Impact of Lesion Characteristics on the Result of Coronary FFR Measurements

Document Type
Doctoral Thesis
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Feyrer, Johannes
  1. Summary 2.1. Background In order to identify significant stenoses of coronary arteries almost one million coronary angiographies are performed in Germany each year. There is no correlation between the angiographically represented severity of coronary stenoses and the resulting ischemia. Therefore, measurement of the Fractional Flow Reserve (FFR) has become routine in clinical practice. The purpose of this study was to systematically analyze indications and consequences of intracoronary pressure measurements in a large patient cohort. In particular, we aimed to identify lesion characteristics that significantly influence the results of pressure wire measurement in clinical practice. The influence of the way of adenosine application on the FFR measurement results is of further interest in this study. 2.2. Methods We prospectively collected data of a cohort of 2000 consecutive patients undergoing clinically indicated FFR, iFR or Pd/Pa measurements in 8 interventional centers in Germany. Data included basic patient characteristics, procedural aspects of intracoronary pressure measurements, visually estimated stenosis degree, measurement results, treatment decisions and associated complications. 2.3. Results During the trial period, 3377 pressure wire measurements were performed. The mean patient age was 68±11 years and 73% of all patients were male. 15% of patients had an acute coronary syndrome and 49.7% had undergone previous revascularization. A mean of 1.69±0.9 measurements were performed per patient. The median visually estimated stenosis degree was 60%. For vasodilation, i.v. adenosine was used in 13%, i.c. adenosine in 87% and Regadenoson in 0.3% (i.v. 7/10). Vasodilator-free measurements were performed in 12.4% of all cases (iFR: 349; Pd/Pa: 69). In 96% of all cases measurements were performed before potential revascularization and in the remaining cases during or following PCI. Most lesions leading to FFR measurement were located in the left anterior descending artery (LAD; 58%) or RCX (22%). In 87.4% of all cases the measurement was performed in main branches. The mean FFR value was 0.87. Measurement in the LAD was most frequently followed by revascularization (28.8%). Overall intracoronary pressure measurement was followed by revascularization in 21.9% of all cases. In 31% (36/117) of all measurements with a visually estimated stenosis degree of over 90%, revascularization was denied due to FFR measurement. In 4.7% of all lesions analyzed by FFR, revascularization was performed even though FFR was > 0.80. Only FFR measurements in native coronary arteries were considered to identify the predictors for pathological FFR values. Thereby 2818 measurements remained. Among men 22.8% of the measurements were pathological, compared to 12.6% in females. Measurements using the microcatheter system revealed significantly more pathological FFR values compared to pressure wire measurements (ACIST: 35.5% vs. St. Jude Medical™:19.4%; Philips/Volcano: 23.2%). Data in the LAD was pathological in 26.5% of all cases. Abnormal measurements in the RCX occurred in 7.8% of all cases. In the RCA 15% of all measurements were pathological. 15.6% of the FFR results in the LM were pathological. Abnormal FFR values in main and side branches occurred in 20.7% and 15.2% of all measurements. During examination of ACS culprit lesions, pathological FFR values were measured in 65% of all cases. Measurements of non-culprit lesions were pathological in 18.4%. The following lesion characteristics turned out to be independent predictors for pathological FFR values: participating sites, sex, pressure wire, stenosis degree, localization of the lesion and ACS culprit lesion. 2.4. Conclusion In clinical practice, the majority of intracoronary pressure measurements are performed in stenoses of intermediate angiographic severity and revascularization is deferred in approximately 80% of all lesions. Most lesions leading to revascularization are located in proximal segments of the LAD or RCX. Study sites, sex, pressure wire, stenosis degree, localization of the lesion and ACS culprit lesion are independent predictors of pathological FFR. The route of adenosine administration has no effect on results.
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