When Routine Becomes Critical

Corresponding Author

Transcatheter aortic valve replacement (TAVR) has evolved into a highly standardized procedure with excellent procedural success and reproducibility across a broad spectrum of patients. Yet, as illustrated by Go et al,¹ in this issue of JACC: Case Reports, even seemingly routine interventions may rapidly deteriorate into complex and life-threatening situations.

In their report, the authors describe a cascade of severe TAVR complications initiated by frame infolding during deployment of a self-expanding (SE) valve, ultimately progressing to valve deformation, embolization, and bailout redo-TAV (TAVR-in-TAVR). Apart from its technical complexity, this case carries substantial educational value, reinforcing a central principle of structural heart intervention: Procedural safety depends not only on technical proficiency but also on anticipation, vigilance, and preparedness for failure.

Frame infolding of SE valves remains an uncommon complication, with reported incidences of approximately 1% to 3%,^2,3 but its consequences may be catastrophic including paravalvular regurgitation, elevated gradients, malignant arrhythmias, valve embolization, hemodynamic collapse, and cardiac arrest. Importantly, bailout maneuvers frequently increase procedural complexity, fluoroscopy time, and contrast exposure, while also raising the risk of secondary complications such as stroke and acute kidney injury.⁴

Fluoroscopically, infolding can be identified by 1 or 2 vertical radiopaque lines within a partially or fully deployed valve, suggesting invagination of the frame with reduction in its transverse diameter⁴—the so-called “string sign.”

These findings may be subtle or even missed depending on fluoroscopic angulation, particularly in the right anterior oblique caudal projection (the projection most commonly used during SE valve deployment). Conversely, a right anterior oblique cranial view may better delineate frame invagination in short-axis orientation. Transesophageal echocardiography may also provide complementary confirmation through the characteristic “Pac-Man sign,” reflecting incomplete circular valve expansion.

Regarding risk factors, infolding has been associated with anatomical, device-related, and procedural variables (Table 1).⁵ It appears more frequently with larger valve sizes, possibly due to lower radial force. Additional contributors include lack of predilatation and improper valve loading.

Table 1.

Risk Factors for Self-Expanding Valve Infolding

Category	Factors
Anatomic factors	•Bicuspid aortic valve •Heavy or eccentric calcification •Annular ellipticity •Vascular tortuosity
Device-related factors	•Improper valve loading •Large prosthesis size
Procedural factors	•Lack of predilatation •Resheathing maneuvers

The table was adapted from Karrowni et al.⁵

Infolding management depends on timing and hemodynamic status, but the fundamental principle is early recognition—ideally before final valve release.

If significant infolding is detected prior to full deployment, the valve should be recaptured and retrieved, followed by reloading onto a new delivery catheter. If recurrence occurs after multiple resheathing attempts, more aggressive predilatation may be required. Switching to a balloon-expandable valve may also be considered as a bailout strategy. In mild infolding cases, postdilatation after full deployment may be sufficient. However, persistent severe infolding, significant paravalvular leak, or hemodynamic instability should prompt immediate escalation strategies such as redo-TAV or surgical conversion.⁶

Beyond the importance of recognizing and managing infolding, this case underscores the importance of meticulous procedural planning, including computed tomography analysis, anticipation of anatomical challenges, appropriate device selection, and predefined bailout strategies. A well-known phrase that aptly applies in this context is the principle that “a successful procedure is performed the day before,” which reflects the importance of comprehensive preprocedural planning before entering the catheterization laboratory.

Finally, this report also serves as an instructive example of an often-underappreciated aspect of TAVR procedures: valve misloading. Misloading of an SE valve such as the EVOLUT platform (Medtronic) is uncommon but strongly associated with frame infolding during deployment.

According to the manufacturers, misloading signals include inflow crown overlap (nonuniform shadow starting at the inflow) extending beyond the fourth node, outflow crown misalignment and/or being placed not parallel to the paddle attachment, a curved or bent capsule, or radiographic evidence of a bent strut. If misloading is identified under fluoroscopic (cine mode) inspection, the safest strategy is replacement of the entire delivery system rather than attempts at correction or reuse. Therefore, a practical recommendation is to systematically record the fluoroscopic loading inspection with a 360° rotation of the loaded valve, ensuring objective confirmation that the device is correctly prepared before implantation.

In summary (Figure 1), the current case illustrates that catastrophic outcomes are often not caused by a single isolated event, but rather by the accumulation of incremental procedural vulnerabilities. In this patient, marked annular eccentricity, severe calcification, large prosthesis size, absence of predilatation, and possible loading-related issues likely interacted synergistically to create a substrate for infolding and the subsequent procedural cascade encountered by the authors.

Figure 1.

Recognition and Management of Infolding During TAVR With SE Valves

CT = computed tomography; INF = infolding; PVL = paravalvular leak; SE = self-expanding; TAVR = transcatheter aortic valve replacement; TEE = transesophageal echocardiography; ViV = valve-in-valve.

Funding Support and Author Disclosures

Dr Tagliari has received speaker fees from Meril Life Sciences.