Automated Algorithm Detecting Physiologic Major Stenosis and Its Relationship With Post-PCI Clinical Outcomes
Condition: Ischemic Heart Disease
MeSH terms: Heart Diseases; Myocardial Ischemia; Coronary Artery Disease
Study type: Observational [Patient Registry]

Summary: 
      The presence of myocardial ischemia is the most important prognostic indicator in patients
      with coronary artery disease. Therefore, the purpose of percutaneous coronary intervention
      (PCI) is to relieve myocardial ischemia caused by the target stenosis. Fractional flow
      reserve (FFR) is an invasive physiologic index used to define functionally significant
      coronary stenosis, and its prognostic implications are supported by numerous studies.
      Contrary to the clear cutoff value and the benefit of FFR in pre-PCI evaluation, there have
      been various results regarding optimal cut-off values for post-PCI FFR. Nevertheless, the
      positive association between post-PCI FFR and the risk of future events has been reproduced
      by several studies.

      PCI with stent implantation is basically a local treatment and post-PCI FFR reflects both
      residual stenosis in the stented segment and remaining disease beyond the stented segment in
      the target vessel(s).

      Therefore, post-PCI FFR alone cannot fully discriminate the degree of contribution of each
      component. The relative increase of FFR with PCI is determined by the interaction of baseline
      severity of a target lesion, baseline disease burden of a target vessel, adequacy of PCI and
      residual disease burden in a target vessel.

      However, the most important problem in stratifying patients with better expected post-PCI
      physiologic results and following clinical outcome would be that there has been no clear
      method to identify these patients in pre-PCI phase.

      In this regard, we hypothesized that the amount of FFR step-up in pre-PCI pullback recording
      would determine the physiologic nature of target stenosis. For example, stenosis with
      sufficient step-up of FFR would deserve local treatment with PCI and these lesions would
      result in higher percent FFR increase, post-PCI FFR, and better clinical outcome than those
      without sufficient amount of FFR step-up.

      For this, we sought to develop automated algorithm to define physiologic major stenosis
      versus minor stenosis using pre-PCI pullback recording.
    

Detailed description: 
      The current study cohort consisted with 3 cohort. In order to derive and validate the optimal
      cut-off values of FFR step-up amount for physiologic major vs minor stenosis and for
      physiologic minor stenosis vs. signal noise, the below 3 cohorts will be used.

        1. Derivation cohort of defining the optimal cut off value of FFR step-up amount for
           physiologic major vs minor stenosis and for physiologic minor stenosis vs. signal noise.

           The cohort of no coronary atherosclerosis confirmed by both angiography and
           intravascular ultrasound will be derived from patients with heart transplantation
           (NCT02798731).

           The cohort of significant focal or diffuse obstructive coronary artery disease with
           functional significance defined by FFR<=0.80 will be derived from post-PCI registry of
           Samsung Medical Center.

        2. Internal validation cohort will be post-PCI registry of Samsung Medical Center which
           enrolled 236 patients who underwent both pre- and post-PCI physiologic assessment after
           angiographically successful PCI using 2nd generation drug-eluting stent. Among this
           cohort, 234 patients with available pre-PCI pullback recording will be analyzed.

        3. External validation cohort will be COE-PERSPECTIVE registry (NCT01873560) which enrolled
           patients who underwent PCI for lesions with FFR<=0.80 and underwent post-PCI physiologic
           assessment.

      Among the 835 patients, 252 patients with available pre-PCI pullback recording will be
      analyzed.

      For the association between physiologic major, minor, or mixed stenosis classified using the
      optimal cut-off values of FFR step-up amount for physiologic major vs minor stenosis and for
      physiologic minor stenosis vs. signal noise, the patient level pooled data of both Samsung
      Medical Center registry and COE-PERSPECTIVE registry will be used.
    

Intervention name(s): Percutaneous coronary intervention
Intervention type(s): Device
Intervention description(s): Pre-PCI FFR pullback recording was done with conventional system
Automated algorithm to calculate delta FFR per unit time was developed
PCI was performed using 2nd generation DES
Other intervention name(s): Fractional flow reserve
Observational model: Case-Control
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients who diagnosed obstructive coronary artery disease and evaluated by pre-PCI FFR
        measurement and pullback recording, then treated by DES with invasive physiologic
        evaluation at the index procedure.
      
Keywords: fractional flow reserve; delta FFR per unit time; percutaneous coronary intervention; prognosis