Transradial Percutaneous Coronary Interventions
– Indication, Success Rates, Clinical Outcome
Johannes B. Dahm (a), Frank van Buuren (b)
(a) Department of Cardiology-Angiology, Heart-& Vascular Center Neu-Bethlehem, Göttingen, Germany
(b) Department of Cardiology, Heart-& Diabetes Center NRW, BadOeynhausen, Germany

The technique of transradial percutaneous coronary intervention has been introduced to reduce bleeding complications and shorten hospital stay while improving comfort of the patient1-3. Since Kiemeneij et al (1997). reported similar procedural and clinical outcomes for percutaneous coronary interventions with transradial, transfemoral, and transbrachial access, the transradial approach has been increasingly used for PCI4. Significant enhanced patients’ comfort and reduced hospital staff workload and hospital costs could have been documented in various studies5,6. First published data showed access failure in 3-7% of cases, compared to 4-5% with the brachial, and 0.3-2.4% with the femoral approach and with small radial vessel size as predictor.

PCI procedures in the database were performed using the radial approach as opposed to femoral PCI.  The vast majority of centers in the US-database reported that they performed <10% of PCI procedures via the radial approach.  PCI success was equivalent between the 2 groups.  After adjustment, rates of bleeding complications were significantly lower among patients receiving radial PCI compared to those receiving femoral PCI (n = 585,290; OR 0.42, 95% CI, 0.31-0.56). There were too few vascular complications in the radial PCI group to perform multivariable adjustment.  In this analysis radial access was also associated with a significantly longer procedural time (WMD 3.1 minutes; 95% CI, 2.4-3.8 minutes; P <0.001), although more experienced operators worked more quickly than those unfamiliar with the radial technique.  Similarly, the radial approach was tied to a longer fluoroscopy time (WMD 0.4 minutes; 95% CI, 0.3-0.5 minutes; P < 0.001).
According Rao et al (2008), the major reasons for the low US-percentage of radial PCI may include difficult and long learning curves associated with the technique (1), unwillingness to adopt a new approach (2), concerns over

Correspondence:Dr Johannes B. Dahm,.Dept. of Cardiolog Heart-& Vascular CenterNeu-Bethelehem Humboldtallee 6, D – 37073 GöttingenGermany
Email:dahm@herz-gefaesszentrum.org

parts of Europe, it accounts for as much as 70% of all catheterizations, consequently showing significant lower complication rates and procedural failures in large prospective studies and meta-analysis2, 8. Moreover in interventional centers with extensive experience of radial access (>70% of all interventions), procedure and fluoroscopy time do not differ in comparison to the femoral access9.

Bleeding complications occur only rarely with radial access as compared to transfemoral access.  According to the most recent meta-analysis, and radial subgroup analyses of large ACS-PCI studies (e.g. PRESTO-ACS), bleeding seems to be the most important predictor of the primary endpoint (e.g. cardiovascular death or myocardial infarction).  In PRESTO-ACS, the transradial group showed a significant decrease in death or reinfarction, bleeding, and net clinical outcome at 1-year follow-up

Table 1. One-Year-Follow-up in PRESTO-ACS

The 1-year estimate of mortality was 28% in patients with bleeding compared to 3.8% in patients without bleeding (P < 0.0001).  Also those with bleeding had a much higher likelihood of suffering death or myocardial infarction at 1 year compared to those without bleeding (OR 11.5, 95% CI, 3.8-35; P < 0.0001).  The high risk associated with bleeding could be justified as early bleeding during acute coronary syndromes leads to early cessation of dual-antiplatelet therapy, which is associated with increased cardiovascular events.  Moreover, bleeding lead to blood transfusions that themselves may lead to increased cardiovascular risk.  Furthermore, despite the introduction of newer pharmacologic agents, bleeding complications at the puncture site represent almost 50% of all hemorrhagic complications, and the best option to decrease periprocedural bleeding is to consider transradial approach.  In PRESTO-ACS, the reduction in bleeding complications in the transradial group was observed despite a significant increase in GP IIb/IIIa inhibitor use. But despite this potential advantage of transradial access, no clinical randomized trials have yet been conducted to compare its impact with that of other access sites on the prognosis of ACS patients.

Radial occlusions after transradial interventions have been reported in 2.5-10% of cases (80% females)5,10. Published reports have associated such incidents with prolonged cannulation times11,12, a problem which has been solved by the technique of immediate sheath removal after the procedure.  Although radial occlusion generally occurs without clinical sequelae (due to collateral circulation to the hand), it should be avoided whenever possible:  not least, to also maintain a patent vascular access site.
Published data has documented a close relationship between access failure and anatomical circumstances (e.g., anomalous radial branching patterns, tortuosity e.g. radial loops, and insufficient palmar collateral flow) and by small radial artery diameters10 leading to radial spasm and postprocedural occlusion as the main complication of radial access especially in patients where the radial diameter-to-catheter ration is < 1.013.  Saito et al (1999). have demonstrated that the mean radial inner diameters of patients dictate that only 71.5% of female and 85.7% of male patients can physically accept 6 Fr guiding catheters (mean radial diameter = 3.1 ± 0.6 mm in males and 2.8 ± 0.6 mm in females)Error! Bookmark not defined. . These conditions lead to impaired radial flow, in turn, to a higher rate of radial spasm.  Campeau (1989) has reported that the incidence of severe radial flow reduction varies between 6% and 7.5% with 6 Fr guiding catheters, and that it exceeds 8-10% with 8F catheters14.
In a prospective randomized study at our center, the main reason for procedural failure was profound radial spasms, which occurred predominantly in patients treated with greater guiding catheters (6F) as compared to those treated with 5F guiding catheters and radial diameter-to-catheter ratio was < 1.0 for all 6 Fr patients in which profound radial spasm occurred15.
It is particularly among the patients with radial diameter-to-catheter ratio < 1.0 that 5 Fr guiding catheter helped to improve procedural success rates and reduced procedural failures and vascular access complications such as radial occlusions and hematomas, however, 5 Fr 0.058" lumen diameter guiding catheter afford less strength, visibility, and back-up compared to 6 Fr16 and lesions which require other devices than POBA or stent implantation (e.g., kissing balloon) can not been treated using 5F guiding catheters.
Radial spasm and postprocedural radial occlusions in transradial coronary interventions are associated with risk factors like smoking, female gender and/or anxious patients.  Preventive measures may be sedation in anxious patients and the administration of intraarterial vasodilatators and heparine.  In a large study, radial spasm occurred in 22.2% of radial cases without vasodilative drugs, 13.3% after intraartrial (i.a.) molsidomin (1 mg), 8.3% after i.a. verapamil (2.5mg), 7.9% after verpamil (5 mg) and only 4.9% after a combination of i.a. verapamil (2.5 mg) plus molsidomin (1 mg), corresponding with a relative risk reduction of 87%17.