Anemia Common in PCI Patients, With Potentially Dire Consequences

A substantial percentage of patients undergoing PCI have some form of anemia that increases their risk for mortality, MACE, bleeding, and MI.

In a paper published online May 29, 2016, ahead of print in the American Journal of Cardiology, researchers conducted a meta-analysis of 44 studies published between 2003 and 2014 that included a total of 230,795 PCI patients. 

The overall prevalence of anemia was 15.5%. Compared with patients without anemia, those with the condition tended to be older, have more comorbid conditions, and have more complex CAD, senior author Mamas A. Mamas, BMBCh, DPhil (University of Keele, Stoke-on-Trent, England), told TCTMD in an email.

“Currently there are no guidelines around how to optimally manage patients with anemia in the setting of PCI, despite anemia affecting one in six patients,” he added.

Doubling of Mortality Observed

Even after adjustment for differences in baseline characteristics, anemia was independently associated with higher mortality and MACE, as well as more MI and bleeding events.

Additionally, the study showed that the risks for these adverse outcomes appeared to rise incrementally with the severity of anemia. Specifically, there was a 20% increased risk of mortality for every 1 g/dL drop in hemoglobin below normal levels.

Sensitivity analysis of a subgroup of studies that had adjusted for baseline hemoglobin, renal impairment, or severity of anemia confirmed that the increased risk was independent of common causes of anemia.

“Our analysis suggests that anemia is independently associated with a two-fold increased risk of major bleeding complications, which themselves are independently associated with increased risk of mortality,” the researchers write. They also note that at least one study has implicated severe anemia in a doubling of the risk of stent thrombosis, which might further contribute to adverse events after PCI.

Lack of Direction for Clinicians

Another issue of importance, Mamas pointed out, is transfusion rates among patients with low hemoglobin. Numbers from the National Cardiovascular Data Registry suggest that there are significant differences in blood transfusion practices in the United States and in the hemoglobin threshold that prompts transfusion, he said, noting that a previous study by his group has suggested that liberal transfusions may up the risk of mortality and MACE events. That knowledge puts the onus on operators to use bleeding-avoidance strategies to minimize the risk for periprocedural transfusion.

But randomized trials have not yielded consistent information on the optimal treatment of anemia for ACS and PCI patients, Mamas and colleagues say. While the CRIT study of MI patients showed that those with anemia who received transfusion had higher in-hospital mortality, reinfarction, or heart failure compared with those who did not receive transfusion, a pilot study of anemic patients undergoing angiography actually demonstrated lower rates of MACE and mortality when transfusion was given versus when it was withheld.

This lack of a clear-cut strategy leaves clinicians with more questions than answers about the relationship between anemia and PCI outcomes and what, if anything, they should be doing differently.

“I think that our work highlights the need for a large prospective randomized, controlled trial to investigate whether targeting anemia prior to PCI improves outcomes,” Mamas said.

Source: 
Kwok CS, Tiong D, Pradhan A, et al. Meta-analysis of the prognostic impact of anemia in patients undergoing percutaneous coronary intervention. Am J Cardiol. 2016;Epub ahead of print. 

Disclosures:

• Mamas declares no relevant conflicts of interest. 

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