Improved Outcomes With Transradial Approach in Alcohol Septal Ablation

Abstract

Background. Transradial cardiac catheterization is equally effective but has fewer vascular complications than transfemoral catheterization. There is a paucity of data on biradial approach for alcohol septal ablation (ASA). This study seeks to study the differences in procedural outcomes between the transradial vs traditional transfemoral approach in ASA. Methods. A total of 274 consecutive patients who underwent ASA were retrospectively assigned to the study subgroups (137 transradial, 137 femoral). Procedural success, reduction in left ventricular outflow tract gradient (LVOTG), contrast volume, fluoroscopy time, and complications were compared between the 2 groups. Results. There were no differences in reduction of resting LVOTG (91% vs 92%; P=.50), provoked LVOTG (80% vs 82%; P=.47) post procedure between transradial vs transfemoral subgroups. Iodinated contrast volume was significantly lower in the transradial group (98 mL vs 111 mL; P=.04), whereas fluoroscopy time was higher in the transradial group (17.42 minutes vs 13.00 minutes; P<.001). The incidence of complications was lower in the transradial group (0.13 vs 0.23; P=.04). Conclusions. ASA via transradial approach is equally effective and associated with significantly less contrast use and fewer complications as compared with the traditional transfemoral approach.

Keywords: alcohol septal ablation, hypertrophic obstructive cardiomyopathy, transradial approach

Hypertrophic obstructive cardiomyopathy (HOCM) is the most common genetic cardiac condition, affecting 1 in 500 individuals.¹ Medical therapy with pharmacological agents is the cornerstone of therapy for HOCM. When medications fail to adequately relieve symptoms or are not tolerated, alcohol septal ablation (ASA) provides an alternative treatment method to surgical myectomy to relieve outflow obstruction and symptoms.^1,2 ASA was traditionally performed via the transfemoral route; however, in recent years the transradial approach has been increasingly used due to lower vascular complication rates,^3,4 greater patient comfort, and earlier ambulation.⁵ Data are lacking to assess the practical differences and outcomes of performing ASA through the transradial vs transfemoral approach. This study seeks to compare the success, efficacy, and safety between the transradial and transfemoral approach in ASA.

Methods

Study design. A total of 274 consecutive ASAs from 2007-2020 were identified in an internally maintained registry and retrospectively analyzed. Variables of interest included baseline resting left ventricular outflow tract gradient (LVOTG), baseline provoked LVOTG, post-ASA resting LVOTG, post-ASA provoked LVOTG, volume of iodinated contrast, fluoroscopy time, and incidence of complications. Provoked LVOTG was obtained via catheter after a premature ventricular contraction (PVC). Procedural complications included incidence of access-site bleeding, hematoma, complete heart block, drop in hemoglobin, coronary dissection, and coronary no-reflow. The transfemoral approach was gradually converted to transradial starting in 2010 and became the preferred approach after 2015 for over 95% of patients. Hence, the transradial group was more contemporary, from 2013-2021, whereas the transfemoral group was mostly from 2005-2015.

Procedural methods. In the contemporary transradial group (n = 137), arterial access was obtained with a 6-Fr introducer sheath in the right radial artery for the coronary guide catheter and 5-Fr introducer sheath in the left radial artery for the left ventricular pigtail catheter (biradial access). A temporary balloon-tipped 5-Fr x 90-cm pacemaker wire (Swan-Ganz bipolar pacing catheter for superior vena cava insertion; Edwards Lifesciences) was inserted via internal jugular vein access. In the traditional transfemoral group (n = 137), arterial access was achieved using a 6-Fr or 7-Fr introducer sheath in the right femoral artery for the coronary guide catheter and 5-Fr or 6-Fr introducer sheath in the left femoral artery for the left ventricular pigtail catheter in 80% of cases. In 20% of transfemoral cases, both arterial accesses were ipsilateral. A temporary, non-balloon-tipped, 4-Fr x 125-cm pacemaker wire (temporary pacing electrode catheter; CR Bard) was inserted via femoral vein access for transfemoral cases.

ASA was performed using the standard technique as described in previous literature. Briefly, a pigtail catheter was positioned in the left ventricle for continuous left ventricular pressure monitoring. A coronary guide catheter was used to cannulate the left main coronary artery and gain wire access to a septal perforating artery. An over-the-wire balloon was then inflated in an appropriate septal artery and after position confirmation using 2-dimensional transthoracic echocardiogram, pure ethanol was injected into the target vessel to induce a local infarction in the hypertrophied septum.

Statistical analysis. Transradial and transfemoral groups were compared using the Student’s t tests (assuming unequal variances). Continuous variables are represented as mean ± standard deviation and a P-value <.05 was used to determine significance.

Results

A summary of baseline characteristics is shown in Table 1. The mean age was similar in the transradial and transfemoral groups (63 ± 13 years vs 61 ± 13 years; P=.08). The subgroups comprised 65% females in the transradial group and 55% females in the transfemoral group. There was no significant difference in baseline resting (67-68 mm Hg) and provoked LVOTG (141-151 mm Hg) between the groups.

After ASA, both groups saw statistically significant reductions in LVOTG compared with baseline (Figure 1). Procedural success was similar between groups (89% in the transradial group vs 90% in the transfemoral group). ASA was equally efficacious in reducing LVOTG, with a mean reduction of 91% in transradial access and 92% in transfemoral access in resting LVOTG (P=.50) and a mean reduction of provoked LVOTG of 80% in transradial access and 82% in transfemoral access (P=.47). The transradial approach was associated with significantly less contrast use than the femoral approach (Figure 2A), with a mean of 98 ± 42 mL and 111 ± 57 mL, respectively (P=.04). The transradial approach was associated with significantly greater fluoroscopy time than the transfemoral approach (Figure 2B), with a mean time of 17.42 ± 10.91 minutes and 13.00 ± 8.48 minutes, respectively (P<.001). The incidence of complications, including access-site bleeding, hematoma, complete heart block, drop in hemoglobin, dissection, and incidence of no-flow, was also significantly different between groups (13% in the transradial group vs 23% in the transfemoral group; P=.04) (Figure 3). The incidence of complete heart block requiring permanent pacemaker was 8% in both groups. The majority of these other complications were minor and local in nature and did not require any intervention or blood transfusion. A summary of the results post ASA can be found in Table 2.

Discussion

Outcomes in ASA using transradial vs transfemoral approach are not well described. Our study is the largest to date and further supports what has already been demonstrated in smaller studies.^6-8 Several case series over the past decade have described procedural success rates exceeding 90% with virtual elimination of vascular complications; however, these case series included a small population of patients and were not powered for statistical analysis.^6-8Table 3 serves as a comparison of results of the current study with those previously published. A meta-analysis was not possible due to incomplete and unpaired data between studies; however, it is clear that our procedural success and complication rates are similar to previously published literature. Moreover, our study contributes to a growing evidence base that supports the transradial approach over the transfemoral approach in many catheter-based procedures to decrease the risks of major bleeding, vascular complications, and death.^9,10

It is worth noting that fluoroscopy time is often higher in transradial procedures, although the overall patient dose may be lower than historically acceptable limits. Dosage data were not available for analysis in our cohort of patients. Furthermore, in biradial approach, catheter engagement and maintenance of stable catheter position are more challenging due to respiratory excursion often exaggerated by sedation. Despite this, we did not observe balloon dislodgment during alcohol injection thereby producing an inadvertent nontargeted infarct or complication in this cohort of patients.

There are conflicting data on the subject; Shah et al completed a meta-analysis that showed no difference in the amount of contrast use in patients undergoing percutaneous coronary intervention; however, other studies have noted that radial access is associated with fewer acute kidney injuries following coronary intervention, which may in part be due to lower amount of contrast usage.^4,11 Undoubtedly, a reduction in iodinated contrast use to avoid renal injury is yet another compelling reason to adopt transradial access for ASA.

Since its inception in 1995, ASA has evolved significantly and procedural methods and outcomes continue to improve. The long-term outcomes and the iterative improvement in the procedure have been detailed in an earlier paper from our group.¹² The major targets for improvement are better localization of septal territories reached by septal perforating arteries, reduction in complications, and reduction in need for temporary pacemaker wire insertion, while also increasing patient comfort level and convenience. Transitioning to transradial approach was a major factor in the reduction of vascular and bleeding complications with this procedure. The procedural outcomes were unaffected by this transition.¹² After the initial learning curve of managing right and left radial artery catheters, this approach has become the default at our institution. Additionally, by using jugular vein access for the temporary pacemaker wire, the groin has been spared completely, thereby making it more comfortable for patients and enabling early postprocedure ambulation.¹²

Study limitations. This study should be interpreted in light of certain methodological limitations. This includes the retrospective nature of the data, longitudinal changes in operator experience, and the evolution of procedural techniques over time. Additionally, there is a bias in regard to patient referral to our institution selectively for ASA. The 2011 updated expert society practice guidelines influenced patient selection from that point forward.¹³ Finally, the statistical analysis may be fraught with unrecognized biases and confounding factors.

Conclusion

ASA can be performed successfully via either transradial or transfemoral approach. Although the transradial approach is associated with longer fluoroscopy time, it is associated with lower iodinated contrast usage and fewer procedural complications. It is also more comfortable and convenient for postprocedure patient care. Whenever possible, transradial access should be the preferred approach for ASA.

Affiliations and Disclosures

From the ¹College of Medicine, Medical University of South Carolina, Charleston, South Carolina; ²Division of Cardiology, Department of Medicine, Medical University of South Carolina, Charleston, South Carolina; and ³Division of Medicine, Medical University of South Carolina, Ralph H. Johnson VA Medical Center, Charleston, South Carolina.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript accepted April 13, 2022.

Address for correspondence: Valerian L. Fernandes, MD, MRCP, FACC, Professor of Medicine, Division of Cardiology, Department of Medicine, Medical University of South Carolina, 114 Doughty Street, MSC 592, Charleston, SC 29464. Email: fernandv@musc.edu

References

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7. Sawaya FJ, Louvard Y, Spaziano M, et al. Short and long-term outcomes of alcohol septal ablation with the trans-radial versus the trans-femoral approach: a single center-experience. Int J Cardiol. 2016;220:7-13. doi:10.1016/j.ijcard.2016.06.127

8. Cuisset T, Franceschi F, Prevot S, et al. Transradial approach and subclavian wired temporary pacemaker to increase safety of alcohol septal ablation for treatment of obstructive hypertrophic cardiomyopathy: the TRASA trial. Arch Cardiovasc Dis. 2011;104(8-9):444-449. doi:10.1016/j.acvd.2011.05.006

9. Nguyen P, Makris A, Hennessy A, et al. Standard versus ultrasound-guided radial and femoral access in coronary angiography and intervention (SURF): a randomised controlled trial. EuroIntervention. 2019;15(6):e522-e530. doi:10.4244/EIJ-D-19-00336

10. Watt J, Austin D, Mackay D, Nolan J, Oldroyd KG. Radial versus femoral access for rotational atherectomy: a UK observational study of 8622 patients. Circ Cardiovasc Interv. 2017;10(12):e005311. doi:10.1161/CIRCINTERVENTIONS.117.005311

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12. Fernandes V, Karimianpour A, Rier JD, et al. Long-term survival after alcohol septal ablation for hypertrophic obstructive cardiomyopathy: a 16-year experience. J Invasive Cardiol. 2021;33(10):E769-E776. Epub 2021 Sep 23.

13. Gersh BJ, Maron BJ, Bonow RO, et. al. ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy. J Am Coll Cardiol. 2011;58(25): 2703-2738. doi:10.1016/j.jacc.2011.06.011

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