Coronary calcification is more prevalent in men older than seventy, compared to women counterpart and younger men cohort [1]. According to the U.S. Census Bureau, the population aged 65 and older is projected to increase by 47 % from 2020 to 2050 and the prevalence of calcific coronary artery disease is projected to increase accordingly [2]. Coronary calcifications can be in intima, media, and peri adventitia coronary layers. Intimal coronary calcification can cause significant luminal obstruction while media and peri adventitia calcification can cause reduction in vascular compliance [3]. All of these hinder device delivery, equipment impairment or entrapment, stent under expansion with overall increased peri procedural complication for percutaneous coronary intervention (PCI).

After angiographically successful PCI, up to 30 % of coronary lesions are still ischemic (FFR < /= 0.8) [4]. It is known to have sub optimal result post PCI defined by FFR in coronary lesions treated with long stent particularly in total stent length exceeded 50 mm [5]. According to the study done by Collet et al., after PCI, in stent pressure gradients were significantly lower in the group treated with intravascular Lithotripsy (IVL) compared to rotational atherectomy group (RA) [6].

Wang et al. published a study in this issue of Cardiovascular Revascularization Medicine, to assess the effectiveness of IVL gauged by anatomical and physiological results in different subtypes of calcifications [7]. Calcification phenotype of eccentric vs concentric was defined by OCT finding of mean calcium arc extension of 180 degree or more. Physiologic/hemodynamic pattern of focal vs diffuse lesion was defined by OCT-fractional flow reserve (OFR) and quantitative flow reserve (QFR). Post PCI OFR/QFR, minimal stent area (MSA), and Angio derived index of microvascular resistance Angio-IMR) were measured. As a limitation of this study, pre or post PCI pullback pressure gradient, PPG was not done.

The study size is small with eighty-eight lesions. IVL was used for lesion modification in all cases, with 1:1 balloon to artery ration measured by OCT. The number of IVL pulses used post IVL balloon dilatation and post stent balloon dilation were at the discretion of operators. OCT was performed prior to IVL, immediately after IVL and after final stenting and optimization. The most diffuse lesions were noted to be in left anterior descending artery. The length of stent in diffuse arm in this study was 34–43 mm. It was not statistically significant in terms of minimal stent expansion between focal and diffuse lesions or concentric vs eccentric lesions, following stenting and optimization. All lesions achieved non ischemic OFR and QFR valves after stent implantation (>/= 0.8). When OFR of >/= 0.9 was used considering high post PCI epicardial flow thresholds, % of lesions achieving 0.9 or more of OFR and QFR were higher in focal lesions, compared to diffuse lesion. Only 43.6 % of diffuse lesions achieved 0.9 or above OFR. No difference was found between concentric vs eccentric lesions. Medium angio-IMR following IVL was below 25, suggesting minimal downstream embolization to distal microvasculature with IVL technique in calcium modification. At multi variate analysis, diffuse calcium pattern was the strongest predictor for sub optimal post PCI QFR values.