QUANTITATIVE CORONARY ANGIOGRAPHY IN CLINICAL PRACTICE

Developments in

Cardiovascular Medicine

VOLUME 145

The titZes published in this series are listed at t, ,e end of this voZume.

QUANTITATIVE CORONARY ANGIOGRAPHY IN CLINICAL PRACTICE

edited by

PATRICK W. SERRUYS, DAVID P. FOLEY andPIM J. DE FEYTER Thoraxcenter, Erasmus University Rotterdam, Rotterdam The Netherlands

with a foreword by

SPENCER B. KING III Director, Andreas Gruentzig, Cardiovascular Center, Emory University, Atlanta, Georgia, u.s.A.

Springer-Science+Business Media, B.V.

Library of Congress Cataloging-in-Publication Data

Quantltative coranary angiography ln cllnlcal practlce ! edlted by Patrick W. Serruys, David P. Foley, and Pim J. de Feyter.

p. cm. -- (Developments ln cardiovascular medlclne ; v. 145) Inc 1 udes index. Includes bibliographiCal references and lndex. ISBN 978-90-481-4295-8 ISBN 978-94-015-8358-9 (eBook) DOI 10.1007/978-94-015-8358-9 1. Angiocardiography. 2. Coronary arteries--Radiography.

1. Serruys, P. W. II. Foley, DaVld P. III. De Feyter, P,m J. IV. Series.

[DNLM, 1. Coronary Angiography--methods. -diagnosls. 3. Coronary Disease--therapy. -physiopathology. W1 DE997VME v. 145 1994 RC683.5.A5Q35 1994 616.1 . 2307572--dc20 DNLM/DLC for Library of Congress

ISBN 978-90-481-4295-8

Printed on acid-free paper

2. Coronary Disease-4. Coronary Vessels­

I WG 141 Q12 1994l

93-22792

Cover illustration by Jan Tuin, clinica! photographer of the Thorax Center, Erasmus University Rotterdam, the Netherlands.

All Rights Reserved © 1994 by Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1994 Softcover reprint ofthe hardcover 1st edition 1994 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic Of mechanical, including photocopying, recording or by any information storage am;! retrieval system, without written permission from the copy-right owners.

Contents

List of Contributors XI

Foreword by Speneer B. King III XVll

Introduetion by Johan H.C. Reiber XIX

Part One: Validation of QCA: In vitro and in vivo, off-Iine and on­line studies

1. Why and how should QCA systems be validated? Johan H.C. Reiber 1

2. Aeeuraey and preeision of quantitative digital coronary arteriography; observer-, as weH as short- and medium-term variabilities Johan H.C. Reiber, Pieter M.J. van der Zwet, Gerhard Koning, Craig D. von Land, Bert van Meurs, Jan J. Gerbrands, Beert Buis and Ad E. van Voorthuisen 7

3. How reliable are geometrie coronary measurements? In vitro and in vivo validation of digital and einefilm-based quantitative eoronary analysis systems with a didactic methodological explanation by Cornelis J. Slager, Jürgen Haase and Johan C.H. Schuurbiers Jürgen Haase, David Keane, Carlo Di Mario, Javier Eseaned, Cornelis J. Slager and Patriek W. Serruys 27

4. Validation of videodensitometry in the assessment of stenosis phantoms: an in vitro and in vivo study Carlo Di Mario, Jürgen Haase, Javier Eseaned, Eline Montau -

and Patriek W. Serruys 51

v

VI Contents

5. Videodensitometry in percutaneous coronary interventions: a critical appraisal of its contributions and limitations Javier Escaned, Jürgen Haase, David P. Foley, Carlo Di Mario, Ad den Boer, Eline Montauban van Swijndregt and Patrick W. Serruys 69

Part Two: The QCA core laboratory: practical lessons learned and application to c1inical practice

6. Post-angioplasty lesion measurement variability of the cardiovascular angiographic analysis system David P. Foley, Jaap Deckers and Patrick W. Serruys 89

7. Methodological problems with the quantitative angiographic assessment of elastic recoil, stretch and balloon-artery ratio Walter R.M. Hermans, Benno J. Rensing and Patrick W. Serruys 103

8. Experiences of a quantitative coronary angiographic core laboratory in re stenosis prevention trials Victor A.W.M. Umans, Walter R.M. Hermans, Jean-Paul R. Herrman, Jaap Pameyer and Patrick W. Serruys 121

9. Visual versus quantitative analysis of coronary artery stenoses treated by coronary angioplasty: can the angiographer's eye be re-educated? Nicolas Danchin, Yves Juilliere, David P. Foley and Patrick W. Serruys 137

Part Three: Physiological applications of QCA, correlation with intracoronary physiological measurements obtained by alternative methodology

10. Intracoronary pressure measurements with a 0.015" fluid-filled angioplasty guide wire Bernard De Bruyne, Nico H.J. Pijls, Pascal J. Vantrimpont, Walter J. Paulus, Stanislas U. Sys and Guy R. Heyndrickx 147

11. Measurement of coronary artery pressure and stenosis gradients - clinical applications Häkan Emanuelsson, Michal Dohnal, Carl Lamm, Carlo Di Mario and Patrick W. Serruys 167

Contents

12. Application of coronary flow measurements to decision making in angioplasty Patrick W. Serruys, Edward S. Murphy and Nico H.J. Pijls

13. On-line versus off-line assessment of coronary flow reserve Marc M.J.M. van der Linden, Jürgen Haase and Patrick W. Serruys

14. Calculation of maximum coronary, myocardial and collateral blood flow by pressure measurements in the coronary circulation Nico H.J. Pijls, K. Lance Gould, Bernard De Bruyne, Hans J.R.M. Bonnier, G. Jan Willem Bech, William Wijns, Guy R. Heyndrickx, Richard L. Kirkeeide and Mamdouh I. EI Gamal

15. Comparison between fractional flow reserve calculation and quantitative coronary arteriography in a non-selected patient population Bernard De Bruyne, Nico H.J. Pijls and Guy R. Heyndrickx

16. Assessment of coronary stenosis severity from simultaneous measurement of transstenotic pressure gradient and flow. A comparison with quantitative coronary angiography Carlo Di Mario, Pim J. de Feyter, Johan C.H. Schuurbiers, Peter P. de Jaegere, Robert Gil, Häkan Emanuelsson, Cornelis J. Slager and Patrick W. Serruys

Part Four: A in the study of vasomotion 17. Application of quantitative coronary angiography in the study of

pharmacologically induced coronary vasomotion

vii

181

231

243

271

283

Harry Suryapranata and Patrick W. Serruys 307

18. Long-term responsiveness to intracoronary ergonovine in variant angina Yukio Ozaki, David Keane, Jürgen Haase, Fumimaro Takatsu and Patrick W. Serruys 317

19. Response of conductance and resistance coronary vessels to scalar concentrations of acetylcholine. Assessment with quantitative angiography and intracoronary Doppler in 29 patients with coronary artery disease Carlo Di Mario, Sipke Strikwerda, Robert Gil, Pim J. de Feyter, Nicolas Meneveau and Patrick W. Serruys 329

viii Contents

20. Angiographic evaluation of coronary bypass grafts vasomotion Claude Hanet, Robert Dion and William Wijns 355

Part Five: QCA in the setting of acute coronary syndromes, evaluation of the role of thrombolysis and balloon angioplasty

21. Evaluation of thrombolytic and monoclonal antiplatelet GPIIb/IIla antibody therapy in refractory unstable angina pectoris: correlation between quantitative assessment of coronary angiograms and clinical course Marcel van den Brand, Maarten L. Simoons, Addy van Miltenburg, Menko J. de Boer, Pim J. de Feyter and the European Cooperative Study Group 371

22. Clinical and quantitative angiographic results of a randomized trial comparing direct coronary angioplasty with intravenous streptokinase in acute myocardial infarction Felix Zijlstra, Menko J. de Boer, Jan C.A. Hoorntje, Johan H.C. Reiber and Harry Suryapranata 387

23. Merits of quantitative coronary angiography after thrombolytic therapy for evolving myocardial infarction Alfred E.R. Arnold and Patrick W. Serruys 397

Part Six: QCA applied to the evaluation of immediate and long term outcome following coronary balloon angioplasty: experiences emerging from large multicentre restenosis prevention trials

24. Elastic recoil after percutaneous transluminal coronary angioplasty. A quantitative angiographic approach Benno J. Rensing, Walter R.M. Hermans and Patrick W. Serruys 415

25. The importance of coronary dissection during and after coronary balloon angioplasty as evaluated by quantitative coronary angiography Walter R.M. Hermans, David P. Foley and Benno J. Rensing 433

26a. Quantitative coronary angiography for the evaluation of pharmacological restenosis prevention trials after successful percutaneous transluminal coronary balloon angioplasty. The results of CARPORT and MERCATOR study Walter R.M. Hermans, Benno J. Rensing, Patrick W. Serruys on behalf of the CARPORT (Coronary Artery Restenosis Prevention on Repeated Thromboxane_antagonism) and

Contents IX

MERCATOR (Multicenter European Research trial with Cilazapril after Angioplasty to prevent Transluminal coronary Obstruction and Restenosis) study groups 451

26b. Quantitative coronary angiography in the assessment of risk factors for luminal renarrowing. A study of clinical, pro ce dural and lesional factors related to long term angiographic outcome in 2 re stenosis prevention trials: CARPORT and MERCATOR Walter R.M. Hermans, Benno J. Rensing, Patrick W. Serruys on behalf of the CARPORT (Coronary Artery Restenosis Prevention on Repeated Thromboxane antagonism) and MERCATOR (Multicenter European Research trial with Cilazapril after Angioplasty to prevent Transluminal coronary Obstruction and Restenosis) study groups 469

27. Restenosis assessed by quantitative angiography. Lessons learned from two European multicenter trials Benno J. Rensing, Walter R.M. Hermans and Patrick W. Serruys

Part Seven: Evaluation of new devices and comparison with balloon angioplasty using QCA

28. Evaluation of the clinical use of directional coronary atherectomy using quantitative coronary angiography Victor A.W.M. Umans, David P. Foley, Annie Robert, Pascal Quaedvlieg, Eline Montauban van Swijndregt, William Wijns

495

and Patrick W. Serruys 537

29. Rotational atherectomy Eugene P. Mc Fadden, Christophe Bauters, Philippe Quandalle, Michel E. Bertrand and Jean-Marc Lablanche 561

30. Critical appraisal of quantitative coronary angiography and endoluminal stent implantation Peter P. de Jaegere, Bradley H. Strauss, Marie-Angele Morel, Pim J. de Feyter and Patrick W. Serruys 573

31. Excimer laser angioplasty Sipke Strikwerda, Eline Montauban van Swijndregt and Patrick W. Serruys 591

32. Evolving quantitative angiographic approaches to the comparative assessment of luminal renarrowing and long·term outcome after different transluminal coronary interventions

x Contents

David P. Foley, Walter R.M. Hermans, Vietor A.W.M. Umans, Benno J. Rensing, Peter P. de Jaegere, Javier Eseaned, Pim J. de Feyter and Patriek W. Serruys 611

Part Eight: QCA applied to the natural history of atherosclerosis 33. Progression or regression of eoronary atherosclerosis:

assessment with quantitative eoronary angiography Pim J. de Feyter, Jeroen Vos, Carlo Di Mario, Patriek W. Serruys and Jos R.T.C. Roelandt 635

34. Coronary atherosclerosis intervention trials using serial quantitative angiography Jeroen Vos and Pim J. de Feyter 653

35. Short and long-term quantitative angiographie follow-up after eardiae transplantation Mare M.J.M. van der Linden, Aggie H.M.M. Balk and Pim J. de Feyter 665

Part Nine: Intravascular ultrasound and QCA 36. Does eoronary lumen morphology influenee vessel eross­

seetional area estimation? An in vitro eomparison of intravaseular ultrasound and quantitative eoronary angiography Javier Eseaned, Pierre Doriot, Carlo Di Mario, David P. Foley, Jürgen Haase, Jose Baptista, Nieolas Meneveau, Ad den Boer, Jos R.T.C. Roelandt and Patriek W.Serruys 681

37. Intravaseular ultrasound -An evolving riyal for quantitative eoronary angiography Carlo Di Mario, Jos R.T.C. Roelandt, Peter P. de Jaegere, Pim J. de Feyter and Patrick W. Serruys 695

Index 717

List of Contributors

Alfred E.R. Arnold Department of Cardiology Medisch Centrum Alkmaar Wilhelminalaan 12 1815 JD ALKMAAR The Netherlands Co-authors: Patrick W. Serruys

Nicolas Danchin CHU Nancy-Brabois Rue du Morvan F-54511 V ANDOEUVRE-LES-NANCY France Co-authors: Yves Juilliere, David P. Foley and Patrick W. Serruys

Peter P. de J aegere Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors: Bradley H. Strauss, Marie-Angele Morel, Pim J. de Feyter and Patrick W. Serruys

Pim J. de Feyter Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors: Jeroen Vos, Carlo Di Mario, Patrick W. Serruys and Jos R.T.C. Roelandt

xi

xii List of Contributors

Bernard De Bruyne Cardiovascular Center O.L.V.-Hospital Moorselbaan 164 B-9300 AALTST Belgium Co-authors Chapter 10: Nico H.J. Pijls, Pascal J. Vantrimpont, Walter J. Paulus, Stanislas U. Sys and Guy R. Heyndrickx Co-authors Chapter 15: Nico H.J. Pijls and Guy R. Heyndrickx

Carlo Di Mario Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The N etherlands Co-authors Chapter 4: Jürgen Haase, Javier Escaned, Eline Montauban van Swijndregt and Patrick W. Serruys Co-authors Chapter 16: Pim J. de Feyter, Johan C.H. Schuurbiers, Peter P. de Jaegere, Robert Gil, Häkan Emanuelsson, Cornelis J. Slager and Patrick W. Serruys Co-authors Chapter 19: Sipke Strikwerda, Robert Gil, Pim J. de Feyter, Nicolas Meneveau and Patrick W. Serruys Co-authors Chapter 37: Jos R.T.C. Roelandt, Peter P. de Jaegere, Pim J. de Feyter and Patrick W. Serruys

Häkan Emanuelsson Division of Cardiology Sahlgrenska Hospital S-413 45 GÖTEBORG Sweden Co-authors: Michal Dohnal, Carl Lamm, Carlo Di Mario and Patrick W. Serruys

Javier Escaned Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The N etherlands Co-authors Chapter 5: Jürgen Haase, David P. Foley, Carlo Di Mario, Ad den Boer, Eline Montauban van Swijndregt and Patrick W. Serruys Co-authors Chapter 36: Pierre Doriot, Carlo Di Mario, David P. Foley, Jürgen Haase, Jose Baptista, Nicolas Meneveau, Ad den Boer, Jos R.T.C. Roelandt and Patrick W. Serruys

David P. Foley Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands

List of Contributors xiii

Co-authors Chapter 6: Jaap Deckers and Patrick W. Serruys Co-authors Chapter 32: Walter R.M. Hermans, Victor A.W.M. Umans, Benno J. Rensing, Peter P. de Jaegere, Javier Escaned, Pim J. de Feyter and Patrick W. Serruys

Jürgen Haase Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors: David Keane, Carlo Di Mario, Javier Escaned, Corne1is J. Slager and Patrick W. Serruys

Claude Hanet Department of Cardiovascular Pathology University Clinic Saint Luc Avenue Hippocrate 10 UCL 10/28.81 B-1200 BRUSSELS Belgium Co-authors: Robert Dion and William Wijns

Walter R.M. Hermans Department of Cardiology Refaja Hospital Dordrecht Van der Steenhovenplein 1 3317 NM DORDRECHT The Netherlands Co-authors Chapters 7 and 26: Benno J. Rensing and Patrick W. Serruys Co-authors Chapter 25: David P. Foley and Benno J. Rensing

Spencer B. King III Andreas Gruentzig Cardiovascular Center Emory University Hospital Suite F606 1364 CHfton Rd., NE ATLANTA, GA 30322 U.S.A.

xiv List o[ Contributors

Eugene P. Mc Fadden Department of Cardiology B CHU Lille 59037 LILLE Cedex France Co-authors: C. Bauters, P. Quandalle, Michel E. Bertrand and Jean-Marc Lablanche

Yukio Ozaki Thorax Center, EE 2332 Erasmus University P.O. Box 1738 300 DR ROTTERDAM The Netherlands Co-authors: David Keane, Jürgen Haase, Fumimaro Takatsu and Patrick W. Serruys

Nico H.J. Pijls Department of Cardiology Catharina Hospital P.O. Box 1350 5602 ZA EINDHOVEN The Netherlands Co-authors: K. Lance Gould, Bernard De Bruyne, Hans J.R.M. Bonnier, G. Jan Willem Bech, Guy R. Heyndrickx, William Wijns, Richard L. Kirkee­ide and Mamdouh 1. EI Gamal

Johan H.C. Reiber Department of Diagnostic Radiology University Hospital Leiden Building 1, C2-S P.O. Box 9600 2300 RC LEIDEN The Netherlands Co-authors: Pieter M.J. van der Zwet, Gerhard Koning, Craig D. von Land, Bert van Meurs, Jan J. Gerbrands, Beert Buis and Ad E. van Voorthuisen

Benno J.W.M. Rensing Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors Chapters 24 and 27: Walter R.M. Hermans and Patrick W. Serruys

Patrick W. Serruys Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands

List 0/ Contributors xv

Co-authors: Edward S. Murphy and Nico H.J. Pijls

Cornelis J. Slager Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors: Jürgen Haase and Johan C.H. Schuurbiers

Sipke Strikwerda Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors: Eline Montauban van Swijndregt and Patrick W. Serruys

Harry Suryapranata Department of Cardiology Hospital "De Weezenlanden" Groot Wezenland 20 8011 JW ZWOLLE The Netherlands Co-author: Patrick W. Serruys

Victor A.W.M. Umans Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors Chapter 8: Walter R.M. Hermans, Jean-Paul R. Herrman, Jaap Pameyer and Patrick W. Serruys Co-authors Chapter 28: David P. Foley, Annie Robert, Pascal Quaedvlieg, Eline Montauban van Swijndregt, William Wijns and Patrick W. Serruys

Marc M.J.M. van der Linden Thorax Center, EE 2332

xvi List of Contributors

Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors Chapter 13: Jürgen Haase and Patrick W. Serruys Co-authors Chapter 35: A.H.M.M. Balk and Pim J. de Feyter

Marcel van den Brand Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-authors: Maarten L. Simoons, Addy van Miltenburg, M.J. de Boer, Pim J. de Feyter and the European Cooperative Study Group

Jeroen Vos Thorax Center, EE 2332 Erasmus University P.O. Box 1738 3000 DR ROTTERDAM The Netherlands Co-author: Pim J. de Feyter

Felix Zijlstra Department of Cardiology Hospital "De Weezenlanden Groot Wezenland 20 8011 JW ZWOLLE The Netherlands Co-authors: Menko Jan de Boer, Jan C.A. Hoorntje, Johan H.C. Reiber and Harry Suryapranata

Foreword

No technique in cardiology is more discussed and less used clinically than quantitative coronary arteriography. This is a serious error. In the early days of coronary angiography, the appearance of coronary steno ses on cineangio­graphy was so imprecise that angiographers were urged to read films while they were being played at rapid frame rates. Stopping in film usually resulted in an image that was blurred beyond recognition. Although film quality improved rapidly, the habits of angiographers more interested in perfor­mance of the procedure than its interpretation continued to ignore the vast amount of data available on the angiographic film. In recent years, angio­graphie systems have evolved to the point that quantification of the degree of obstruction is not only possible but is necessary in order to promote proper communication in clinical practice.

Perhaps the greatest stimulus to the development of quantitative coronary arteriography came with the advent of interventional cardiology. When Gruentzig began to alter arte rial obstructions with balloons, he also measured those changes from optically magnified images. Quantification became the gold standard even if not universally applied.

Much of the impetus for state of the art quantitative coronary arteriography came from the Thoraxcenter in Rotterdam and the principal eheerleader for its application in clinical medicine has been Patrick Serruys. Dr. Serruys, in this book, brings together many of those who have made significant contribu­tions to the development of coronary anteriography.

The angiographer reading this volume will be impressed by the breadth of the treatment of the subject. The volume begins with chapters discussing the validation of the method and progresses through a discussion of physiologie correlates of coronary artery dimensions. Coronary fiow and fiow reserve judged angiographically and the relationships of pressure and fiow to the angiographic findings are treated in depth. The important area of vasomotion in both large conduit arteries as weIl as resistance vessels completes the extensive evaluation of the technique itself. The editor then selected those who have applied the technique in clinical settings. The use of quantitative coronary arteriography in primary myocardial infarction, in cases of compli-

XVll

xviii Foreword

cations of interventional techniques and assessing results with new interven­tional technologies such as atherectomy, stents, and laser angioplasty is extensively explored.

The crucial role of quantitative arteriography in evaluating re stenosis trials is an area in which the editors has great experience. Application of consistent quantitative angiographic core laboratories to drug restenosis trials has al­lowed for highly precise measures of luminal dimensions in the late follow­up period. Important consistencies have been found between trials of various ineffective drug regimens. Quantitative coronary arteriography has also helped investigators understand the proliferative process following these in­terventions by precisely defining the luminal results of the procedure and the changes in dimensions found over the follow-up period. Although quantita­tive coronary arteriography has made major contributions, the authors are equally appreciative of the limitations of the technique and conclude the book with chapters on intravascular ultrasound, the new technology vying for the title of "gold standard".

This volume will be of enormous help to those angiographers involved in the design of clinical trials as well as those trying to provide a better assess­ment of their clinical results. Those who choose to use such methods will produce data which will be of signficant value in management of their pa­tients. Documentation of results will improve communication among phys­icians and those outside of medicine with a strong interest in patient outcome so they can better understand the value of collecting precise clinical infor­mation. Kluwer Academic Publishers, in producing this book, continue their tradition of making available the best thinking regarding the status of modern technology in cardiology at a time when that information is most needed. Both editors, authors and publisher are to be congratulated for an excellent contribution to the understanding of the clinical value of a valuable and underused too1.

Spencer B. King III

Introduction

In 1986 the undersigned, Patrick W. Serruys and Cees J. Slager wrote our first book on Quantitative Coronary and Left Ventricular Cineangiography: Methodology and Clinical Applications, that was entirely based on work carried out at the Thoraxcenter. At that time 40% of the clinical chapters were devoted to the quantification of left ventricular function and the remain­ing chapters to quantitative coronary arteriography (QCA). However, over the last decade the scale in our common technological and clinical research interests has definitely tipped over towards QCA. This is clearly evident from the four books that we have edited since then in the Kluwer series Developments in Cardiovascular Medicine. These books describe exclusively the developments in the analytical QCA software packages and their clinical applications. Likewise, this new book from the Thoraxcenter covers the advantages, limitations and applications of QCA in clinical practice, covering work performed at the Thoraxcenter as weH as at other cardiological centers.

Of course, this shift in interest is not unexpected. Two major clinical developments have stimulated this enormous growth in QCA clinical re­search. First of aH, the exponential rise in intervention al catheterization procedures foHowing the first coronary baHoon dilatation (PTCA) by An­dreas Gruentzig in 1977 Since that time, PTCA has established itself as a routine revascularization procedure with a known re stenosis rate of approxi­mately 33%, depending on the criteria used. Since then many multicenter re stenosis prevention trials have been carried out in attempts to solve this re stenosis problem. At the same time the number of QCA Core-Iaboratories have mushroomed worldwide without a weH defined Quality Assurance pro­gram on the quality of these labs established.

Many new approaches have ·been invented over the last decade to re ca­nalize the obstructed coronary arteries, including thrombolysis in the acute myocardial infarction situation with various pharmacological agents, and various recanalization devices, such as stents, mechanical atherectomy de­vices, lasers, etc. To study the efficacy, restenosis rates and other limitations of these approaches, carefully acquired coronary arteriographic data pre- and

xix

xx Introduction

immediate post-intervention as well as at follow-up need to be interpreted in great detail.

Secondly, there has been an enormous growth in the development and use of cardiovascular drugs directed at the regression or no-growth of existing coronary artery disease, or the delay in the formation of new lesions. These approaches require the precise comparison of the arterial dimensions in a control group versus those in a treated group studied over a long period of time (typically 2-3 years).

It has been well accepted that the conventional visual interpretation of coronary arteriograms is no longer acceptable to study the efficacy and limitations of all these different intervention procedures. The results must be evaluated in an objective and reproducible manner on the basis of absolute parameters describing accurately the baseline coronary morphology and sub­sequent changes therein. The off-line cinefilm-based approaches for QCA has been used exclusively in such clinical research studies. In parallel to and triggered by these clinical applications, major developments have taken place in these QCA-systems. There has been adefinite shift from the more tra­ditional PDP and Vax computers to workstations and very powerful personal computers (PC's), characterized by decreased cost and highly increased per­formance. In addition, major advances have taken place in the development of the analytical software packages. Progress has been made towards more routinely applicable user-interfaces, more robustness of the software itself coupled with a higher degree of automation (less user interaction) and repro­ducibility in the derivation of the clinically relevant parameters.

in addition, there has been a significant progress in X-ray imaging technol­ogy. Image quality is continually improving due to the availability of higher quality X-ray sources, image intensifiers, TV chains, the use of pulsed fluor­oscopy, and real-time image enhancement. It is now also possible to store the dynamic pictorial information on-line in digital format at high spatial and temporal resolution. The application of gap filling techniques allows a reduction in the acquisition frame rates with a concomitant reduction in X­ray radiation dose. Quantitative data on coronary arterial dimensions can now be made available at the time of the catheterization procedure (on-line) measured directly from digitally acquired arteriograms.

However, sofar these on-line techniques have been used predominantly for clinical decision making, balloon and stent sizing, etc.

From the QCA data functional measures have also been derived such as pressure gradients at various assumed flow values, the stenotic flow reserve (SFR), etc. These approaches have always been difficult to validate. More recently, major developments in guide wire technology have allowed much more reliable intracoronary pressure and Doppler flow measurements. This will allow integrated approaches for the assessment of coronary pathophysiol­ogy.

Finally, Intravascular Ultrasound (IVUS) has emerged as a new technique to study the morphology of the coronary vessels. Of course, both QCA and

Introduction xxi

IVUS have their own advantages and limitations. It will be interesting to see how IVUS will compete with QCA, and how these can complement each other.

As the majority of new catheterization laboratories are equipped with digital imaging systems, on-line quantification of coronary morphology, flow reserve and left ventricular function will become feasible with state-of-the­art analytical packages featuring a high success score and a short processing time. The use of these analytical software packages is expected to increase significantly in the coming years. This process may be accelerated if quality assurance issues are demanded by insurance companies and/or government agencies. As patients who have been involved in clinical research studies are followed up over longer periods of time, more prognostic information about the progress of coronary artery disease will become available. Therefore, it is not unlikely that in the future the results from QCA will be used by the more general cardiologists to predict any future sequelae. Further develop­ments in analytical software packages are directed among others at the processing of the entire coronary tree with the automated selection of signifi­cant lesions. These results will then be presented in coronary reporting schemes to be included in the patient's status. Such a graphical representation can then be transferred to the referring physicians leading towards a wider dissemination of the QCA message.

Johan H.C. Reiber