI)/transcatheter aortic valve replacement (TAVR)

Computed tomography (CT) plays an important role in the workup of patients who are candidates for implantation of a catheter-based aortic valve, a procedure referred to as transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR). Contrast-enhanced CT imaging provides information on the suitability of the peripheral access vessels to accommodate the relatively large sheaths necessary to introduce the prosthesis. CT imaging also provides accurate dimensions of the ascending aorta, aortic root, and aortic annulus which are of importance for prosthesis sizing, and initial data indicate that compared with echocardiographic sizing, CT-based sizing of the prosthesis may lead to better results for postprocedural aortic valve regurgitation. Finally, CT permits one to predict appropriate fluoroscopic projections which are oriented orthogonal to the aortic valve plane. This consensus document provides recommendations about the use of CT imaging in patients scheduled for TAVR/TAVI, including data acquisition, interpretation, and reporting.