PCI at Centers Without On-Site Surgery Backed by Analysis

Reed Miller

December 13, 2011

December 13, 2011 (Rochester, Minnesota) — A large meta-analysis of 15 controlled studies shows that patients undergoing PCI at centers without on-site surgery capabilities are no more likely to die or need emergency bypass coronary surgery than comparable patients treated at centers with on-site surgery capabilities [1].

"No matter how you look at it, there was no difference in the in-hospital mortality or the need for emergency bypass surgery in patients who had either primary PCI for ST-elevation or for non-primary PCI [with or without on-site surgery]," Dr Mandeep Singh (Mayo Clinic, Rochester, MN), the lead author of the meta-analysis published in the Journal of the American Medical Association, explained to heartwire . "The results were pretty homogenous [across all the studies]. All the studies were right-on in demonstrating that the mortality is similar or lower in centers without on-site surgery. This is important, because these centers are community hospitals where we're promulgating an approach for easier access to these patients where 'time is muscle' and there may not be a big tertiary-care hospital that they can go to."

Several studies, including the randomized C-PORT E study of patients with elective procedures, show similar outcomes with PCI at hospitals with or without backup surgery capabilities, but in a survey on elective PCI without backup surgery on-site, conducted jointly by theheart.org and US News & World Report and covered by heartwire today, shows that a third of respondents said the practice cannot be done safely and effectively.

Singh said the current meta-analysis is an important addition to the literature on this issue because of the large number of patients included and the quality of studies analyzed. The analysis includes patients from every controlled study of PCI at centers with and without surgery on-site over the past 20 years but does not include any uncontrolled case series. The study includes 124 074 patients undergoing primary PCI for ST-segment elevation MI and 914 288 patients undergoing "non-primary" PCI, either elective or urgent.

"We can safely say that we now have a large body of evidence to upgrade the ACC/AHA guidelines. We have the necessary scientific evidence to do that, where previously it was lacking," Singh said. The new ACC/AHA guidelines on PCI have favorably revised the recommendations on PCI at hospitals without on-site surgery. The practice was once listed in the guidelines as "not useful/effective and may be harmful" but is now in the "may-be-considered" category for elective procedures. Primary PCI at such centers is now classified as "reasonable to perform." In either type of case, the recommendations stress that the decision on what kind of revascularization to perform should be made by a team including a surgeon and an interventionalist.

In an accompanying editorial [2], Dr Scott Kinlay (Harvard Medical School, Boston, MA) agrees that successful PCI in hospitals without coronary bypass surgery capabilities requires experienced operators, experienced nursing staff, and clear plans and agreements for rapid transport of patients to a facility with CABG surgery when necessary. He also recommends that all hospitals providing PCI participate in national clinical registries in order to "help evaluate and perhaps modulate PCI practice in order to keep adverse events low."

No Difference in Key Outcomes

Singh et al used random-effects models to estimate pooled odds ratios (OR) and compare the risks of an outcome among patients undergoing PCI at centers without on-site surgery with the outcomes of patients treated at centers with on-site surgery. They use the I 2 statistic to examine the heterogeneity of effect sizes in the overall aggregations: I 2 <25% indicates low heterogeneity, an I 2 around 50% indicates moderate heterogeneity, and an I 2 of >75% indicates high heterogeneity.

For STEMI patients, the meta-analysis found no increase in in-hospital mortality for patients undergoing PCI with no on-site surgery backup compared with patients treated at centers with on-site surgery capabilities. The observed risk of in-hospital mortality in the two groups was 4.6% vs 7.2%, with an OR of 0.96 and an I 2 of 0%. For the outcome of emergency bypass, the observed risks were 0.22% vs 1.03%. The OR was 0.53, and the I 2 was 20%.

For the 914 288 non-primary PCIs in the meta-analysis, the rates of in-hospital mortality were 1.4% vs 2.1% for the no-surgery-backup and surgery-backup groups, respectively. The OR was 1.15 and the I 2 was 46%. For the outcome of emergency bypass following non-primary PCI, the observed risks were 0.17% vs 0.29% for an OR of 1.21. The I 2 was 5%. So there was no significant difference between the outcomes at centers without or with on-site surgery.

A Lot More Still Unknown

The study authors call for the collection of more outcome data, including rates and indications for urgent or emergency transfers, particularly in patients undergoing non-primary PCI at centers without on-site surgery.

They point out that only one of the studies in the meta-analysis, the 609-patient Norwegian randomized trial, had a randomized design, so hospitals with on-site surgery may also be different from those without it in ways not measured in the studies. The presence of surgery facilities on-site may be a proxy for other differences in the quality of trainee operators, case mix, number of operators and experience, and skills of the nonmedical catheter-laboratory team. Also, variation among the studies' definitions of acute MI and overlapping indications for PCI prevented Singh et al from separately analyzing the results of very low-risk, elective PCI. Instead, Singh et al had to aggregate the results for all non-primary PCIs, "which may not truly reflect the outcomes of elective PCI," the authors state. Furthermore, they note that most of the studies did not report a composite end point of death and emergency CABG surgery, "precluding the chance to study whether one is being traded for another."

Kinlay adds that "hospitals without CABG surgical facilities may (appropriately) be more inclined to avoid performing PCI in higher-risk patients or in someone with higher-risk coronary anatomy, particularly in the non-STEMI setting in which PCI is more elective. Evidence to support this is circumstantial but could be inferred from the lower PCI rates among patients presenting with STEMI and non-STEMI in hospitals without CABG surgery."

No conflicts of interest were reported.

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