Right versus left radial approach in percutaneous coronary interventions: A comparative study of access efficiency and procedural outcomes

The radial artery has increasingly become the preferred access site for both diagnostic and interventional percutaneous coronary procedures. Radner [1] reported the first trans-radial access (TRA) for cardiovascular diagnostics, performing an aortography via the radial artery in 1947.

In 1989, Campeau published the first case series of 100 coronary angiographies performed via the radial approach, highlighting their safety and the rapid post-procedural mobilization of patients [2].

Compared to transfemoral access, TRA is associated with improved patient safety and comfort (including fewer bleeding complications), as well as earlier ambulation [3]. These advantages have contributed to its widespread adoption; the 2023 and 2024 ESC guidelines for management of ACS and CCS, respectively, stated that radial access is the standard recommended approach for both coronary angiography and PCI [4], [5].

With regard to primary PCI, both RRA and LRA provide a high efficacy, rate of procedure success and needle-to-balloon time [6]. Most clinical studies have focused on the right radial approach (RRA), leaving the left radial approach (LRA) under-investigated. The RRA is associated with certain anatomical challenges, including a higher incidence of radial-ulnar artery loop tortuosity [7], [8]. Additionally, many operators prefer the RRA due to ergonomic reasons, especially when standing on the patient’s right side. The LRA, however, may offer some procedural advantages. It has been linked to shorter fluoroscopy times and reduced arterial tortuosity; these findings were clearly evident in previous important trials comparing the two approaches—namely, the TALENT and PREVAIL studies—indicating that it is a viable alternative access method for coronary catheterization [9], [10], [11].

Radial access failure is primarily due to puncture failure and radial artery spasm, though other factors, such as prior occlusion, arterial rupture, dissection, and tortuosity, also play a role. Radial artery occlusion remains the most frequent complication, though it is often reversible within 1–3 months [12].

This study aims to compare the feasibility, procedural efficiency, and complication rates between the right and left radial approaches in patients undergoing coronary interventions.

This cross-sectional, observational, non-randomized, single-center study was conducted to assess the feasibility of the right and left radial approaches and rate of complications in patients undergoing percutaneous coronary procedures.

From November 2022 to November 2023, we prospectively enrolled patients presenting at Assiut University Heart Hospital for any diagnostic and/or interventional coronary procedures with radial access. A total of 100 patients were included in our analysis, of which 52 underwent the right radial approach (RRA) and 48 underwent the left radial approach (LRA).

We included all patients presenting to the Assiut University catheterization laboratory who were eligible for the radial coronary procedure (diagnostic or interventional). We excluded patients with acute coronary syndrome presentation; chronic ischemia of the right or left upper limb; prior arteriovenous fistula; or significant renal impairment. Patients were also excluded if radial artery cannulation failed.

The minimum sample size needed in this study to reasonably detect a statistical difference in the occurrence of arterial tortuosity on right versus left radial access sites was determined to be 76 patients, with 38 assigned to each group. The calculation was done in G*Power software version 3.1.9.2, assuming alpha error of 0.05; statistical power of 0.90; and a 1:1 allocation ratio. A two-proportion z-test would be the primary statistical analysis.

Registration of the study was completed at ClinicalTrials.gov under NCT05626660.

All patients enrolled into the study underwent an identical protocol that began with the physician performing a complete clinical assessment, taking into account the patient’s age, gender, and their history of diabetes mellitus (DM), hypertension (HTN), and cardiovascular disease (CVD), as well as their completion of the mandatory 12-lead electrocardiogram (ECG) and transthoracic echocardiography (TTE). Depending on clinical indications, patients were to proceed to diagnostic coronary angiography and/or elective percutaneous coronary interventions (PCI). The access site to be used for the procedure, and the techniques to treat each lesion, were left to the attending operator’s discretion. The operator was always positioned on the right side for both right radial access (RRA) and left radial access (LRA).

After hyper-extending the wrist on an arm board with appropriate skin prep, local anesthesia was achieved using 2-3 mL of 1% lidocaine. The radial artery was punctured with a 20-G cannula (Bard, Tempe, AZ). After backflow was obtained, a 0.025-inch guidewire was advanced, and either a 5-Fr or 6-Fr radial sheath was placed.

Before continuing to the intra-arterial administration, radial arteries were cannulated for the purpose of procedure standardization, and intra-arterial medications were administered to all patients. Each patient received intracoronary verapamil (5 mg) to reduce vasospasm and unfractionated heparin (5,000 IU) as intra-arterial medications to prevent thrombotic complications. If patients experienced radial artery spasm, an optional intra-arterial dose of nitroglycerin (100 ug) was administered, provided that their systolic blood pressure allowed for it.

In cases where patients received PCI, additional doses of unfractionated heparin were added, for a target value of 70–100 IU/kg. All PCI patients received acetylsalicylic acid and a P2Y12 inhibitor as a loading dose before the procedure.

Selective catheterization of the right and left coronary arteries was generally performed with Judkins catheters. Other cuts of the catheter were used if needed. During angiography, whenever possible, at least two views were taken of the right coronary artery, and at least four views of the left coronary artery.

Post-procedure, the radial sheath was removed, and hemostasis was achieved with a TR Band (Terumo Interventional Systems). Radial artery patency was verified via palpation. No follow-up was conducted after hospital discharge.

The main endpoints of the study were meant to evaluate and compare procedural performance and safety of the radial approaches, including the incidence of radial artery spasm; radial and/or subclavian artery tortuosity; ease of cannulating the left main (LM) and the right coronary artery (RCA); incidents and type of complications during and after the procedure; and patient comfort levels. Other important endpoints included the crossover rate to either the contralateral radial site or to the femoral access site due to procedural difficulties, and the total radiation exposure time taken for each approach.

All statistical analyses were performed using SPSS, version 21 (IBM Corp., Armonk, NY). Descriptive statistics summarized demographics using means with standard deviations (SD) for normally-distributed variables, medians with interquartile ranges (IQR) for non-normally distributed variables, and frequency distributions for categorical variables. Continuous variables were compared using Student’s t-test if the data met the assumption of normality, and the Mann-Whitney U test if it violated the assumption of normality. Categorical variables used either the Chi-square or Fisher’s exact test, depending on which test’s assumptions were met. We used logistic regression analysis to identify variables that independently predicted tortuosity of the subclavian artery. A p-value of < 0.05 was interpreted as statistically significant for this study.

Figure 1

Rates of procedural outcomes among the two groups.

A total of 100 patients were enrolled over a one-year period. Of these, 52 underwent coronary interventions via the right radial approach (RRA), and 48 via the left radial approach (LRA). The interventional cardiologist selected the access site. Patients with acute coronary syndrome, chronic upper limb ischemia, arteriovenous fistula, severe renal impairment, or failed radial artery cannulation were excluded.

The average age of the study population was 63.2 ± 6.3 years. The cohort was 51% males and 49% female, with 47% reporting their status as smokers. Diabetes mellitus was present in 36% of the cohort; 64% had a history of hypertension; 61% reported a history of ischemic heart disease; 12% had a family history of CAD. A total of 2% of the patients had prior CABG, while 9% of patients had structural valvular heart disease. Collaborative demographic and clinical characteristics were similar across both groups, with no statistically significant differences (p > 0.05 for all variables; Table 1).

Chest pain on admission was reported in 83 patients, with dyspnea present in 28 patients. There were no statistically significant differences between the RRA and LRA groups’ heart rate, blood pressure, or pulmonary and cardiac exam findings.

Electrocardiography, echocardiography, and coronary angiography results were similar for both groups, and the results were not statistically significant. Both groups underwent percutaneous coronary intervention (PCI) with stenting at the same session, including 13 patients (25%) in the RRA group and 14 patients (29.2%) in the LRA group (p = 0.639).

Radial artery spasm occurred in 8.3% of patients in the LRA group (n = 4) and 44.2% of patients in the RRA group (n = 23) (p < 0.001). Radial artery tortuosity occurred in 2.1% (n = 1) of LRA cases and was more prevalent in the RRA group (23.1%, n = 12), with a p-value of 0.002. Subclavian artery tortuosity was less frequent in the LRA group (14.6%, n = 7) than in the RRA group (32.7%, n = 17), with a p-value of 0.034.

Figure 2

Difference in median exposure time (in seconds) between the studied groups.

Regarding coronary cannulation, there were no significant differences between the two groups. The left main (LM) coronary artery was successfully cannulated in 84.6% of RRA cases and 95.8% of LRA cases (p = 0.062), while the right coronary artery (RCA) was cannulated in 88.5% of RRA cases and 93.8% of LRA cases (p = 0.356).

In terms of radiation exposure time, the LRA group had a significantly shorter time—median 129.0 seconds (IQR: 87.75– 246.5)—compared to the RRA group, which had a median of 254.0 seconds (IQR: 161–469.5, p < 0.001). No significant procedural complications connected to access site were seen in either group. This finding could potentially have been influenced by the limited size of the study.

The LRA group had significantly greater patient comfort, with 100% (n = 48) feeling comfortable or better, compared to only 75% (n = 39) feeling comfortable or better in the RRA group (p < 0.001). Patient discomfort in the RRA group could potentially be related to the unwelcome occurrence of radial artery spasm.

Crossover to the opposite radial site occurred in 9.6% of the total RRA group, compared to 2.1% of the total LRA group (p = 0.207). Crossover to femoral access was required in 5.8% of RRA cases and in 2.1% of LRA cases. However, these differences were not statistically significant (p = 0.619).

In patients ≥ 65 years old, the LRA approach had notable advantages over the RRA approach. The frequency of radial artery spasm was lower in this group (8.6%) than in the RRA group (33.3%, p = 0.048). Radial tortuosity was experienced in 2.9% of the elderly patients under the LRA approach and 22.2% under the RRA approach (p = 0.040). The occurrence of subclavian artery tortuosity was also much lower in this group, with only 17.1% of elderly LRA patients showing spiral tortuosity, compared to 61.1% in the RRA group (p = 0.001). The time to disseminated radiation was also much shorter in elderly patients undergoing LRA, with a median of 129 seconds, versus those undergoing RRA, which had a median of 254 seconds (p < 0.001).

There was a more than two-fold increase in the incidence of operator-reported subclavian tortuosity in RRA compared to LRA, and this difference was significant (p-value = 0.034). At a multivariate logistic regression, independent predictors of subclavian tortuosity were age ≥ 65 years (OR: 5.8, 95%; CI: 1.8–18.9; P = 0.003) and RRA (OR: 6.1, 95%; CI: 1.9–19.5; P = 0.002). The overall regression was statistically significant (p < 0.001), demonstrating a strong predictive value.

The right radial artery (RRA) is the preferred access site for many interventional cardiologists because of its ergonomic advantage to the operator standing on the right side of the patient. However, RRA has anatomical and procedural limitations. The left radial artery (LRA) resembles the transfemoral approach, potentially allowing for smoother catheterizations. There are often issues when performing a LRA in obese patients or right-handed operators due to operator discomfort, so the LRA is considered only when RRA and transfemoral access are not feasible [13], [14], [15]. A survey of 50 interventional cardiologists showed a unanimous initial access site preference for RRA, only turning to LRA when RRA was not accessible [16].

Our study provides a clear comparison between RRA and LRA that highlights the advantages of LRA in our study population, including reduced arterial tortuosity and radiation exposure time, especially in patients aged ≥ 65 years. This makes it a suitable option in this age group for future use as a primary access site in CA and PCI.

The markedly lower incidence of radial artery spasm in the LRA group can be explained by the higher number of female patients in the RRA group. Female patients have a smaller radial artery diameter, making them more prone to spasm than males. Anxiety and pain experienced by patients may have also contributed to the greater occurrence of spasm with RRA, as well as the subjective manner in which it was reported.

Roczniak et al. reported similar results, with almost 90% of radial spasms occurring during RRA procedures [17]. In contrast, Youn et al. reported no radial spasms in either group, while Toprak et al. found a greater—though not statistically significant—incidence of spasm in RRA (122 cases) versus LRA (44 cases) [18], [19].

Our results differ from Cázares Díazleal et al., who found a higher—but not statistically significant—incidence of spasm in the LRA group [20]. These study findings may be due to differences in sample size and the use of anatomic snuffbox access, which is associated with smaller radial artery diameter and higher incidence of spasm.

The incidence of tortuous radial artery was significantly lower in the LRA group compared with the RRA group. This corroborates findings from Lang et al., who reported a 12.1% rate of tortuosity of the radial artery in RRA cases [21]. Youn et al., however, did not report a significant difference in tortuous radial artery incidence when comparing the two techniques [18].

The higher rate of radial artery tortuosity in our study may be due to differences in the study population, small sample size, and lack of systemic radial angiography.

The LRA group also demonstrated a significantly lower incidence of subclavian artery tortuosity, confirming the findings of Kara et al. (6.1% in the LRA vs. 23.2% in the RRA, p < 0.001) [22].

Similar trends were noted by Youn et al. (1.3% in the LRA vs. 9.5 % in the RRA, p = 0.001) [18]. Xia et al. reported that subclavian artery tortuosity occurred significantly more often in patients with RRA (RR = 0.27, 95%; CI: 0.14–0.50; p < 0.0001), and Shah et al. [18], [23], [24].

Anatomical tortuosity of the right subclavian artery, in particular the S-shaped geometry of the subclavian-innominate aorta, can hinder catheter maneuverability, increase procedure time, and expand radiation exposure [23], [24]. This well-reported anatomical variation in the right subclavian artery contributed to the higher incidence of subclavian artery tortuosity in the RRA in our study.

The LRA group had a significantly shorter radiation exposure time than the RRA group, and this difference was especially pronounced in the group of patients 65 years and older. Our data agrees with findings from the TALENT trial, which showed significantly shorter fluoroscopy times in its LRA group, with particular relevance to patients ≥ 70 years (149 vs. 168 seconds, p = 0.0025) [10]. Similarly, the PREVAIL study, as well as Youn et al., Will et al., Shah et al., and Park et al., all noted much lower radiation exposure times in the LRA group than in the RRA group [11], [18], [25], [24], [26]. In contrast, Kara et al. found no significant difference in radiation exposure times based across access sites; this may have been related to operator experience, which was not previously factored into that analysis [22].

This present study found no significant adverse events in either group, likely due, at least in part, to its small sample size. The reported of complication rates were low, similar to those in the TALENT trial, although there was one stroke reported in the RRA group [10].

Uncomplicated bleeding events were also infrequent, as was also observed in the PREVAIL study; in the meta-analysis of Shah et al. involving 6,450 patients; and in the registry analysis of Park et al., which involved 1,653 patients [11], [24], [26].

Patients reported significantly more comfort and convenience with LRA than with RRA. The discomfort associated with RRA may relate to the higher incidence of radial spasm and tortuosity. Additionally, for right-handed individuals, using the left radial artery preserves use of the dominant hand following the procedure while preventing movement on the left-wrist access site [27]. Cázares Díazleal et al., however, did not find a difference in comfort with approach; potential differences in study size and subjective reporting may explain these differences in results [20].

The rate of crossing over to the opposite radial or femoral access was not statistically different between groups, although RRA had a greater tendency to necessitate cross-over. Our results are similar to those reported by Youn et al., who reported crossover rates of 3.1% for RRA vs. 1.2% for LRA (p = 0.448) [18].

There are a number of limitations relating to our study that should be taken into account when interpreting the results. First, given that this study was conducted at a single center, the applicability of our findings to a wider population or different clinical setting may be limited. Second, this study design did not have a randomized component, and thus there was a risk of selection bias in the allocation of patients to the right or left radial approach. Third, evaluation of the presence of radial artery spasm was based on clinical judgment rather than objective measures, and the evaluation of this outcome was thus subject to some degree of subjectivity. Finally, there was no follow up post-discharge, which limited this study’s ability to evaluate long-term complications and radial artery patency over a significant time interval.

The left radial approach is a feasible, safe, and effective alternative to the right radial approach in percutaneous coronary interventions. It offers several clinical advantages, including significantly a lower incidence of arterial spasm and tortuosity, reduced radiation exposure, and superior patient comfort. These benefits are particularly pronounced in elderly patients (≥ 65 years).

In summary, based on our findings on procedure success, we recommend considering the left radial artery as the access site for coronary procedures, particularly in older patients. There is a need for larger, randomized, multi-center trials to further validate our findings and substantiate the accepted guidance for radial access.