The concept of the "ischemic cascade" is generally accepted hypothesis, according to which whenever ischemia of the myocardium occurs there is a consequence of events, that always occur in a given order - diastolic dysfunction first, followed by systolic dysfunction, then changes on electrocardiogram (ECG) and finally chest pain sensation. The occurrence of every next stage of cascade means more severe ischemia and respectively - more severe myocardial damage. We propose that mechanical and electrical changes in the myocardium during ischemia appear simultaneously.

The development of an ischemic event, whether silent or painful, represents the cumulative impact of a sequence of pathophysiologic events. Each ischemic episode is initiated by an imbalance between myocardial oxygen supply and demand that may ultimately be manifested as angina pectoris. The ischaemic cascade is the concept that progressive myocardial oxygen supply-demand mismatch causes a consistent sequence of events, starting with metabolic alterations and followed sequentially by myocardial perfusion abnormalities, wall motion abnormalities, ECG changes, and angina. This concept would suggest that investigations that detect expressions of ischaemia earlier in the cascade should be more sensitive tests of ischaemia than those that detect expressions appearing later in the cascade.Visualization of a regional decrease in the systolic movement of the endocardium and a decrease in myocardial thickening are the main principles for the diagnosis of myocardial damage. However, the concept of ischaemic cascade is entirely based on clinical observations. It is not clear, which changes (mechanical or electrical) appear first during an episode of ischemia and which are prognostically more important. The objective of this study is to compare ischemic cascade towards ischemic constellation regarding beginning, duration and sequence of the electric, kinetic and haemodynamic signs of ischemia by FFR, icECG and wall motion abnormalities sign (M-sign - deformation and shortening of the wire tip) in patients with coronary bifurcation stenosis

Inclusion Criteria:

• Subject at least 18 years of age.
• Subject able to verbally confirm understandings of risks, benefits of receiving PCI for true bifurcation lesions, and he/she or his/her legally authorized representative provides written informed consent prior to any study related procedure.
• Target main branch lesion(s) located in a native coronary artery with diameter of ≥ 2.5 mm and ≤ 4.5 mm. Target side branch lesion(s) located in a native coronary artery with diameter of ≥ 2.0 mm.
• Target lesion(s) amenable for PCI with balloon angioplasty of the side branch.

Exclusion Criteria:

• Subjects with significant ST-T change (≥ 1mm).
• Non-cardiac co-morbid conditions are present with life expectancy <1 year or that may result in protocol non-compliance (per site investigator's medical judgment).
• Subjects who refuse to give informed consent.
• Subjects with the following angiographic characteristics: left main coronary artery stenosis, total occlusion before occurrence of SB, lesion of interest located at infarct-related artery.
• Subjects with LVEF < 30%.
• Subjects with moderate or severe degree valvular heart disease or primary cardiomyopathy.
• LBBB, RBBB, atrial fibrillation/flutter with no identifiable isoelectric line.

• Significant, >50% diameter stenosis artery scheduled for intervention of the main vessel (Medina types: 1x1, x11, 111);
• Side branch vessel at least 2.0 mm