Displacement of Calcium Nodules of the Native Valve as a Possible Cause of Left Main Occlusion Following Transcatheter Aortic Valve Implantation

ABSTRACT: We describe the case of an 89-year-old woman who developed severe left main coronary artery stenosis shortly after transcatheter aortic valve implantation (TAVI) with the Medtronic CoreValve Revalving System. Urgent coronary angiography revealed the protrusion of a large calcium nodule of the native valve as the cause of left main narrowing, which was treated with bare-metal stent implantation. Angiographic and intravascular ultrasound findings at follow-up are reported. This case describes one of the mechanisms of a dreadful complication of TAVI and its difficult management.

J INVASIVE CARDIOL 2011;23:E106–E109

Key words: aortic stenosis, aortic valve calcification, complications, coronary arteries, transcatheter aortic valve implantation

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Case Report. An 89-year-old woman with a history of systemic hypertension and chronic atrial fibrillation developed rapidly progressive effort dyspnea over the previous 12 months, due to severe degenerative aortic stenosis [aortic valve area (AVA) = 0.46 cm²; indexed AVA = 0.3 cm2/m²]. She was evaluated for surgical aortic valve replacement and declined by the cardiac surgeon on the basis of very high surgical risk (Logistic EuroSCORE = 25.28%; Society of Thoracic Surgery mortality risk = 8.4%). Surgical risk was mainly driven by advanced age, frailty (qualitative evaluation of physical status and body shape: weight 50 kg, height 1.55 m, body surface area = 1.41 m²) and pulmonary hypertension (pulmonary systolic pressure = 85 mmHg). The patient underwent urgent percutaneous balloon aortic valvuloplasty (BAV) and screening for transcatheter aortic valve implantation (TAVI) following 2 episodes of traumatic syncope. She presented dyspnea New York Heart Association (NYHA) class III/IV, not responding to full medical treatment. Pre-procedural transaortic peak and mean gradients were 110 mmHg and 65 mmHg, respectively. Following the BAV procedure, the patient recovered very well despite a mild improvement of echocardiographic parameters (peak and mean gradient = 95/50 mmHg; AVA = 0.74 cm²) and was scheduled for TAVI with the Medtronic CoreValve Revalving System (Medtronic, Minneapolis, Minnesota). Transthoracic echocardiography measurements were 20 mm for the aortic annulus and 33 mm for the ascending aorta; the distance between the annulus and the coronary artery ostia measured by multislice computed tomography (CT) scan was 12 mm; the minimum diameter of the right femoral artery measured by angiography and CT scan was 6.8 mm. Coronary arteries were normal.

A 26 mm in-flow prosthesis, which is recommended for annulus between 20–23 mm in size, was successfully implanted percutaneously through the right femoral artery. The procedure was performed under deep sedation and the early post-procedural course was uneventful. The electrocardiogram (ECG) showed a new left bundle branch block. Echocardiographic assessment showed a well functioning prosthesis, with an area of 1.4 cm2 and a peak gradient of 12 mmHg. Four days later, the patient developed rest angina without significant ECG changes. On the basis of clinically suspicious and recurrent symptoms, we performed a coronary angiogram (Figure 1). Coronary angiography showed a severe stenosis of the left main trunk caused by the protrusion of a large calcium nodule of the native valve, which was compressed behind the bioprosthesis. We were not able to advance an intravascular ultrasound (IVUS) probe through the lesion at this stage. The patient was treated with a 3.5 x 8 mm stent, post-dilated with a non-compliant 4.0 mm balloon inflated at very high pressure. Final IVUS examination is shown in Figure 2. A follow-up coronary angiography was planned after 4 months and Figure 3 summarizes angiographic and IVUS findings. There was clear recoil of the stent caused by external compression from the calcific native valve cusp, with an extreme lumen eccentricity documented by IVUS. In order to increase the radial force of the stent, we implanted a second stent within the previous one. Despite several high-pressure inflations with a non-compliant balloon, the final result was suboptimal (Figure 4). A second angiographic evaluation planned 9 months later confirmed the persistence of a mild narrowing of the left main ostium without significant neointimal hyperplasia.

Discussion. TAVI has recently emerged as an effective therapeutic option for patients with symptomatic degenerative aortic stenosis and absolute or relative contraindications to surgical aortic valve replacement. Two TAVI systems have seen wide clinical application: the balloon-expandable Edwards-Sapien valve (Edwards Lifesciences, Irvine, California), and the self-expandable Medtronic CoreValve ReValving system. TAVI obviates the need for sternotomy and extracorporeal circulation and, in most cases, can be performed without general anesthesia. To date, available results from large clinical registries suggest that both devices are able to achieve hemodynamic and clinical improvement in the short term.^1,2 Despite being less invasive than open-chest aortic valve replacement, TAVI remains associated with the potential for serious complications, including cerebrovascular events, myocardial perforation and cardiac tamponade, conduction disorders requiring permanent pacing, access-site related complications, mitral valve injury and others.³ In this manuscript, we describe another potentially catastrophic complication following TAVI: coronary occlusion. This entity has been already reported with both transcatheter valve systems^2,4 and can be caused by incorrect positioning of the obstructive portion of the valve frame directly over a coronary ostium. However, the most frequent mechanism appears to be the displacement of a native valve cusp and/or of a large calcium nodule over the coronary ostium, as illustrated by our case. The main way to prevent this fearful complication is measurement with multislice CT scan of the distance between the aortic annulus and the coronary ostia, which should be greater than 10 mm. However, although this is quite effective to predict the “landing zone” of the cusp in relationship to the ostium, it seems less reliable as far as native valve calcific nodules are concerned. For this purpose, aortic root injection during balloon aortic valvuloplasty could be useful, because it allows direct observation of how the leaflet and calcium nodules behave with respect to the left main. The management of this complication is not simple. In the acute phase, it can cause myocardial infarction and death if not resolved very quickly. However, the resistance to compression offered by bulky calcified native leaflet may exceed the radial force of a stent and represent a serious clinical problem during follow-up as well, as shown in our case. Another worrisome observation in our patient was the occurrence of symptoms only several days after the procedure. In fact, whereas a complete occlusion of the left main manifests immediately, a partial compromise can be initially silent and be responsible for adverse events during follow-up, including sudden death. In conclusion, development of new tools for the management and, mainly, for the prevention of this complication is advisable.

References

1. Grube E, Buellesfeld L, Mueller R, et al. Progress and current status of percutaneous aortic valve replacement: Results of three device generations of the CoreValve Revalving system. Circ Cardiovasc Interv 2008;1:167–175.
2. Webb JG, Pasupati S, Humphries K, et al. Percutaneous transarterial aortic valve replacement in selected high-risk patients with aortic stenosis. Circulation 2007;116:755–763.
3. Masson JB, Kovac J, Schuler G, et al. Transcatheter aortic valve implantation: Review of the nature, management, and avoidance of procedural complications. JACC Cardiovasc Interv 2009;2:811–820.
4. Piazza N, Grube E, Gerckens U, et al. Procedural and 30-day outcomes following transcatheter aortic valve implantation using the third generation (18 Fr) CoreValve revalving system: Results from the multicentre, expanded evaluation registry 1-year following CE mark approval. EuroIntervention 2008;4:242–249.

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From the Institute of Cardiology, University of Bologna — Policlinico S. Orsola-Malpighi, Bologna, Italy.
The authors report no conflicts of interest regarding the content herein.
Manuscript submitted September 3, 2010, provisional acceptance given September 9, 2010, final version accepted September 13, 2010.
Address for correspondence: Francesco Saia, MD, PhD, Institute of Cardiology — University of Bologna, Policlinico S. Orsola-Malpighi (Pad 21), Via Massarenti, 9, 40138 Bologna (Italy). Email: francescosaia@hotmail.com