For reimbursement purposes, Medicare recognizes 3 coronary arteries: right coronary, left circumflex coronary, and left anterior descending coronary. In multivessel PCI, it is possible that a physician may report up to 3 percutaneous interventions if an intervention is performed in each of the 3 coronary arteries or their branches. The first reported procedure must use a primary code (CPT codes 92980 and 92982) corresponding to the most complex procedure performed. The procedures performed in the other 1 or 2 coronary arteries (including their branches) are reported with the CPT add-on codes (CPT codes 92981 and 92984). Therefore, multivessel PCI, as per Medicare billing guidelines, was defined as intervention in a vessel different from the vessel in which an initial stent was placed, billed separately and in addition to the initial vessel that received intervention. This definition differentiated multivessel stenting from both single-vessel stenting and multiple stents being placed within a single vessel (which was billed as single-vessel stenting).

From 2001 to 2009, the use of PCI with stenting increased from 10.2 to 12.4 per 1000 beneficiaries. Similar to the temporal trend seen with diagnostic catheterizations between 2001 and 2004, the mean year-to-year change in coronary stenting increased 11.3% per year per 1000 patients, but from 2004 to 2009, there was a mean annual decrease of 2.4% (Figure 2). PCI using balloon angioplasty alone decreased steadily between 2002 and 2005 and remained at roughly 1 per 1000 beneficiaries for the remainder of the period (Figure 1). Overall, the average annual increase in PCI (stenting and angioplasty alone) per 1000 beneficiaries was 1.3% over the 9-year period. The increase in volume primarily was seen between 2001 and 2004, whereas a mean annual rate of decline of 2.5% was seen between 2004 and 2009 (Figure 2).

The use of coronary angiography and PCIs increased annually from 2001 and peaked in 2004, whereas there were notable percentage decreases in 2005 and 2007. In 2009, the number of diagnostic catheterizations and PCI procedures increased slightly compared to 2008, but were still well below the 2004 levels. In contrast, CABG procedures declined consistently from 2001 to 2008 by ≈4% to 7% per year followed by a slight increase in CABG procedures per beneficiary in 2009. The ratio of PCI to CABG procedures performed increased steadily from 1.05 in 2001 to 1.72 in 2009, demonstrating that the rate of decline in CABG was greater than PCI over the entire period. The number of multivessel stenting procedures remained relatively constant over time at ≈12% of PCIs using stents (Table).

There are numerous possible explanations about why coronary catheterization rates have started to decline over the past several years. One explanation might be increased treatment of atherosclerotic risk factors over the past decade. It has been previously estimated that 44% of the reduction in US deaths due to coronary heart disease from 1980 to 2000 was due to risk factor modification.¹⁴ The Centers for Disease Control and Prevention recently published a report that showed that the prevalence of smoking among US adults decreased by 3.5% from 1998 to 2008.¹⁶ There also are data showing that an increasing percentage of the US population is achieving target blood pressure and cholesterol goals.^17,18 The Medical Expenditure Panel Survey published a report in 2008 that showed nearly a doubling in statin prescriptions from 2000 to 2005 (89.7 versus 173.7 million) in the US population. ¹⁹ There is also evidence for increasing prescriptions for β-blockers among patients with known coronary artery disease.²⁰

Another possible explanation for these trends could be the increasing use of DES during this period. After their initial approval by the US Food and Drug Administration in 2003, DES were used in as many as 90% of all PCIs in the United States by 2006.²¹ In a similar Medicare population, it was reported that the use of bare-metal stents in PCI decreased from 89% in 2001 to 19% in 2004. Similarly, the use of DES increased to 75% of all stents placed in this population in 2008. Concurrently, significant reductions were found in the need for repeat revascularization in this population over that period.¹⁵ The reduction of in-stent restenosis from the use of DES could have led to fewer repeat angiograms and repeat revascularization procedures. On the other hand, the concerns for increased stent thrombosis of DES in the latter part of this period also may have contributed to the decrease in PCI seen after 2004.²²

Additionally, it is possible that more patients with stable angina are being primarily medically managed or evaluated with noninvasive imaging before diagnostic catheterization or coronary revascularization. In a recent single-center study, patients referred for angiography following publication of the COURAGE trial were more often treated with aggressive disease-modifying agents before referral for catheterization than were pre-COURAGE patients. In the same study, it also was noted that patients with stable angina and significant coronary artery disease on angiography were more likely to receive medical therapy rather than revascularization as initial treatment management post-COURAGE.²⁰ An increased use of primary medical management along with an increasing use of noninvasive coronary imaging²³ likely have contributed to decreasing catheterization and revascularization rates, although the COURAGE trial itself would not explain our results because it was not published until 2007.

During the same period in which PCI rates have been decreasing, the rates of IVUS and FFR use per catheterization have been steadily increasing within the Medicare population. This increased use could be related to the increased complexity of coronary artery disease being managed percutaneously. Conversely, the increased hemodynamic assessment of coronary lesions using FFR and anatomic assessment using IVUS could have contributed to the decrease in PCI. However, these changes in procedure volume were comparatively small, and their contribution to the overall changes in revascularization volumes was likely trivial.

There are several limitations to our study. First, patient-level data, the indication for each type of procedure, procedure priority (emergent versus nonemergent), and stent type (bare metal versus drug eluting) were not available for our study population, making it difficult to evaluate the contribution of these factors on the observed trends. Another limitation, inherent to studies based on physician billing codes, is that we were unable to account for the contribution of improper billing on our results. Underbilling due to accidental physician omission or overbilling for multivessel PCI (eg, billing for multivessel PCI when stenting the left anterior descending coronary artery plus a diagonal artery, which should be billed as single-vessel PCI) are 2 such examples. Finally, the older population within Medicare may not reflect the patient population of the United States as whole because trends in the use of diagnostic and interventional cardiac procedures may differ between older and younger patients. Nevertheless, Medicare is the largest insurance carrier in the United States and is likely representative of national trends.¹⁵

In summary, the use of diagnostic and interventional coronary catheterizations within the Medicare population has been steadily declining since 2004. Although there was some stabilization of these trends in 2009, they are reminiscent of the decline in CABG rates that started in the late 1980s, which was initially attributed to the expanding use of PCI. Given the declines in both CABG and PCI since 2004, the use of PCI does not appear to entirely explain the decline in CABG rates. Potentially, the decline in CABG surgery volume was simply the canary in the coal mine that signaled larger-scale reductions in the need for coronary revascularization as risk factor modification and cardiovascular therapeutics continue to improve.