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Administration of systemic heparin before transradial catheterization for coronary angiography may not be necessary in all patients. Preventing radial artery occlusion may be possible with provisional heparin administered only when patency cannot be otherwise maintained, according to a study published April 10, 2012, online ahead of print in the American Journal of Cardiology.

The PHARAOH (Provisional Heparin Therapy on Radial Artery Occlusion after Transradial Coronary Angiography and Patent Hemostasis) study, led by Samir B. Pancholy, MD, of the Commonwealth Medical College (Scranton, PA), included 400 patients undergoing transradial catheterization who were randomized to either routine or provisional heparin administration. There were no baseline differences between the 2 study groups.

Fewer Patients Need Heparin

Patent hemostasis was feasible in 134 patients in the routine group (67%) and in 149 patients in the provisional group (75%; P = 0.10), drastically cutting down on the heparin required for the provisional group. There were no differences with regard to incidence of early (24 hours) or late (30 days) radial artery occlusion (table 1).

Table 1. Outcomes According to Heparin Strategy

All procedures lasted less than 20 minutes, and the average procedure time did not differ between the routine and provisional groups (9.8 ± 2.7 minutes vs. 9.6 ± 2.7 minutes; P = 0.54). The total nursing time required, however, was lower with routine use (15 ± 0.3 minutes vs. 22 ± 0.2 minutes; P = 0.0008).

Overall, radial artery occlusion occurred more frequently in women (6.5% vs. 3%; P = 0.006), patients with diabetes (7.5% vs. 2%; P = 0.001), those who did not receive heparin (6% vs. 3.9%, P = 0.0001), and those without radial artery patency during hemostasis (9% vs. 0.5%, P = 0.0001). Multivariate analysis showed that artery patency and diabetes were independent predictors of late radial artery occlusion, but heparin use was not.

Proof-of-Concept Study

“Maintenance of radial artery patency during hemostasis is a very potent way of preventing radial artery occlusion even in absence of anticoagulation,” Dr. Pancholy told TCTMD in an e-mail communication. He stressed that this trial was merely a proof-of-concept and its findings do not suggest any change of practice for day-to-day transradial procedures. “Heparin administration still continues to be a ‘best-practice’ measure,” he said.

Because heparin is a major trigger for non-access site bleeding in high-risk patients, Dr. Pancholy said, the provisional approach could be a viable strategy to lower bleeding risk, though only in centers where good monitoring of radial artery patency is possible. Certain patients will not be good candidates for the provisional heparin approach; these include women with diabetes and others at high risk of occlusion.

In an e-mail communication with TCTMD, Ian C. Gilchrist, MD, of Hershey Medical Center (Hershey, PA), commented, “This [study] suggests that radial occlusion is from clot formation during hemostasis or sealing of the artery and is not happening during the catheter procedure itself.”

He noted that systemic heparin may have other benefits beyond prevention of radial artery occlusion, such as reduction of stroke risk. It is theorized that transradial procedures could raise stroke risk because the catheter passes close to the carotid artery, and heparin may counter such a risk. “Since the risk of stroke is on the order of 1:1,000, you need a very large study to see if not using heparin raises the risk,” Dr. Gilchrist said.

Sunil V. Rao, MD, of Duke University Medical Center (Durham, NC), said in an e-mail communication that it has been clear for some time that 3 factors are required to maintain radial artery patency: adequate anticoagulation, smaller-sized arterial sheaths, and nonocclusive hemostasis. “The problem is that, before this study, we never knew the relative importance of [these factors]. This study suggests that it’s the nonocclusive hemostasis that is the most important thing,” Dr. Rao said.

Thus, reserving heparin for only the 30% or so of patients in whom achieving hemostasis is not possible is a reasonable plan, Dr. Rao noted, adding that this study was likely underpowered to detect true differences in occlusion rates.

Study Details

In the routine heparin group, 50 U/kg or a maximum of 5,000 U of unfractionated heparin was administered after sheath insertion. A TR band (Terumo Medical, Tokyo, Japan) was applied to achieve patent hemostasis after the procedure.

In the provisional group, patency was evaluated following TR band application and every 15 minutes afterward until the band was removed and hemostasis completed. In cases in which radial artery patency could not be maintained, physicians administered a bolus of unfractionated heparin at the same dose level.

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