Does the AHA/ACC task force grading system predict outcome in multivessel coronary angioplasty?

Utility of the ACC/AHA Lesion Classification to Predict Outcomes After Contemporary DES Treatment: Individual Patient Data Pooled Analysis From 7 Randomized Trials

Background Use of the modified American College of Cardiology (ACC)/American Heart Association (AHA) lesion classification as a prognostic tool to predict short- and long-term clinical outcomes after percutaneous coronary intervention in the modern drug-eluting stent era is uncertain. Methods and Results Patient-level data from 7 prospective, randomized trials were pooled. Clinical outcomes of patients undergoing single lesion percutaneous coronary intervention with second-generation drug-eluting stent were analyzed according to modified ACC/AHA lesion class. The primary end point was target lesion failure (TLF: composite of cardiac death, target vessel myocardial infarction, or ischemia-driven target lesion revascularization). Clinical outcomes to 5 years were compared between patients treated for noncomplex (class A/B1) versus complex (class B2/C) lesions. Eight thousand five hundred sixteen patients (age 63.1±10.8 years, 70.5% male) were analyzed. Lesions were classified as A, B1, B2, and C in 7.9%, 28.5%, 33.7%, and 30.0% of cases, respectively. Target lesion failure was higher in patients undergoing percutaneous coronary intervention of complex versus noncomplex lesions at 30 days (2.0% versus 1.1%, P=0.004), at 1 year (4.6% versus 3.0%, P=0.0005), and at 5 years (12.4% versus 9.2%, P=0.0001). By multivariable analysis, treatment of ACC/AHA class B2/C lesions was significantly associated with higher rate of 5-year target lesion failure (adjusted hazard ratio, 1.39 [95% CI, 1.17-1.64], P=0.0001) driven by significantly higher rates of target vessel myocardial infarction and ischemia-driven target lesion revascularization. Conclusions In this pooled large-scale analysis, treating complex compared with noncomplex lesions according to the modified ACC/AHA classification with second-generation drug-eluting stent was associated with worse 5-year clinical outcomes. This historical classification system may be useful in the contemporary era for predicting early and late outcomes following percutaneous coronary intervention.

Inflammatory protein levels and depression screening after coronary stenting predict major adverse coronary events

BACKGROUND

Traditional risk factors cannot account for the majority of future major adverse coronary events (MACE) in patients diagnosed with heart disease. We examined levels of inflammatory proteins to be possible predictors of future MACE and physiological and psychological factors that initiate temporal increases in inflammatory protein levels.

METHODS

Peripheral blood samples and depression data were collected 4 to 12 hr after elective coronary stent insertion in 490 patients. Depression screening was assessed by a single-question screening tool. Predictive modeling for future MACE was performed by using survival analysis, with time from the index event (placement of the stent) to future MACE as the dependent variable.

RESULTS

Patients with high-sensitivity c-reactive protein (hsCRP) in the second and third quartiles were 3 and 2.5 times more likely to have a MACE than patients with hsCRP in the first quartile, respectively. As levels of vascular cell adhesion molecule and monocyte chemoattractant protein-1 increased, so did the risk of future MACE. Patients who screened positive for depression were approximately 2 times more likely to have a MACE within 24 months after stent placement than were patients who did not screen positive.

CONCLUSIONS

Our results suggest that hsCRP, vascular cell adhesion molecule, and monocyte chemoattractant protein-1 levels, measured after coronary stent insertion in patients with coronary heart disease, are prognostic of future MACE. Furthermore, positive depression screening is an independent predictor of future MACE.

Simplified scoring system for predicting mortality after percutaneous coronary intervention

OBJECTIVES

We sought to develop a simplified scoring system based on pre-intervention clinical characteristics to predict in-hospital mortality after percutaneous coronary intervention (PCI).

BACKGROUND

Percutaneous coronary intervention is associated with variety of complications, including the risk of death. Factors leading to poor outcomes need to be identified. Currently available indexes are cumbersome and therefore seldom used.

METHODS

Crude mortality and univariate odds ratios (ORs) for mortality associated with multiple clinical characteristics were calculated for 9,954 patients undergoing PCI at the William Beaumont Hospital during 1996 to 1998. Based on the OR, each factor was assigned a weighted score. Using these scores, a classification was constructed to determine the probability of death after PCI, with classes I through IV representing an increasing probability of procedural mortality. This classification was validated in a separate group of patients.

RESULTS

The factors with the highest univariate odds of dying and their scores were: myocardial infarction <14 days = 7; elevated creatinine = 4; multivessel disease = 4; and age >65 years = 3. Classes were created based on the presence of these factors in a given patient. The odds of dying and mortality increased significantly with each class. These results were reproduced in the validation subset.

CONCLUSIONS

Preprocedural clinical risk factors have a differential influence on the probability of death after PCI. Risk classification based on these factors can be used to accurately predict the procedural outcome. This simple classification can be used by interventionalists to assist in management decisions, to provide an estimate of procedural risk to the patients and relatives, and for quality assurance.

ABC stenosis morphology classification and outcome of coronary angioplasty: reassessment with computing techniques

BACKGROUND

The American College of Cardiology/American Heart Association (ACC/AHA) stenosis morphology classification (MC) stratifies coronary lesions for probability of success and complications after coronary angioplasty (PTCA). Modern computing techniques were used to evaluate the individual predictive value of MC in random PTCA cases.

METHODS AND RESULTS

MC was attributed to the target lesions by consensus of 2 observers. The predictive value regarding procedural success (PS) and major adverse cardiac events (MACE) of MC was analyzed by conventional logistic regression analyses and by inductive machine learning models. The study was adequately powered for the methods applied with 325 target lesions of 250 cases. Overall, PS decreased and MACE increased from type A to type C lesions. Regression analysis identified no single factor as predictive. Logistic regression showed an error rate of 42%. Machine learning techniques achieved an individual predictive error of only 10%, which could be further reduced to 2% by addition of parameters. For PS, MC parameters showed a high ranking for building the model. For MACE, variables of the medical history showed more impact.

CONCLUSIONS

MC per se cannot individually predict PS or MACE. However, when all MC parameters are integrated together with additional lesion-specific and history variables, a high individual predictive value can be achieved. This technique may be clinically helpful for risk stratification in the catheterization laboratory and improvement of classification systems in interventional cardiology.

A simplified lesion classification for predicting success and complications of coronary angioplasty. Registry Committee of the Society for Cardiac Angiography and Intervention

In 1988, the American College of Cardiology/American Heart Association (ACC/AHA) Task Force on Assessment of Diagnostic and Therapeutic Cardiovascular Procedures presented a classification of coronary lesions utilizing 26 lesion features to predict the success and complications of balloon angioplasty. Using data from the Registry of the Society for Cardiac Angiography and Interventions (SCAI) we evaluated the ability of this classification to predict success and complications. Lesion success, death in hospital, emergency cardiac bypass surgery, and major adverse events were evaluated in 41,071 patients who underwent single-vessel angioplasty from January 1993 to June 1996. Logistic models using the ACC/AHA lesion classification, vessel patency, or both, were compared. A new classification based on the interaction of the ACC/AHA classification plus lesion patency was compared with the existing ACC/AHA classification. Vessel patency, added to the ACC/AHA classification, improved prediction of lesion success (p </=0.0001). Class A and patent B lesions had similar success and complication rates, so a simplified classification (SCAI) using only 7 lesion characteristics could be created. This system (I: non-C patent, II: C patent, III: non-C occluded, and IV: C occluded) improved prediction of lesion success compared with the ACC/AHA classification (Bayesian Information Criterion statistic: ACC/AHA 16539, SCAI 15956; and area under the receiver- operating characteristics curve 0.659, 0.693, respectively). The SCAI classification was preferred for predicting major complications and in-hospital death and was similar to the ACC/AHA classification for predicting emergency bypass surgery.

The relative influence of lesion length and other stenosis morphologies on procedural success of coronary intervention

As coronary interventional technology improves, the influence of lesion length (LL) on procedural success and device selection may vary. Thus, the authors prospectively analyzed 957 consecutive coronary interventions (CI) in 1,404 stenoses to ascertain the influence of lesion length on CI outcome. Stenosis morphology was prospectively classified by the AHA/ACC criteria. LL was analyzed both as dichotomous (S: < 10 mm, L: > 10 mm) variables and by the three-tiered AHA/ACC criteria (I: < 10 mm, II: 10-20 mm, III: > 20 mm). There was a significant univariate relationship between CI success and S stenosis (S: 95.8% vs L: 91.8%, p = 0.002 and I: 96.0%, II: 91.7%, III: 89.3%). Numerous interrelationships involving the morphologic characteristics were noted: lesion morphologies associated with S lesions were concentric (p = 0.0001) and had smooth contour (p = 0.0001), ostial location (p = 0.05) and little calcification (p = 0.0007), while irregular contour (p=0.0001), calcification (p=0.0076), eccentric (p=0.0001), thrombus (p = 0.0001), recent (p = 0.0001) or chronic (p = 0.001) total occlusion were associated with L lesions. When these relationships were taken into account by multiple logistic regression analysis, lesion length was not predictive of procedural outcome (p = 0.099). One morphologic type was associated with increased CI success: irregular contour (p = 0.022); recent (p < 0.0001) or chronic (< 0.0001) occlusions were associated with decreased CI success. Another factor considered was device selection: S lesions were associated with greater balloon angioplasty usage (p = 0.002), whereas more coronary stents (p = 0.024) and rotoblator (p = 0.018) devices were used in L lesions. More balloon angioplasty was performed in concentric (p < 0.0001) lesions; interventional devices were employed more often in eccentric (p < 0.0001) and irregular lesions (p < 0.0001). More complications were noted in lesions with thrombus (p = 0.0002), but lesion length was not predictive (p = NS). Lesion length is not a significant predictor of procedural success when adjusted for other lesion morphologies in the modern interventional era. The availability of new devices has improved the results in longer lesions since the AHA/ACC criteria were originally proposed.

Prognostic value of the modified american college of Cardiology/American heart association stenosis morphology classification for long-term angiographic and clinical outcome after coronary stent placement

Background-The modified American College of Cardiology/American Heart Association (ACC/AHA) lesion morphology criteria are predictive of early outcome after various coronary catheter interventions. Their potential prognostic value after stent implantation and, in particular, for restenosis and long-term clinical outcome has not been studied. We assessed the prognostic value of the modified ACC/AHA criteria for the long-term angiographic and clinical outcome of patients after coronary stenting. Methods and Results-This study includes 2944 consecutive patients with symptomatic coronary artery disease treated with coronary stent placement. Modified ACC/AHA lesion morphology criteria were used to qualitatively assess the angiograms; type A and B1 lesions were categorized as simple, and type B2 and C lesions were designated complex. Primary end points were angiographic restenosis and 1-year event-free survival. Restenosis rate was 33.2% in complex lesions and 24.9% in simple lesions (P<0.001). It was 21. 7% for type A, 26.3% for type B1, 33.7% for type B2, and 32.6% for type C lesions. One-year event-free survival was 75.6% for patients with complex lesions and 81.1% for patients with simple lesions (P<0. 001). It was 85.2% for patients with type A, 79.4% for type B1, 75. 9% for type B2, and 75.2% type C lesions. The higher risk for restenosis and an adverse outcome associated with complex lesions was also maintained after multivariate adjustment for other clinical and angiographic characteristics. Conclusions-The modified ACC/AHA lesion morphology scheme has significant prognostic value for the outcome of patients after coronary stent placement. Lesion morphology is able to influence the restenosis process and thus the entire 1-year clinical course of these patients.

Value of the American College of Cardiology/American Heart Association stenosis morphology classification for coronary interventions in the late 1990s

The goal of this study was to reassess the accuracy of the American College of Cardiology/American Heart Association (ACC/AHA) stenosis morphology classification for predicting coronary intervention success and complications in the era of new devices. Previous studies performed in the early part of this decade for percutaneous transluminal coronary angioplasty in patients with multivessel coronary artery disease found that these criteria were predictive of success rates but not complication rates. Data for 957 consecutive coronary interventions in 1,404 lesions from June 1994 to October 1996 were prospectively classified according to ACC/AHA guidelines and entered into a database. Ninety-one and 9/10 of coronary interventions were successful, defined as <50% residual stenosis of each vessel attempted in the absence of major in-hospital complications, including Q-wave myocardial infarction, ventricular arrhythmia, need for emergency coronary artery bypass surgery, or death. Success rates did not differ between A (186 of 193, 96.3%), B1 (211 of 221, 95.5%), and B2 (676 of 711, 95.1%) lesions, but each was more successful than C (246 of 279, 88.2%) lesions (p <0.003, p < 0.004, and p = 0.0001, respectively). The class of lesion (A, B, or C) did not predict device (atherectomy, rotablator, and stent) use but specific morphologic characteristics of lesions within these classes were predictive of which device was used. Multiple regression analysis revealed that total occlusion and vessel tortuosity were predictive of procedure failure. Lesion type (A, B, or C) was not predictive of complications, but bifurcation lesions (p = 0.0045), presence of thrombus (p = 0.0001), inability to protect a major side branch (p = 0.0468), and degenerated vein graft lesions (p = 0.0283) were predictive. Thus, the ACC/AHA grading system is predictive of successful coronary intervention outcome, particularly of C-type characteristics, but not of complications or device success rate and selection. Although lesion type (A, B, or C) was not predictive of complications, specific lesion morphologies were predictive of adverse events and device use.

Does low individual operator coronary interventional procedural volume correlate with worse institutional procedural outcome?

OBJECTIVES

To assess the relation between individual operator coronary interventional volume and incidence of complications, the in-hospital outcome at a single, moderate volume urban academic center was prospectively collected over a 3-year period.

BACKGROUND

A minimum of 75 coronary interventions/operator per year may be required in the future to obtain formal certification. However, few data exist regarding individual operator volumes and procedural outcome.

METHODS

Between January 1993 and December 1995, 1,389 consecutive procedures were performed or supervised by nine geographic full-time operators: 171 (12.3%) utilized various devices, and 350 (25.2%) involved multivessel coronary intervention. Left ventricular ejection fraction was 59 +/- 15% (mean +/- SD), and there were 1.7 +/- 0.7 vessels diseased (with > or = 70% stenosis). Clinical indications included stable angina in 22.5% of cases, unstable angina in 31.9%, acute myocardial infarction (MI) in 2.9%, post MI in 20.6%, shock or acute heart failure in 3.0% and restenosis in 19.1%. In the last consecutive 857 lesions in 655 cases, 20.7% type A, 55.5% type B and 23.8% type C lesions were categorized before coronary intervention.

RESULTS

Average yearly operator volume ranged from 26 to 83 cases (mean 51 +/- 26). Each operator has performed a total of 590 +/- 268 coronary interventions, with 10.0 +/- 4.3 years of coronary interventional experience. The mean angioplasty volume rating for the nine operators was 180 +/- 37 (> 170 considered adequate). The in-hospital major complication rate was 1.4% (95% confidence interval 0.7% to 1.893%) for all coronary interventions, including death in 3 patients, bypass surgery in 13, arrhythmia in 3 and Q wave MI in 2. To ascertain how these outcomes compared with standard measures of coronary interventional outcome, four previously published registries were reanalyzed in a similar manner. The rate of complications in the present study was found to be significantly lower than that of the 1992-1993 Society for Cardiac Angiography and Intervention registry (1.9%, n = 19,594, p < 0.05 [excludes ventricular arrhythmias]), the 1994 American College of Cardiology database (3.9%, n = 38,963, p = 0.001), the Mid-America Heart Institute outcome in 1988 (2.3%, n = 5,413, p = 0.02) and the 1985-1986 National Heart, Lung, and Blood Institute Registry (7.2%, n = 1,801, p = 0.001). Odds ratios and 95% confidence intervals showed the outcome in the current study to be at least comparable to the standard registries.

CONCLUSIONS

Despite individual operator volumes below those currently being considered for credentialing, the overall institutional outcome was excellent in a diverse and complex patient population.

Comparison of heparin therapy for < or = 48 hours to > 48 hours in unstable angina pectoris

Of 450 consecutive patients with unstable angina admitted to a tertiary care, university-based medical center over a 24-month period, 334 were administered heparin and aspirin for some length of time. Two groups of 98 patients matched for acuity and gender at baseline were treated with either < or = 48 hours (group 1) or > 48 hours (group 2) of heparin. The acuity model used in this study incorporates 6 factors: age, recent myocardial infarction, treatment with intravenous nitroglycerin, previous therapy with beta blockers or calcium antagonists, baseline ST depression, and diabetes. Despite similar risks and overall clinical outcome, group 2 had significantly more myocardial infarction or death after 48 hours than group 1 (p = 0.01). In part, this was due to a delay in the performance of coronary angiography (2.8 +/- 1.4 vs 3.5 +/- 15 days, p = 0.01), coronary intervention (2.7 +/- 1.8 vs 5.1 +/- 2.3 days, p = 0.01), and bypass surgery (3.8 +/- 3.6 vs 7.0 +/- 5.6 days, p = 0.02). There was no difference between groups regarding the success of coronary intervention (90% vs 88%, p = NS). Heparin duration was influenced by the finding of intracoronary thrombus or ulceration on angiography before revascularization, as each finding was seen more often in group 2 (thrombus, 12% vs 24%; ulceration, 38% vs 60%). These results suggest that the optimal duration of heparin therapy is up to 48 hours after admission in unstable angina; a longer time period is associated with increased adverse consequences.

Development and validation of simplified predictive index for major complications in contemporary percutaneous transluminal coronary angioplasty practice. The Registry Committee of the Society for Cardiac Angiography and Interventions

OBJECTIVES

This study was designed to determine the preprocedural risk factors for major complications (emergent coronary bypass surgery, myocardial infarction or death) of coronary angioplasty and to derive and validate a simplified index that predicts patients' a priori risk of complications.

BACKGROUND

Previous studies of risk factors for complications after coronary angioplasty may not be generalizable to current, broad-based angioplasty practice. Furthermore, to our knowledge a clinically useful predictive index has not been derived and independently validated.

METHODS

From data collected prospectively for the Registry of the Society for Cardiac Angiography and Interventions for 1992, multivariable logistic regression was used to determine which variables were independently associated with complications in 10,622 first angioplasty procedures. Stepwise regression and receiver operating characteristic curves then were used in this registry to develop a predictive index for complications that was validated using 5,250 first angioplasty procedures in the 1993 registry.

RESULTS

Predictors of major complications were multivessel disease, unstable angina, recent myocardial infarction, type C lesion or left main angioplasty, shock, age, geographic region and absence of previous coronary bypass surgery. The derived predictive index consisted of the first six of these variables plus aortic valve disease and classified patients into four risk groups: low (1.3% complications), moderate (2.8%), high (12.7%) and very high (29.7%) risk. This index demonstrated consistent reliability and discriminatory ability when applied to the 1993 data.

CONCLUSIONS

Predictors of major complications identified in selected populations also apply currently in broad-based practice. From these variables, a predictive index can stratify patients into risk groups before angioplasty, thus aiding in risk assessment, resource allocation and risk adjustment.

Utility of various clinical, noninvasive, and invasive procedures for determining the causes of recurrence of myocardial ischemia or infarction > or = 1 year after percutaneous transluminal coronary angioplasty

In patients with recurrent symptoms > or = 1 year after successful percutaneous transluminal coronary angioplasty (PTCA), the decision of whether to proceed directly with coronary angiography or to evaluate the patient noninvasively can be difficult. To determine which demographic, historical, clinical, and laboratory factors are useful in helping to make this decision, 76 consecutive patients who presented > 1 year (768 +/- 309 days) after successful PTCA with resolution of symptoms were studied. The initial PTCA successfully treated all stenoses (except chronically occluded vessels) in all major vessels and segments. The patient group was predominantly men (68%), with a mean age of 64 +/- 10 years. A prior myocardial infarction was present in 39 patients (51%), and there was a mean of 2.8 risk factors per patient. In patients who presented with recurrent symptoms, the Canadian Cardiovascular Society functional class was 2.0 +/- 0.9; 2 patients presented with acute infarctions, 57 were admitted to the hospital with unstable angina, and 17 had stable angina. New electrocardiographic changes at rest were found in 19 of 74 patients (26%) with recurrent angina. A thallium stress test was performed in 40 patients (53%), with a sensitivity of 77% and a specificity of 36% for the presence of a significant stenosis. No nonangiographic variable was predictive of angiographic findings. At angiography, the number of coronary arteries with > or = 50% diameter narrowing was 1.4 +/- 1.0. Forty-two patients had stenosis at a new site, 7 had restenosis, and 27 had no new stenoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphological and quantitative angiographic analyses of progression of coronary stenoses. A comparison of Q-wave and non-Q-wave myocardial infarction

BACKGROUND

The purpose of this study was to determine differences in coronary stenosis severity and morphology and time course of progression between Q-wave and non-Q-wave myocardial infarction (MI).

METHODS AND RESULTS

We studied 32 patients with new Q-wave MI and 38 patients with new non-Q-wave MI who underwent coronary angiography both before and after MI without interval revascularization procedures. Quantitative coronary angiographic analysis was performed by the caliper method, and morphological analysis of coronary angiograms was obtained before and soon after acute MI. Before infarction, the stenosis severity at the site of future MI was worse in Q-wave (44 +/- 25%) versus non-Q-wave (23 +/- 35%) MI patients (P < .01). Eccentric and irregular plaques were more common in Q-wave MI patients (18 of 32, 56%, versus 5 of 38, 13%; P < .001). Non-Q-wave MI patients were more frequently found to have significant collaterals after MI compared with Q-wave MI patients (18 of 38, 47%, versus 1 of 32, 3%; P < .001) despite no difference in post-MI stenosis severity. Analysis according to time interval after pre-MI angiography showed that 9 of 11 patients (82%) with Q-wave MI < 18 months later had a stenosis of > or = 50% versus 7 of 21 (33%) with an interval > 18 months (P < .05). By comparison, non-Q-wave MI patients tended to fall into two categories regardless of time of progression: Either minimal or no stenosis (< 20%) or else a severe stenosis (> 70%) was typically present.

CONCLUSIONS

The atheromatous plaque substrate is different in Q-wave and non-Q-wave MI. Non-Q-wave MI occurs typically at a site shown by pre-MI angiography to involve either minimal luminal narrowing or a severe stenosis before MI, which is usually nonulcerated. By comparison, Q-wave MI follows a moderate stenosis in which the plaque is eccentric and ulcerated. Such differences culminate in differences in thrombus lability and collateral development and consequently in different clinical profiles.

Use of a monoclonal antibody directed against the platelet glycoprotein IIb/IIIa receptor in high-risk coronary angioplasty

BACKGROUND

Platelets are believed to play a part in the ischemic complications of coronary angioplasty, such as abrupt closure of the coronary vessel during or soon after the procedure. Accordingly, we evaluated the effect of a chimeric monoclonal-antibody Fab fragment (c7E3 Fab) directed against the platelet glycoprotein IIb/IIIa receptor, in patients undergoing angioplasty who were at high risk for ischemic complications. This receptor is the final common pathway for platelet aggregation.

METHODS

In a prospective, randomized, double-blind trial, 2099 patients treated at 56 centers received a bolus and an infusion of placebo, a bolus of c7E3 Fab and an infusion of placebo, or a bolus and an infusion of c7E3 Fab. They were scheduled to undergo coronary angioplasty or atherectomy in high-risk clinical situations involving severe unstable angina, evolving acute myocardial infarction, or high-risk coronary morphologic characteristics. The primary study end point consisted of any of the following: death, nonfatal myocardial infarction, unplanned surgical revascularization, unplanned repeat percutaneous procedure, unplanned implantation of a coronary stent, or insertion of an intraaortic balloon pump for refractory ischemia. The numbers of end-point events were tabulated for 30 days after randomization.

RESULTS

As compared with placebo, the c7E3 Fab bolus and infusion resulted in a 35 percent reduction in the rate of the primary end point (12.8 vs. 8.3 percent, P = 0.008), whereas a 10 percent reduction was observed with the c7E3 Fab bolus alone (12.8 vs. 11.5 percent, P = 0.43). The reduction in the number of events with the c7E3 Fab bolus and infusion was consistent across the end points of unplanned revascularization procedures and nonfatal myocardial infarction. Bleeding episodes and transfusions were more frequent in the group given the c7E3 Fab bolus and infusion than in the other two groups.

CONCLUSIONS

Ischemic complications of coronary angioplasty and atherectomy were reduced with a monoclonal antibody directed against the platelet IIb/IIIa glycoprotein receptor, although the risk of bleeding was increased.

Optimizing surgical backup for multiple simultaneous percutaneous transluminal coronary angioplasty procedures

At busy interventional centers, it may be difficult to coordinate surgical backup for multiple simultaneous PTCA procedures. We sought to determine the actual risk of two simultaneous cases requiring surgery, and to identify a group in which multiple simultaneous PTCA procedures could be performed at low risk. We prospectively applied the ACC/AHA A/B/C lesion classification system and an empiric low/medium/high risk classification (based on patients' overall clinical picture) to 1,128 PTCA procedures over a 9 month period; 22 of these patients (1.9%) went directly from the catheterization laboratory to emergency CABG. The incidence of emergency CABG by groups was A-low 1/166, A-medium 1/71, A-high 0/22, B-low 1/116, B-medium 10/481, B-high 2/52, C-low 2/47, C-medium 3/88, and C-high 2/85. The patients were divided into two groups: minimal risk (A + B-low: 3/375 or 0.8%) and increased risk (B-med/high + C: 19/753 or 2.5%). The difference between the groups was significant using chi square with an alpha < 0.05. The risk of two cases requiring surgery at the same time was calculated as a function of the number of simultaneous PTCA procedures performed. Six or fewer minimal risk PTCA, one increased risk plus up to three minimal risk, and a maximum of two increased risk cases were found to have a risk of < 0.001. We conclude that it is possible to identify a group of patients with minimal risk, in whom multiple simultaneous procedures can be performed with a negligible probability of two cases requiring surgery at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)