PCI Volumes Rise in US and Japan, but for Different Reasons

The number of PCIs performed in the United States and Japan is up in recent years, more so in Japan, but the types of cases driving the increase differs between the two countries, according to a new comparative analysis of temporal trends in PCI volume. In Japan, the increase in PCIs was driven by a rise in elective cases, whereas the bump in volume stateside was mainly the result of an increase in nonelective PCIs, report investigators.

Stress testing, mainly myocardial perfusion imaging, was far more common in the United States, while coronary CT angiography (CTA) was the most common imaging test used prior to PCI in Japan. There also were differences in the baseline characteristics of patients treated in the two countries, with the Japanese cohort significantly older and having a much different comorbidity profile. Quality performance in Japan was generally lower than in the United States, except for the administration of antiplatelet agents and the use of transradial PCI.

“This finding highlights that despite improvements over time in Japan, there are still important opportunities to improve the quality of PCI further in both countries,” according to Taku Inohara, MD, PhD (Japanese Association of Cardiovascular Intervention and Therapeutics, Tokyo), and colleagues.

In an editorial, Harold Dauerman, MD (University of Vermont, Burlington), and Michael Mack, MD (Baylor Scott & White Health, Dallas, TX), say they can’t really explain the uptick in PCI volume, since there have been no new trials, guidelines, technologies, or reimbursement changes that would encourage the increase. One possible reason is that interventional cardiologists might simply be embracing percutaneous solutions for CAD “by a mechanism of cultural drift.” Specifically, they think that trials such as FAME, FAME 2, and SCOT-HEART, as well as the low-risk TAVR trials, might have emboldened physicians to better refine patient selection and to optimize percutaneous solutions to cardiovascular disease. 

Elective vs Nonelective: A Blurry Line

Published last week in the Journal of the American College of Cardiology, the new study captures temporal trends in PCI volume between 2013 and 2017 using numbers from the US National Cardiovascular Data Registry (NCDR) CathPCI Registry and the Japanese PCI (J-PCI) registry. In the US, there were 2,965,457 PCIs over the 5-year period, ranging from 550,872 in 2013 to 637,650 in 2017, a 15.8% increase. In Japan, PCI volume grew from 181,750 procedures in 2013 to 247,274 in 2017, a 36% rise.

The climb in PCI volumes in the US was mainly the result of more nonelective PCIs (P < 0.001 for trend), although the number of elective PCIs also increased. In Japan, the increase in PCI volume was largely the result of increasing number of elective PCIs (P < 0.001 for trend). For example, the proportion of elective cases increased from 58.9% in the first quarter of 2013 to 61.2% in the last quarter of 2017.

Ajay Kirtane, MD (NewYork-Presbyterian/Columbia University Irving Medical Center, New York), who wasn’t involved in the study, said these types of global comparisons are challenging given that there are so many variables between two countries located so far apart geographically. Even the diligence with which operators fill out case report forms might differ. Nonetheless, he was struck by just how different the results were between Japan and the US and questioned whether the findings reflect clinical practice.

“To me, these differences are just so great that I personally think this is more of a coding issue, or a way the data is captured, rather than true differences in clinical practice,” said Kirtane. “That’s just my opinion. We interact with a lot of Japanese colleagues at meetings, and I don’t ever get the sense that practice patterns are that disparate, so I can’t help but think this might be related to how the data is captured and/or looked at.”

He added that accurately classifying a case as urgent, elective, or nonelective is not as straightforward as it appears and can be challenging in borderline situations. “Distinctions are there,” said Kirtane. “I think some of [these disparate findings] might have to do with that.” He added that in the wake of COURAGE, more patients were treated with medical therapy and patients coming to the cath lab in the US may be presenting with more symptoms, a possibility that might explain why there was a rise in nonelective cases in the NCDR CathPCI Registry.

In their paper, the researchers posit some possibilities to explain the practice patterns but say the exact reason for them is unknown. The increase in nonelective PCIs might reflect an increase in ACS with an aging population and more-sensitive troponin assays. “Upcoding” patients to classify more as unstable might also be a factor. Like Kirtane, they note that an increased number of patients were managed conservatively after COURAGE and the introduction of appropriate use criteria (AUC) might have resulted in more unplanned revascularizations. In Japan, the increase in elective PCIs might reflect the older cohort having more risk factors for atherosclerotic cardiovascular disease as well as advances in technology that have expanded indications for more-complex procedures.

Overall, just 15.3% of elective procedures in Japan involved stress testing to evaluate ischemia, compared with 55.3% of PCIs in the US. In contrast, CTA was used in 22.3% of elective PCIs in Japan, compared with just 2.0% of cases in the US.  

“The relatively higher proportion of elective PCIs in Japan may be explained by the finding that, in Japan, anatomic information has traditionally been considered the most decisive factor in performing PCI, and functional ischemic assessments have not been emphasized,” according to Inohara and colleagues.  

CTA Used Infrequently in the US

There was a larger prevalence of three-vessel disease and left main coronary artery disease in the Japanese cohort. Researchers used several variables identified by Japan’s professional interventional society to classify the quality of PCIs performed between the two countries and determined that, overall, a significantly larger proportion of PCIs performed in the US were for ACS (81.0% vs 39.3%) and nonelective reasons (66.2% vs 27.3%; both P < 0.001) when compared with Japan. The door-to-balloon time was significantly shorter in the US (57.0 vs 71.0 minutes; P < 0.001), but radial access was more frequent in Japan. 

To TCTMD, Kirtane said he was struck by the different utilization rates of coronary CTA, although he said this may reflect simple economics, given CTA reimbursement difficulties in the US. In terms of the big picture, Kirtane said the determination of “quality” is very challenging when using registry data from the NCDR or J-PCI.

“Even the quality metrics they proposed in their paper, you could argue that there are other things that better define whether somebody ought to have a PCI or not,” he said. “Many of those measures are subjective and less well gathered in a registry such as this. My general sense is that we have to do better at our ability to discern the quality of the indication and the performance of the procedure.”