Percutaneous Transluminal Coronary Angioplasty of Occluded Coronary Arteries New Angiographic Features Related to Success

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1 Clinical Studies Percutaneous Transluminal Coronary Angioplasty of Occluded Coronary Arteries New Angiographic Features Related to Success Simon M. HORNER, M.A., M.B., B.S., M.R.C.P. SUMMA Percutaneous transluminal coronary angioplasty of coronary artery occlusions forms a routine part of cardiological practice. However, only a few angiographic variables which might predict success have been investigated and identified. Video densitometry was used to assess structural features of the occlusion that have not been investigated previously. The sharpness and eccentricity of the tapering, the presence of any distal vessel and the presence of a reservoir or atrium in which the end of the wire could become trapped were measured. Other measurements taken from the cineangiogram included the minimum radius of curvature of the artery immediately before the occlusion, the number of bends and the distance traversed before the occlusion. The number, size, location and angle of branching of side branches from the artery in question were noted. The number of bridging collaterals and presence of distal opacification were noted. There was a significantly higher success rate in patients with less than 3 bends before the occlusion (p=0.01) and a distance down the artery to the occlusion of less than 27mm (p<0.05). An atrium was present in 36% and was associated with an unsuccessful outcome (p=0.02). Distal opacification, despite occlusion of the artery, was found to be associated with failure to cross the lesion (p<0.05). The angle of branches of the artery was only found to be important near (within 7.5mm) the occlusion (p<0.05). None of the video densitometric measurements of the fine structure of the stump of the coronary artery were found to be helpful. (Jpn Heart J 34: , 1993) Key Words: Coronary artery Occlusion Angioplasty Ischemic heart disease ERCUTANEOUS transluminal coronary angioplasty (PTCA) of coronary artery occlusions forms a routine part of cardiological practice. However, only a few angiographic variables which might predict success have been investigated.1) The identification of variables associated with success would allow the use From the Department of Cardiology, The Middlesex. Hospital, London, England. Address for correspondence: The Department of Cardiology, The Middlesex Hospital, Mortimer Street, London, England. W1C8AA. Received for publication January 4, Accepted June 16,

2 686 HORNER Jpn. Heart J. November, 1993 of PTCA to be extended to cases which at present would not be attempted. This approach would also conserve health care resources by allowing those in whom PTCA was unlikely to be successful to be treated in an alternative manner. This study thus set out to investigate angiographic variables that have the potential to influence the prognosis. METHODS Study patients Forty-five consecutive patients who underwent PTCA for total coronary artery occlusion were analysed. The left anterior descending coronary artery was involved in 51%, the left circumflex coronary artery in 18% and the right coronary artery in 31% of the patients. The median length of time of coronary artery occlusion was 11 weeks. Angioplasty procedure All patients received aspirin mg on the morning of the PTCA, and 10,000U heparin were given at the start of the procedure and 5,000U every 20 minutes thereafter. Angioplasty was performed using an over the wire technique. A 0.014J wire (USCI) and ACX catheter (ACS) of the appropriate size for the vessel were used. If this combination was not successful either the wire or balloon was changed depending upon which had difficulty crossing the lesion; the wire was exchanged for a Hi-Torque Intermediate wire (ACS) and the balloon catheter for a 2mm ACX (ACS). Angiographic analysis The cineangiograms were digitised using a Hitachi HV-700 series high resolution black and white camera and an Electric Studios video digitising board into an image of 768 by 576 pixels with 256 grey scales. Software was written to allow the cross-sectional display of grey scales along lines of interest and subsequent adjustment of grey scale allocation. To assist in the discrimination of the smallest grey scale changes when measurements were being taken, the digitised angiograms were viewed simultaneously in monochrome and pseudocolour. The occlusion was digitised in the standard right (30 ) and left (45 ) anterior oblique views. The sharpness and eccentricity of the tapering, the presence and degree of opacification of any distal vessel apparent by computer analysis (but which was not apparent to the operator) was noted and the presence of a reservoir or atrium was noted (Fig. 1). Other measurements taken from the cineangiogram in the orthogonal view included the minimum radius of curvature of the artery immediately before the occlusion, the number of bends and the

3 Vol.34 No.6 PTCA OF OCCLUDED CORONARY ARTERIES 687 Fig. 1. Diagram showing the measurements made on each coronary artery. Fig. 2. Occluded coronary artery in which PTCA was not successful. Note the proximal curves in opposite directions, the branch close to the occlusion and the atrium (arrow).

4 688 HORNER Jpn. Heart J. November, 1993 distance traversed before the occlusion (Fig. 2). The number, size, location and angle of branching of side branches from the artery in question were noted. The number of bridging collaterals and distal opacification were noted. Statistics Categorical variables were assessed using the chi-square test, with Yates' correction where necessary. The Student's t-test was used for comparing continuous normally distributed variables. A p value<0.05 was considered significant. RESUL The mean age of the patients was 57 years (standard deviation 9 years) and 72% were male. PTCA was successful in 59%. There was a significantly higher success rate in those with less than 3 bends before the occlusion (p=0.01) and a distance down the artery to the occlusion of less than 27mm (p<0.05). An atrium (Fig. 2) was present in 36% and was associated with an unsuccessful outcome (p=0.02). Distal opacification, despite occlusion of the artery, was found to be associated with failure to cross the lesion (p<0.05). This is in keeping with other studies which have shown that bridging collaterals, which will opacify distally are associated with failure of PTCA. The angle of branches of the artery was only found to be important near (within 7.5mm) the occlusion (p<0.05) with a smaller angle being associated with a greater degree of success. The width of the branches was not found to be important (Table). Table DISCUSSI The success rate for. percutaneous transluminal coronary angioplasty (PICA) of occluded arteries is 72%,1)-3) which is 24% lower than that for PTCA of non-occluded arteries. However, the presence of tapering stump and the absence of collaterals have previously been found which are predictive of success.

5 Vol.34 No.6 PTCA OF OCCLUDED CORONARY ARTERIES 689 This study found additional variables related to a successful PTCA of an occluded coronary artery, namely the number of bends before the occlusion, the distance from the occlusion to the origin of the artery and distal opacification. When there was a branch near the occlusion, the angle at which the branch left the main trunk was related to the outcome. Computerised measurement Video densitometry is an established method for assessing coronary artery disease.4) Any X-ray image contains areas of different light intensities or grey scales. Since the human eye can only appreciate 32 grey scales, whereas a computer can routinely discriminate 256, it was hypothesized that computerised analysis would be helpful in assessing the likelihood of success if PTCA were attempted. However none of the extensive range of computerised measurements were found to be helpful. Angiographic variables A previous study examined a variety of clinical and angiographic variables in 100 patients1). The only variables that were related to success were a tapering occlusion and the absence of bridging collaterals. There was no definition of the dividing line between "tapering" and "abrupt". In an earlier study of 76 patients the distinction between tapering and abrupt had been found to be irrelevant5). This study did not find the angle of tapering or tangent of the angle of tapering to be significantly associated with a successful outcome. Angiographic features previously found not to be related to success rate were lesion location, extent of disease, functional as opposed to absolute occlusion and the presence of nonbridging collaterals1). However, two parameters reflecting the location of the lesion were found to be important in the present study: the number of bends in the artery before the occlusion and the distance down the artery to the occlusion. This is hardly surprising because each bend will mean some loss of torque control. The distance down the artery would also be expected to make a difference since the "backup" for the wire declines progressively as the distance increases and cannot be offset completely by advancing the balloon. A new feature of this study was that the presence of an atrium was related to an unsuccessful outcome. This is presumably because if the wire is allowed to curl up in the atrium it will not point in the direction of the axis of the vessel; since it is fixed more proximally, it is held rigidly in this unfavourable configuration. Although length of the lesion was not independently related to the success rate in one study,1) an earlier study5) reported an independent effect. In the

6 690 HORNER Jpn. Heart J. November, 1993 current study, too many of the occlusions were total with no obvious distal end to the occlusion to comment on this aspect. Bridging collaterals have been found to be associated with a reduced success rate of PTCA in treating coronary artery occlusion1). These collaterals will cause distal opacification of the occluded vessel and, hence, distal opacification may be associated with the failure of PTCA in treating coronary artery occlusion. The mechanism by which bridging collaterals are associated with an unsuccessful outcome in the treatment of coronary artery occlusion by PTCA is unknown. Anatomical continuity across the occlusion, that is the difference between total and functional total occlusion, was not found to be important1). This was also seen in a study by DiSciascio et al6) in which the success rate for total and functional total occlusions was 56% and 69%; this difference was not significant. In other studies, however, this has been found to be an important distinction with success rates of 63% v 78%7) and 45% v 81%,8) respectively. CONCLUSION This study investigated the relationship between angiographic indices of coronary artery occlusion and successful PTCA. Five variables related to a successful outcome were identified. The presence of less than three bends before the occlusion was associated strongly with a successful outcome, as were a distance of less than 27mm down the artery to the occlusion, the absence of a branch near the occlusion and a paucity or absence of distal opacification. The presence of a reservoir or atrium was associated strongly with an unsuccessful outcome. Video densitometry was not helpful in identifying occlusions that could be dilated successfully. ACKNOWLEDGEMEN This work was carried out with the assistance of a grant from the National Heart and Circulation Trust. REFERENCES 1. Stone GW, Rutherford BD, McConahay DR, Johnson WL Jr, Giorgi LV, Ugon RW, Hartzler GO: Procedural outcome of angioplasty for total coronary artery occlusion; an analysis of 971 lesions in 905 patients. J Am Coll Cardiol 15: 849, Laarman GJ, Planted S, de Feyter PJ: PTCA of chronically occluded coronary arteries. Am Heart J 119: 1153, Hamm CW, Kupper W, Kuck KH, Hofmann D, Bleifeld W: Recanalization of chronic, totally occluded coronary arteries by new angioplasty systems. Am J Cardiol 66: 1459, Nichols AB, Gabrieli CF, Fenoglio JJ Jr, Esser PD: Quantification of relative coronary arterial stenosis

7 Vol.34 No.6 PTCA OF OCCLUDED CORONARY ARTERIES 691 by cinevideodensitometric analysis of coronary arteriograms. Circulation 69: 512, Kereiakes DJ, Selmon MR, McAuley BJ, McAuley DB, Sheehan DJ, Simpson JB: Angioplasty in total coronary artery occlusion; experience in 76 consecutive patients. J Am Coll Cardiol 6: 526, Sabri MN, DiSciascio G, Cowley MJ, Goudreau E, Warner M, Kohli RS, Bajaj S, Kelly K, Vetrovec G: Immediate and long-term results of delayed recanalization of occluded acute myocardial infarctionrelated arteries using coronary angioplasty. Am J Cardiol 69: 575, Safian RD, McCabe CH, Sipperly ME, McKay RG, Baim DS: Initial success and long-term follo up of percutaneous transluminal coronary angioplasty in chronic total occlusions versus conventional stenoses. Am J Cardiol 61: 23G, Serruys PW, Umans V, Heyndrickx GR, van den Brand M, de Feyter PJ, Wijns W, Jaski B, Hugenholtz PG: Elective PTCA of totally occluded coronary arteries not associated with acute myocardial infarction; short-term and long-term results. Eur Heart J 6: 2, 1985