Transradial access may be met with greater anatomic variability in the course of radial/subclavian artery as well as challenges in cannulation of the coronary arteries. These Factors may increase the procedure time and account for higher rate of cross over to the femoral access. Starting initially with elective PCIs will help improve the confidence in quickly overcoming anatomic challenges and successful manipulation of the guide catheters for transradial PPCIs. We routinely use standard femoral guides for transradial PPCI JR-4 for right coronary and Launcher EBU-3.0 (Medtronic, Inc., Minneapolis, MN, USA) guide for LM cannulation from right radial access. From left radial access, we use Launcher EBu 3.5 guide for UN and JR-4 guide for reight coronary artery cannulation. We use buddy wire in same artery or adjacent branch to stabilize the guide catheter if needed. Especially taken using right radial access.

Radial primary PCI procedure in STEMI patients may be associated with significantly longer procedure time especially if performed in low volume radial PCI centers [25]. A recent meta-analysis of 12 randomized controlled trials of radial versus femoral access for STEMI PPCI found a mean of 1.52 min increase in procedure time (p = 0.01) with radial access versus femoral access. Despite slightly longer procedure times the data suggests significant reduction in mortality, major bleeding and access site bleeding [15]. Most of the studies included in this meta-analysis are either single center or include only a few centers, with high concentration of experienced radial operators. Therefore, the minimal increase in procedure time for PPCI when performed by experienced radial operators, may not be generalizable to the practice in the US.

The subgroup analysis of the STEMI cohort from the RIVAL (Radial versus Femoral access for Coronary Intervention Trial) showed that with considerably experienced radial operators (median 400 radial cath or PCI procedures/year), transradial PPCI is associated with similar contrast use (median 180 ml contrast use for both access sites, p = 0.2223) and longer fluoroscopy time (radial 9.3 min vs. femoral 8.0 min, p = <0.0001) [26]. In the randomized trial of radial vs. femoral approach for primary PCI in STEMI patients by experienced operators (the STEMI-RADIAL trial) in both access sites, the contrast utilization was actually lower (mean 12 ml lower in radial vs. femoral approach) [16]. A review of five year data (from 2007 to 2011) of CathPCI Registry of the NCDR, including 90,879 patients undergoing primary or rescue PCI for STEMI (6.8 % transradial, 93.2 % transfemoral) at 541 US sites, suggested that transradial access was associated with longer fluoroscopic time (median 1.4 min longer for transradial) and less contrast use (median 5 ml less for transradial) [2]. Therefore, transradial PPCI performed by an experienced operator is not associated with increase contrast use compared to femoral access.

In the subgroup analysis of the STEMI cohort from the RIVAL (Radial versus Femoral access for Coronary Intervention Trial) showed that with considerably experienced radial operators (median 400 radial cath or PCI procedures/year), transradial PPCI is associated with reduced major vascular access site complications and mortality [26]. The RIFLE-STEACS (Radial versus femoral randomized investigation in ST-elevation acute coronary syndrome) trial showed that radial access was associated with decrease in the rate of major adverse cardiac events driven by reduction in mortality and bleeding. The operators in RIFLE-STEACS performed >150 PCIs per year (of which >50 % radial PCIs) [27]. By contrast, the STEMI-RADIAL (A Prospective randomized trial data of radial vs. femoral access in patients with ST-segment elevation myocardial infarction) trial conducted at 4 high volume radial centers, showed a significant reduction in bleeding and access site complications with radial access, but did not demonstrate a mortality benefit for radial access over femoral access for PPCI [16]. A meta-analysis of randomized controlled trials of radial versus femoral access for STEMI PPCI found a 45 % decrease in mortality (p < 0.001) associated with radial access [15]. An analysis of the NCDR data from 2007 to 2011, including 90,879 patients undergoing primary or rescue PCI for STEMI (6.8 % transradial, 93.2 % transfemoral) at 541 US sites, found a 24 % reduction in mortality (p = 0.0455) associated with radial access [2].

The MATRIX trial (Minimizing Adverse Hemorrhagic Events by Transradial Access Site and Systemic Implementation of angioX) randomized 8404 patients with ACS (52 % NSTEMI/48 % STEMI) to coronary angiography and PCI using radial vs. femoral access, demonstrated significant reduction in BARC major bleeding unrelated to CABG (33 % relative risk reduction) and all-cause mortality (28 % relative risk reduction) with radial access compared to femoral access. In the MATRIX trial, the operators performed at least 75 PCIs and at least 50 % of interventions in ACS via the radial route during the previous year. Despite including the skilled operators, in the MATRIX trial, there was a significant interaction of proportion of PCIs undertaken transradially by each center to the outcome of each co-primary endpoints and mortality, but not for major bleeding. The greatest benefit of radial access was seen in highest volume radial centers (ie, those doing at least 80 % of their procedures via radial access). This suggests that although the bleeding benefit accrues at an earlier stage of the learning curve of transradial intervention, but superior efficacy compared with femoral access needs substantial expertise that can be met only by high-volume radial operators [28, 29]. This data is also supported by the prespecified subgroup analysis of the RIVAL trail suggesting that primary outcome (death, MI, stroke, non CABG major bleeding) was reduced with radial versus femoral access in high volume radial centers (>146 radial PCI/year/operator) but not in intermediate (61–146 radial PCI/year/operator) or low volume (≤60 radial PCI/year/operator) radial centers. Low-volume radial centers performed 20 % of PCI procedures per year via radial access, whereas high-volume centers performed 75 % of PCIs per year via radial access. Therefore suggesting that procedural volume and expertise of the radial centers are important, particularly for radial PCIs [25].

Radial artery access for PPCI is also appealing in patients with coagulopathy, elevated international normalized ratio due to warfarin, novel anticoagulants, or morbid obesity. Therefore in STEMI patients undergoing primary PCI, the radial approach is associated with favorable outcomes and should be the preferred approach for experienced radial operators.

Most recent STEMI guidelines by ACCF/AHA, give radial access for STEMI Class IIa designation [23]. 2011 ACCF/AHA/SCAI Guideline for PCI recommends patients to be evaluated for risk of bleeding before PCI and measures considered to minimize the risks of bleeding complications that include among others radial artery access site [11].

Transradial PPCI through either arm is a feasible and safe approach. The use of left radial approach for PPCI in STEMI patients is associated with comparable success rates and reperfusion times when compared with right radial approach [30]. Left radial approach for PPCI may be considered in patients with features associated with failure of right radial approach i.e. history of prior CABG, right subclavian tortuosity, age >75 years and short stature [31].

PPCI in STEMI is a stressful situation with patients that are acutely sick, having acute symptoms and possibly hemodynamic compromise. Obtaining quick angiogram followed by timely revascularization of the culprit coronary artery using the access site that is to provide the best clinical outcome for that specific patient is the primary goal. Radial access for PPCI for STEMI patients is associated with better clinical outcomes and reduced duration and cost of hospitalization. The data supporting transradial PPCI is derived mostly from studies involving operators highly skilled in transradial PCIs. Therefore, in order to replicate these findings in clinical practice, PPCI for STEMI using radial access requires experienced operators at high volume radial catheterization laboratories. Data from a large unselected patient population derived from the British Cardiovascular Intervention Society database suggests that the benefits of adoption of transradial PPCI can be achieved in real world practice [32]. This led to a bold editorial comment by Di Mario C and Secco G “Radial Primary Angioplasty- The Gold Standard Treatment for STEMI patients” [33]. Adoption of transradial PPCI is becoming essential but needs training and physicians will have to go through the discomfort of a learning curve. In order to avoid losing precious time overcoming the transradial access related technical/learning curve issues, it is important to initially start with transradial catheterization/PCI in elective cases and gradually ease into the ACS/NSTEMI cases followed by PPCI in STEMI. The SCAI’s Transradial Working Group recommends best practices for transradial interventions and recommends operators and sites not to start performing transradial PPCI until they have performed at least 100 elective PCI cases with a “radial first” approach and their femoral cross over rate is ≤4 % [18]. This gradual transition is very important to obtain the best outcomes of transradial approach for PPCI in STEMI patients.