Unstable angina pectoris: national cooperative study group to compare medical and surgical therapy. I. Report of protocol and patient population

Percutaneous coronary intervention versus coronary artery bypass graft surgery for patients with medically refractory myocardial ischemia and risk factors for adverse outcomes with bypass: a multicenter, randomized trial. Investigators of the Department of Veterans Affairs Cooperative Study #385, the Angina With Extremely Serious Operative Mortality Evaluation (AWESOME)

BACKGROUND

Percutaneous coronary intervention (PCI) and coronary artery bypass graft surgery (CABG) are being applied to high-risk populations, but previous randomized trials comparing revascularization methods have excluded a number of important high-risk groups.

OBJECTIVES

This five-year, multicenter, randomized clinical trial was designed to compare long-term survival among patients with medically refractory myocardial ischemia and a high risk of adverse outcomes assigned to either a CABG or a PCI strategy, which could include stents.

METHODS

Patients from 16 Veterans Affairs Medical Centers were screened to identify myocardial ischemia refractory to medical management and the presence of one or more risk factors for adverse outcome with CABG, including prior open-heart surgery, age >70 years, left ventricular ejection fraction <0.35, myocardial infarction within seven days or intraaortic balloon pump required. Clinically eligible patients (n = 2,431) underwent coronary angiography; 781 were angiographically acceptable; 454 (58% of eligible) patients consented to random assignment between CABG and PCI.

RESULTS

A total of 232 patients was randomized to CABG and 222 to PCI. The 30-day survivals for CABG and PCI were 95% and 97%, respectively. Survival rates for CABG and PCI were 90% versus 94% at six months and 79% versus 80% at 36 months (log-rank test, p = 0.46).

CONCLUSIONS

Percutaneous coronary intervention is an alternative to CABG for patients with medically refractory myocardial ischemia and a high risk of adverse outcomes with CABG.

A multicenter, randomized trial of percutaneous coronary intervention versus bypass surgery in high-risk unstable angina patients. The AWESOME (Veterans Affairs Cooperative Study #385, angina with extremely serious operative mortality evaluation) investigators from the Cooperative Studies Program of the Department of Veterans Affairs

This multicenter, prospective randomized trial was designed to test the hypotheses that percutaneous coronary intervention (PCI) is a safe and effective alternative to coronary artery bypass grafting (CABG) for patients with refractory ischemia and high risk of adverse outcomes. As a comparison of revascularization strategies, the trial specifically allows surgeons and interventionists to use new techniques as they become clinically available. After 42 months of this 72-month trial, 17,624 patients have been screened and 2022 met eligibility requirements: 341 have been randomized to either CABG or PCI, and the remaining 1681 are being prospectively followed in a registry. The 3-year overall survival of patients in the registry and randomized trial is comparable. To enhance accrual into the randomized trial, site visits were conducted, a few low-accruing hospitals were put on probation and/or replaced, eligibility criteria were reviewed at annual meetings of investigators, and the accrual period was extended by 1 year. These data demonstrate that a prospective randomized trial and registry of coronary revascularization for medically refractory high-risk patients is feasible.

Coronary artery bypass grafting in patients with chronic renal failure: A reappraisal

BACKGROUND AND AIMS

Chronic renal failure (CRF) is known to increase the morbidity and mortality in patients undergoing cardiac operations. Successful outcome of coronary artery bypass grafting (CABG) in some patients with CRF has been reported, but remains controversial.

METHODS

Forty-four patients with CRF who underwent CABG were examined. Two groups were analyzed. Group I consisted of 13 patients with end-stage renal disease on hemodialysis. Group II consisted of 31 patients with a creatinine > or = 1.6 gm/dL for a minimum of 6 months, but were not on dialysis. There were 36 male and 8 female patients, with a mean age of 71 years.

RESULTS

The hospital mortality was 10 patients (23%) with 4 (31%) hospital deaths in Group I, and 6 (19%) in Group II. There was major morbidity in 35 (80%) patients. In Group II there were 8 (26%) patients who required permanent postoperative dialysis. A control group of 547 patients 70 years of age who underwent CABG had 30 hospital mortalities (5%) and 75 morbidities (13%). The average length of stay was 27 days. Fifteen patients died at a mean of 34 months after being discharged from the hospital. Nineteen of the original 44 patients remain alive at a mean of 32 months. The total mortality at 6 years and 4 months was 57%.

CONCLUSIONS

Older and sicker patients with CRF who undergo CABG are at an exceptionally high risk for mortality and morbidity. For CRF patients not on dialysis with a creatinine 2.5 gm/dL, there is a strong likelihood of permanent postoperative dialysis. Long-term follow-up shows survival to be well below their non-CRF counterparts.

Effectiveness of percutaneous transluminal coronary angioplasty for patients with medically refractory rest angina pectoris and high risk of adverse outcomes with coronary artery bypass grafting

This study was undertaken to test the hypothesis that percutaneous transluminal coronary angioplasty (PTCA) is a reasonable alternative to coronary artery bypass grafting (CABG) for some high-risk patients with medically refractory rest angina. Over a 5-year period, 1 operator at a tertiary Veterans Affairs Medical Center performed angioplasty on 624 patients, of whom 441 had unstable angina. Of these 441 patients, 288 had rest angina and 225 had medically refractory rest angina. Medically refractory unstable angina was defined as reversible myocardial ischemia occurring at rest in an intensive care unit setting with low flow oxygen despite the following medications: (1) oral aspirin, intravenous heparin, or both; (2) some combination of beta blocker, calcium blocker, and/or nitrate so that resting heart rate is < 70 beats/min or resting blood pressure < 140 mm Hg, or both. There were 207 patients with medically refractory rest angina who had > or = 1 of the following characteristics predictive of a more than twofold increased risk of operative death at CABG: age > 70 years, prior CABG, recent myocardial infarct, need for intravenous nitroglycerin, need for intraaortic balloon pump, and left ventricular ejection fraction < 0.35. Of these 207 patients, 11 died (5%) during index hospitalization, 196 (95%) were discharged, and 186 (90%) went home angina free. There were 2 emergency CABGs and 9 acute myocardial infarctions. At follow-up (3 to 60 months, average 24), there were 27 late deaths (for a total of 38 [18%]), 8 (4%) late CABGs, and 44 (21%) late PTCAs (with 17 [8%] late myocardial infarctions). The 2-year mortality of 18% for this cohort is comparable to a 21% 2-year mortality observed in a group of 1,073 "high-risk" patients who underwent CABG in the Veterans Affairs Medical Center from 1987 to 1988. These data support the hypothesis that PTCA provides an alternative to CABG in some high-risk patients with medically refractory rest angina.

Outcome of percutaneous transluminal coronary angioplasty in subsets of unstable angina pectoris

OBJECTIVES

The purpose of this study was to characterize the outcome of coronary angioplasty according to the various presentations of unstable angina pectoris.

BACKGROUND

Although unstable angina is a mosaic of clinical manifestations, a comprehensive analysis of short- and long-term outcome of coronary angioplasty in subsets of unstable angina is not available.

METHODS

Data from 15 clinical centers for the 857 patients with unstable angina in the 1985-1986 National Heart, Lung, and Blood Institute percutaneous transluminal coronary angioplasty registry were analyzed. Five-year follow-up was available in > 96.5%. Patients were first classified as those with (679 [79%]) or without (178 [21%]) rest angina. Patients were also allocated to five mutually exclusive categories of decreasing unstable angina severity: postinfarction angina, acute coronary insufficiency, plain rest angina, accelerating angina and new onset angina.

RESULTS

The group with rest angina had more older patients (p < 0.01) and women (p < 0.001), and a greater proportion had a previous myocardial infarction (p < 0.001) and a left ventricular ejection fraction < or = 50% (p < 0.01) than did the group without rest angina. Angiographic characteristics were nearly the same, whereas procedural characteristics and outcome were the same for both categories. At 5-year follow-up, there was a higher crude mortality rate in patients with than without rest angina (p < 0.05). Resolution into five subsets yielded additional information. Women were more represented only in the acute coronary insufficiency and plain rest angina subsets (p < 0.001). Patients with angina after myocardial infarction had the second shortest history of angina (p < 0.001), the highest percent of smokers (p < 0.01) and, with those with acute coronary insufficiency, the highest incidence of congestive heart failure (p < 0.05) and an ejection fraction < or = 50% (p < 0.001). They had the highest percent of totally occluded arteries, coronary thrombus and collateral blood flow received but also the lowest rate of severe stenoses (p < 0.001 for all). Patients with new onset angina had the highest prevalence of single-vessel disease (p < 0.05), critical and complex stenoses (p < 0.001) and no coronary angioplasty-related deaths. The crude 5-year mortality rate was higher for both postinfarction and acute insufficiency groups (p < 0.05) than for the other subsets. After adjustments for risk factors, no significant differences in adverse event rates remained among the different unstable angina subgroups.

CONCLUSIONS

Analysis of the diverse clinical presentations of unstable angina supports underlying pathogenetic differences. Coronary angioplasty is safe and effective in all subsets of unstable angina. Long-term survival is good in general but is related to the baseline status of left ventricular function.

Prediction of degree of residual stenosis in coronary thrombolysis

In order to predict the residual stenosis in coronary thrombolysis, the factors easily obtained from clinical history--age, gender, history of angina before acute myocardial infarction (AMI), family history, hypertension, diabetes, hypercholesterolemia, smoking, and interval between onset of AMI and recanalization--were observed in 114 patients with successful coronary thrombolysis. In 55 patients with angina before AMI, 29 patients had residual stenosis greater than or equal to 75% and 26 patients had residual stenosis less than 75%. In 59 patients without angina before AMI, 15 patients had residual stenosis greater than or equal to 75%, and 44 patients had residual stenosis less than 75%. The presence or absence of angina before AMI was the main variable that discriminated the groups of residual stenosis of more or less than 75%, which was the only significant independent variable to predict the residual stenosis. These data suggest that the presence of angina pectoris before AMI is likely to be associated with a significant degree of residual stenosis after thrombolysis.

Comparison of the natural history of new onset and exacerbated chronic ischemic heart disease. The Chest Pain Study Group

To compare the natural history of patients with new onset ischemic heart disease with that of patients with exacerbations of chronic ischemic heart disease, short- and long-term outcomes of 3,465 emergency room patients with acute ischemic heart disease at four community and three university hospitals were evaluated. Acute myocardial infarction was diagnosed in 598 (33%) of the 1,835 patients with a prior history of infarction or angina and 934 (57%) of the 1,630 without such a history (p less than 0.001). Patients with new onset ischemic heart disease with acute myocardial infarction were more likely than patients with infarction and exacerbated chronic ischemic heart disease to have Q wave infarction (57% versus 36%) and to receive thrombolytic therapy (11% versus 5%); they also had higher maximal creatine kinase levels (1,088 +/- 1,299 versus 733 +/- 906 U/liter) (p less than 0.0001 for all three). After adjustment for differences in clinical presentation and initial triage, patients with new onset ischemic heart disease with acute myocardial infarction were less likely than the comparison group to have congestive complications (odds ratio 0.63, 95% confidence interval 0.47 to 0.84, p less than 0.01) but not less likely to have arrhythmic, ischemic or overall complications. Among patients with angina without acute myocardial infarction, patients with new onset ischemic heart disease were less likely to have recurrent ischemic pain and congestive heart failure. In multivariate analysis of long-term follow-up data on 457 patients from one hospital, patients with new onset ischemic heart disease had better cardiovascular survival rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical judgment and therapeutic decision making

Clinical decision making is under increased scrutiny due to concerns about the cost and quality of medical care. Variability in physician decision making is common, in part because of deficiencies in the knowledge base, but also due to the difference in physicians' approaches to clinical problem solving. Evaluation of patient prognosis is a critical factor in the selection of therapy, and careful attention to methodology is essential to provide reliable information. Randomized controlled clinical trials provide the most solid basis for the establishment of broad therapeutic principles. Because randomized studies cannot be performed to address every question, observational studies will continue to play a complementary role in the evaluation of therapy. Randomized studies in progress, meta analyses of existing data, and increased use of administrative and collaborative clinical data bases will improve the knowledge base for decision making in the future.

Presence of angina pectoris before acute myocardial infarction and degree of residual stenosis after coronary thrombolysis

This study tested the hypothesis that the degree of residual stenosis after coronary thrombolysis reflected that of original stenosis presented by symptom of angina before acute myocardial infarction (AMI). The relation between the presence of angina before AMI and the degree of residual stenosis after coronary thrombolysis was observed in 57 patients with successful coronary thrombolysis for AMI. Patients with significant coronary artery stenoses other than the artery responsible for AMI were excluded from this study. In 22 patients with chronic angina for 2 weeks or longer before AMI, 14 patients had a residual stenosis of 75% or more and 8 patients had a residual stenosis of less than 75%. In 35 patients with angina for less than 2 weeks or not at all before AMI, 9 patients had a residual stenosis of 75% or more, and 26 patients had a residual stenosis of less than 75% (p less than 0.01). In the course of progression of coronary artery disease, some patients had AMI without severe underlying stenosis and others with severe underlying stenosis. Patients with chronic angina before AMI might tend to have AMI with acute occlusion superimposed on the severe organic stenosis. Patients without chronic angina before AMI would be more at risk for AMI caused by acute occlusion without underlying severe stenosis.

Electrocardiographic manifestations and in-hospital prognosis of transient acute myocardial ischemia at rest

From January 1970 to June 1985, transient electrocardiographic changes at rest were documented in 652 patients admitted to our coronary care unit. Patients were stratified according to the type of electrocardiographic alteration at rest: 295 had ST-segment elevation (group 1), 106 T-wave changes (group 2) and 251 ST-segment depression (group 3). Patients in group 3, compared with groups 1 and 2, were more likely to have symptoms of coronary artery disease dating back many years (p less than 0.01 and p less than 0.01, respectively), a previous myocardial infarction (p less than 0.05 and difference not significant), a positive exercise test (p less than 0.01 and p less than 0.01), transient ST-T changes occurring in a higher number of electrocardiographic leads (p less than 0.01 and p less than 0.01), multivessel disease (p less than 0.001 and p less than 0.01) and poor ventricular function (p less than 0.01 and p less than 0.05). Despite these differences, the occurrence of acute myocardial infarction and cardiac death during hospitalization was much more frequent in group 1 compared with groups 2 (p less than 0.02) and 3 (p less than 0.05). However, death occurred in those patients who had poor ventricular function and severe atherosclerosis. A greater susceptibility of group 1 patients to severe vasoconstriction documented by the ergonovine test and by the occurrence of spontaneous spasm seems to account for different in-hospital outcome.

Health care technology and quality of care

The increasing costs and complexity of technologic advances in diagnosis and treatment have been accompanied by other important issues. They are often moral or ethical in nature; they include the public's desire and determination to have access to these "high-tech" advances; and the quality and equity with which those advances are apportioned and applied must be addressed. Seven criteria that can be applied to technology assessment are identified as is a process for that assessment. Together, these procedures can provide valuable information and assistance to those who make decisions about health benefits coverage--both in the public and the private sectors.

Influence of left ventricular dysfunction on flecainide therapy

Seventy-six patients with ventricular tachyarrhythmias (40 sustained and 36 nonsustained) were treated with oral flecainide. Radionuclide left ventricular ejection fraction was 30% or less in 33 patients and greater than 30% in 43 patients. Before flecainide, compensated heart failure was present in 23 patients (ejection fraction less than or equal to 30% in 15 and greater than 30% in 8). Flecainide mean dose was 150 mg twice daily and mean plasma concentration was 720 ng/ml. New or worsened congestive heart failure occurred in seven patients on flecainide therapy, all with an ejection fraction of less than 30%; six had a previous history of compensated heart failure and of these, three died. Ejection fraction was the only independent variable that significantly influenced efficacy and tolerance of flecainide. After 1 year of therapy, efficacy and tolerance was 58% (25 of 43) in patients with an ejection fraction greater than 30% and 12% (4 of 33) in patients with an ejection fraction of 30% or less (p less than 0.001). Thus, congestive heart failure can occur during flecainide therapy, particularly in patients with a previous history of congestive heart failure and ejection fraction of less than 30%, and may particularly limit therapy in these patients. Clinical efficacy and tolerance were significantly lower in patients with an ejection fraction of less than 30%.

Coronary arteriographic findings soon after non-Q-wave myocardial infarction

Complete occlusion of the infarct-related coronary artery is a frequent finding soon after Q-wave (transmural) myocardial infarction. We performed coronary arteriography to study the frequency of total coronary occlusion and of angiographically visible collateral vessels in 341 patients within one week of non-Q-wave myocardial infarction. In this cross-sectional study, 192, 94, and 55 patients underwent coronary arteriography within 24 hours of peak symptoms, between 24 and 72 hours after peak symptoms, and between 72 hours and seven days after peak symptoms, respectively. In the three groups, total occlusion of the infarct-related vessel was found in 26 percent (49 of 192), 37 percent (35 of 94), and 42 percent (23 of 55) of the patients, respectively (P less than 0.05). The presence of visible collateral vessels increased in parallel: 27 percent (52 of 192), 34 percent (32 of 94), and 42 percent (23 of 55), respectively (P less than 0.05). The frequency of subtotal occlusion (i.e., greater than or equal to 90 percent stenosis) decreased inversely: 34 percent (65 of 192), 25.5 percent (24 of 94), and 18 percent (10 of 55), respectively (P less than 0.05). Thus, in contrast to Q-wave infarction, total coronary occlusion of the infarct-related vessel is infrequently observed in the early hours of non-Q-wave infarction, but it increases moderately in frequency over the next several days. These cross-sectional data suggest that non-Q-wave infarction may be related to a preserved but marginal blood supply, which sufficiently disrupts the relation between the supply of and the demand for myocardial oxygen to cause tissue necrosis.

Angina pectoris before and during acute myocardial infarction: relation to degree of physical activity

One hundred ninety-seven patients with a history of acute myocardial infarction (AMI) were interviewed to evaluate the character of angina pectoris relative to physical activity before AMI and at the onset of AMI. Ninety-two patients had no angina before AMI and 105 had angina. Among the 105 patients with angina, 58 had chronic stable angina that did not change before AMI, 22 noted worsening of symptoms within 2 weeks before AMI, and 25 had onset of angina within 2 weeks before AMI. In the 92 patients without angina before AMI, AMI occurred during heavy exertion in 10 (11%), mild exertion in 43 (47%), at rest in 28 (30%), and during sleep in 11 (12%). In the 58 patients with chronic stable angina, 47 had angina during exertion, 7 during rest and 4 during both. However, subsequent AMI occurred during heavy exertion in 9 (15%), during mild exertion in 16 (28%), at rest in 25 (43%), and during sleep in 8 (14%). In the patients without angina, or with chronic stable angina without worsening of symptoms, AMI occurred unpredictably or differently from the mode of physical activity precipitating angina before AMI.

Effects of the presence or absence of preceding angina pectoris on left ventricular function after acute myocardial infarction

Left ventricular (LV) function was evaluated in 31 patients, who had total occlusion of the left anterior descending coronary artery and less than 70% stenosis of the other two major coronary arteries or any branch. Fifteen of 31 patients had a history of angina pectoris before acute myocardial infarction (AMI) and 16 of 31 patients had no history of angina pectoris before AMI. The patients with angina pectoris before AMI had a significantly better ejection fraction, percentage of abnormally contracting segment, and regional wall motion than those without angina pectoris before AMI. These data suggest that the symptom of angina pectoris before AMI could be a favorable sign in preserving LV function when the patients subsequently had AMI.

The prognosis for patients with new-onset angina who have undergone cardiac catheterization

We investigated the prognostic significance of new-onset angina in patients in whom coronary anatomic characteristics were known. New onset angina was defined as angina of less than 3 months duration. Consecutive patients (n = 1727) with significant coronary artery disease (diagnosed at cardiac catheterization) and who had not had a prior myocardial infarction or congestive heart failure were studied. In patients with new-onset angina (n = 329) there was a higher incidence of single-vessel disease (43% vs 27%) and a lower incidence of triple-vessel (23% vs 35%) and left main artery (5% vs 10%) disease compared with patients with chronic angina (n = 1398). Patients were classified by the presence or absence of preinfarction angina (severe and prolonged angina at rest requiring hospitalization to rule out myocardial infarction). In patients treated without surgery and who did not have preinfarction angina, survival at 1 year was 97% for patients with new-onset angina and 98% for those with chronic angina (p = .27). Among patients not treated surgically who did not have preinfarction angina, at 1 year 16% with new-onset angina and 7% with chronic angina had suffered a cardiac event (nonfatal myocardial infarction or death, p = .006). In patients treated surgically who did not have preinfarction angina, survival at 1 year was 96% both for those with new-onset angina and those with chronic angina (p = .99). The risk of an event in patients treated surgically at 1 year was not statistically different in patients with new-onset angina and those with chronic angina (12% vs 11%, p = .27). Survival and event-free rates were lower in patients with preinfarction angina than in patients who did not have it.(ABSTRACT TRUNCATED AT 250 WORDS)

Variable susceptibility to dynamic coronary obstruction: an elusive link between coronary atherosclerosis and angina pectoris

Growing evidence suggests that dynamic coronary obstructions play an important but elusive role in the genesis of ischemic events. Dynamic coronary obstructions can develop during certain phases of coronary disease as a result of a variable combination of vasoconstriction, arterial wall lesions, and increased thrombotic tendency. In a certain phase of their disease some patients develop dynamic coronary obstruction, while others with a similar degree of fixed atherosclerotic obstruction do not.

Unstable angina with episodic ST segment elevation and minimal creatine kinase release culminating in extensive, recurrent infarction

The syndrome of episodic angina at rest, recurrent ST segment elevation (mean = 9 mV) and nontransmural infarction characterized by minimal serum creatine kinase (CK) (mean 243 IU; upper normal limit 132 IU) was studied in 15 patients who presented with these findings. All were initially managed with intensive nitrate and beta-receptor blocker therapy. Eleven patients underwent intraaortic balloon counterpulsation for refractory angina and 13 underwent cardiac catheterization. High grade (greater than or equal to 90%) stenosis of the proximal left anterior descending coronary artery was demonstrated in 11 patients, and coronary spasm without significant, fixed occlusive disease was noted in 2 patients. Urgent aortocoronary bypass surgery was performed in seven patients with recurrent pain or electrocardiographic injury, or both, unresponsive to maximal medical therapy. The initial mean ST segment elevation and CK elevation for this group was 10 mV and 232 IU, respectively. No surgical patient developed recurrent infarction; there was one late death after reoperation. Eight patients whose condition stabilized initially on medical therapy did not undergo urgent surgery. However, five subsequently developed large transmural anterior reinfarction despite intensive medical therapy, and three died from pump failure. These patients on medical therapy did not differ from the surgical group in magnitude of ST segment elevation or increase in serum CK. Their initial mean ST segment elevation and CK elevation were 8 mV and 254 IU, respectively (difference not significant). Thus, repetitive episodes of rest angina with marked anterior wall ST segment elevation and mild CK elevations may define a subset of patients who appear to progress rapidly from minimal nontransmural necrosis to massive transmural infarction. Prompt recognition of this syndrome, followed by cardiac catheterization and urgent aortocoronary bypass surgery, may prevent extensive cardiac muscle loss.

Titrates for treatment of unstable angina pectoris and coronary vasospasm

The treatment of a patient with unstable angina at the time of the initial presentation of the physician can begin with nitrates. The beneficial action of nitrates are several. Nitrates dilate epicardial coronary arteries as well as many coronary artery stenoses. They may be effective because of this action plus a marked effect on decreasing ventricular volume and ventricular end diastolic pressure. Perhaps the best way to manage patients with severe angina that may be in part related to coronary artery vasoconstriction is to combine a long-acting nitrate with a calcium antagonist. The combined use of nitrates and calcium antagonists will (1) dilate the coronary arteries to maintain coronary blood flow, (2) decrease systemic arterial pressure and thus decrease peripheral vascular resistance, and (3) dilate peripheral veins and thus decrease ventricular volume and pressure. When proper doses are used, the combination may be more effective than either drug alone. Of course, proper dosing must be determined for the individual patient by the physician. Initial treatment with the nitrates should begin with small doses and gradually build up. Similar dosing schedules should be used for the calcium antagonists. Both doses can be increased to high levels is the clinical situation warrants it.

Ten-year survival after coronary bypass surgery for unstable angina

We have assessed the long-term results of coronary bypass surgery performed for unstable angina in 1282 patients from 1970 to 1982. The operative mortality was 1.8 per cent; in the first 4 years it was 2.5 per cent, and in the last 8 1/2 years it was 1.7 per cent. Using actuarial techniques, we determined that the 5-year and 10-year survival rates (mean +/- S.E.) were 92 +/- 1 per cent and 83 +/- 2 per cent, respectively, for the whole group. For patients with "normal" left ventricular function, they were 92 +/- 2 per cent and 86 +/- 3 per cent, and for patients with "abnormal" left ventricular function 91 +/- 2 per cent and 79 +/- 4 per cent (P = 0.14). No significant differences were observed in the long-term survival for any of the three clinical subgroups of patients with unstable angina--angina at rest, angina after recovery from acute myocardial infarction, and progressive angina of recent onset (P = 0.49). The reoperation rates at 5 and 10 years were 6 +/- per cent and 17 +/- 3 per cent. Currently, 61 per cent of the survivors have no angina; angina occurs on severe exertion in 20 per cent, on ordinary exertion in 14 per cent, and on mild exertion in 5 per cent. We conclude that coronary bypass surgery is an effective form of therapy (for up to 10 years) in patients with unstable angina.

Randomized surgical clinical trials for treatment of coronary artery disease

The impact of randomized clinical trials of surgical therapy for treatment of coronary artery disease is evaluated. Trials are reviewed leading to the following suggestions: 1. Large multicenter trials have a major impact on clinical practice; 2. Small trials have less impact; 3. Findings in agreement with current practice are accepted enthusiastically; 4. Findings disagreeing with current practice are met very critically; and 5. Surgical trials have special problems because of a great variability between clinics, the potential of uneven learning curves, and potential "cross-over" from medical to surgical therapy.

Nifedipine in unstable angina: a double-blind, randomized trial

We assessed the efficacy of adding nifedipine to the conventional treatment of unstable angina in 138 patients in a prospective, double-blind, randomized, placebo-controlled trial. There was no difference between the two groups in the dose of conventional antianginal medication or in age, prior myocardial infarction, ejection fraction, or other risk factors. Failure of medical treatment (defined as sudden death, myocardial infarction, or bypass surgery within four months) occurred in 43 of 70 patients given placebo and in 30 of 68 given nifedipine. Kaplan-Meier survival-curve analysis of the number and time dependence of treatment failures demonstrated a benefit of nifedipine over placebo (P = 0.03). The benefit was particularly marked in patients with ST-segment elevation during angina (P = 0.02). Side effects (transient hypotension or diarrhea) required withdrawal of the drug from four patients given nifedipine and from one given placebo. We conclude that the addition of nifedipine to conventional therapy is safe and effective in unstable angina.

Assessment of cardiac risk 10 days after uncomplicated myocardial infarction

A total of 188 patients with uncomplicated acute myocardial infarction (long-term Norris prognostic index 3.2) were rapidly mobilised, underwent a symptom-limited exercise test around the day of discharge from hospital (day 10), and returned to work at a median of six weeks after the acute event. The incidence of cardiac death six months, one year, and three years after infarction was 2.7%, 4.5%, and 7.3% respectively, and the corresponding figures for recurrent heart attacks were 3.4%, 8.2%, and 18.5% respectively. The risk of recurrence of heart attack was predicted by three variables assessed at discharge--namely, a history of classical effort angina (p less than 0.01), radiological heart failure (p less than 0.05), and angina induced by the exercise test (p less than 0.05). The presence of any of these risk factors defined a group of patients with a sevenfold risk of recurrent heart attacks within six months of the initial acute infarct. It is concluded that these risk factors identify a group of patients with a high risk of recurrence early after infarction, in whom vigorous secondary prophylaxis is desirable.

Prospective study of medical and urgent surgical therapy in randomizable patients with unstable angina pectoris: results of in-hospital and chronic mortality and morbidity

At the Massachusetts General Hospital, all 190 patients who presented with the clinical and ECG criteria of the national Unstable Angina Pectoris Study (NUAPS) for unstable angina pectoris (UAP) were prospectively evaluated from their entrance between 1972 and 1976 (the entry period for NUAPS). Coronary angiography was performed in 166 patients. Of these, 83 patients (50%) were not eligible for randomization because of obstruction in the left main coronary artery (4%), inoperable diffuse coronary disease (11%), failure of initial medical therapy (20%), minimal coronary disease (13%), or other reasons (2%). The other 83 patients (50%) were eligible for randomization by NUAPS criteria; 39 received medical therapy and 44 underwent urgent coronary artery bypass surgery (CABG). The medical and surgical patients were comparable in terms of clinical characteristics and extent of anatomical disease. In-hospital (3% medical and 2% surgical) and late (5% medical and 5% surgical) mortality were similar over a mean follow-up period of 46 months. Myocardial infarction rate was statistically similar in-hospital (5% medical and 11% surgical) and during chronic evaluation (5% medical and 14% surgical). However, late severe angina (NYHA class III or IV) occurred in a significantly higher percentage of medical patients (28% medical versus 9% surgical; p less than 0.05) and nine medical patients (23%) required late elective CABG for relief of persistent angina. This experience is comparable to NUAPS, and supports the conclusion that acute management of unstable angina pectoris may begin with intensive medical treatment followed later by more elective CABG for those patients with persistent angina despite medical therapy.

Evaluation of the role of coronary angioplasty in patients with unstable angina pectoris

Seventeen patients presenting with unstable angina pectoris underwent percutaneous transluminal coronary angioplasty (PTCA). Despite vigorous medical therapy, all patients were disabled with 10 experiencing refractory in-hospital angina. PTCA was judged successful in 13 patients and resulted in decreased coronary diameter narrowing from 80 +/- 16% to 34 +/- 13% and reduced transstenotic pressure gradient from 69 +/- 13 to 23 +/- 12 mm Hg. Regional coronary blood flow (CBF) and myocardial metabolism were assessed at rest and during pacing tachycardia in six patients with left anterior descending coronary stenosis. Prior to PTCA, neither regional CBF increased nor coronary vascular resistance declined during rapid pacing; myocardial lactate extraction fell, indicating a shift from aerobic to anerobic metabolism. Following PTCA, however, rapid pacing resulted in increased regional CBF, decreased coronary vascular resistance, and preservation of aerobic metabolism. Following PTCA, successfully dilated patients demonstrated marked relief of angina symptoms, increase in functional capacity, and objective exercise ECG and thallium scintigraphic evidence of relief of previously ischemic myocardium. This investigation demonstrates that PTCA, when combined with medical therapy, can be performed safely and successfully in selected patients who present with otherwise refractory unstable angina, and indicates the procedure deserves further study as a therapeutic alternative in this condition.

Unstable angina pectoris of new onset: a prospective clinical and arteriographic study of 75 patients

Seventy-five patients with unstable angina pectoris of new onset (defined as of less than 90 days' duration) were prospectively evaluated in terms of clinical and arteriographic findings. In all patients the angina was considered unstable in terms of ease of provocation of anginal attacks and frequency of occurrence of attacks. Sixty patients had significant obstruction of at least one coronary artery, whereas 15 had insignificant disease (less than 70 percent arterial narrowing) or normal coronary arteries. Thirty-one patients (52 percent) had single vessel coronary disease, 11 (18 percent) had double vessel disease and 9 (15 percent) had triple vessel disease; the remaining 9 (15 percent) had left main coronary artery disease, either alone or in association with other vessel involvement. Of the 31 patients with single vessel disease, 24 (77 percent) had stenosis of the left anterior descending artery. The patients with single vessel disease did not differ from the patients with multivessel involvement with respect to risk factors or clinical presentation. It is concluded that patients with unstable angina of new onset have an unusually large incidence of single vessel coronary artery disease predominantly involving the left anterior descending coronary artery. Thus, these patients constitute a unique subset of patients with angina pectoris.

Treatment of unstable angina pectoris with percutaneous transluminal coronary angioplasty (PTCA)

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 40 patients (34 male, 6 female; 51.0 +/- 8.5 years) with the typical clinical picture of unstable angina. All had a short history of pain (2.9 +/- 2.0 months), angina at rest, transient ST and/or T wave changes during this period, and little or no enzyme elevations. The patients had a total of 41 stenoses (39 single, one double; one main-stem, 26 left anterior descending, 14 right coronary artery). The degree of the stenoses was 95.5 +/- 4.9% (area method) and 81.8 +/- 10.7% (diameter method). PTCA was successfully performed in 26 cases (63%), reducing the stenoses to 61.5 +/- 12.4% (area method) and 39.1 +/- 10.0% (diameter method). One patient (2.5%) received an immediate bypass operation because of an acute vessel occlusion. Eleven of the 14 not successfully treated patients received an aortocoronary bypass within the next three to 35 days. All still had symptoms of unstable angina. Three patients refused operation. Their treatment consisted of nitroglycerin, beta-blockers and nifedipin. Seventeen of the 26 successfully treated patients were restudied after 4.9 +/- 1.7 months. The degree of stenosis had risen to 69.2 +/- 17.4% (area method). While the stenoses in 12 patients were equal or less than before PTCA, stenosis recurred in five cases. Two patients were successfully retreated. PTCA can be performed with a good early success rate and a low concentration rate in patients with unstable angina. Relief of pain and improvement of blood supply to the jeopardized myocardium can be provided immediately and with a limited amount of expense. The method can therefore be regarded first-stage treatment in such patients.