Alexander C Fanaroff (Division of Cardiology, Duke University, Durham, USA) and others report in the Journal of the American College of Cardiology that nearly half of percutaneous coronary intervention (PCI) operators in the USA perform fewer than the recommended target of 50 procedures per year. However, they add that—given that the absolute risk differences between high- and low-volume operators are small—focusing on improving process and outcome performances may be more appropriate than determining an optimal operator volume.
The American College of Cardiology, American Heart Association, and the Society for Cardiovascular Angiography and Interventions, in a joint guideline, used to advise that PCI operators should, at a minimum, perform 75 procedures a year. However, in 2013, they reduced this figure to 50 procedures a year. According to Fanaroff et al, no volume-operator relationship studies have been performed after this change was made. “Importantly, operator volume recommendations were based on expert opinion that the increasing safety of PCI minimises differences in outcomes across operators regardless of the number of procedures they perform rather than on objective data,” they add.
Therefore, in this present study, they sought to assess median operator volumes of PCI procedures, evaluate potential differences in patient and procedural characteristics for high-, intermediate- and low-volume operators, and determine the relationship between operator volumes and patient outcomes. Using data from the National Cardiovascular Data Registry (NCDR) CathPCI registry, Fanaroff et al identified data for 10,496 operators who collectively performed 3,747,866 PCI procedures between July 2009 and March 2015. The median annual operator volume was 59 procedures.
The authors found that nearly half (44%) of operators performed fewer than 50 procedures per year, with 29% of operators performing 50 to 100 procedures per year and 27% performing more than 100 procedures per year. They comment: “High-volume operators were more likely to practise at an urban or teaching hospital, and practised at larger hospitals with higher median annual hospital PCI volumes.” Furthermore, high-volume operators and intermediate-volume operators were significantly more likely to treat patients with cardiovascular comorbidities than were low-volume operators. Low-volume operators, by contrast, were more likely to perform PCI in patients with ST-segment elevation myocardial infarction (STEMI) and more likely to perform emergency PCI.
Overall, between 80% and 81.6% of procedures performed were, according to US guidelines, appropriate and >92.5% of procedures were successful. However, in-hospital mortality increased by 4% with every 50-case decrease in operator volume. Fanaroff et al note: “The relationship between operator volume and in-hospital mortality was significant in patients presenting with STEMI, unstable angina, non-STEMI, and stable angina.”
When operator volume was used a categorical variable, after risk adjustment, in-hospital mortality was still significantly higher with intermediate- and low-volume operators compared with high-volume operators. However while in-hospital mortality was significantly higher for low-volume operators in all presentations, it was not higher for intermediate-volume operators in STEMI and stable angina groups. Also, after further adjustment for PCI process measures, the relationship between operator volume and mortality was attenuated. “In hospital mortality remained higher for low-volume operators but not for intermediate-volume operators,” the authors state.
Fanaroff et al say that, because of small absolute risk differences between operator volume groups, the numbers of PCIs that would need to be “shifted from lower to higher volume operators to prevent one death” were large: 263 for low- vs. high-volume operators and 769 for intermediate- vs. high-volume operators. They add: “Moreover, post PCI in-hospital mortality increases linearly with decreasing operator volume without an inflection point to suggest a minimum annual number of PCIs.”
The authors suggest that any volume threshold “appears arbitrarily determined” and “caution should be exercised when applying specific operator volume recommendations to individual operators”. “Rather than firm annual volume recommendations, a focus on improving process and outcome performance measures for PCI across all operators, regardless of volume, might be more appropriate,” Fanaroff et al observe.
In an accompanying editorial, Dharam Kumbhani (Division of Cardiology, University of Texas Southwestern Medical Center, Dallas, USA) and Brahmajee Nallamothu (Division of Cardiology, University of Michigan, Ann Arbor, USA) write that a comprehensive evaluation of operator PCI quality is needed. Fanaroff told Cardiovascular News that he agrees with this view, comments: “Kumbhani and Nallamothu’s framework for a comprehensive evaluation includes procedure volume, but also incorporates post-procedure care (prescription of antiplatelet agents and statins, for example), selection of appropriate patients and lesions for PCI, participation in quality improvement discussions, use of evidence-based best practices (radial access for high-risk patients, fractional flow reserve for intermediate lesions, etc.), and risk-adjusted short- and long-term patient outcomes (death, recurrent myocardial infarction, procedural bleeding, target lesion revascularisation). This type of evaluation is more complex than simple counting, but would better reflect quality.” He adds that it also “very important” to evaluate operators in the context of the hospital environment in which they practice, noting that his and his colleagues study “showed that all classes of operators (high-, intermediate-, and low-volume) had better outcomes when performing PCI at higher volume hospitals”.