Intravascular imaging improves PCI outcomes in meta analysis

Stone said there have been a lot of studies on this in the past, and people have done meta-analysis to try to synthesize all the data from past studies. But those studies just were not powered with enough patients to see whether or not there is really a reduction in death or myocardial infarction. He said this new meta analysis was properly powered and includes the studies presented at ESC 2023 and others that include OCT, which has been lacking because it is a newer technology. 

"We basically found was that all of intravascular imaging combined versus angiographic guidance provided real tremendous benefits for the patient. There was a 31% reduction in target lesion failure, overall major adverse events, and there was a 46% reduction in cardiac death. And for the first time ever, we were able to show a 25% reduction in all cause mortality. So one quarter reduction in all cause mortality. We showed that myocardial infarctions were fewer. And very importantly, stent thrombosis was more than 50% reduced with intravascular imaging guidance," Stone explained.

Key takeaways in the study of IVUS vs. OCT. vs angiography

The results of this comprehensive analysis were nothing short of groundbreaking. Intravascular imaging guidance, whether utilizing IVUS or OCT, led to a remarkable 31% reduction in target lesion failure when compared to angiography guidance. 

The primary endpoint of the study was "target lesion failure," which encompasses a composite of cardiac death, target vessel myocardial infarction, or target lesion revascularization. Secondary endpoints included cardiac death, target vessel myocardial infarction, target lesion revascularization, stent thrombosis, as well as all-cause death, all myocardial infarction, and target vessel revascularization.

In addition, Stone said in terms of effectiveness, the data show the target lesion and target artery vascularization were reduced by about 30% with intravascular imaging. 

"So intravascular imaging is one of those rare adjuncts that both enhance the safety and the effectiveness of the stenting procedure," Stone explained.

Digging deeper into the secondary endpoints, intravascular imaging-guided PCI also resulted in a 46% reduction in cardiac death, a 20% reduction in target vessel myocardial infarction, a 29% reduction in target lesion revascularization, and a staggering 52% reduction in stent thrombosis when compared to angiography guidance. Moreover, the study unveiled a remarkable 25% reduction in all-cause mortality, underscoring the life-saving potential of intravascular imaging.

OCT vs. IVUS, which is better?

When comparing OCT and IVUS, Stone said the outcomes were very similar, without any statistical differences between them. Based on the study, Stone said the data show using either type of intravascular imaging is helpful to improve outcomes beyond angiography alone. He said each modality has its pros and cons.

OCT offers much higher resolution imaging, making it much easier for an operator to see structure in the vessel wall and plaques. Its exceptional resolution is particularly valuable in identifying thin cap, lipid core plaques, which are notoriously challenging to detect, Stone said. With a resolution of 10 to 20 microns, OCT can pinpoint plaques with thin fibrous caps, a critical factor in assessing the risk of rupture. The sharper images also help make more accurate measurements.

However, OCT requires a saline flush to clear the blood to enable the light based technology to work. Also being a light-based technology, it has very shallow depth penetration.

IVUS, with its sound wave-based technology, offers excellent depth of penetration, especially in lipid-rich plaques, Stone said. However, its image resolution is much lower, so the images tend to be very grainy and can sometimes be difficult for novice operators to interpret.

Challenges and opportunities for intravascular imaging 

While the findings from this meta-analysis are promising, the broader adoption of intravascular imaging still faces challenges. One significant hurdle is the need for improved training for cardiologists in using these technologies effectively. Not all physicians are familiar with intravascular imaging, and incorporating it into standard practice requires education and hands-on experience. Stone said the cardiology community must invest in training programs to ensure that more physicians are proficient in its use.

Reimbursement for use of intravascular imaging also varies widely. Stone said Japan leads the way in routine reimbursement for intravascular imaging and as a result it is used in about 80% of PCI cases. In the United States and Europe, its utilization remains lower, highlighting the need for consistent reimbursement policies to encourage wider adoption.