Orbital atherectomy is associated with less acute microvascular injury than rotational atherectomy, reported Ziad Ali (St Francis Hospital & Heart Center, Roslyn, USA) at the EuroPCR (19–21 May, Paris, France) 2026 congress, yet underscored the “dynamicity” of the microcirculation, noting that physiological differences between the two modalities normalised by the end of the procedure.
Providing background for their hypothesis, Ali described that “severely calcified lesions may sometimes necessitate atherectomy to facilitate PCI [percutaneous coronary intervention]”. “It’s unquestionable that atherectomy generates microparticles that may embolise and then induce arrhythmia as well as potentially compromise haemodynamics,” Ali told EuroPCR attendees.
“There have been anecdotal reports, perhaps even experiential, where there was less pacing and less haemodynamic compromise using orbital versus rotational atherectomy. There are a number of purported reasons why this might be. So, we hypothesised that orbital atherectomy has less impact on the microcircuitry function compared to rotational atherectomy,” he said.
The investigators of the mechanistic randomised controlled trial enrolled 40 patients—20 to each study arm. Ali noted that included patients were required to have calcium lesion lengths of more than 20mm to ensure contact between the arthrotome to create debris. Each patient underwent baseline physiology assessments which were repeated immediately before and after treatment. The study’s primary endpoint was post-atherectomy on the Index of Microcirculatory Resistance (IMR).
Between groups, baseline characteristics were similar; patients had an average age of 66 years, 67% were male and 95% of both arms presented with hypertension. Importantly, Ali added that ejection fraction was similar between the two groups. Patients in the orbital and rotational atherectomy arms had “relatively” long lesions of 34mm and 44mm, respectively.
Procedural characteristics were similar between groups; however, Ali made mention of the lengthy procedure times across both groups, attributing this to repeated microvascular assessments during cases. Between groups there was no difference in total number of runs, although the total procedure duration was longer using orbital atherectomy. Ali added that lower peri-PCI blood pressure was noted with rotational atherectomy when compared to orbital.
The investigators found a significant increase in the median IMR with rotational atherectomy immediately following treatment. Displaying a spaghetti plot for the EuroPCR audience, Ali illustrated the “sudden spike” in IMR during the procedure, drawing attention to its similarly sharp resolution by the end of intervention.
“What we’re really seeing is a transient microcirculation dysfunction, likely from particular debris, and it shows the dynamicity of the microcirculation, which can recover very quickly and is very consistent with what we see in STEMI [ST-segment elevation myocardial infarction],” Ali stated.
During atherectomy, or peri-atherectomy, Ali described that coronary flow velocities reduce with rotational atherectomy. “Very interestingly and correspondingly, post-atherectomy FFR [fractional flow reserve] increases. That’s likely because the microcirculation is paralysed and is unable to react to adenosine,” he added.
During discussion, Ali was asked whether these findings should make operators more mindful about the technique used during rotational atherectomy, for example, using shorter passes and waiting longer between passes, so that any debris or “clogging” has time to wash out before moving on to the next pass. To this, Ali admitted that a caveat to the present study was that procedures were performed to standard of care and according to each operator’s usual rotational atherectomy technique, and so they could not determine correlation between technique and outcomes. “Technique could have a lot to do [with the results],” Ali said.
Subsequently, Ali addressed whether reduced flow translates to myocardial injury, stating that the investigators did collect serial cardiac enzyme measurements in these patients.
“Unfortunately, midway through the study, we changed assays, which makes it difficult to perform a consistent analysis across the entire cohort, which is unfortunate, because it would have helped answer exactly how much myocardial injury was occurring,” Ali stated. “If I were redesigning the study, I would collect serial cardiac enzyme data and keep patients in hospital long enough to construct those curves. I would also include pre- and post-procedure MRI [magnetic resonance imaging]. We attempted to do this, but unfortunately it was not feasible.”
