Design of comparative clinical studies of percutaneous transluminal coronary angioplasty using estimates from the Coronary Artery Surgery Study.

The design of a prospective randomized trial of PTCA is discussed. It is suggested that patients with proximal subtotal occlusion of 1 or more vessels may be candidates for such a trial. Medical therapy as a control of 1-vessel CAD, medical or surgical therapy as a control for 2-vessel CAD (with 1 dilatable vessel) cases and surgical therapy as a control for 3-vessel CAD are most congruent with current practice. Possible criteria for comparison of PTCA with a control therapy include vital status, angina with daily activities, angina upon maximal exercise testing, MI, hospitalization, work status, cost, follow-up angiographic assessment, follow-up radionuclide ventriculography, measurement of immediate anatomic or hemodynamic change during initial treatment and quality-of-life indexes. These 10 measures are evaluated with respect to 9 desirable attributes for outcome criteria: the importance of the quantity measured, reproducibility, accuracy, low influence of investigator bias, low influence of subject bias, the measure is inexpensive and easy to obtain, sufficient occurrence to detect important differences, convenient to patients and measuring impairment due to disease. Examination of data from the Coronary Artery Surgery Study suggests that (1) a trial based on mortality alone is not feasible (because of a needed sample size in the thousands); (2) a trial using a combined death and/or MI end point would need approximately 1,000 cases even for patients with multivessel CAD; (3) approximately 950 patients would be needed in a trial to evaluate return to work (within 10%); (4) a trial based on pain relief (within 15% of the control group) would need 500 subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Guidelines for radiation protection in the cardiac catheterization laboratory.

Even though radiation levels in the catheterization laboratory are the highest encountered during any commonly performed diagnostic study, dose levels to laboratory personnel should not approach the maximum permissible. A certain minimum amount of radiation is necessary to produce optimal diagnostic images. Therefore, optimum use of radiation protection devices and measures is essential. The goal should be dose minimization, keeping personnel radiation dose as low as reasonably achievable. In the cardiac angiographic suite this goal can be assumed to have been accomplished if: (1) maximum use is made of suitable radiation protection devices, (2) film-and video-imaging chains are optimized, (3) good radiographic technique is employed, (4) strict ongoing quality control programs are maintained for radiographic equipment and cine processor, and (5) there is compliance with all federal, state and local regulations for the safe use of ionizing radiation.

A life table and Cox regression analysis of patients with combined proximal left anterior descending and proximal left circumflex coronary artery disease: non-left main equivalent lesions (CASS).

Combined proximal left anterior descending and proximal left circumflex artery stenoses greater than or equal to 70% have been referred to as "left main equivalent" lesions. We compared the survival rates of medically treated patients who have this type of coronary anatomic characteristics with the survival rates of patients who have left main coronary artery stenoses greater than or equal to 70% by use of a stratified life table approach and a Cox regression model. Comparison of the patients with left main coronary artery stenoses with those who have left main equivalent lesions by use of life table analysis and three different calculations of patient exposure time revealed a poorer prognosis for the patients who had left main coronary artery disease (p less than or equal to .04 for all three methods). The stepwise Cox analysis also determined that patients who had left main artery stenoses had a significantly poorer prognosis than patients who had left main equivalent coronary disease (p = .002), even after consideration of important baseline variables known to affect survival rates. We then compared the patients who had combined proximal left anterior descending and proximal left circumflex artery disease with patients who had combined stenoses greater than or equal to 70% in the nonproximal left anterior descending stenosis influenced survival rates. The 5 year to determine if location of the left anterior descending stenosis influenced survival rates. The 5 year survival rate was not as high for the patients who had proximal left anterior descending artery disease (55% vs 70%, p = .001). In conclusion, combined proximal left anterior descending and proximal left circumflex artery disease identifies a high-risk (as determined by angiography) patient subset.(ABSTRACT TRUNCATED AT 250 WORDS)

Follow-up of patients from the coronary artery surgery study (CASS) potentially suitable for percutaneous transluminal coronary angioplasty.

To determine the proper place for percutaneous transluminal coronary angioplasty (PTCA) among the therapeutic options available for patients with coronary heart disease, one must compare the results of PTCA with those obtained by conventional medical and surgical therapy. To develop a cohort comparison group, we interrogated the Coronary Artery Surgery Study (CASS) registry, and patients with proximal discrete subtotal stenosis (70% to 99%) involving the right, left anterior descending, circumflex, or left main coronary artery, singly or with stenoses in two of the three major coronary arteries, were selected; 796 patients (3.7% of all patients enrolled in CASS from 1975 to 1979) met these selection criteria. Surgical therapy was chosen in 53.3%; surgical mortality was low and there was excellent 4-year actuarial survival. There was significant improvement in functional class. Survival was also excellent in medically treated patients. Medically treated patients also had significant improvement in functional class in comparison with baseline values. The data presented here characterize a cohort group against which the clinical results of PTCA can be evaluated and compared.

Optimal resources for examination of the heart and lungs: cardiac catheterization and radiographic facilities. Examination of the Chest and Cardiovascular System Study Group.

This is a revision of the 1976 report published under the auspices of the Inter-Society Commission for Heart Disease Resources. These guidelines provide a description of optimal resources, personnel, and working arrangements and should not be used to set minimal, standard, or uniform criteria or practices for all institutions. Included in the report are specifications for radiologic and physiologic equipment, description of case loads for maintaining safe and effective performance and considerations or complication rates. Also discussed are professional staff qualifications and relationships between physicians and technical and administrative services personnel. Other topics reviewed included laboratory location, electrical safety, and radiation protection as well as optimal facilities and equipment criteria for conventional x-rays. Newer imaging modalities are briefly considered, primarily to to emphasize that the field is rapidly changing. It is not possible, however to make specific recommendations concerning how these modalities will complement and/or replace more conventional techniques and approaches now considered appropriate and optimal.

Left main coronary artery stenosis: angiographic determination.

Reliability of angiographic assessment of the left main coronary artery segment was evaluated by review of 106 coronary cineangiograms from the Coronary Artery Surgery Study. The films were interpreted by three groups of angiographers: those at a clinical site, those at a quality control site, and those on a study census panel. Among the readings of these three groups, there was 41% to 59% agreement on the severity of the lesion, with 80% agreement on whether the lesion was greater or less than 50%. The severity of lesion, its location, or presence of ectasia or calcium did not affect the discrepancy rate, whereas segments that were unusually short, diffusely diseased, or obscured by overlapping vessels were especially difficult to interpret.

Aneurysmal coronary artery disease.

To examine the clinical and historical features and the natural history of aneurysmal coronary disease, we reviewed the registry data of the Coronary Artery Surgery Study (CASS). Nine hundred seventy-eight patients, representing 4.9% of the total registry population, were identified as having aneurysmal disease. No significant differences were noted between aneurysmal and nonaneurysmal coronary disease patients when features such as hypertension, diabetes, lipid abnormalities, family history, cigarette consumption, incidence of documented myocardial infarction, presence and severity of angina, and presence of peripheral vascular disease were examined. In addition, no difference in 5-year medical survival was noted between these two groups. These findings suggest that aneurysmal coronary disease does not represent a distinct clinical entity but is, rather, a variant of coronary atherosclerosis.

[Comparison of the cumulative survival among patient groups with a left main coronary artery lesion after surgical and therapeutic treatment]. / Sravnenie sovokupnoi vyzhivaemosti sredi grupp patsientov s porazheniem glavnogo stvola levoi koronarnoi arterii posle operativnogo i terapevticheskogo lecheniia.

In order to evaluate survival patterns in patients with left main coronary artery (LMCA) disease, 1492 patients with LMCA disease admitted to the U. S. Collaborative Study on Coronary Artery Surgery (CASS) were followed up. Of the 1492 patients, 1183 (79%) underwent coronary artery bypass (CABG) with an operative mortality of 4.2% and an average of 2.7 grafts/patient inserted. Allocation to surgery was by patient and physician preference and not random. Surgical patients generally had more severe angina, a higher prevalence of beta blocker usage, worse ventricular function and more severe LMCA stenosis than medically treated patients. Overall (4 years) survival of the surgical group was 88% compared to 63% in the medical group (p less than 0.001). Other independent predictors of mortality included angiographic left ventricular (LV) dysfunction score, age, % LMCA stenosis, hypertension, dominance, and presence of significant right coronary artery (RCA) stenosis greater than or equal to 50%. CABG was not shown to significantly improve survival in women, in LMCA patients with left dominant circulation, in LMCA patients with non-diseases dominant or balanced RCA circulation or in LMCA patients with greater than or equal to 50% RCA stenosis but good LV function. These data indicate that CABG prolongs life in most patients with left main coronary artery disease, particularly those with severe LMCA narrowing or severe LV dysfunction, however, subgroups of LMCA patients are identifiable who may fare with medical treatment alone.

[Variability in the interpretation of coronary angiograms by different specialists based on data from the cooperative Coronary Artery Surgery Study]. / Variabel'nost' interpretatsii koronarnykh angiogramm raznymi spetsialistami po dannym Kooperativnogo izucheniia khirurgicheskogo lecheniia koronarnykh arterii.

Randomly selected cine arteriographic films of 30 diseased patients were read twice by each of three experienced observers. The intrareader variability was less than one-half of the interreader variability in reading the stenosis of segments of the coronary anatomy - a statistically significant difference (p less than 0.001). When extent of disease was evaluated by the number of diseased vessels, interreader variability was larger than intrareader variability (p less than 0.01). One reader read considerably less disease than the other two readers. The films were rated as to quality of the arteriographic films and the completeness of the study. In each case there was a greater interreader than intrareader variability (p less than 0.01). The films were rated good, acceptable, or poor. One of the three interpreters consistently gave worse ratings than the other two readers. It was particularly noteworthy that a larger amount of interreader variability was observed in both the left main coronary artery and the proximal left anterior descending artery.

Reproducibility of coronary arteriographic reading in the coronary artery surgery study (CASS).

Eight hundred seventy arteriograms from the Coronary Artery Surgery Study (CASS) were independently read by readers at two different clinics to evaluate the reproducibility of the interpretation of coronary arteriograms. Among proximal segments, the interpretation of lesions of the left main coronary artery were the least reproducible, P less than .02. When one angiographer reads a stenosis of 50% or more in the left main coronary artery, it is estimated that a second reader will report no lesion 18.6% of the time. In 94.7% of the films, the number of significantly (greater than or equal to 70% stenosis) diseased vessels was the same for both readers (72.1%) or differed by one vessel (22.6%). The reproducibility of interpretation of films of good or acceptable quality or completeness was better than the reproducibility of readings of arteriograms judged to be of poor quality or incomplete studies. The mean absolute difference between readings of the percent stenosis decreased over the time of the patient enrollment, 1975 to 1978. This may have resulted from major collaborative efforts made during the course of the study to improve the quality of angiography and to standardize the reading of the cine films.

Interobserver variability in interpreting contrast left ventriculograms (CASS).

Randomly selected left ventricular cineangiograms performed by 14 medical centers (clinical sites) participating in a large multicenter study of medical and surgical treatment of coronary artery disease (CASS) were systematically recalled and reread by one of four designated quality control centers. The end diastolic volume (EDV), end systolic volume (ESV), and ejection fraction (EF) calculated by the quality control center were compared with those calculated by the clinical site, and correlation coefficients of 0.71, 0.84, and 0.79, respectively, were obtained. Regional left ventricular (LV) wall motion abnormalities were assessed by dividing the LV wall as viewed in the right anterior oblique (RAO) and left anterior oblique (LAO) views into five segments each and grading the motion of each segment according to six categories of increasing abnormalities from normal to aneurysm. When discrepancies based on "nearest neighbor" differences in naming adjacent segments were eliminated and only marked differences of more than one degree of severity of wall motion abnormality were considered, interobserver differences were 7% and 10% for RAO and LAO segments, respectively. Agreement was less frequent in designating a segment "aneurysmal." When each LV segment was assigned a numerical score based on increasing severity of wall motion abnormality and a total LV score for each ventriculogram computed, the quality control and clinical site readings were in good agreement with a correlation coefficient of 0.83.

Effect of coronary bypass surgery on survival patterns in subsets of patients with left main coronary artery disease. Report of the Collaborative Study in Coronary Artery Surgery (CASS).

The 3 year cumulative survival rate of 1,492 patients with left main coronary artery disease (50 percent or greater stenosis of luminal diameter) enrolled in the Collaborative Study in Coronary Artery Surgery (CASS) was 91 percent for the surgical group and 69 percent for patients treated medically (p less than 0.0001). Mortality was significantly greater in patients with impaired left ventricular function. The difference between medical and surgical therapy was significant for patients who had normal, moderately abnormal and severely impaired left ventricular function and for patients with stenosis of the left main coronary artery of 50 to 59, 60 to 69, 70 to 79 and 80 percent or greater. Aortocoronary bypass surgery did not significantly improve survival in patient subgroups who had (1) a nonstenotic dominant right or balanced coronary circulation, (2) a stenotic dominant right coronary artery and normal left ventricular function, and (3) left main coronary stenosis of 50 to 59 percent and normal or mildly abnormal left ventricular function. The Cox proportional hazards model was used to select baseline variables that were independent predictors of long-time mortality. The model selected left ventricular score, age, congestive heart failure score, hypertension, percent left main coronary arterial stenosis and coronary arterial dominance as the baseline variables most predictive of long-term survival. A clinical and angiographic prognostic risk index developed from these six baseline variables showed significantly improved survival for the surgical cohort in each of four risk categories. In the best and worst risk category, the 3 year survival rate was 97 and 82 percent, respectively, for the surgical group and 85 and 34 percent, respectively, for the medical group (p less than or equal to 0.0002). The data from this observational study show that coronary bypass surgery prolongs life in most patients with left main coronary artery disease, particularly those who have severe narrowing of the left main coronary artery or impaired left ventricular function. The results permit a better understanding of the natural history of left main coronary artery disease and permit a more accurate estimate of long-term survival for individual patients through the use of a clinical-angiographic risk index.

Angiographic prevalence of high-risk coronary artery disease in patient subsets (CASS).

The prevalence of coronary artery stenoses greater than or equal to 70% or left main stenosis greater than or equal to 50% was evaluated in 20,391 patients who underwent angiography in the Coronary Artery Surgery Study from 1975-1979. After the patients with unstable angina or myocardial infarction were excluded, the disease prevalence in the 8157 patients with definite angina, probable angina, and nonspecific chest pain was 93%, 66% and 14% in men and 72%, 36% and 6% in women (p less than 0.001). The age and sex of the patients and character of chest pain were important determinants of disease prevalence and severity. Left main or three-vessel coronary disease occurred in more than 50% of middle-aged men and older women with definite angina and in more than 50% of men who had probable angina and were older than 60 years of age. In contrast, left main coronary disease occurred in less than 2% of 1282 men and less than 1% of 1397 women with nonspecific chest pain regardless of age. In this latter patient subset, less than 5% of men and less than 1% of women in each decade under 60 years had left main or three-vessel coronary artery disease. Thus, high-risk coronary disease is common in middle-aged patients with definite angina and older patients with probable angina, but is rare in patients with nonspecific chest pain. Indications and guidelines for diagnostic noninvasive tests and coronary angiography could be based on these results.

Operative risk factors in patients with left main coronary-artery disease.

To identify the factors associated with operative mortality, we evaluated clinical, angiographic, and surgical variables in 1172 patients with left main coronary-artery stenoses of at least 50 per cent, who underwent coronary-bypass procedures in the Collaborative Study in Coronary Artery Surgery (CASS). The operative mortality was 4.2 per cent overall and was less than 3 per cent in seven of the 15 participating hospitals. Historical variables associated with an increase in operative mortality were age, female sex, and duration and severity of angina. Other variables associated most closely with poor survival were urgency of operation, left coronary-artery dominance, severity of left main coronary-artery stenosis, and impairment of left ventricular contraction. The results of this multicenter study show that aortocoronary bypass surgery in patients with left main coronary-artery disease can be performed with a low mortality and that patients at high risk can often be identified before surgery.

Complications of coronary arteriography from the Collaborative Study of Coronary Artery Surgery (CASS).

Data were collected prospectively on 7553 consecutive patients undergoing coronary arteriography. The studies were performed at 13 clinics of the Collaborative Study of Coronary Artery Surgery (CASS) using brachial and femoral techniques. There were eight deaths 0--24 hours and seven deaths 24--48 hours after arteriography (2/1000). There were 15 non-fatal myocardial infarctions (MIs) 0--24 hours and four MIs 24--48 hours after arteriography (2.5/1000). Of 657 cases with left main stenosis greater than or equal to 50%, five died and three had MI. Left main disease increased risk of death by 6.8 times (p less than 0.001). Other factors increasing risk were unstable angina, congestive heart failure, multiple premature ventricular contractions, and hypertension. Of the 1187 patients studied from the brachial artery, six died (0.51%) and five had MIs (0.42%). In 6328 patients studied from the femoral artery, nine died (0.14%) and 14 had MIs (0.22%). The brachial artery technique increased the risk of death 3.6 times compared with the femoral approach (p less than 0.05). This result did not apply when analysis was restricted to laboratories with 80% or more brachial procedures. Risk was not altered by heparin. Thus, a prospective, multicenter analysis of complications reveals low risk of coronary arteriography but significant difference between two techniques.

Particulate myocardial perfusion scintigraphy: its clinical usefulness in evaluation of coronary artery disease.

The determination of myocardial viability is a crucial parameter in the evaluation of a patient with coronary artery disease. Particulate myocardial perfusion scintigraphy (PMPS) is one of several methods available for this determination. A brief comparison between PMPS and two other commonly used methods is described in this review. The technique and analysis are described and applied to 194 patients with 366 surgically bypassed regions. The patients are analyzed for postoperative regional wall function and for total ventricular function as expressed by ejection fraction. PMPS is a highly accurate and unique study for clinically predicting myocardial viability.