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News and Views

IJC 00186

Percutaneous transluminal coronary angioplasty in patients with prior coronary bypass surgery *

(Key words: coronary bypass grafting; percutaneous transluminal coronary angio-

plasty)

Current surgical treatment of coronary artery disease represents the culmination of an evolutionary process that began with early ineffective procedures such as

thoracic sympathectomy, epicardial abrasion, and internal mammary artery ligation. Coronary artery bypass grafting today offers immediate palliation of symptoms in

the vast majority of individuals with the promise of improved longevity in many patients. With its extremely low operative mortality, it is easy to understand why

coronary bypass grafting has become the most common major surgical procedure in the United States. Despite its merits, disease progression in the native circulation

and in grafts poses a continuing threat to the individual patient [l-6]. Recurrent or

worsening symptoms are reported in 5 to 10% of postoperative patients annually

[1,5,6], leading to reoperation in up to 10% of individuals followed long term [7-91. Reoperations are technically difficult and are associated with more frequent compli- cations and a higher operative mortality [lO,ll].

Since its introduction by Gruentzig in 1977 [12], percutaneous transluminal

coronary angioplasty (PTCA) has become a widely accepted alternative means of revascularization in some individuals with obstructive coronary disease. With proper case selection and experienced teams, complication rates are low and intermediate- term follow-up is favorable [13-191. In addition to avoidance of the risks of reoperation, FTCA boasts a lower procedural cost and has demonstrated better preservation of patient productivity [20,21]. Despite early reports from the National Heart, Lung and Blood Institute Registry of higher in-hospital mortality of angio-

plasty in patients with prior bypass grafting [17,18], more recent experience has been favorable. Douglas et al. have previously reported our early experience with this subset of patients [22]. This report presents the results of 168 consecutive patients

undergoing PTCA at Emory University Hospital after previous coronary bypass grafting to further define initial success and complication rates and examine more

recent trends.

Patient Population and Clinical Profile

From January 1978 to June 1983, 168 patients underwent coronary angioplasty (180 procedures) after prior coronary bypass surgery. The mean age of the group

* From Interventional Cardiovascular Medicine, Department of Medicine, Emory University School

of Medicine, Atlanta, Georgia.

International Journal of Cardiology, 6 (1984) 645-650 0 Elsevier Science Publishers B.V.

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was 55.2 years (range 37-72); 143 (85%) were men and 25 (15%) were women. The mean interval between coronary bypass surgery and coronary angioplasty was 27.1

months (range 2 to 132).

On a clinical basis, patients were selected because of disabling symptoms despite

adequate medical therapy with nitrates, beta-blockers and/or calcium antagonists.

Angiographically the stenosis subtending the jeopardized vascular bed had to appear acceptable for dilatation. Multiple stenoses in a single vessel or graft or in several

vessels were in general referred for surgery.

Technique

Although described previously, the technique of percutaneous transluminal

coronary angioplasty has continued to evolve. Technical advances that have fostered recent success include the following: (1) advanced radiographic equipment capable of multiangular projections and multiple field sizes, (2) high-resolution recorders and video disks that permit constant display of appropriate frames for comparison with

real-time images, (3) a variety of guiding catheters in both 8 and 9 French sizes, and

(4) a selection of dilatation catheters including multiple sizes, tandem arrangement, and low profile configuration.

Proximal anastomosis (13)

Distal anastomosis (54)

Native coronky artery (83)

Fig. 1. Sites of 180 first transluminal angiophsty attempts. IMA = internal mammary artery graft.

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Protocol

Following definition of functional capacity utilizing exercise testing with nuclear imaging, the patient is taken to the laboratory where the femoral artery and vein are cannulated. Pharmacologic dilatation and anticoagulation are accomplished with sublingual nifedipine and heparin respectively and the pacing catheter is positioned

in the right ventricular apex. The appropriate guiding catheter is then selected as to allow adequate seating in the coronary or graft ostium but still avoid wedging with

limitation of flow. Judkins-type right coronary guiding catheters, Rowe-Castillo- Amplatz type, and multipurpose guiders were most frequently used to engage graft ostia. Baseline angiograms are obtained and frozen for reference and a balloon

catheter is chosen based on the severity of the stenosis and the size of the adjacent

vessel.

Under biplane fluoroscopic control the soft-tipped guidewire is carefully steered across the stenosis and down the distal vessel. Next the dilatation catheter is slowly advanced over the guidewire until the stenosis is bridged as evidenced by fluoros- copy and the recording of a pressure gradient between the guiding catheter and the

balloon catheter tip. Once correct position is assured, balloon inflation (actually a misnomer as the balloon contains a mixture of saline and contrast material) is begun. Care is taken to note the deformity imposed by the lesion on the balloon to further confirm position. Inflations are maintained for approximately 15 to 60 set

and are repeated until the pressure gradient is optimally reduced. The wire is then advanced simultaneously with dilatation catheter withdrawal so that the wire re- mains distal to the stenosis and the balloon is positioned proximal to the site of the

original stenosis. Injections are performed through both the guide and balloon catheters to define the status of the dilated vessel segment. With favorable results the balloon catheter is removed and a repeat angiogram is obtained.

Postangioplasty care is designed to monitor the patient for signs and symptoms of

myocardial ischemia. Included in the routine protocol are serial electrocardiograms, telemetry for 18 h, and serial CK measurements. Before discharge, all data pertinent

in assessing the consequences of the procedure are reviewed. These include: (1) pre-

and post-angioplasty exercise tests, (2) review of PTCA films to measure pre- and post-PTCA stenoses and evaluate angiographic degree of intimal disruption, (3) initial and final gradients, (4) serial electrocardiograms, and (5) serial CK values. Routine medications at discharge include a calcium antagonist and one aspirin per

day.

Initial Results

Successes, Failures and Complications. Angiographic success (> 20% absolute reduction in stenosis) was obtained in 161 (89%) of 180 first attempts at translumi-

nal angioplasty. Mean stenosis calculated by the diameter method in the 161 successful procedures was reduced from 77 k 13% (mean f SD) to 26 f 14% with a concomitant pressure gradient fall from 48 &- 17 to 11 f 8 mm Hg. It was not

possible to cross the stenosis with the balloon catheter in 12 patients (7%) and 10 of these patients underwent elective reoperation; 2 patients refused surgery and con-

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tinued on medical therapy. Five patients required emergency bypass grafting; 4 because of dissection at the dilatation site at the time of balloon passage; 1 because of distal embolization of the plaque. One patient with juvenile onset diabetes sustained an anterior infarction the night after apparent successful dilatation of an

LAD graft. Other complications were: CK-MB > 20 U (2 patients), prolonged ischemic pain

requiring intraaortic balloon pumping (1 patient) and ventricular fibrillation (3

patients). There were no early deaths. One late death was recorded after failure to

cross the stenosis in a patient who subsequently refused surgery. The patient died

suddenly 14 months later.

Native Coronary Artery Stenosis. Eighty-three coronary angioplasty procedures were performed in 81 patients for stenosis of the native coronary arteries. Seventy-one

(86%) of these procedures were successful with the success rate being lowest in the right coronary artery (79%) and highest in the left anterior descending artery (95%).

Distal Anastomosis (Sapbenous Vein to Coronary Artery Junction). Fifty-four patients underwent angioplasty of lesions involving the distal anastomosis. In 35 patients (65%) the vein graft was to the left anterior descending artery, in 14 patients (26%) to the right coronary artery, and in 5 patients (9%) it was to the circumflex

artery. In 51 patients (94%) the dilatation was successful. In 1 patient the saphenous vein could not be cannulated with the guiding catheter and in another coronary dissection with occlusion dictated emergency coronary bypass surgery.

Saphenous Vein Independent of Anastomoses. Transluminal dilatation was at-

tempted on the body of the graft in 29 patients; in 14 patients the graft supplied the right coronary artery, in 12 the left anterior descending, and in three, the circumflex.

Initial success was achieved in 27 patients (93%). One individual required emergency bypass surgery because of dissection with occlusion while the other failure was due to inability to reduce the degree of stenosis in another diseased graft. Angioplasty was attempted in one patient with stenosis of the mid-portion of an internal

mammary graft; the stenosis could not be crossed and coronary bypass surgery was

recommended.

Proximal Anastomosis (Saphenous Vein to Aorta). In 13 patients dilatation was attempted for stenosis at the site of aortic implantation. The procedure was successful in 12 patients with the single failure due to inability to cannulate the severely stenosed graft orifice. This individual underwent elective reoperation.

Follow-up

At present, follow-up has been compiled only on the first 116 patients as reported earlier by Douglas et al. [22]. According to their original data, at a mean follow-up of 8.3 months, 88 patients (76%) were free of angina or in improved condition. In patients followed up for at least 6 months, evidence of restenosis occurred in 9 (53%)

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of 17 saphenous veins, 1 (50%) of 2 proximal graft anastomoses, 4 (18%) of 22 distal graft anastomoses and 5 (14%) of 37 native coronary arteries.

Discussion

The role of transluminal angioplasty continues to be defined as applied to patients post-bypass grafting. Despite the initial NHLBI report suggesting increased hazard in this subgroup of individuals [17,18], more recent efforts have dem-

onstrated high success rates and infrequent complications [22]. The initial success rate in the group of patients discussed in this report was 89%. This compares favorably with our recent total experience with coronary angioplasty. Examining the

data for the year 1983, PTCA was successful in 1296/1424 vessels attempted (91%)

1231. Complications at the time of the procedure were infrequent - contrasting earlier

data. Since the low frequency of significant complications also paralleled those results from our total experience, it would appear that it is operator experience and not prior bypass surgery that played a major role in the NHLBI data.

Late Results of Angioplasty in Patients after Bypass. While the long-term outcome of patients after PTCA continues to be defined, intermediate follow-up in the post-coronary artery bypass grafting subgroup appears favorable. Patency after dilatation appears to be particularly excellent at distal anastomotic sites. Less favorable sustained results were noted after dilatation of mid-saphenous vein grafts

where the recurrence rate in this small group was > 50% [22]. PTCA at this site and

at the proximal anastomosis requires further investigation.

Clinical Implications. Examining the safety and efficacy of the procedure,

transluminal coronary angioplasty represents a viable alternative to reoperation for

progressive coronary disease. Despite the advanced state of the art of present-day bypass surgery, repeat procedures are significantly more hazardous. Even with the

characteristic less extensive revascularization, operative morbidity and mortality is significantly increased. At Emory University Hospital and at the Cleveland Clinic operative mortality rate in reoperations was four times that of first operations, perioperative infarctions occurred three times more frequently and the risk of infection and blood transfusion-related complications was significantly higher [10,22]. Coupling this knowledge with the fact that the cost of PTCA is approximately

one-third that of bypass grafting [20,22] and convalescence is short, the appeal is evident. As the pool of patients having undergone prior bypass grafting grows, the number with recurrent symptoms secondary to progressive disease will also grow. Percutaneous angioplasty now offers a gentle effective mode of therapy to a significant subgroup of these individuals with favorable vascular anatomy.

Department of Medicine

Emory University School of Medicine

1364 Clifton Road N.E.

Atlanta, GA 30322, U.S.A.

David Hall Orlando Corzo

John Douglas Andreas R. Gruentzig

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