Operator Volume Matters in Left Main PCI: BCIS Analysis

NATIONAL HARBOR, MD—Patients with unprotected left main coronary artery disease treated by high-volume operators have better clinical outcomes, including fewer major adverse cardiovascular events and improved survival, than those treated by low-volume operators, according to a new analysis from the British Cardiovascular Intervention Society (BCIS) national database.

When compared with the lowest-volume operators performing an average of just two left main stem PCIs each year, the adjusted risk of death at 1 year was 46% lower in patients treated by interventionalists who performed an average of 21 left main PCIs each year (OR 0.54; 95% CI 0.39-0.73).

“Previous studies of operator volume of PCI and outcomes in unselected cohorts have yielded rather mixed results, with some studies showing a relationship with higher volume and outcomes and others showing a lack of relationship,” lead investigator Tim Kinnaird, MD (University Hospital of Wales, Cardiff), said at CRT 2020 last week. “That may be because for many unselected PCIs, it was not technically challenging and the experience of the operator may not be that important. Obviously, given the complexity of the left main distal bifurcation and the amount of myocardium in jeopardy, operator experience might be relevant for outcomes in left main PCI.”

In 2016, a study from China suggested that operator volume is an important variable to consider when seeking to optimize clinical outcomes after PCI for left main CAD. At that single center, patients treated by an experienced operator—one who did at least 15 left main PCIs annually for 3 consecutive years—had significantly lower rates of cardiac death at 30 days and 3 years.  

In the BCIS database, the researchers identified 6,724 PCIs of the left main stem performed between 2012 and 2014. Operator volume ranged from one to 54 procedures annually and operators were stratified by annual mean volume into four quartiles—Q1: two procedures (n = 347), Q2: five procedures (n = 134), Q3: 10 procedures (n = 59), and Q4: 21 procedures (n = 29).

At the end of the day, what would you want for your family? Would you want it done by a guy who does two a year or somebody who does 20 a year? Tim Kinnaird

To TCTMD, Kinnaird noted that higher-volume operators were less selective in the patients they took on, treating older patients with more comorbidities than those less experienced in left main PCI. Higher-volume operators also were more likely to engage in more complex procedures, such as tackling the proximal LAD and/or left circumflex artery in addition to the left main stem.

When compared with Q1 operators, the adjusted the odds of in-hospital MACE and in-hospital mortality was 59% and 61% lower, respectively, in patients treated by operators in Q4. Additionally, the risk of periprocedural MI and any procedural complications were 88% and 36% lower, respectively, in the most experienced operators compared with the least experienced.

What’s the Magic Number?

Kinnaird said the big question with respect to guidelines and establishment of services for the treatment of left main CAD is the appropriate number of cases an operator should perform each year to ensure optimal outcomes. In their analysis, they observed an improvement in the adjusted rate of death at 1 year in operators who performed 16 to 20 procedures each year.

“I guess that if you were to pick a number, you might pick 16 [cases per year],” said Kinnaird. “That’s the first time you see a ‘step-down’ in 12-month mortality. That’s a magic number you might consider as the minimum for improved outcomes.”

Taisei Kobayashi, MD (Hospital of the University of Pennsylvania, Philadelphia), said that in the United States, if unprotected left main CAD is identified on the diagnostic angiogram, operators in smaller, community hospitals will typically take the patient off the table and refer them to larger centers with physicians more experienced in left main PCI. In the United Kingdom, Kinnaird said that like in the US, there is variability in how left main PCI is treated.

“We have ad hoc [PCI], we have staged in-house, and we have staged referred, but I don’t think there is that much staged PCI referred to a different hospital, which I think is a shame,” said Kinnaird. “I think egos and empire building and financial incentives potentially get in the way of patient pathways. I think this data supports what we’ve seen the orthopedic surgeons do in our hospital. We’re a big teaching hospital, and we have two or three guys that just do a particular knee operation, for example. I don’t think we’ve matured in that way in interventional cardiology, but data like this should support that type of inter- and intrahospital referral pathway. It would benefit the patient.”

Overall, left main PCI represents approximately 3% of overall PCIs. The way it works out, an average interventional cardiologist might not see more than two, three, or four cases per year, said Kinnaird.

While some centers might be reluctant to hand patients with left main disease over to another hospital, these results imply that “you’d want to have the PCI done by somebody who knows what they’re doing and have done enough procedures,” Kinnaird told TCTMD. “At the end of the day, what would you want for your family? Would you want it done by a guy who does two a year or somebody who does 20 a year?