Over the past decade, transcatheter aortic valve implantation (TAVI) has evolved from a therapeutic option limited to patients at very high surgical risk to an established alternative for low- to intermediate-risk patients. Technological advances in percutaneous prostheses, with ongoing improvements toward reducing the size of introducers and delivery systems, have allowed femoral access to remain the access of choice whenever feasible. Consequently, the proportion of non-transfemoral (TF) access has declined from 20% to 5% in recent registries. However, it is important to note that in a significant number of TF-TAVI patients, TF access is not ideal due to excessive calcification, tortuosity, or limited femoral artery diameter. Indeed, in the intermediate-risk population treated with second-generation percutaneous prostheses via TF access, the risk of major, life-threatening bleeding complications was excessively high (8-12%).

This review seeks to provide current evidence for each of the existing alternative access options, enabling well-informed decisions when choosing the most appropriate and safe access based on each patient’s clinical and anatomical characteristics.

Transthoracic Access: Transapical (TA) and Transaortic (TAo)

From a technical perspective, in the early stages of TAVI procedures, transthoracic access became a preferred alternative due to the high profile of introducer sheaths that prevented safe peripheral access. TA-TAVI, first performed in 2005, offers advantages such as easy guidewire crossing through the aortic valve and comfortable maneuverability of the prosthesis due to the short distance required. However, this approach is consistently associated with a certain degree of myocardial damage, as well as with rare but technique-related complications, such as cardiac tamponade, mitral subvalvular apparatus damage, or uncontrollable bleeding from the ventricular apex. TAo-TAVI, first performed in 2010, is a more anecdotal transthoracic alternative that generally requires a partial upper sternotomy, although it can sometimes be performed via the suprasternal notch. Contraindications include previous sternotomies or severely calcified ascending aortas.

In terms of outcomes, large registries of high-risk patients indicate similar 30-day and 1-year mortality rates for both transthoracic accesses, at approximately 12% and 25%, respectively. There are also no significant differences in other complications.

Comparing transthoracic and transfemoral TAVI is challenging because the former is typically used in higher-risk patients. Some propensity score-matching studies suggest that outcomes are similar; however, in most comparative studies, transthoracic TAVI yields worse results in terms of major adverse events as well as in-hospital and late mortality. The incidence of neurological events is similar or lower with transthoracic TAVI, despite a higher incidence of postprocedural atrial fibrillation, likely due to the absence of retrograde catheter manipulation in the aortic arch. Additionally, overall costs are higher with this alternative access, owing to longer hospital stays and a higher incidence of readmissions. Consequently, there has been a progressive decline in the use of this approach; for example, according to the French TAVI registry, it decreased from 19% in 2010 to 4% in 2015.

Peripheral Arterial Access: Transcarotid (TC) and Transsubclavian/Axillary (TS)

From a technical standpoint, the progressive reduction in introducer and delivery system diameters has promoted the use of alternative peripheral arteries other than TF access. Both TC and TS access theoretically allow the procedure to be performed under local anesthesia with sedation. TS access was first used in 2007. The primary surgical complexity lies in the variable depth of this artery depending on the patient’s body habitus, the close proximity of the brachial plexus, and the relatively fragile arterial wall due to a less robust media layer compared to the femoral artery. Furthermore, achieving optimal coaxial alignment is technically challenging, especially if the right subclavian artery is used and the aortoventricular angle is <70º. Although some studies report similar outcomes for percutaneous versus surgical access, surgical access is generally preferred because managing vascular complications can be very challenging given the artery’s limited accessibility and difficulty with compression. TC access, first employed in 2010, requires a surgical incision. Given that the common carotid artery typically has less atherosclerosis than the internal carotid or femoral arteries and is superficially located, surgical dissection is technically simple, even in obese patients. It is considered accessible if the minimum luminal diameter is ≥6 mm and there is no significant stenosis (≥70%) in the contralateral artery. The left side also offers better coaxial alignment between the aorta and the prosthesis delivery system.

Analyzing outcomes in intermediate- to high-risk populations, both accesses provide similar results in terms of major adverse events and 30-day and 1-year mortality (5% and 15%, respectively). Regarding vascular complications, both accesses show a low incidence; however, in some studies, such as the French TAVI registry, the incidence is significantly lower with TC access (TC: 0.2% vs. TS: 1.3%). In a significant sub-study of the STS/ACC TVT registry with propensity score matching, the incidence of stroke was significantly lower with TC access (TC: 4.2% vs. TS: 7.4%), as were fluoroscopy time, total contrast volume, and hospital stay.

Comparing peripheral arterial (non-transfemoral) TAVI to transthoracic TAVI, recent data suggest that TC/TS access yields better survival at 30 days and 2 years, with a lower rate of most major adverse events except stroke.

Comparing peripheral arterial (non-transfemoral) and TF-TAVI, the most relevant propensity score-matched study by Beurtheret et al. found no significant differences in major adverse events, except for vascular complications, which were lower with non-transfemoral TAVI (TC/TS: 0.68% vs. TF: 1.36%). In the few studies that directly compare TC-TAVI and TF-TAVI, such as Watanabe et al. (without propensity matching), there were no significant differences in clinical outcomes; in the propensity-matched study by Folliguet et al., there was no difference in 1- and 2-year mortality, though TC-TAVI had a higher incidence of stroke, bleeding, and renal failure but a lower rate of vascular complications. Overall, TS-TAVI outcomes were also very similar to those of TF-TAVI. In summary, promising results have been achieved with both TC and TS access, and previous concerns about neurological outcomes with TC-TAVI seem to be dissipating.

Transcaval (TCv) Access

The most recent approach, TCv access, is generally used when other options are not feasible. This procedure requires detailed preoperative assessment using computed tomography of the descending aorta to determine the optimal location for the caval-aortic crossing. While it has a very high success rate (99%), it is associated with a higher incidence of bleeding complications and vascular complications near 20%, a non-negligible rate of aortocaval fistula that does not seem to affect mortality or readmission rates, and a mortality rate of 8% and 29% at 30 days and 1 year, respectively.

Lastly, this update provides a highly useful decision-making algorithm used at the Quebec Heart and Lung Institute. TF-TAVI would be the first option, with alternative access selected based on each patient’s characteristics, with TC as the first alternative option, followed by TS, TAo, and TA in successive order.

COMMENTARY:

This article by Junquera et al. is an excellent, concise, yet comprehensive review that any cardiac surgeon looking to learn, improve, and expand the use of TAVI via alternative access should read and have in their collection. The most relevant meta-analysis comparing TC versus TF-TAVI, published by Abraham et al. this month in Am J Cardiol, reinforces this review’s findings. Although TC-TAVI patients have a higher risk profile, the meta-analysis demonstrates excellent outcomes for both accesses, although with a 30-day mortality advantage for TF-TAVI (TC: 3.7% vs. TF: 2.6%, p= 0.02) and vascular complications in favor of TC-TAVI (TC: 1.5% vs. TF: 3.4%, p = 0.04).

Despite the potential advantages and satisfactory outcomes of TC and TS access, these approaches are available in only 10% and 39%, respectively, of centers performing TAVI in industrialized nations, whereas TA-TAVI continues to be offered in 70% of these centers. At our center in A Coruña (CHUAC), we have accumulated over 10 years of experience with more than 400 non-transfemoral TAVI cases, primarily TA-TAVI until two years ago, and since then, we have transitioned to TC/TS-TAVI, with over 120 cases and excellent results corroborating the findings of this review. It is essential that any hospital performing TAVI is familiar with at least one alternative access to optimize outcomes for aortic stenosis treatment.

Given the outstanding results shown in the current review by Junquera et al. regarding TC/TS access, it is advisable to consider these alternative peripheral options in cases where femoral access presents a higher risk of complications.

In our institution, we have already implemented this strategy in patients with borderline femoral access, opting for alternative peripheral access, primarily TC access, instead of TF access. It is essential that the choice of the most suitable access be personalized by a multidisciplinary Heart Team, considering each patient’s specific characteristics. Lastly, it would be highly recommended to establish decision-making algorithms in each center to help determine the best therapeutic option in daily practice.

REFERENCE:

Junquera L, Kalavrouziotis D, Dumont E, Rodés-Cabau J, Mohammadi S. Paradigm shifts in alternative access for transcatheter aortic valve replacement: An update. J Thorac Cardiovasc Surg. 2023 Apr;165(4):1359-1370.e2. doi: 10.1016/j.jtcvs.2021.04.075.

Abraham B, Sous M, Sedhom R, Megaly M, Roman S, Sweeney J, et al. Meta-Analysis on Transcarotid Versus Transfemoral and Other Alternate Accesses for Transcatheter Aortic Valve Implantation. Am J Cardiol. 2023 Apr 1;192:196-205. doi: 10.1016/j.amjcard.2023.01.023.