Transradial PCI May Improve Long-term Survival in NSTEMI

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Patients with non-ST-segment elevation myocardial infarction (NSTEMI) live longer after percutaneous coronary intervention (PCI) if the procedure is performed using transradial versus transfemoral access, suggests a retrospective registry study published online June 24, 2014, ahead of print in Circulation: Cardiovascular Interventions. The advantage appears to be greater when centers have more experience with radial procedures.

Methods
Miles Dalby, MD, of the Royal Brompton and Harefield NHS Foundation Trust (Middlesex, England), and colleagues examined outcomes among 10,095 consecutive NSTEMI patients (average age 65 years, 26.1% female) who underwent transradial (n = 2,275) or transfemoral (n = 7,820) PCI at 8 tertiary cardiac centers in London from January 4, 2005, to November 18, 2011. They used information from British Cardiac Intervention Society databases and Britain’s Office of National Statistics.
Compared with those treated femorally, patients treated through the radial artery (23%) were more likely to have hypertension, hypercholesterolemia, and peripheral artery disease but less likely to have had a prior MI.


Radial Procedures Gain Favor, May Improve Outcomes

The proportion of radial procedures increased from 7% in 2005 to 40% in 2011. Transradial access also became more commonly used over time in left main artery, graft, multivessel, and CTO interventions. 

Compared with transfemoral procedures, those done via the radial artery were associated with lower overall rates of bleeding and improvements in survival after multivariate adjustment (table 1). 

Table 1. Radial vs Femoral Outcomes

 

Adjusted OR

95% CI

P Value

Total Bleeding

0.21

0.08-0.57

.002

Major Bleeding

0.21

0.07-0.69

.009

Access-Site Bleeding

0.28

0.10-0.78

.015

30-Day Mortalitya

0.53

 0.31-0.91

.021

1-Year Mortalitya

0.72

 0.54-0.94

.017

aExpressed as hazard ratio.

Propensity matching confirmed the 1-year survival advantage for transradial vs transfemoral access (HR 0.60; 95% CI 0.42-0.58; P = .005). An additional instrumental variable analysis showed that radial PCI was associated with a 5.8% lower absolute risk of dying within the first year (P = .039). 

Transradial access was also associated with lower 1-year mortality at centers with a high volume of radial procedures (HR 0.70; 95% CI 0.51-0.97; P = .031) but not at those with a low volume (HR 0.80; 95% CI 0.47-1.38; P = .428). 

Dr. Dalby and colleagues attribute the fact that the 1-year mortality advantage for transradial vs transfemoral was not observed from 2005 to 2007 (adjusted HR 0.81; 95% CI 0.51-1.28) to “the learning curve and increased experience and expertise seen with [transradial access] over time.” 

Further, in a landmark analysis of patients who survived to 30 days, there was no difference in 1-year mortality between the transradial and transfemoral groups (HR 0.81; 95% CI 0.59-1.11). The researchers say this indicates “that the mortality benefit conferred by [transradial access] at 1 year was likely a result of differences in the periprocedural and early outcomes that [were] maintained in the long-term.” 

RIVALing Prior Data?

Use of transradial PCI has been tied to reductions in bleeding and vascular complications, with some evidence—from the RIVAL and RIFLE-STEACS trials, for example—that the access route might reduce the risk of mortality in patients with STEMI. Little information is available about the potential survival benefit in patients with NSTEMI, however.

The subgroup of patients with NSTE-ACS in the RIVAL trial did not have reduced mortality with transradial access, but only 62% of those participants had positive cardiac biomarkers, Dr. Dalby and colleagues point out. 

“This finding may not be directly applicable to patients with NSTEMI,” they write. “Troponin elevation is a marker of increased risk, and these patients are more likely to receive more potent antithrombotic therapies and thus have a greater bleeding risk.”

The current analysis, which comes with the limitations inherent to a registry study, “lends support to the evaluation of [transradial access] in NSTEMI with prospective, adequately-powered, randomized controlled trials,” they add. 

Unclear Mechanism

The findings are consistent with previous studies, “but we have to be careful when looking at observational data,” said Sunil V. Rao, MD, of Duke University (Durham, NC).

“No matter what techniques are used, one cannot account for all of the confounding (especially the unmeasured confounders),” he told TCTMD in an email. “It’s difficult to come up with a mechanism by which radial would reduce mortality in NSTEMI since the bleeding rates are lower than in patients with STEMI, and prior studies have shown that the majority of the bleeding events in patients with NSTE-ACS are unrelated to the vascular access site.” 

He added, however, that “although not the strongest evidence, [the study] does add to the body of data supporting the use of radial access.”

 


Source: Iqbal MB, Arujuna A, Ilsley C, et al. Radial versus femoral access is associated with reduced complications and mortality in patients with non-ST-segment elevation myocardial infarction: an observational cohort study of 10,095 patients. Circ Cardiovasc Interv. 2014;Epub ahead of print.

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Todd Neale is the Associate News Editor for TCTMD and a Senior Medical Journalist. He got his start in journalism at …

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Disclosures
  • The study was supported by the National Institute for Health Research Cardiovascular Biomedical Research Unit of Royal Brompton and Harefield National Health Service Foundation Trust and Imperial College London.
  • Dr. Dalby reports no relevant conflicts of interest.
  • Dr. Rao reports serving as a consultant for Terumo Medical.

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