Patrick W. Serruys

Comparative validation of quantitative coronary angiography systems. Results and implications from a multicenter study using a standardized approach.

BACKGROUND Computerized quantitative coronary angiography (QCA) has fundamentally altered our approach to the assessment of coronary interventional techniques and strategies aimed at the prevention of recurrence and progression of stenosis. It is essential, therefore, that the performance of QCA systems, upon which much of our scientific understanding has become integrally dependent, is evaluated in an objective and uniform manner. METHODS AND RESULTS We validated 10 QCA systems at core laboratories in North America and Europe. Cine films were made of phantom stenoses of known diameter (0.5 to 1.9 mm) under four experimental conditions: in vivo (coronary arteries of pigs) calibrated at the isocenter or by use of the catheter as a scaling device and in vitro with 50% contrast and 100% contrast. The cine films were analyzed by each automated QCA system without observer interaction. Accuracy and precision were taken as the mean and SD of the signed differences between the phantom stenoses, and the measured minimal luminal diameters and the correlation coefficient (r), the SEE, the y intercept, and the slope were derived by their linear regression. Performance of the 10 QCA systems ranged widely: accuracy, +0.07 to +0.31 mm; precision, +/- 0.14 to +/- 0.24 mm; correlation (r), .96 to .89; SEE, +/- 0.11 to +/- 0.16 mm; intercept, +0.08 to +0.31 mm; and slope, 0.86 to 0.64. CONCLUSIONS There is a marked variability in performance between systems when assessed over the range of 0.5 to 1.9 mm. The range of accuracy, intercept, and slope values of this report indicates that absolute measurements of luminal diameter from different multicenter angiographic trials may not be directly comparable and additionally suggests that such absolute measurements may not be directly applicable to clinical practice using an on-line QCA system with a different edge detection algorithm. Power calculations and study design of angiographic trials should be adjusted for the precision of the QCA system used to avoid the risk of failing to detect small differences in patient populations. This study may guide the fine-tuning of algorithms incorporated within each system and facilitate the maintenance of high standards of QCA for scientific studies.

Quantitative coronary angiography in clinical practice

Foreword. Introduction. Part I: Validation of QCA: In vitro and in vivo, off-line and on-line studies. Part II: The QCA Core Laboratory: practical lessons learned and application to clinical practice. Part III: Physiological applications of QCA, correlation with intracoronary physiological measurements obtained by alternative methodology. Part IV: QCA in the study of vasomotion. Part V: QCA in the setting of acute coronary syndromes, evaluation of the role of thrombolysis and balloon angioplasty. Part VI: QCA applied to the evaluation of immediate and long term outcome following coronary balloon angioplasty: experiences emerging from large multicentre restenosis prevention trials. Part VII: Evaluation of new devices and comparison with balloon angioplasty using QCA. Part VIII: QCA applied to the natural history of atherosclerosis. Part IX: Intravascular ultrasound and QCA. Index.

Advances in Quantitative Coronary Arteriography

Part 1: quantitative coronary arteriography (QCA) versus other modalities. Part 2: QCA - cinefilm versus digital arteriography. Part 3: quality control in QCA. Part 4: coronary blood flow and flow reserve. Part 5: QCA in regression/progression of atherosclerotic disease. Part 6: QCA in restenosis studies. Part 7: QCA after recanalization techniques in coronary arteries. Part 8: QCA and intracoronary prostheses. Index.

Progress in quantitative coronary arteriography

Part 1 Endothelial Function: Endothelium control of vascular tone and growth - potential role in coronary artery disease T.F. Luescher. Endothelial function in athersclerosis F. Charbonneau, I.T. Meredith, T.J. Anderson, M. Gerhard, M. Dyce, D. Delagrange, A.P. Selwyn, P. Ganz. Part 2 QCA - Digital and Cine Coronary Arteriography: Why and how should QCA systems be validated? J.H.C. Reiber, G. Koning, C.D. von Land, P.M.J. van der Zwet. Percutaneous implantation of coronary stenosis phantoms in an anaesthetized swine model to validate current quantitaive angiography analysis systems J. Haase, D. Keane, C. Di Mario, J. Escaned, Y. Ozaki, C.J. Slager, R. van Bremen, W.J. van der Giessen, P.W. Serruys. Comparison of accuracy and precision of quantitative coronary arterial analysis between cinefilm and digital systems J.H.C. Reiber, C.D. von Land, G. Koning, P.M.J. van der Zwet, R.C.M. van Houdt, M.J. Schalij, J. Lesperance. Angiographic core laboratory analyses of arterial phantom images - comparative evaluations of accuracy and precision G.J. Beauman, J.H.C. Reiber, G. Koning, R.C.M. van Houdt, R.A. Vogel. Task force of the ESC on digital cardiovascular imaging R. Simon. Which media are most likely to solve the archival problem? J.T. Cusma, T.M. Bashore. Part 3 Intracoronary Pressure, Coronary Blood Flow and Flow Reserve: Control and mechanics of the coronary circulation J.A.E. Spaan. Possibilities and limitations of myocardial flow reserve F. Zijlstra, P. Widimsky, H. Suryapranata. Myocardial flow reserve - on-line versus off-line assessment techniques M.M.J.M. van der Linden, J. Haase, P.W. Serruys. On-line assessment of myocardial flow reserve M.J. Schalij, M.J.A. Geldof, P.M.J. van der Zwet, E.T. van der Velde, E.M. Nagtegaal, V. Manger Cats, J.H.C. Reiber, A.V.G. Bruschke. Relationship between transstenotic pressure gradients and coronary angiographic parameters H. Emanuelsson, C. Lamm, M. Dohnal. Intracoronary pressure measurements for calculation of flow reserve N.H.J. Pijls, B. De Bruyne, S. El Biltagui, M. El Gamal, H.J.R.M. Bonnier, G.R. Heyndrickx, K.L. Gould, R. Kirkeeide, G.J.W. Bech, J.J. Koolen, H.R. Michels, F.A.L.E. Bracke, W. Wijns. Intracoronary Doppler flow velocity in coronary interventions M.J. Kern. The instantaneous hyperemic pressure-flow relationship in conscious humans C. Di Mario, R. Krams, R. Gil, N. Meneveau, P.W. Serruys. (Part contents).

Restenosis after intervention with new mechanical devices

Assessment of stenosis/restenosis - present and future intravascular imaging restenosis and new techniques stents atherectomy rotational ablation lasers.

New developments in quantitative coronary arteriography

This selection of contributions to a symposium held in Rotterdam in June 1987 serves as an aid to clinical decision making through the application of more rigorously quantitative analysis to coronary angiograms. Topics include arterial stenosis quantitation, coronary flow and myocardial perfusion, c

Percutaneous implantation of coronary stenosis phantoms in an anesthetized swine model to validate current quantitative angiography analysis systems

Computerized quantitative coronary angiography (QCA) has basically altered our approach to the assessment of interventional techniques and strategies aimed at the prevention of restenosis and progression of coronary artery disease [1, 2]. With an increasing number of QCA systems being developed, and a growing number of core laboratories for the analysis of multicenter angiographic studies, it has become crucial that the performance of QCA systems, upon which much of our scientific understanding has become integrally dependent, is evaluated in an objective and uniform manner [3].

How to assess the immediate results of PTCA. Should we use pressure gradient, flow reserve or minimal luminal cross-sectional area?

Intracoronary blood flow velocity measurements with a Doppler probe, and the radiographic assessment of myocardial perfusion with contrast media have previously been used to investigate regional coronary flow reserve. We have applied both techniques in the same patients to measure the immediate improvement in coronary flow reserve as a result of angioplasty. In a group of 13 consecutive patients with a single proximal stenosis, coronary flow reserve was measured pre- and post-angioplasty by digital subtraction cineangiography, while Doppler measurements before and after papaverine were obtained pre- and post-angioplasty in the proximal part of the stenotic vessel. As a result of the angioplasty, coronary flow reserve measured with the radiographic technique (mean ± s.d.) increased from 1.1. ± 0.4 to 2.2 ± 0.4 (p < 0.001), while coronary flow reserve measured with the Doppler probe (mean ± s.d.) increased from 1.2 ± 0.3 to 2.4 ± 0.4 (p < 0.001). Pharmacologically induced hyperemia measured with the radiographic technique and with the Doppler probe were linearly related (r = 0.91 with an SEE = 0.3); this excellent relation confirmed the reliability of the intracoronary measurements. Using these two independent techniques coronary flow reserve immediately after angioplasty was found to be substantially improved but still abnormal. In a more recent study, we selected 18 patients without angina and with normal exercise thallium scintigraphy 5 months after successful percutaneous transluminal coronary angioplasty. We compared their coronary flow reserve with the flow reserve of 24 patients with angiographically normal coronary arteries, to establish whether angioplasty can restore coronary flow reserve of atherosclerotic coronary arteries to a normal level. We studied the quantitative cineangiographic changes and the concomitant alterations in coronary flow reserve resulting from angioplasty, as well as the subsequent changes 5 months later. Coronary flow reserve was measured with digital subtraction cineangiography. Angioplasty resulted in an increase in minimal obstruction area (mean ± s.d.) from 1.0 ± 0.5 to 3.6 ± 0.8 mm2 and in coronary reserve (mean ± s.d.) from 1.0 ± 0.3 to 2.5 ± 0.6 immediately following angioplasty. Five months later, a substantial and significant (p < 0.05) late increase in obstruction area (4.3 ± 1.4 mm2) and flow reserve (3.8 ± 1.1) had occurred. In 72% of our patients coronary flow reserve was restored to normal, 5 months after angioplasty.

The instantaneous hyperemic pressure-flow relationship in conscious humans

Background. The limitations and inaccuracies in the measurement of stenosis geometry, especially after coronary interventions, have prompted investigators to use functional indexes of stenosis severity, assessing the reduction of flow induced by the stenosis under study. Coronary flow reserve is greatly affected by the hemodynamic conditions at the time of the measurement and can not be applied for the immediate assessment of the results of coronary interventions.

Pressure gradient, exercise thallium 201 scintigraphy, quantitative coronary cineangiography: in what sense are these measurements related?

During cardiac catheterization, the pressure-flow relationship across a coronary stenosis cannot be determined. On the other hand, the pressure distal to a coronary stenosis is measured routinely during the PTCA-procedure. The physiologic value of these measurements, even those obtained with the smallest catheters, must be questioned since the catheter impedes flow through the obstruction. In addition, it is well known that the mean pressure gradient is affected by phasis changes in flow velocity. In the present study, we attempted to assess the relationship between the pressure gradient measured during angioplasty, the angiographic severity of stenosis and the inducibility of regional perfusion defects during exercise Thallium-scintigraphy. As a first step, we decided to investigate the values and limitations of the transstenotic pressure gradient measured during PTCA by comparing the transstenotic gradient with the theoretical pressure drop calculated from the arterial dimensions and fluid- dynamic equations. Flow was measured in the great cardiac vein, (Q, ml/sec) in 13 patients, before (n = 10) and/or after (n = 10) angioplasty (PTCA) of a proximal LAD, not filled by collaterals. The mean transstenotic gradient (Grad, mmHg) measured with the balloon catheter was compared to the ΔP calculated from the occlusion area (occl A, mm2). A 4-fold increase in the luminal area was associated with a 4-fold decrease in gradient (Grad). The occlusion A and the measured gradient were linearly correlated: Grad= 69–17. occl A; (r = 0.76). For the computed gradient ΔP the following relation was found: ΔP = 15. (occl A)-2; (r = 0.87). Although, the present study clearly showed that the absolute values of the transstenotic pressure gradients obtained during angioplasty did not reflect accurately the flow resistances, we were still convinced that useful information could be derived from the gradient determination, at least in the setting of angioplasty. It is this concept that we tried to test in the second part of the study.