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ORLANDO, FLA. -– Duke Clinical Research Institute and Canadian cardiologists have estimated that 25 percent of patients who unexpectedly require emergency heart surgery after a failed angioplasty are at risk of harm or death if any delays to the surgery are encountered.
While the number of patients potentially at risk is relatively low -– between one and two per 1,000 angioplasty procedures –- the researchers believe that it is a significant health care issue, especially if the center performing the angioplasties places the financial benefits of the popular and profitable procedure ahead of patient safety.
The results of the analysis were presented today (Nov. 12, 2003) at the 76th annual scientific session of the American Heart Association (AHA) by Mat Lotfi, M.D., researcher at the Duke Clinical Research Institute.
Debate continues within the cardiology community about whether "free-standing" angioplasty centers that do not have ready access to heart surgery place patients at undue risk, should something go wrong during the artery-opening procedure. Current guidelines of the AHA and American College of Cardiology state that institutions without surgical capability need to have a system in place to get patients to an operating room within one hour.
However, the investigators believe resorting to such transfers is not always in the best interest of patients, since not only can it be difficult to transfer a patient from one institution to another in less than an hour, but often the patients are too medically unstable after a failed angioplasty to survive a trip in an ambulance or helicopter.
"The results of our analysis show the unpredictability of the need for emergency surgery and demonstrate that certain patients will undoubtedly be put at increased risk without the immediate availability of cardiac surgery," Lotfi said. "We as cardiologists should develop strategies that ensure that our patients are not being placed at increased risk of adverse events in angioplasty programs without on-site surgery."
To get a better handle on the potential for harm for these patients, the team wanted to determine how many patients at a large tertiary care center would likely have had bad outcomes after a failed angioplasty. Before reviewing the patients' records, they developed a set of criteria based on published data that have been associated with worse outcomes after failed angioplasty -– hemodynamic instability, perforation of the artery or heart, or sustained lack of blood flow to the heart.
With these criteria in mind, they performed reviews of all angioplasties performed from 1996 to 2000 in the University Health Network in Toronto, a major tertiary care center. Of the 6,582 angioplasties performed during that period, there were 45, or 0.7 percent, of cases referred for emergency heart surgery after failed angioplasty. Lotfi said the 0.7 percent is in-line with the rates at major U.S. centers.
"Of those 45 cases, the prespecified criteria identified 11 patients who would have been at high likelihood of harm with additional delays to surgery," Lotfi said. "Therefore, the number of patients potentially harmed by delays to emergency surgery we estimated to be approximately one to two patients per 1,000 angioplasties (25 percent of 0.7 percent)."
Within the group of 45 patients, two died, resulting in a death rate of 4.4 percent. However, Lotfi said that two more patients were rushed to the operating room immediately and that an additional two patients were too unstable to be transferred, suggesting that had there been any delays to surgery, there would have been an additional four deaths, resulting in a death rate of 13.3 percent.
Of the 45 patients, 25 had surgeries started within four hours, 15 waited at least 12 hours. All 11 of patients who met the criteria were taken to the operating room within two hours.
Lotfi pointed out that these estimates of event rates are likely conservative, since the Toronto site is a high-volume center, and studies have demonstrated that high-volume centers tend to have lower rates of adverse events than smaller centers that do not perform as many of the procedures.
Complicating the issue is the inability of physicians to accurately predict which patients might be at higher risk for having adverse reactions to an angioplasty. Of all the characteristics of the patients in the study, only one factor -– complexity of the plaque being treated -– was higher in the patients needing emergency surgery.
"It is clear from recent studies that selected patients can have an angioplasty in a high-volume center without on-site surgery with acceptable risk," Lotfi said. "However, concern arises when the data from larger and more experienced centers is used to determine risk when in fact many of the centers interested in starting their own programs are low-volume with less experienced operators.
"Our study supports the unpredictability of the need for emergency surgery and shows that certain patients will undoubtedly be put at increased risk without the immediate availability of cardiac surgery," Lotfi said.
Lotfi's Canadian colleagues were Karen Mackie, Vladimir Dzavik, M.D., and Peter Seidelin, M.D. Lotfi received no outside funding for his analysis.