The most recent epidemiological data from 2007 showed that the overall death rate from cardiovascular disease in the United States was 204.3 per 100 000 persons, making it the leading cause of death in both men and women.13
However, the age-adjusted death rate for coronary heart disease has been steadily decreasing since the 1980s, likely as a result of improved risk factor modification and cardiovascular therapies. 14
The trends in coronary catheterization volumes observed in our study from 2001 to 2004 are consistent with previous reports that showed steady increases in PCI volumes during that period.15
Our data also show that the total and per-beneficiary numbers of diagnostic and interventional catheterizations in the Medicare population have been decreasing steadily since 2004. Although there was stabilization in the number of catheterizations in 2009, the overall trend from 2004 to 2009 remained in decline, with the total number of coronary revascularizations (PCI and CABG combined) declining over the 9-year period studied. The rate of decline in CABG surgeries continued to outpace that of the decline in PCI.
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.
WHAT IS KNOWN
- In prior decades, diagnostic and interventional coronary catheterization rates have increased, whereas there has been a concurrent decrease in coronary artery bypass graft (CABG) surgery rates in the United States.
- Several factors, such as the publication of the COURAGE (Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation) trial, may have influenced rates of diagnostic and interventional coronary catheterization in recent years.
WHAT THE STUDY ADDS
- Diagnostic and interventional coronary catheterization rates within the Medicare population have steadily declined since 2004.
- Rates of intravascular ultrasound and fractional flow reserve use per catheterization have steadily been increasing within the Medicare population over the past several years.
- Given the declines in both CABG surgery and percutaneous coronary intervention since 2004, the use of percutaneous coronary intervention does not appear to entirely explain recent declines in CABG surgery rates.