Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) are becoming increasingly popular among interventional cardiologists. This is not without reason, as a new study clearly shows that IVUS and OCT have an advantage when it comes to long-term survival.
Coronary angiography is in a state of upheaval. In the past, the X-ray image alone was relied upon, but now better visualization options are available for everyday clinical use. Initially, intravascular ultrasound (IVUS) made its way into the catheter laboratory. With it, the coronary vessel walls can also be displayed without contrast medium. This was followed by optical coherence tomography (OCT), a technique known from ophthalmology. It offers much sharper images than the IVUS and can also detect calcified plaques well. With both methods, stents can be placed more safely and accurately than with traditional percutaneous coronary intervention (PCI). Both methods are still used comparatively rarely, but their use has increased noticeably within a decade. The reason why IVUS- and OCT-supported PCIs have not yet arrived in the mainstream is the lack of good endpoint studies.
A recently published observational study has now for the first time compared the 5-year outcome of the various PCI methods. The study included 87,166 patients who underwent coronary intervention in Greater London between 2005 and 2015. The majority (86.1%) received conventional coronary angiography, while IVUS imaging was used in 12.6% of patients and OCT in 1.3%. Patients with acute ST-elevation myocardial infarction or PCI with Fractional Flow Reserve (FFR) measurement were excluded from the study. In the baseline data, the groups differed in some points. Patients with conventional PCI were about 1-2 years older (on average 65 years), presented more frequently with coronary single vessel disease and generally received their first coronary angiography. For patients with IVUS and OCT therapy, it was often the second intervention. In addition, the two newer procedures were only used to a very limited extent in emergencies.
After five years, 15.7% of patients in the group with conventional PCI died, 12.2% in the IVUS group and 7.7% in the OCT group. In terms of all-cause mortality, the OCT-PCI was superior to the other two methods (p < 0.0001).
Since the results are difficult to interpret due to the different baseline characteristics, the scientists generated three comparable therapy groups by means of a so-called propensity score analysis. Patients with OCT-PCI showed a lower 5-year mortality rate than patients with standard PCI (9.6% vs. 16.8%; p < 0.0001). But the difference between IVUS and OCT PCI now disappeared (9.0% vs. 10.2%; p = 0.12). The same was shown for the rate of severe cardiovascular events (major adverse cardiac event, MACE). Patients with OCT-PCI had a lower risk of developing a MACE compared to patients with standard PCI (0.8% vs. 2.0%; p = 0.01), while OCT and IVUS did not differ (0.8% vs. 1.0%; p = 0.8).
Since the propensity score analysis found no significant differences between IVUS and OCT treatment, the researchers combined both methods and compared them again with conventional coronary angiography. It was found that intravascular visualization - be it with IVUS or OCT - generally leads to fewer deaths (12.3% vs. 15.8%; p < 0.0001). The probability of dying after 5 years is reduced by 37% by PCI with IVUS or OCT (hazard ratio 0.63; 95% confidence interval 0.33 - 0.84; p = 0.0001).
For the first time, it could be shown that IVUS- and OCT-supported coronary angiographies significantly improve long-term survival compared to conventional PCIs. There is even evidence that OCT may offer even more advantages than IVUS-based PCIs. One criticism of the study remains that OCT-PCIs were only performed in very few patients. Another confounder could be the surgeon's expertise. In particular, experienced cardiologists used the possibilities of intravascular visualization. The question remains as to whether they would have produced similarly good results without the novel processes. Overall, however, the data of the study are very promising, so that it is to be expected that they will also find attention in the catheter laboratory.
Jones DA et al. Angiography Alone Versus Angiography Plus Optical Coherence Tomography to Guide Percutaneous Coronary Intervention. JACC: Cardiovascular Interventions. Volume 11, Issue 14, July 2018. DOI: 10.1016/j.jcin.2018.01.274