The purpose of this observational study is to compare the impact of rotational atherectomy to conventional stenting and to investigate how it may affect coronary microcirculation in patients with calcified coronary artery lesions and stable CAD.

The study's objectives are to:

• investigate the impact of rotational atherectomy on the prevalence of post-percutaneuos coronary intervention coronay microvascular dysfunction;
• investigate the impact of conventional stenting on the prevalence of post-percutaneuos coronary intervention coronay microvascular dysfunction; and
• compare the impact of both percutaneuos coronary interventions on coronary microvascular dysfunction.

Patients with calcified lesions will be enrolled prospectively and will have serial invasive and non-invasive microvascular testing prior to and after rotational atherectomy or conventional stenting.

Rotational atherectomy (RA) is a medical procedure used to treat patients with severe atherosclerosis, a condition that causes plaque buildup within the artery walls, resulting in narrowing of the blood vessels and decreased blood flow to the heart. RA is a technique that involves breaking up and removing plaque from the artery with a small, high-speed rotating burr.

However, RA is not without risks. One of the major risks associated with RA is the potential damage to the artery wall and surrounding tissue. This can lead to complications such as bleeding, blood clots, or injury to the heart or other organs. Additionally, the high-speed rotation of the burr can generate heat, which may damage the artery wall or cause the release of harmful particles into the bloodstream.

Another hypothesized risk of RA is its impact on microcirculation, which refers to the smallest blood vessels in the body. RA can cause disruption to these vessels, leading to a decrease in blood flow and potentially causing damage to tissues and organs that depend on them.

The purpose of this study is to look into the effect of rotational atherectomy on coronary microcirculation.

Inclusion Criteria:

• Patient diagnosed with stable coronary artery calcified lesion requiring Percutaneous coronary intervention

Exclusion Criteria:

• patients with a history of old myocardial infarction or history of coronary artery bypass grafting (CABG) or Percutaneous coronary intervention PCI
• Patients with signs of chronic infection, prolong usage of corticosteroids or compromised immune system
• patients had contraindication of adenosine triphosphate (ATP);
• had a history of liver or renal function dysfunction
• Patients with dementia
• Patients being referred to CABG
• unable to provide informed consent;
• had pregnancy or life span < 1 year.
• Presence of sever structural valvular heart disease
• Presence of significant left main disease
• Unability to measure the index of microcirculatory resistance due to (death or retraction from the study ...etc)
• Inability to perform successful PCI