The American Association for

Thoracic Surgery

66TH ANNUAL MEETING

Scientific Program

MONDAY MORNING, April 28, 1986

8:30 a.m. Business Session (Limited to Members)

8:45 a.m. Scientific Session - Grand Ballroom

1. Predictors of Reoperation after Myocardial Revascularization

DELOS M. COSGROVE, FLOYD D. LOOP,

BRUCE W. LYTLE*, CARL C. GILL*,

LEONARD A.R. GOLDING*, CHRISTOPHER GIBSON*,

ROBERT W. STEWART*, PAUL C. TAYLOR*

and MARLENE GOORMASTIC*

Cleveland, Ohio

The first 1,000 patients undergoing primary isolated myocardial revascularization each year from 1971-1978 were analyzed to define the determinants of reoperation and reoperation-free survival. There were 79 operative deaths (1%). Mean follow-up was 8.8 ± 2.7 years. Forty-one patients (0.5%) were lost to follow-up and 66,566 patient years of follow-up were available for analysis.

Reoperation occurred in 766 patients (9.7%) at a mean of 6.8 ± 3.2 years (range 0-13) postoperatively. Ninety-six percent and 86% were reoperation-free at 5 and 10 years respectively. Reoperation-free survival was 90.8% and 70.8% at 5 and 10 years. The annual incidence of reoperation increased as the length of follow-up increased, being 0.9% and 2.7% at 5 and 10 years. The cumulative percent of reoperation was 18.9% at 12 years.

Reoperation-free percents at 5 and 10 years were 95.2% and 81.5% for patients <40 and 99.1% and 98.1% for patients >70, p<0.0001.

Reoperation-free percents at 5 and 10 years were 98.4% and 92.2% for patients with internal mammary artery [IMA] grafts and 96.7% and 86.7% for patients with only vein grafts, p<0.0001. Reoperation-free survival at 5 and 10 years was 94.0% and 79.4% for patients receiving an IMA graft and 89.1% and 66.7% for patients with vein grafts, p<0.0001.

Univariately significant factors were entered into a Cox Model to determine the predictors of reoperation and reoperation-free survival. Young age is the most important factor influencing reoperations followed by no IMA and incomplete revascularization. No IMA is the most important risk factor influencing reoperation-free survival followed by smoking and incomplete revascularization. Type of conduit was the most important predictor of reoperation and reoperation-free survival for all age groups.

We conclude that IMA grafting reduces the incidence of reoperation and improves reoperation-free survival.

*By Invitation

8:55 a.m.

2. Evaluation of Postoperative Flow Reserve in Internal Mammary Artery Bypass Grafts

ALAN M. JOHNSON*, IRVING L. KRON*,

DENNY D. WATSON*, ROBERTS. GIBSON*

and STANTON P. NOLAN

Charlottesville, Virginia

The internal mammary artery (IMA) has been advocated for use in bypass grafting due to its superior long-term patency when compared to saphenous vein. Concern exists that the flow through the IMA may be inadequate during periods of peak myocardial demand. To investigate this, 24 consecutive patients with a mean proximal LAD stenosis of 87.5% were selected for coronary bypass using the IMA. Within 8 weeks of operation, all underwent evaluation with exercise Thallium-201 (TL-201) scintigraphy. A mean maximum predicted heart rate of 101% and rate pressure product of 29.9 x 10³ were achieved at a mean workload of 8.1 METS. TL-201 activity, expressed as a ratio of anteroseptal activity to posterolateral wall activity (or inferior wall activity if the posterolateral wall was deemed abnormal) was 0.97 ± 0.15. A second group of 25 patients, determined to be normal by either normal ventriculography and coronary angiography (16 patients) or a normal history, physical examination, graded exercise treadmill test, and myocardial distribution of TL-201 (9 patients), was similarly evaluated. This group reached a mean maximum predicted heart rate of 85.3% and a mean rate pressure product of 23.7 x 10³, at a mean workload of 9.6 METS. The mean septal to posterolateral wall TL-201 activity ratio for these normal patients was 1.0 ± 0.15. No significant difference in relative post-exercise anteroseptal TL-201 activity between normal patients and IMA bypass recipients can be demonstrated. A group of 34 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) was compared to the IMA study group. TL-201 activity for the angioplasty group, 0.92 ± 0.16, was not significantly different from that for the IMA group. The internal mammary artery provides excellent coronary flow at peak myocardial demand and compares favorably to PTCA.

*By Invitation

9:00 a.m.

3. Free (Aorto-Coronary) Internal Mammary Artery Graft: Late Results

FLOYD D. LOOP, BRUCE W. LYTLE*,

DELOS M. COSGROVE, LEONARD A.R. COLDING*,

PAUL C. TAYLOR* and ROBERT W. STEWART*

Cleveland, Ohio

Free internal mammary artery (IMA) grafts were performed in 156 patients (1971-1985). Preoperative clinical and angiographic variables were similar to those of other isolated coronary bypass series. Of 244 total IMA grafts, 166 were in the aorto-coronary position and were performed mainly because of unsuitable saphenous veins or to gain additional graft length. One patient (0.6%) died during hospitalization. Perioperative complications included respiratory dysfunction in 16 (10.3%), reoperation for bleeding in 14 (9.0%), stroke in 4 (2.6%), myocardial infarction in 3 (1.9%), and wound complications in 2 (1.3%). Morbidity occurred significantly more often in the 1971-1975 period. Subsequently, 5 (3.2%) had reoperation (6-122 months; mean 91 months). After a 92-month mean follow-up, ten-year actuarial survival (including all causes of death) was 78.6%.

Of 44 free grafts restudied within 18 months of operation, 34 (77.3%) were patent. The higher rate of early closure is attributed to technical problems early in our experience, especially construction of the aortic anastomosis. However, 30 of 31 (96.8%) free grafts studied >18 months (mean 85 months) were open. Forty-nine of 58 (84.5%) free IMA grafts placed to the anterior descending coronary artery, 9 of 9 (100%) to the circumflex, and 6 of 8 (75.0%) to the right coronary artery were patent. Sequential catheterization showed that of 22 free grafts open at 10 months, 21 remained patent at 73 months; when 6 of these were restudied at 93 months (third catheterization) and 2 (fourth catheterization) at 125 months, all were patent. These late studies of free IMA grafts showed no evidence of graft atherosclerosis. Free IMA grafts, like in situ IMA grafts, appear to have relative immunity from atherosclerosis. These findings expand the versatility of IMA grafting and justify wider use of free IMA grafts.

*By Invitation

9:05 a.m.

4. Angiographic Assesment of Complex Mammary Artery Bypass Grafting

J. SCOTT RANKIN*, GLENN E. NEWMAN*,

THOMAS M. BASHORE*, LAWRENCE H. MUHLBAIER*,

VICTOR S. BEHAR* and DAVID C. SABISTON, JR.

Durham, North Carolina

The internal mammary artery (IMA) has become the coronary bypass graft of choice in recent years because of enhanced long-term patency. Along with this trend, sequential, bilateral, and free IMA grafts have been employed more frequently in an effort to maximize the number of distal IMA anastomoses. This approach of maximally utilizing the IMA (complex mammary grafting, CMG) seems logical, but at present, little information is available about patency of the newer types of IMA grafts to justify this more complicated surgical procedure. Over a 15 month period, 207 patients underwent bypass graft angiography from 1-32 weeks postoperatively, representing an 85% restudy rate of a consecutive series of coronary bypass procedures. Patency was defined as complete filling of the graft and distal vessel bypassed. There were a total of 841 distal vessels grafted or 4.1 per patient; overall patency was 91% for 503 distal vein graft (VG) anastomoses and 99% for 338 IMAs. Individual patencies of distal anastomoses expressed as number patent/total (% patent) were: simple VG 262/285 (92%); sequential VG 196/218 (90%); left (L) IMA to LAD 109/110 (99%); LIMA to CMA 14/14 (100%); right (R) IMA to RCA 19/20 (95%); RIMA to LAD 10/10 (100%); RIMA to CMA via transverse sinus 18/20 (90%); sequential LIMA to LAD system 133/134 (99%); sequential LIMA to CMA system 15/15 (100%); free IMA 9/9 (100%); free sequential IMA 6/6 (100%). Of the 18 patent transverse sinus RIMA grafts to the CMA, 3 exhibited very slow flow and probably were not functional. Thus, based on postoperative graft patency data, expanded use of the more complicated types of IMA grafts seems justified. For whatever reason, function of the RIMA to CMA graft was suboptimal, and this method has been discontinued. All other CMG techniques had excellent patency rates as compared to vein grafts, and these differences may become even more significant late postoperatively. Based on these findings, CMG is proposed as the current procedure of choice for the surgical treatment of ischemic heart disease.

9:10 a.m. Discussion

*By Invitation

9:30 a.m.

5. Percutaneous Transluminal Coronary Angioplasty: A Growing Surgical Problem

U. SCOTT PAGE*, J. EDWARD OKIES,

LEON Q. COLBURN*, JOHN C. BIGELOW*,

NEAL W. SALOMON* and ALBERT H. KRAUSE

Portland, Oregon

The incidence of PTCA pts who come to surgery is doubling yearly at our hospital. The incidence in 1985 has risen to 12.3% (52/420). Since the operative mortality and MI rates are 2.5 times higher in the PTCA group (5.5% vs 1.9% mortality, and 14% vs 5.5% MI) a careful analysis of this group is needed.

128 such pts are compared to 2236 non-PTCA pts. PTCA pts are younger (59 vs 61.3 years), have better ejection fractions (65 vs 63%), and require fewer grafts (1.9 vs 2.99). 21.9% of the PTCA pts were emergent cases and 4.7% were desperate (cardiac massage). The non-PTCA pts had 5.6% emergent and 0.4% desperate operations.

PTCA pts are divided into 4 groups. In Group I are 44 pts taken immediately to surgery (3 deaths and 17 MI's). Group II contains 46 pts operated from 1 to 20 days post-PTCA (11 MI's and 3 OP deaths). Group III contains 34 pts operated more than 20 days post-PTCA (1 MI and 1 OP death). 6 additional Mi's occurred at the time of PTCA in this group. 13 Group III pts had 2 PTCA's prior to surgery. Group IV pts had an MI treated with streptokinase followed by PTCA that failed followed by surgery. All 4 of these pts had MI's but there were no deaths. Of 18 Group II pts who had a poor result at PTCA but delayed CABG, 10 developed an MI (55%) with 1 death.

Group I pts allow a detailed study of our ability to prevent infarction after acute occlusion of a coronary. 18 of 33 pts taken directly to surgery with occluded vessels survived without an MI. Of the remaining 15 there were 2 deaths.

There is increasing need to respond rapidly to the acute occlusion in the cath. lab and to proceed with surgery immediately if PTCA decreases the stability of the patient. A recent PTCA increases surgical risk.

9:40 a.m. Discussion

*By Invitation

9:50 a.m.

6. Early and Late Results of Coronary Endarterectomy: Analysis of 3,369 Patients

JAMES J. LIVESAY*, DENTON A. COOLEY,

GRADY L. HALLMAN, GEORGE J. REUL,

DAVID A. OTT and J. MICHAEL DUNCAN*

Houston, Texas

The effectiveness of coronary revascularization has been questioned in patients with diffuse coronary disease. Over a 14 year period (1970-1984), 30,464 patients have undergone surgical revascularization at one institution using coronary artery bypass (CAB) alone in 27,095 patients (Group I) or combined with coronary endarterectomy in 3,369 patients (12.4%) Group II. Analysis of preoperative variables has shown no significant difference between patient groups with respect to age, sex distribution, risk factors for atherosclerosis, or number of diseased vessels. Surgical indications for coronary endarterectomy included multi-segment disease, long diffuse stenosis, total occlusion, and plaque separation during arteriotomy. Coronary endarterectomy was performed in the right coronary artery (83%), in the let anterior descending (LAD) (9%), in the circumflex (4%), and in multiple vessels (4%).

The early results following revascularizaion indicate a small increase in surgical risk after coronary endarterectomy. (30 day mortality: Group I 2.6°7o vs. Group II 4.4%)* Early mortality was significantly increased by endarterectomy in the LAD )8.5%) compared to non-LAD (4.2%)* In a sample of 4,473 patients, myocardial complications were also found to be increased after coronary endarterectomy. (Perioperative myocardial infarction: Group I 2.5% vs. Group II 5.6%).* Both fatal and non-fatal cardiac arrest increased (Group 1 1.7% vs. Group II 3.5%)* suggesting the failure mode of unsuccessful endarterectomy. Surgical results have improved significantly over the latter half of the study period since the introduction of cold cardioplegia and techniques for complete revascularization. Early mortality after coronary endarterectomy (Group II) decreased substantially from 1970-76 (6.4%) to 1977-84 (3.5%)*. Actuarial analysis of long-term survival after endarterectomy has demonstrated the same sustained improvement in survival as seen after CAB alone. (5 year survival: Group I 90%, Group II 86% and 10 year survival: Group I 74%, Group II 67%).

Despite the small increase in surgical risk associated with coronary endarterectomy, the early and long-term results support the selective application of this procedure in patients with diffuse distal disease and demonstrate its beneficial effect on long-term survival.

*P<0.01

10:00 a.m. Discussion

10:10 a.m. Intermission - Visit Exhibits - Exhibit Hall

*By Invitation

10:50 a.m. Scientific Session - Grand Ballroom

7. Early and Late Results of Operation Following Thrombolytic Therapy for Acute Myocardial Infarction

JOHN A. PETROVICH*, JOEL A. SCHNEIDER*,

GEORGE J. TAYLOR*, FRANK L. MIKELL*,

JOHN E. BATCHELDER*, H. WESTON MOSES*,

JAMES T. DOVE* and HARRY A. WELLONS

Springfield, Illinois

Recent reports have established the efficacy of thrombolytic therapy in limiting myocardial infarction. Between September 1981 and September 1984, we treated 355 patients with intracoronary (87) or intravenous (268) streptokinase (SK) within 6 hours of acute myocardial infarction. Thrombolysis was successful in 63% of intracoronary and 81% of intravenous treated patients. Because residual critical stenosis is usually present and predisposes the patient to reinfarction, revascularization procedures were investigated as an extension of thrombolytic therapy. One hundred ninety-one patients age 56 ± 10 (25-77) years underwent early surgical revascularization 4.1 ± 3.6 days after intracoronary SK or intravenous SK for acute MI. Eighty-nine percent (170/191) had a successful outcome to SK therapy. Thirteen patients (6.8%) underwent emergency coronary artery bypass grafting (CABG) for failed percutaneous angioplasty (PTCA). There were 3.2 ± 1.4 grafts per patient and 3.8 ± 2.9 units of blood administered in the perioperative period. Operative mortality was 4.2% (8/191) with a 15.4% mortality in the failed PTCA group (2/13). Mean hospitalization time following surgery was 10.9 ± 6.8 days. Follow-up was 27 ± 8 (12-48) months and was obtained on all patients. Late cardiac mortality was 1.0% (2/183). Ninety percent of the follow-up group was without angina and only 1.7% showed no improvement after surgery. Reinfarction rate was 2.2% with known graft failure in 2 patients. Our experience indicates that early revascularization after thrombolytic therapy may be performed with low operative mortality and morbidity and is associated with excellent late results.

11:00 a.m. Discussion

*By Invitation

11:10 a.m.

8. Superiority of Surgical Over Medical Revascularization in the Treatment of Acute Coronory Occlusion

BRADLEY S. ALLEN*, GERALD D. BUCKBERG,

MARCUS SCHWAIGER*, LAWRENCE YEATMAN*,

JAN TILLISCH*, NOBUYUKI KAWATA*,

JOHN MESSENGER* and CURTIS LEE*

Los Angeles, California

Functional recovery and avoidance of infarction are thought almost impossible after 6 hours of coronary occlusion in medical or surgical settings. This clinical study shows that surgical control of reperfusion using substrate enriched blood cardioplegia + total vented bypass after prolonged ischemia (>8 hours) allows consistent recovery while medical reperfusion (i.e. streptokinase ± angioplasty) after shorter ischemia (<4.5 hours) does not.

Methods: Thirty-three consecutive patients with acute coronary occlusion underwent either medical or surgical revascularization. Medical reperfusion was with normal blood in 21 patients in the cath lab (i.e. streptokinase, n=11, ±angioplasty, n=10). Surgical reperfusion was with substrate enriched (glutamate + aspartate) blood cardioplegia during CABG after naturally occurring coronary occlusion in 12 patients. The mean time to revascularization was comparable after streptokinase and/or angioplasty (4.5 vs 4.3 hours) but prolonged 8.8 ± 0.6 hours* in 12 patients undergoing CABG for acute natural occlusion (range 7.4-13.5 hours).

Results: Medical revascularization produced cardiogenic shock in 7 of 21 previously hemodynamically stable patients (5 with single vessel disease), whereas surgical revascularization reversed cardiogenic shock in 5 of 10 patients with pre-operative hemodynamic instability secondary to coronary occlusion. Surgical results were superior in incidence of ECG infarction (50% vs 100%)*, severe ventricular tachyarrhythmias (0% vs 43%)*, recovery of global injection fraction (47% vs 41 %), and recovery of significant regional contractility (100% vs 9%)*, and hospitalization (8.8 vs 11 days)* despite delay of surgical treatment for up to 13 hours. No patient died.

Conclusions: Surgical control of the composition and conditions of reperfusion decreases infarction, reduce arrhythmias, restores regional and global wall motion significantly more than medical reperfusion and shortens hospitalization. These preliminary findings imply that acute coronary occlusion is treated best surgically where a reperfusion injury can be avoided by controlling the conditions (bypass) and composition (cardioplegia) of reperfusion.

*p<0.05

11:20 a.m. Discussion

11:30 a.m. Presidential Address - Grand Ballroom

"New York, A Bellwether for Thoracic Surgery"

James R. Malm, M.D., New York, New York

*By Invitation