The radial approach is an attractive alternative to the classical femoral approach for CAG and PCI. The radial artery is very superficial, making it easy to puncture, and bleeding is controlled by compression. There are no major nerves or veins near the radial artery, thus minimizing the risk of nerve and vascular injuries [10, 11]. The benefits of TRA have been documented in many studies. These benefits include less bleeding [10,11,12,13,14,15,16,17], lower morbidity, early ambulation, lower total hospital costs [10, 18], patient preference and comfort, same-day discharge is possible, less chance of developing ischemia due to dual blood supply of the hand, and easy access for the patients with myocardial infarction (MI) and aortic aneurysm [10, 19, 20]. The approach is advantageous for people with severe occlusive aortoiliac disease or difficulty lying down (e.g., due to back pain, obesity, or congestive heart failure) [8, 21].
As has been shown in several studies, the radial access permits treatment of the same type of patients and lesions as femoral access provides [11, 17, 22,23,24,25,26,27]. The radial artery readily accommodates 6-F sheaths, and sheathless 7-F techniques have recently been described [28, 29]. Thus, there is no limitation to performing complex PCI successfully via the radial approach [30]. High-risk subsets such as unprotected left main coronary artery [31], bifurcational lesions, and chronic total occlusions [32] can all be readily addressed through radial access [30]. Results from our study show that the transradial PCI was associated with high procedural success rates (96.5%) and favorable clinical outcomes in all patients, both in the elective and emergency (STEMI) setting.
Patients with STEMI are the most intensely anticoagulated, and many had received thrombolytic therapy prior to arrival at the PCI center, so they have high risk of bleeding. Thus, the potential for access-site complications is highest in this group and the potential benefit from TRA is greatest [33, 10, 34]. Bleeding after an acute myocardial infarction (MI) is associated with worse short- and long-term outcomes and prolonged hospitalization [35, 36]. Many trials have proved that TRA has lower risk of bleeding in STEMI patients as compared to transfemoral approach (TFA). The RIVAL (radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes) study showed that TRA is associated not only with a lower rate of local vascular complications in the overall population, but also with a reduction in mortality in the setting of acute PCI [37, 38]. These results have been confirmed in another randomized study, the RIFLE-STEACS study (radial versus femoral randomized investigation in ST-segment elevation acute coronary syndrome). This trial specifically compared the TRA and the TFA for primary PCI, in which a relative reduction in access-site complications and in mortality of nearly 40% was found with TRA [38,39,40].
According to the latest (2018) European Society of Cardiology (ESC) guidelines on myocardial revascularization, the radial access should be the standard approach for coronary angiography and PCI in all clinical settings (class I, level of evidence A) [41].
Currently, it is well established that TRA nearly abolishes access-site complications in all patients. All studies comparing TRA versus TFA have demonstrated a reduction in major bleeding with TRA, both in the elective and the acute setting [38, 42, 43]. When access-site complications still occur after TRA, they usually have a benign course and do not influence the prognosis of patients [38]. Surgical intervention for the treatment of hematoma or arteriovenous fistulae has been rarely observed [5, 44]. The incidence of complications in our study matches the literature findings.
The advantages of TRA extend to the elderly patients as well. In a recent meta-analysis of 777,841 elderly patients by Alnasser et al [45], TRA compared to the TFA was associated with a significant reduction in vascular complications and stroke, but mortality benefit was seen only among patients presenting with STEMI.
Despite the aforementioned advantages, there are potential disadvantages to the TRA [8]. The TRA is technically more complex than the TFA due to the greater difficulty in cannulating the artery, the possibility of spasm, anatomical variations in the arteries of the upper limb, and the change in manipulation of the catheters that is necessary to cannulate the coronary arteries [11, 46, 47]. All these difficulties result in an increase in the length of procedural time and the need for a significant learning curve [8, 11, 47]. Some interventions may be technically challenging via the radial route due to the size of the technology required, e.g., large bore rotational atherectomy [8, 48]. Moreover, TRA is usually more demanding and needs longer procedural time in elderly patients because of the frequent presence of specific vascular abnormalities such as tortuosity, calcifications, or arterial loops [4].
TRA has been associated with a greater access crossover rate, which was reported to be 4–7% in various studies [4, 49, 50]. Louvard et al. reported a crossover rate of 10% in the first 50 cases, and 3–4% after other 500 cases; then, it stabilizes at less than 1% after 1000 procedures [1, 51]. In our study, the crossover rate was 4.4%, with higher rate in older patients (≥ 60 years old) than younger patients (5.6% versus 3.5% respectively). However, the difference between the two groups was statistically not significant. In the meta-analysis of elderly patients by Alnasser et al., access site crossover rate was higher for TRA compared to the TFA (11% vs. 3%, p = 0.0003), but remains acceptably low [45].
While serious bleeding complications are uncommon, the TRA bears the risk of radial artery occlusion (RAO). The incidence of RAO varies between 3 and 10%, according to different studies and protocols [40, 52, 53]. RAO rarely results in serious adverse events nor is it symptomatic, but the artery is lost for future procedures [33, 40, 54]. Therefore, any effort should be taken to reduce the risk of RAO [40].
The occurrence of RAO is determined by one or more of the following three factors, and all of them are operator dependent and therefore preventable: incomplete anticoagulation, catheter- artery mismatch, and prolonged arterial compression [38, 55]. The incidence of RAO is directly related to the ratio between the sheath and artery size [1, 55, 56]. Therefore, smaller guiding catheters are potentially advantageous leading to less arterial spasm, pain, and post-procedural RAO [1]. Prolonged and forceful post-procedure radial artery compression is perhaps the most common cause of RAO [33, 55]. Patent or non-occlusive artery hemostasis—that is, applying enough pressure to the radial access site to achieve hemostasis and yet maintaining antegrade flow in the radial artery—has been shown to drastically reduce the incidence of RAO [38, 40, 55].
In our study, the rate of RAO was 3.7%. Moreover, 123 patients had second TRA (as part of staged PCI) reflecting the preserved patency of the radial artery after TRA, or it may indicate that RAO is temporary in some cases. The use of 6F radial sheath in all procedures, followed by routine administration of heparin (5000 IU) into the radial artery after sheath insertion, and the controlled pressure over the radial artery with “radial compression device” all resulted in the reduction of the incidence of RAO.
Since the introduction of TRA, it has been recommended to assess dual hand circulation before use [57]. This assessment is done by using Allen’s test which is subjective, or the more objective oximetry/plethysmography test. In most TRA studies, patients with abnormal tests were excluded from the studies. In our study, the majority of patients (71.2%) underwent transradial procedure without any assessment of dual hand circulation (group B); however, this did not result in worse outcomes such as hand ischemia or higher rates of access crossover or RAO. In an international transradial practice survey by Bertrand et al. [57] which included 1107 interventional cardiologists from 75 countries, 23.4–30.8% of operators did not assess dual hand circulation at all. Because the Allen test or the oximetry/plethysmography test have not been shown to be predictive of hand ischemia in case of RAO, it remains uncertain whether the assessment of dual hand circulation before TRA is required [57].
