Rotational atherectomy is reasonable for fibrotic or heavily calcified lesions that might not be crossed by a balloon catheter or adequately dilated before stent implantation.514,515,520 (Level of Evidence: C) The presence of coronary calcification is a marker for significant CAD and increased long-term mortality.753 Calci- fied coronary lesions are not a homogenous entity, and their response to PCI varies according to severity of calcification. Levine et al 2011 ACCF/AHA/SCAI PCI Guideline e611 Severely calcified lesions respond poorly to balloon angio- plasty,230,754 and when stents are implanted in such lesions, an incomplete and asymmetrical stent expansion occurs in the majority of cases.755 Attempts to remedy the underexpanded stents with aggressive high-pressure balloon dilatation may result in coronary artery rupture.756 All the published pro- spective RCTs that evaluated the various catheter-based coronary interventional devices excluded patients with se- verely calcified lesions. Therefore, the evidence base for best PCI practices in patients with severely calcified lesions comes from nonrandomized single-arm studies. Among the various adjunct devices that are used to facilitate PCI in severely calcified lesions, only rotational atherectomy has been shown to have potential utility.514,757 Although rota- tional atherectomy increases the chances of angiographic success in severely calcified lesions, its use as a stand-alone device has not led to a reduction in restenosis.520,521,758 Several retrospective studies have shown that in patients with severely calcified lesions, the use of rotational atherectomy before implantation of BMS514 or DES515 is safe. Intermediate-term patency is more favorable with DES than 5.9. PCI in Specific Patient Populations Several specific patient subsets with higher risks for PCI, and at times higher absolute clinical benefit, have traditionally been underrepresented in RCTs and are described below. 