Preinfarctional (unstable) angina--a prospective study--ten year follow-up. Prognostic significance of electrocardiographic changes

High-sensitivity cardiac troponin assays and unstable angina

The term unstable angina has been conventionally applied to patients with myocardial ischemia without myocardial necrosis. However, while the clinical context has remained constant over time, the biomarkers of myocardial injury and acute myocardial infarction have evolved. High-sensitivity cardiac troponin assays have several key analytical differences from prior cardiac troponin assay generations, which may alter the diagnosis and frequency of unstable angina, as well as affect our understanding of previously developed risk stratification strategies. This document reviews the current challenges in regards to unstable angina when using high-sensitivity cardiac troponin I and T assays.

Unstable Angina Pectoris: An Interventional Approach to Management

The therapy of unstable angina has changed consider ably in the last 15 years. An improved understanding of the pathophysiology has led to many of the changes. Thrombus, platelet activation, progression of athero sclerosis, and coronary vasospasm all appear to have a role. Initial management in unstable angina should begin with aggressive medical therapy with nitrates, calcium antagonists, beta blockers, and aspirin. In patients who are refractory to aggressive medical management, early cardiac catheterization and coronary arteriography is in dicated. The literature appears to confirm that patients with unstable angina who are stabilized with aggressive medical therapy fare as well as those treated with emer gency bypass surgery. Percutaneous transluminal coro nary angioplasty (PTCA) is the treatment of choice in medically refractory unstable angina patients with single-vessel coronary disease.

New approaches include culprit lesion angioplasty, thrombolytic therapy, coronary sinus retroperfusion, and new catheter-based revascularization methods such as intracoronary stents, laser methods and atherectomy. Culprit lesion angioplasty involves angioplasty of only the angina-producing artery in patients with multivessel coronary disease. Early data suggest that this may be an effective short-term alternative to multivessel PTCA or bypass surgery. Recent data also suggest a beneficial role for thrombolytic therapy and synchronized coronary si nus retroperfusion with arterial blood in patients with unstable angina. New catheter-based approaches are in the early stages of development, and their eventual role in the treatment of coronary artery disease and unstable angina remains to be elucidated.

Role of a streamer-like coronary thrombus in the genesis of unstable angina

INTRODUCTION

It is generally believed that the coronary occlusion occurs at the site of plaque disruption in acute coronary syndromes. An exceptional mechanism of coronary occlusion, namely a streamer-like thrombus (SLT) originating in a nonstenotic lesion extended distally to obstruct a just distal nondisrupted stenotic segment, was found by angioscopy in patients with unstable angina (UA). This study was carried out to examine the incidence of this phenomenon and its relationship to the subtypes of UA.

METHODS

The culprit coronary artery was investigated by angioscopy in successive 48 patients (mean +/- SE age, 61.0 +/- 2.3 years; 10 females and 38 males) with UA.

RESULTS

SLT originating in a nonstenotic lesion extended distally, and obstructed the just distal most stenotic segment (DMSS) by its tail in 11 patients (eight with class III and three with class II according to Braunwald's classification). Recurrent anginal attacks were observed in all. The nonstenotic lesion in which the SLT originated was a disrupted yellow plaque in most cases. The SLT was frequently red and yellow in a mosaic pattern, indicating a mixture of fresh thrombus and plaque debris. The plaques that constructed the DMSS were not disrupted. Angiographically, the SLT was not detectable and the entry of the DMSS showed a "tapering" configuration.

CONCLUSIONS

Obstruction of the DMSS by the tail of SLT originating in a nonstenotic lesion is another mechanism of UA. Therefore, treatment of both the nonstenotic lesion and DMSS is needed to prevent recurrent thrombus formation and consequent reattacks.

The significance of ST and T changes for the development of coronary events in patients with acute coronary chest pain, treated in a coronary care unit without verified acute myocardial infarction

The one-year prognosis for patients with a confirmed diagnosis of acute myocardial infarction (AMI) was compared with that of non-AMI patients treated in the coronary care unit (CCU). The one-year incidence of coronary events (CE) after discharge from CCU was 37% in the 51 AMI patients and 20% in the 81 non-AMI patients. The one-year mortality rates were 27 and 4%, respectively. Among the non-AMI patients, well known risk factors such as hypertension, previous AMI, congestive heart failure, smoking, diabetes and hyperlipaemia were not more common in those who developed a CE. ST segment depression and T wave inversion, each of at least 0.1 mV, in three or more ECG leads were selective criteria for a high-risk group with respect to CE. Preventive measures should be considered in this group of patients without verified AMI.

Unstable angina: prognosis of the individual patient

Not all patients diagnosed with unstable angina have the same outcome. Thus, it is incumbent on the physician caring for these patients to try to identify factors that will risk-stratify them. These factors include the degree of coronary angiographic stenosis, the lesion morphology, severity of symptoms, presence or absence of transient myocardial ischemia, and state of left ventricular function. In addition, many other factors including the patient's age, gender, and coexisting medical disorders must be considered when trying to prognosticate an individual patient. Clinical experience indicates that clinical indices that combine information provided by all of the above related variables should have more powerful prognostic significance than any individual variable.

The evolution of management of acute coronary syndromes (unstable angina and non-ST segment elevation myocardial infarction): Part l

As I advanced through medical school at Johns Hopkins, and throughout my subsequent training, I was constantly reminded of the contributions made to medicine by our predecessors. Many of whom were at Johns Hopkins, but many were not. As I continue active involvement in the education of medical students and physicians, it seems to me we have not done a good job of relating the history of how the modern management of patients with cardiovascular disease developed to our students, house staff, and fellows.

Exercise testing in chest pain units: rationale, implementation, and results

Chest pain units are now established centers for assessment of low-risk patients presenting to the emergency department with symptoms suggestive of acute coronary syndrome. Accelerated diagnostic protocols, of which treadmill testing is a key component, have been developed within these units for efficient evaluation of these patients. Studies of the last decade have established the utility of early exercise testing,which has been safe, accurate, and cost-effective in this setting. Specific diagnostic protocols vary, but most require 6 to 12 hours of observation by serial electrocardiography and cardiac injury markers to exclude infarction and high-risk unstable angina before proceeding to exercise testing. However, in the chest pain unit at UC Davis Medical Center,the approach includes "immediate" treadmill testing without a traditional process to rule out myocardial infarction. Extensive experience has validated this approach in a large, heterogeneous population. The optimal strategy for evaluating low-risk patients presenting to the emergency department with chest pain will continue to evolve based on current research and the development of new methods.

Long-term prognosis of clinical variables, coronary reserve and extent of coronary disease in patients with a first episode of unstable angina

Clinical and ECG prognostic markers, ischemic threshold (IT) and extent of coronary disease were analyzed in 383 patients with unstable angina (UA) and correlated with long-term events. Patients >74 years or those with severe heart failure or previous revascularization procedures were excluded. There were 369 events in 245 patients: 87 deaths, 96 myocardial infarction (MI), 111 coronary artery bypass grafting (CABG), and 75 angioplasty procedures (PTCA). Follow-up was obtained in 367 hospital survivors (99%, 114 (44) months) and ST depression on admission ECG, a modest enzyme rise, refractory angina (>2 episodes), two to three vessel coronary disease and a reduced IT (<==130 beats/min) were each associated with cardiac events. A multivariate analysis, however, showed refractory angina (p<0.001) and multivessel disease (p<0.001) as most significant predictors. After their exclusion, IT was most relevant predictor (p<0.001). However, the predictive value of these markers was essentially centered on first-year events (249, 67%). Moreover, refractory angina, minor enzyme rise and admission ST depression were each highly correlated with a reduced IT (p<0.006) and with multivessel disease (p<0.0001). Therefore, these findings underscore that the prognostic value of conventional clinical markers in patients with UA is limited to first-year events and that their remarkable correlation with extensive coronary disease and reduced coronary reserve reveal the anatomical substrate of this prognostic significance.

Acute ischemic syndromes. Chest pain center concept

CPCs have been developed to meet the clinical challenge posed by the diverse group of patients presenting to the ED with findings suggestive of a coronary event. Using a protocol-driven approach, high- and low-risk patients can be identified on presentation, facilitating urgent therapy in the former and triage of the latter to more deliberate management. Most CPCs focus on low-risk patients who are being increasingly managed by accelerated diagnostic protocols. These methods comprise systematic strategies that include innovative diagnostic approaches during a 6 to 12 hour period of observation with serial ECGs, continuous monitoring and cardiac biomarker measurements. A negative evaluation is usually followed by predischarge stress testing, and positive findings mandate admission. An essential aspect of the CPC strategy is continuity of care for patients with negative cardiac evaluations. Current data indicate that management of low-risk patients with chest pain in a CPC is safe accurate, and appears to be cost-effective.

Mode and timing of treatment failure (recurrent ischemic events) after hospital admission for non-ST segment elevation acute coronary syndromes

BACKGROUND

Clarification of the specific clinical course of non-ST-segment elevation acute coronary syndromes (NSTEMI ACS), including recurrent ischemic events and need for coronary revascularization, is important given the increasing economic pressure to shorten the length of hospitalization and therefore the duration of acute therapy. To examine the mode and timing of subsequent cardiac events, we analyzed pooled data from the ESSENCE and TIMI 11B studies of antithrombotic therapy in NSTEMI ACS.

METHODS

The daily event rates (with confidence intervals) during the first 43 days and the monthly average event rates during the first year were tabulated for 7081 patients.

RESULTS

The median antithrombotic treatment duration was 3.2 days, whereas the highest absolute frequency of recurrent angina prompting urgent revascularization, myocardial infarction, or death after hospital admission occurred on day 2, day 3, and day 8, respectively. Coronary revascularization was performed in 32% of patients, with the greatest number occurring on day 4. Only 12% of the end point events were adjudicated as being periprocedural. The median length of hospital stay was 7 days.

CONCLUSIONS

Despite aggressive antithrombotic therapy, a significant proportion of patients with NSTEMI ACS have recurrent ischemia precipitating urgent revascularization or infarction within the first few days, whereas the highest risk of death occurs later, after the first week.

Guidelines for the acute coronary syndromes

Traditional measures employed in the immediate management of patients presenting with an acute coronary syndrome have markedly reduced the risk of early death or myocardial infarction. Further incremental benefit is seen with the substitution of enoxaparin for unfractionated heparin, and in the use of glycoprotein IIb/IIIa inhibitors during percutaneous coronary intervention. However, the evidence for benefit from the glycoprotwin IIb/IIIa inhibitors with medical management alone is unconvincing. Newer data also suggest an aggressive approach to the high-risk patient offers a better ultimate outcome than a conservative one.

[Prognostic value of cardiac perfusion scintigraphy associated with the dobutamine test in acute coronary syndromes]

OBJECTIVES

This study aimed to establish the value of myocardial ischemia induced by the dobutamine infusion test associated to 99m technetium isonitrile single photon emission computed tomography in patients with unstable angina or non Q-wave infarction during the first days in the Coronary Care Unit.

METHODS

Fifty three patients with unstable coronary syndromes and common medical treatment were studied with a moderate-dose dobutamine test (5 to 20 microgram/Kg/min) using a 99mTc-MIBI SPECT. The results were correlated with the incidence of recurrent angina, infarction, death or revascularization.

RESULTS

The dobutamine test induced a reversible perfusion defect in 36 patients (68%) and angina in 12 of them (12/36, 33%). However, the patients who had a positive test had a similar incidence of events as those with a negative test (58% vs 59%). Thus, while the sensitivity of the dobutamine test to identify patients at risk was relatively high (68%), its specificity (32%) and its negative predictive value (41%) were low. The patients with dobutamine-induced angina, however, had a higher scintigraphy score (3.0 +/- 1,7 vs 1.6 +/- 1.8, p < 0.02) and a higher incidence of recurrent angina (8/12, 67% vs 13/41, 31%, p < 0.04) than those without, at a comparable double product.

CONCLUSIONS

In conventionally treated patients with unstable coronary syndromes, the specificity of the inducible scintigraphic ischemia with moderate dose of dobutamine performed during the first days is too low to be used as a marker for in-hospital events. However, inducible angina with dobutamine suggests an extensive jeopardized area and/or a particularly reduced ischemic threshold.

Predictors of recurrent ischemic events and death in unstable coronary artery disease after treatment with combination antithrombotic therapy

BACKGROUND

Patients with non-Q-wave acute coronary syndromes (ACS) have substantial rates of recurrent ischemic events, but prognostic studies have been small or preceded the routine use of aggressive combination antithrombotic therapy. We sought to identify predictors of these events after antithrombotic treatment of non-Q-wave ACS.

METHODS

We assessed 30-day rates of a composite triple end point (death, infarction, or refractory angina) and double end point (death or infarction) among 3171 patients with non-ST-segment elevation ACS randomly assigned to enoxaparin or heparin, plus aspirin, for 2 to 8 days. We created multivariable regression models to predict these end points from baseline factors.

RESULTS

Overall, 682 patients (21%) reached the triple end point and 220 (6.8%) reached the double end point. Independent predictors of the triple end point were admission with myocardial necrosis, ST-segment depression, prior angina severity, symptom duration, and allocation to enoxaparin treatment in patients with ST-segment depression (significant interaction). Independent predictors of the double end point were admission with myocardial necrosis, ST-segment depression, enrollment region, age >75 years, prior angina severity, and rales. By deciles, the average predicted risk for the double end point ranged from 2% to 20%: a patient aged <75 years with no risk factors had a 3.5% risk, whereas a patient aged >75 years with 2 additional high-risk features (myonecrosis and ST depression) had a risk of death or reinfarction of 26%.

CONCLUSIONS

Patients with non-ST-segment elevation ACS exhibit a broad range of risk of adverse recurrent ischemic events. The predictive power of the model for the triple end point, using baseline variables, was modest. However, a subgroup at very low risk of the double end point (average 2%) can be identified with baseline variables.

Surface 12-Lead Electrocardiographic Findings and Plasma Markers of Thrombin Activity and Generation in Patients with Myocardial Ischemia at Rest

Background: Myocardial ischemia at rest is typically associated with atherosclerotic coronary artery disease, atherommous plaque rupture, and intracoronary thrombosis. In areas of advanced disease and vascular injury, the extent of thrombus is influenced largely by a delicate balance of procoagulant factors, favoring thrombus initiation, growth, and development, and anticoagulant factors, attempting to limit potentially flow-limiting coronary thrombosis. Thrombin, a 308 amino acid serine pretense, is considered the most patent procoagulant factor in the setting of acute vessel wall injury, playing an essential role in the conversion of fibrinogen to fibrin, accelerating the prothrombinase complex, activating platelets, and stabilizing fibrin polymers. The purpose of this study was to determine the relationship between electrocardiographic abnormalities and markers of thrombin activity and generation among patients with unstable angina and non-Q.wave myocardial infarction. Mehtods and Results: In a study of 36 patients (59.1+/- 11.0 years) with myocardial ischemia at rest participating in the Thrombolysis in Myocardial Ischemia (TIMI) IIIB trial, thrombin activity in plasma, as determined by fibrinopeptide A (FPA), prothrombin fragment 1.2 (F 1.2), and thrombin-antithrombin III complexes (TAT) concentrations, were found to be increased significantly when compared with healthy volunteers (p < 0.004). Thrombin generation was also increased modestly compared with age-matched patients with stable coronary artery disease undergoing elective cardiac catheterization. Given that,he surface 12-lead electrocardiogram (ECG) is frequently abnormal in patients with ischemic chest pain at rest and represents a readily available, first-line diagnostic test for assessing disease activity and treatment response, we investigated whether ECG abnormalities and thrombin activity/generation in plasma were correlated. Twenty-six patients (72%) had ECG changes compatible with myocardial ischemia at the time of study entry, including 18 (50%) with newly inverted T waves (or pseudonormalization), 14 (39%) with reversible ST-segment depression, and 4 (11%) with transient (<30 minutes) ST-segment elevation. Within the predefined ECG groups there were no differences in plasma thrombin activity between patients with and those without confirmed abnormalities. Similarly, there were no differences in either plasma thrombin activity or generation between the predefined ECG groups. Conclusion: Although ECG abnormalities supporting the presence of myocardial ischemia occur commonly in patients with chest pain at rest, they do not correlate closely with markers of thrombin activity and generation in plasma. The diagnostic and prognostic capabilities of these diagnostic tools, considered either alone or together, require further investigation.

Transmyocardial laser revascularization in the patient with unmanageable unstable angina

BACKGROUND

Transmyocardial laser revascularization (TMR) provides relief for patients with chronic angina, nonamenable to direct coronary revascularization. Unmanageable, unstable angina (UUA) defines a subset of patients with refractory angina who are at high risk for myocardial infarction and death. Patients were classified in the UUA group when they had been admitted to the critical care unit with unstable angina for 7 days with three failed attempts at weaning them off intravenous antianginal medications.

METHODS

Seventy-six treated patients were analyzed to determine if TMR is a viable option for patients with unmanageable unstable angina. These patients were compared with 91 routine protocol patients (protocol group [PG]) undergoing TMR for chronic angina not amenable to standard revascularization. The procedure was performed through a left thoracotomy without cardiopulmonary bypass. These patients were followed for 12 months after the TMR procedure. Both unmanageable and chronic angina patients had a high incidence of at least one prior surgical revascularization (87% and 91%, respectively).

RESULTS

Perioperative mortality (< or = 30 days post-TMR) was higher in the UUAG versus PG (16% vs 3%, p = 0.005). Late mortality, up to 1 year of follow-up, was similar (13% vs 11%, UUAG vs PG; p = 0.83). A majority of the adverse events in the UUAG occurred within the first 3 months post-TMR, and patients surviving this interval did well, with reduced angina of at least two classes occurring in 69%, 82%, and 82% of patients at 3, 6, and 12 months, respectively. The percent improvement in angina class from baseline was statistically significant at 3, 6, and 12 months. A comparable improvement in angina was found in the protocol group of patients.

CONCLUSIONS

TMR carried a significantly higher risk in unmanageable, unstable angina than in patients with chronic angina. In the later follow-up intervals, however, both groups demonstrated similar and persistent improvement in their angina up to 12 months after the procedure. TMR may be considered in the therapy of patients with unmanageable, unstable angina who otherwise have no recourse to effective therapy in the control of their disabling angina.

Four-year survival of patients with acute coronary syndromes without ST-segment elevation and prognostic significance of 0.5-mm ST-segment depression

We prospectively evaluated all patients admitted to our coronary care unit during 1993 with ischemic chest pain but without ST-segment elevation on the presenting electrocardiogram, and determined the influence of the extent of ST-segment depression, measured using calipers and blinded to the outcome, on 4-year survival. The presenting symptoms of 367 patients (mean age 64 years) were coded according to the Braunwald classification, 86% being in class IIIB (primary unstable angina with rest angina within 48 hours) and 7.4% in class IIIC (postinfarction angina). Thirty-two patients (8.6%) had myocardial infarction at presentation (defined as a creatine kinase level exceeding twice the reference range within 18 hours). During hospitalization 97% of patients received aspirin, 67% received intravenous heparin, 37% underwent angiography, and 35% underwent revascularization. The vital status of 99% of the patients was determined after a median of 52 months (interquartile range 48 to 55). At follow-up, 88% of patients were taking aspirin, 45% were taking beta blockers, and 50% had undergone revascularization. The survival rate was 70% in patients with > or = 0.5-mm ST-segment depression (53%, 77%, and 82% survival for > or = 2-, 1-, and 0.5-mm ST-segment depression, respectively; p <0.0001). Patients with a normal electrocardiogram had a greater survival rate (94%) than that of patients with 0.5-mm ST-segment depression (82%, p = 0.020), but not significantly different from that of patients with T-wave inversion (84%, p = NS). Independent predictors of mortality (odds ratio [95% confidence interval]) were: age in yearly increments (1.05 [1.03 to 1.06], p = 0.003), revascularization during follow-up (0.40 [0.29 to 0.56], p = 0.006), pulmonary edema (3.45 [2.19 to 5.45], p = 0.007), and ST-segment depression (1.37 [1.20 to 1.55], p = 0.015). Thus, ST-segment depression of > or = 0.5 mm predicts 4-year survival in patients with acute ischemic syndromes.

Immediate exercise testing of low risk patients with known coronary artery disease presenting to the emergency department with chest pain

OBJECTIVES

The purpose of this study was to demonstrate the safety and utility of immediate exercise treadmill testing (IETT) of low risk patients presenting to the emergency department with known coronary artery disease (CAD).

BACKGROUND

More than 70% of the two million patients admitted to U.S. hospitals annually for suspected acute myocardial infarction (AMI) are found not to have had a cardiac event. We have previously demonstrated the safety and efficacy of IETT of selected low risk patients without known CAD presenting to the emergency department with chest pain. This study extends this approach to selected patients with a history of CAD.

METHODS

One hundred patients evaluated by the chest pain emergency room to rule out AMI underwent IETT using a modified Bruce protocol upon admission to the hospital (median time <1 h).

RESULTS

Twenty-three patients (23%) had positive exercise electrocardiograms (ExECGs); an uncomplicated non-Q wave AMI was diagnosed in two patients. Thirty-eight patients (38%) had negative ExECGs and 39 patients (39%) had nondiagnostic ExECGs. Of these 100 patients, 64 were discharged immediately after IETT, 19 were discharged in less than 24 h after negative serial cardiac enzymes and stable electrocardiograms and 17 were discharged after further evaluation and treatment. There were no complications from exercise testing and no late deaths or AMI during six-month follow-up.

CONCLUSIONS

Immediate exercise treadmill testing of low risk patients with chest pain and known CAD is effective in further stratifying this group into patients who can be safely discharged and those who require hospital admission.

The health care burden of unstable angina

Worldwide, UA represents a significant allocation of resources. UA represents a syndrome where not only do many therapies exist, but considerable clinical trial evidence has accumulated. Universal application of effective practice patterns is warranted if we are to successfully reduce the burden of UA. Economic analyses cannot resolve many of the underlying societal issues that affect decision making. Often, the acceptability of an economic burden is dependent on the willingness of both individuals and society to pay. In an interesting study, Chestnut et al evaluated the willingness of 50 patients to pay for avoiding a worsening of their angina symptoms. On average, the patients were willing to pay between $210 and $499 to avoid four to eight additional angina episodes each month. The "rule of rescue" suggests that society is often willing to pay large sums of money to save those in extreme need, such as the 55-year-old man rushed to the emergency department clutching his chest. Only recently has attention been paid to how much this disease entity costs us. Whereas the 1980s and 1990s saw a focus on costs, the next century will increasingly focus on value--obtaining the best health outcome for the dollars spent. Debate has shifted, at least in part, from purely financial costs to medical effectiveness and outcomes management. Continuing assessments of value of interventions and application of evidence based-management strategies permit rational selection of therapy and allow us best to bear the burden of UA.

Incremental prognostic value of serum levels of troponin T and C-reactive protein on admission in patients with unstable angina pectoris

Management of unstable angina is largely determined by symptoms, yet some symptomatic patients stabilize, whereas others develop myocardial infarction after waning of symptoms. Therefore, markers of short-term risk, available on admission, are needed. The value of 4 prognostic indicators available on admission (pain in the last 24 hours, electrocardiogram [ECG], troponin T, and C-reactive protein [CRP]), and of Holter monitoring available during the subsequent 24 hours was analyzed in 102 patients with Braunwald class IIIB unstable angina hospitalized in 4 centers. The patients were divided into 3 groups: group 1, 27 with pain during the last 24 hours and ischemic electrocardiographic changes; group 2, 45 with pain or electrocardiographic changes; group 3, 30 with neither pain nor electrocardiographic changes. Troponin T, CRP, ECG on admission, and Holter monitoring were analyzed blindly in the core laboratory. Fifteen patients developed myocardial infarction: 22% in group 1, 13% in group 2, and 10% in group 3. Twenty-eight patients underwent revascularization: 37% in group 1, 35% in group 2, and 7% in group 2 (p <0.01 between groups 1 or 2 vs group 3). Myocardial infarction was more frequent in patients with elevated troponin T (50% vs 9%, p=0.001) and elevated CRP (24% vs 4%, p= 0.01). Positive troponin T or CRP identified all myocardial infarctions in group 3. Only 1 of 46 patients with negative troponin T and CRP developed myocardial infarction. Among the indicators available on admission, multivariate analysis showed that troponin T (p=0.02) and CRP (p=0.04) were independently associated with myocardial infarction. Troponin T had the highest specificity (92%), and CRP the highest sensitivity (87%). Positive results on Holter monitoring were also associated with myocardial infarction (p=0.003), but when added to troponin T and CRP, increased specificity and positive predictive value by only 3%. Thus, in patients with class IIIB unstable angina, among data potentially available on admission, serum levels of troponin T and CRP have a significantly greater prognostic accuracy than symptoms and ECGs. Holter monitoring, available 24 hours later, adds no significant information.

Unstable angina: good long-term outcome after a complicated early course

OBJECTIVES

This study was performed to investigate the long-term outcome of patients with unstable angina within subgroups of the Braunwald classification.

BACKGROUND

Long-term follow-up studies of patients with unstable angina are rare and date from more than two decades ago. This study was performed to establish the prognosis of different subgroups of patients with unstable angina (Braunwald criteria) during a 7-year follow-up period.

METHODS

We registered a well defined group of 417 consecutive patients, admitted to the hospital for suspected unstable angina. The definite diagnosis was unstable angina in 282 patients (68%) and evolving myocardial infarction in 26; in 109 patients (26%), the symptoms were attributed to other or nonspecific causes. Patients with definite unstable angina were subclassified according to the Braunwald classification. Survival, survival without infarction and survival without infarction or intervention were determined for each class.

RESULTS

After a median follow-up period of 94 months, the mortality rate in the first year was 6% and 2% to 3% in the following years. The frequency of revascularization was 47% in the first year, and that for myocardial infarction was 11% in the first year and 1% to 3% thereafter. The Braunwald classification appeared to be appropriate for risk stratification in the first year. However, at 7 years the event rates in all classes were similar. In particular, the Braunwald classification had no long-term impact on mortality or infarction rates. However, patients with acute angina at rest or postinfarction angina and patients with extensive anginal treatment had high intervention rates.

CONCLUSIONS

To our knowledge, this study is the first to demonstrate that despite a complicated course during the first year, current management results in good long-term outcome in patients with unstable angina.

C-reactive protein elevation and early outcome in patients with unstable angina pectoris

C-reactive protein, a reactant of the acute phase of inflammation, has been shown to be increased in patients with unstable angina. Moreover, it has recently been found that increased C-reactive protein is associated with a poor outcome during hospitalization in selected patients with severe unstable angina. The aim of this study was to investigate the prognostic value of C-reactive protein elevation in a large population with unstable angina. We measured serum levels of this marker in 140 patients hospitalized with unstable angina (class IIIB of the Braunwald classification, mean time from last anginal episode 5 +/- 5 hours). Thirty-nine of them (28%) had increased serum levels on hospital admission and 33 (24%) experienced an adverse outcome (myocardial infarction or refractory angina) during hospitalization. Kaplan-Meier analysis showed that the probability of developing cardiac events during hospitalization was not different between patients with and without abnormal C-reactive protein levels. Furthermore, the incidence of ischemia at Holter monitoring during the first 72 hours after hospitalization was not different between patients with and without abnormal C-reactive protein. In a representative population of patients with unstable angina, a sizable proportion had increased serum C-reactive protein levels; however, abnormal concentrations of C-reactive protein do not predict an adverse outcome in the early phase after the acute episode.

Unstable angina: are we able to recognize high-risk patients?

It is difficult to identify characteristics of patients with unstable angina that are predictive of a high likelihood of developing clinical events. However, several features have been recognized. Patients with a clinical history of previous stable exertional angina symptoms who began to experience rest pain appear to be at risk and tend to have more extensively underlying coronary disease. When the ischemic episodes are accompanied by rates, a new or worsening mitral regurgitation murmur, or hypotension, there is a high likelihood of significant coronary artery disease and one should triage these patients to early cardiac catheterization and prompt revascularization. An angiographic feature that carries a high risk is a lesion in the proximal left anterior descending or in the left main coronary artery. Certain typical ECG patterns are very suggestive for a critical narrowing in these coronary arteries. If chest pain and ST-segment changes recur on vigorous medical management, early invasive evaluation should be strongly considered. Even so, the left ventricular function is very important prognostically. According to serologic tests, the level of C-reactive protein and serum amyloid A protein suggesting that there may be active inflammation predicts an early poor outcome. However, these serologic abnormalities do not have much clinical value. An increased platelet activation and a reduced fibrinolytic capacity play a role in the pathogenesis of unstable angina, but thrombolytic therapy does not improve the prognosis in patients with unstable angina.

The electrocardiogram predicts one-year outcome of patients with unstable angina and non-Q wave myocardial infarction: results of the TIMI III Registry ECG Ancillary Study. Thrombolysis in Myocardial Ischemia

OBJECTIVES

We sought to determine the prognostic value of the admission electrocardiogram (ECG) in patients with unstable angina and non-Q wave myocardial infarction (MI).

BACKGROUND

Although the ECG is the most widely used test for evaluating patients with unstable angina and non-Q wave MI, little prospective information is available on its value in predicting outcome in the current era of aggressive medical and interventional therapy.

METHODS

ECGs with the qualifying episode of pain were analyzed in patients enrolled in the Thrombolysis in Myocardial Ischemia (TIMI) III Registry, a prospective study of patients admitted to the hospital with unstable angina or non-Q wave MI.

RESULTS

New ST segment deviation > or = 1 mm was present in 14.3% of 1,416 enrolled patients, isolated T wave inversion in 21.9% and left bundle branch block (LBBB) in 9.0%. By 1-year follow-up, death or MI occurred in 11% of patients with > or = 1 mm ST segment deviation compared with 6.8% of patients with new, isolated T wave inversion and 8.2% of those with no ECG changes (p < 0.001 when comparing ST with no ST segment deviation). Two other high risk groups were identified: those with only 0.5-mm ST segment deviation and those with LBBB, whose rates of death or MI by 1 year were 16.3% and 22.9%, respectively. On multivariate analysis, ST segment deviation of either > or = 1 mm or > or = 0.5 mm remained independent predictors of death or MI by 1 year.

CONCLUSIONS

The admission ECG is very useful in risk stratifying patients with non-Q wave MI. The new criteria of not only > or = 1-mm ST segment deviation but also > or = 0.5-mm ST segment deviation or LBBB identify high risk patients, whereas T wave inversion does not add to the clinical history in predicting outcome.

Pathophysiology of transient myocardial ischemia in acute coronary syndromes. Characterization by continuous ST-segment monitoring

BACKGROUND

Transient ischemia in stable coronary disease peaks in the morning, reflecting increased myocardial oxygen demand and coronary vasomotor tone after walking. In acute coronary syndromes, however, ischemia may result from transient thrombus formation or coronary spasm at the site of a ruptured plaque. We report on the pathophysiological mechanisms underlying transient ischemia in acute coronary syndromes despite optimal therapy, on the basis of analysis of heart rate changes preceding ischemia and its circadian variation.

METHODS AND RESULTS

Two hundred fifty-six patients with unstable angina or non-Q-wave myocardial infarction underwent continuous ST-segment monitoring for 48 hours while receiving maximal medical therapy. All ischemic episodes were characterized by their timing, duration, association with pain, and heart rate changes before the onset of ischemia. During 10,629 hours of monitoring, 44 patients (17.2%) had 176 episodes of transient ischemia. The mean heart rate at onset of ischemia was 68 +/- 12.8 bpm, and > 55% of ischemic episodes were not preceded by a significant increase in heart rate. Ischemic activity had a single nocturnal peak, with 64% of all episodes occurring between 10 PM and 8 AM, this nocturnal preponderance being evident for episodes with or without a preceding increase in heart rate. The characteristics and timing of transient ischemia were similar in unstable angina and non-Q-wave myocardial infarction, but transient ischemia was more frequent (27.3% versus 15.1%; P < .05) and prolonged (median, 20 versus 13.5 minutes; P < .01) in non-Q-wave myocardial infarction.

CONCLUSIONS

In acute coronary syndromes, transient ischemia has a low threshold, occurs predominantly without an increase in myocardial oxygen demand, and is present mainly at night rather than in the morning. These findings in patients receiving maximal medical therapy suggest significant pathophysiological differences underlying transient ischemia compared with stable coronary disease.

Comparison of immediate and long-term outcome of coronary angioplasty performed for unstable angina and rest pain in men and women

OBJECTIVE

To determine whether a sex-related difference in outcome is present among patients who undergo percutaneous transluminal coronary angioplasty (PTCA) for unstable angina.

DESIGN

We retrospectively analyzed the results after PTCA was performed between January 1981 and June 1993 in a series of 2,073 men and 941 women with unstable angina and rest pain.

RESULTS

The success rates of PTCA were similar for women and men (87.9% and 87.2%, respectively), as were the in-hospital mortality rates (4.1% and 3.2%, respectively) and the need for emergency coronary artery bypass operation (3.1% and 3.5%, respectively). Fewer women than men had Q-wave myocardial infarction (0.5% versus 1.6%; P = 0.02). During the follow-up period (mean, 4 years), no significant differences were noted between women and men in overall survival (81% and 85% at 6 years, respectively) or survival free of Q-wave myocardial infarction (81% and 83% at 6 years, respectively) with use of the Kaplan-Meier method. Women were less likely than men to have had coronary artery bypass grafting (19% versus 22% at 6 years; P = 0.02), and the occurrence of severe angina was higher in women than in men (52% versus 44% at 6 years; P = 0.001). A subgroup analysis of patients who had myocardial infarction within 7 days preceding PTCA showed a similar pattern of results.

CONCLUSION

After PTCA performed for unstable angina and rest pain, survival rates were excellent in both women and men, and no difference was observed in subsequent myocardial infarction rates. During follow-up, however, women were more likely to have severe angina and were less likely to have had coronary artery bypass grafting. Concerns about possible sex-related complications should not dissuade physicians from performing PTCA when clinically indicated for unstable angina and rest pain.

Prospective study of the role of cardiac troponin T in patients admitted with unstable angina

OBJECTIVE

To examine the prognostic significance and role in risk stratification of the biochemical marker troponin T in patients admitted with unstable angina.

DESIGN

Single centre, blinded, prospective study of patients admitted with chest pain.

SETTING

Coronary care unit of a district general hospital.

SUBJECTS

460 patients admitted with chest pain and followed up for a median of three years. 183 patients had a final diagnosis of unstable angina.

MAIN OUTCOME MEASURES

Cardiac death, need for coronary revascularisation, or readmission with non-fatal myocardial infarction as first events.

RESULTS

62 (34%) unstable angina patients were troponin T positive. This group had significantly increased incidence rates of subsequent cardiac death (12 cases (19%) v 14 (12%)), coronary revascularisation (22 (35%) v 26 (21%)), death or revascularisation (33 (53%) v 40 (33%)), and death or non-fatal myocardial infarction (18 (29%) v 21 (17%)) compared with the troponin T negative group. In multiple logistic regression troponin T status was a highly significant predictor for the end points coronary revascularisation and cardiac death or revascularisation as first events.

CONCLUSION

Troponin T in the serum of patients with unstable angina identifies a subgroup at higher risk of subsequent cardiac events and its measurement aids in risk factor stratification. The increased risk extends to two years after admission. Prospective randomised trials are required to identify optimum therapeutic strategies for this subgroup.

Prior myocardial infarction and prognostic outcome in patients with unstable angina in a postdischarge follow-up

The authors investigated how a previous myocardial infarction (MI) affects the prognosis of unstable angina pectoris in patients with maintained or slightly reduced left ventricular performance. From January 1991 to August 1993, 131 patients hospitalized with the diagnosis of Braunwald's class II-III unstable angina and ejection fraction > 40% were included. The enrolled patients were divided into two groups: (1) group I: unstable angina with prior MI (n = 70, 49 men, 21 women, aged between fifty-one and eighty years, mean: 65.7 +/- 8.5 years, Braunwald's class III: 71.4%), (2) group II: unstable angina with previous infarction (n = 61, 31 men, 30 women, aged between forty-nine and eighty, mean: 66.3 +/- 7.9 years, Braunwald's class III: 83.6%). The follow-up varied between six and twenty-four months. The frequency of major cardiovascular events (deaths, MI, reinfarction, heart failure, and recurrent unstable angina) and the number of revascularization procedures (percutaneous transluminal coronary angioplasty [PTCA] and coronary artery bypass grafting [CABG]) established during follow-up were evaluated. Hospitalization was 10.1 +/- 2.9 days in group I and 8.6 +/- 2.6 days in group II (P < 0.01). The duration of the follow-up was comparable between the two groups. Based upon predischarge noninvasive evaluation, patients in both groups were selected to undergo coronary and ventricular angiography: 38 of 70 (55.7%) in group I and 39 of 61 (62.3%) in group II; among them, 52.9% in group I and 24.6% in group II (P < 0.05) were submitted to coronary revascularization, while the others received medical treatments: 33 of 70 in group I and 46 of 61 in group II (P < 0.05). In the subset of patients submitted to angiography, the severity of coronary disease did not differ between the groups, and group I showed a statistically lower ejection fraction than group II (P < 0.005). The frequency of major cardiovascular events demonstrated a mortality rate of 2.9% in group I and 1.6% in group II. Acute MI/reinfarction accounted for 2.9% of the cases in group I and 3.3% in group II. Heart failure was present in 2.9% of group I. Recurrence of unstable angina was diagnosed in 11.4% of group I and 6.5% of group II. CABG and PTCA were performed, respectively in 7.1% and 5.7% in group I and in 6.6% and 4.9% in group II. During follow-up 75.7% of patients in group I and 80.3% in group II were asymptomatic. No significant differences in the frequency of cardiovascular events were reported between the two groups. As result of more aggressive therapeutic approaches following the detection of residual ischemia in patients with prior infarction, the authors conclude that the prognosis of unstable angina in the group with previous infarction does not seem to differ from that of unstable angina in the absence of prior necrosis in patients whose left ventricular function is maintained or slightly decreased.

The prognostic value of serum troponin T in unstable angina

BACKGROUND

Cardiac troponin T is a regulatory contractile protein not normally found in blood. Its detection in the circulation has been shown to be a sensitive and specific marker for myocardial cell damage. We used a newly developed enzyme immunoassay for troponin T to determine whether its presence in the serum of patients with unstable angina was a prognostic indicator.

METHODS

We screened 72 patients with unstable angina (Class III, acute unstable angina) for serum creatine kinase activity, creatine kinase myocardial band (isoenzyme M) activity, and troponin T, every 8 h for 2 days after admission to the hospital. The outcomes of interest during the hospitalization were death and myocardial infarction.

RESULTS

Troponin T was detected in the serum of 24 of the 72 patients (34%) with acute angina at rest. Only four of these patients had elevated creatine kinase M activity. Of the 24 patients who were positive for troponin T, 12 had myocardial infarction, and 6 of these died during hospitalization. In contrast, only 2 of the 48 patients with angina at rest who were negative for troponin T had an acute myocardial infarction, and these patients died. Thus, 12 of the 14 patients with myocardial infarctions had detectable levels of troponin T; only 2 had elevated creatine kinase M activity.

CONCLUSIONS

Cardiac troponin T in serum appears to be a more sensitive indicator of myocardial-cell injury than serum creatine kinase MB activity, and its detection in the circulation may be a useful prognostic indicator in patients with unstable angina.

Early continuous ST segment monitoring in unstable angina: prognostic value additional to the clinical characteristics and the admission electrocardiogram

BACKGROUND AND OBJECTIVE

In unstable angina, clinical characteristics, resting electrocardiography, and early continuous ST segment monitoring have been individually reported to identify subgroups at increased risk of adverse outcome. It is not known, however, whether continuous ST monitoring provides additional prognostic information in such a setting.

DESIGN

Observational study of 212 patients with unstable angina without evidence of acute myocardial infarction admitted to district general hospitals, who had participated in a randomised study comparing heparin and aspirin treatment versus aspirin alone.

METHODS

Clinical variables and a 12 lead electrocardiogram (ECG) were recorded at admission, and treatment was standardised to include aspirin, atenolol, diltiazem, and intravenous glyceryl trinitrate, in addition to intravenous heparin (randomised treatment). Continuous ST segment monitoring was performed for 48 h and all inhospital adverse events were recorded.

RESULTS

The admission ECG was normal in 61 patients (29%), showed ST depression in 59 (28%) (17 > or = 0.1 mV), and T wave changes in a further 69 (33%). The remaining 23 had Q waves (18), right bundle branch block (four), or ST elevation (one). During 8963 h of continuous ST segment monitoring (mean 42.3 h/patient), 132 episodes of transient myocardial ischaemia (104 silent) were recorded in 32 patients (15%). Forty patients (19%) had an adverse event (cardiac deaths (n = 3), non-fatal myocardial infarction (n = 6) and, emergency revascularisation (n = 31)). Both admission ECG ST depression (P = 0.02), and transient ischaemia (P < 0.001) predicted an increased risk of non-fatal myocardial infarction or death, while no patients with a normal ECG died or had a myocardial infarction. Adverse outcome was predicted by admission ECG ST depression (regardless of severity) (odds ratio (OR) 3.41) (P < 0.001), and maintenance beta blocker treatment (OR 2.95) (P < 0.01). A normal ECG predicted a favourable outcome (OR 0.38) (P = 0.04), while T wave or other ECG changes were not predictive of outcome. Transient ischaemia was the strongest predictor of adverse prognosis (OR 4.61) (P < 0.001), retaining independent predictive value in multivariate analysis (OR 2.94) (P = 0.03), as did maintenance beta blocker treatment (OR 2.85) (P = 0.01) and admission ECG ST depression, which showed a trend towards independent predictive value (OR 2.11) (P = 0.076).

CONCLUSIONS

Patients with unstable angina and a normal admission ECG have a good prognosis, while ST segment depression predicts an adverse outcome. Transient myocardial ischaemia detected by continuous ST segment monitoring in such patients receiving optimal medical treatment provides prognostic information additional to that gleaned from the clinical characteristics or the admission ECG.

Correlation between clinical and morphologic findings in unstable angina

This study was undertaken to verify the hypothesis that the discrepant findings in published reports on the prevalence of thrombus in unstable angina depend on the inclusion of different clinical subsets in the various studies. We therefore correlated the clinical characteristics of patients included under the label of unstable angina with the morphologic features assessed by coronary angiography and intravascular ultrasound, and with histopathologic findings of atherectomy specimens. Fifty-eight patients with unstable angina (class B of the Braunwald classification) undergoing coronary arteriography followed by either coronary angioplasty (n = 20) or directional coronary atherectomy (n = 38) were studied. Fifteen patients were in class IB and 43 were in class II to IIIB. Among these 43 patients with angina at rest, 28 had ST-segment elevation during pain, and 15 had ST-segment depression, and 26 developed negative T waves on the baseline electrocardiogram (ECG) as a result of prolonged or repeated episodes of resting chest pain. Intravascular ultrasound examination of the culprit lesion was performed in 43 patients before the interventional procedure, and histopathologic analysis of atherectomy specimens was performed in 38 patients. Complex lesion morphology by angiography was observed in 31 patients (53%) without any significant relation to various clinical subsets. Patients in Braunwald class IB had more calcific plaques than patients in class II to IIIB (p < 0.001). Among patients with angina at rest, those with negative T waves on the baseline ECG, as well as those with transient ST elevation during pain, had a significantly higher incidence of noncalcific lesions (p = 0.001 for both). Analysis of atherectomy specimens revealed acute coronary lesions (thrombus and/or intraplaque hemorrhage) in 18 patients (47%). The incidence of acute coronary lesions was significantly higher in patients with than without negative T waves on the baseline ECG (p = 0.005), and increased further when negative T waves were combined with ST elevation during pain (p = 0.001). Multivariate analysis revealed that the presence orf negative T waves on the baseline ECG was the only explanatory variable related to the presence of acute coronary lesions by histology (p = 0.03). Patient subsets included in the broad spectrum of unstable angina have different morphologic features and incidence of acute coronary lesions by histology. These data provide an explanation for the discrepant findings in published reports on the relevance of thrombus formation in the pathogenesis of unstable angina.

Calcium channel antagonists in the management of anginal syndromes: changing concepts in relation to the role of coronary vasospasm

Despite the increasing evidence that alterations in coronary vascular tone can and do occur in patients with anginal syndromes, only in a minority of such patients with Prinzmetal's angina is there decisive evidence that the coronary vasodilation induced by calcium channel antagonists (CCAs) plays a specific therapeutic role. CCAs may also give therapeutic benefit in a number of conditions in which coronary vasoconstriction may contribute to ischemia, such as hyperventilation, cold-induced angina, or silent ischemia not caused by an increase in heart rate. Thus, the decision of whether or not to use CCAs in angina syndromes will often have to be made on grounds other than what appears to be a minor role of vasospasm in the overall spectrum of angina. There are preliminary indications that the long-term prognosis may be different among different categories of CCAs.

Effect of the increasing use of coronary angioplasty on outcome at one year in patients with unstable angina

OBJECTIVE

To determine whether the increasing use of percutaneous transluminal angioplasty in patients with unstable angina has reduced the need for bypass surgery and whether this change in the choice of treatment affected the outcome at one year in patients with unstable angina who were admitted to hospital in two different periods of time.

DESIGN

Retrospective analysis of consecutive patients with unstable angina (angina at rest with ST-T changes during pain) who underwent coronary arteriography in two different periods of time.

PATIENTS

158 patients were admitted to hospital between January 1988 and June 1989 (group 1) and 140 patients admitted between January 1992 and June 1993 (group 2).

RESULTS

Coronary angioplasty procedures nearly doubled from 29% in group 1 to 56% in group 2 whereas bypass surgery decreased from 36% in group 1 to 23% in group 2 (P < 0.01). Coronary angioplasty increased and bypass surgery decreased in patients with one vessel disease (P < 0.01), two vessel disease (P < 0.05), and three vessel disease (P < 0.01). Coronary angioplasty also increased and bypass surgery decreased in refractory angina and in patients with ejection fraction < 0.50 (both P < 0.05). At 1-year follow up, 14 patients in group 1 (9%) and 10 in group 2 (7%) either died or had myocardial infarction (P = NS). Revascularisation procedures were needed in 16 group 1 patients (10%) and 27 group 2 patients (19%, P < 0.05).

CONCLUSIONS

Coronary angioplasty became more widely used in patients with unstable angina. This reduced the need for bypass surgery in patients with multivessel disease, refractory angina, and depressed left ventricular function. This change in treatment did not affect 1-year mortality or the myocardial infarction rate. More patients in the more recent group in which angioplasty was the preferred treatment required a further revascularisation procedure than in the earlier group in which bypass grafting was more often used as the initial treatment.

Comparative study of left ventricular function in patients with unstable angina, non-Q wave myocardial infarction and stable angina pectoris: assessment with atrial pacing and digital ventriculography

To compare left ventricular global and segmental function at rest and during right atrial pacing in patients with unstable angina, non-Q wave myocardial infarction, and stable angina (class III angina), low-dose digital subtraction ventriculography was performed at rest and after abrupt cessation of pacing in 42 patients with unstable angina, 8 patients with non-Q wave myocardial infarction and 15 patients with stable angina during selective coronary arteriography. Left ventricular ejection fraction was significantly lower at rest in patients with unstable angina (P < 0.01) and non-Q wave myocardial infarction (P < 0.05) and during pacing (P < 0.01). These two groups of patients had significantly higher values of left ventricular end-diastolic and end-systolic volumes at rest and during pacing as compared with stable angina group. In comparing various clinical patterns of unstable angina, ejection fraction was significantly (P < 0.05) lower during pacing in patients with crescendo angina than in new-onset angina. However, ejection fraction was significantly (P < 0.01) lower in crescendo angina only at rest as compared with rest angina. The length of zone of severe hypokinesia was greater in unstable angina (P < 0.01) as well as in non-Q wave myocardial infarction (P < 0.05) both at rest and during pacing as compared with stable angina. Contractility of region of hypokinesia during pacing was higher (P < 0.01) in stable angina than in unstable angina and non-Q wave myocardial infarction. In analyzing segmental function in various subgroups of unstable angina, the authors found that the length of total hypokinesia was significantly higher (P < 0.05) during pacing in crescendo angina than in new-onset angina. Contractility of region of hypokinesia was lowest at rest and during pacing in patients with crescendo angina. This study demonstrates that patients with unstable angina as well as non-Q wave myocardial infarction were characterized by more pronounced global and segmental left ventricular dysfunction at rest and during pacing as compared with patients with stable angina, which may explain the poorer prognosis in the former two groups. This study also shows that patients with crescendo angina have more profound left ventricular global and regional dysfunction as compared with patients with new-onset as well as rest angina.

Prediction of acute coronary syndromes by percutaneous coronary angioscopy in patients with stable angina

To pinpoint the link between plaque characteristics and acute coronary syndromes, we performed a 12-month prospective follow-up study in 157 patients with stable angina pectoris in whom regular coronary plaques were observed by percutaneous coronary angioscopy. Acute coronary syndromes occurred more frequently in patients with yellow plaque than in those with white plaques (11 of 39 vs 4 of 118; p = 0.00021). Moreover, the syndromes occurred more frequently in patients with glistening yellow plaques than in those with nonglistening yellow plaques (9 of 13 vs 2 of 26; p = 0.00026). Thrombus arising from the ruptured identical plaques was confirmed by angioscopy as the culprit lesion of the syndromes. The results indicate that acute coronary syndromes occur frequently and in a short time in patients with glistening yellow plaques and that angioscopy but not angiography is feasible for prediction of the syndromes.

A new clinical classification for hospital prognosis of unstable angina pectoris

Unstable angina represents a heterogeneous spectrum of clinical entities between chronic stable angina and acute myocardial infarction. To facilitate prognostication of in-hospital outcome, we prospectively tested on a priori unstable angina classification scheme based on information available at the time of acute presentation. Prospective database enrollment at the time of emergency room presentation was performed and patients were classified into 1 of the following categories: class IA, acceleration of previous exertional angina without electrocardiographic (ECG) changes; class IB, acceleration of previous exertional angina with ECG changes; class II, new-onset exertional angina; class III, new-onset rest angina; class IV, protracted rest angina with ECG changes. The study consisted of 1,387 consecutive patients with unstable angina. Baseline demographics and aggregate in-hospital major cardiac event rates were recorded (myocardial infarction, refractory angina, and death). There was a significant increasing trend in cardiac events from class I to IV (p < 0.0001). Class IA patients had the lowest aggregate event rate at 2.7% (p = 0.0005). Paired chi-square tests of adjacent categories showed no differences in event rates for class IB and II (p = 0.3). A significantly higher rate of adverse events was seen for class III patients (20.1%, p < 0.0001). Class IV patients demonstrated the highest rate of in-hospital adverse events (42.8%, p < 0.0001). We conclude that this easily deduced, universally applicable categorization of unstable angina is highly prognostic of in-hospital adverse cardiac events and hence could have potential use for triage decisions regarding hospital admission and intensity of therapy.

Incidence and follow-up of Braunwald subgroups in unstable angina pectoris

OBJECTIVES

This study was performed to establish the prognosis of patients with unstable angina within the subgroups of the Braunwald classification.

BACKGROUND

Among many classifications of unstable angina, the Braunwald classification is frequently used. However, the incidence and risk for each subgroup in clinical practice have not been established.

METHODS

Prospective data for 417 consecutive patients admitted for suspected unstable angina were analyzed. Patients were classified according to Braunwald criteria and followed up for 6 months. Survival, infarct-free survival and infarct-free survival without intervention are reported for each class.

RESULTS

After in-hospital observation the final diagnosis was acute myocardial infarction in 26 patients (6%), noncoronary chest pain in 109 (26%) and definite unstable angina in 282 (68%). Recurrence of chest pain was significantly different for the different severity classes (28%, 45% and 64% for classes I [accelerated angina], II [subacute angina at rest] and III [acute angina at rest], respectively) but not for clinical circumstances (49% and 53% for classes B [primary unstable angina] and C [postinfarction unstable angina], respectively). Six-month and infarct-free survival (96% and 88%, respectively) were not significantly different between severity classes but were significantly different (p = 0.01) between classes B (97% and 89%) and C (89% and 80%). Infarct-free survival without intervention was best for class II (72%), intermediate for class I (53%) and worst for class III (35%). In multivariate analysis, elderly age, male gender, hypertension, class C and maximal (intravenous) therapy were independent predictors for death; elderly age and class C for infarct-free survival; and male gender, class III, class C, electrocardiographic changes and maximal therapy were associated with infarct-free survival without intervention.

CONCLUSIONS

Braunwald classification is an appropriate instrument to predict outcome. Risk stratification by these criteria provides a tool for patient selection in clinical trials and for evaluation of treatment strategies.

Arteriographic morphology and intracoronary thrombus in patients with unstable angina, non-Q wave myocardial infarction and stable angina pectoris

Coronary artery lesions were compared in 71 patients with unstable angina, 15 patients with non-Q wave myocardial infarction (MI), and 40 patients with stable angina. In the unstable angina group, 29 patients had new-onset angina, 31 had crescendo angina, and 11 had rest angina. In a subgroup of patients with unstable angina, three-vessel disease was less frequently (P < 0.05) seen in patients with new-onset angina (10.3%) than in the patients with crescendo angina (51.6%) or rest angina (54.5%). An angina-producing artery could be identified in 59 patients with unstable angina, in 11 with non-Q wave MI, and in 30 with stable angina. Type II eccentric stenosis (asymmetric narrowing with narrow neck and overhanging irregular edges) was present in 31 patients (52.5%; P < 0.01) with unstable angina, in 7 (63.6%; P < 0.01) with non-Q wave MI, and in only 2 (6.7%) with stable angina. Abrupt occlusion of a vessel was observed in 7 patients (11.9%) with unstable angina and in 2 (18.2%) with non-Q wave MI. None of the patients with stable angina had this type of occlusion. In the group of unstable angina and non-Q wave MI, angiographic evidence of intracoronary thrombi was present in 16 (27.1%) and 3 patients (27.3%), respectively, but in stable angina in only 1 patient (3.3%; P < 0.05). Intracoronary thrombi were most frequently found in rest angina (88%; P < 0.001) and crescendo angina (33.3%; P < 0.01) compared with new-onset angina (3.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive testing in the diagnosis and management of unstable angina

Patients presenting with a clinical diagnosis of unstable angina comprise a heterogenous population and a wide spectrum of patients with varying degrees of underlying coronary artery disease, severity and prognosis are categorized in this syndrome. A very small number of patients with unstable angina who are refractory to adequate in-hospital medical therapy should undergo urgent coronary angiography and, if suitable, revascularization. The vast majority of patients do, however, stabilize on medical therapy and an invasive approach, such as a coronary angiography should not be performed routinely to all of these patients. Early recognition of clinical and non-invasive test variables indicating an adverse outcome is of paramount importance in unstable angina. This review focuses on the importance of baseline clinical markers and the usefulness of a non-invasive approach with exercise testing, myocardial perfusion imaging, stress echocardiography, and Holter monitoring in the diagnosis, risk stratification, and management of patients with unstable angina.

Utility and safety of immediate exercise testing of low-risk patients admitted to the hospital for suspected acute myocardial infarction

More than 2 million patients are admitted to U.S. hospitals annually for clinical suspicion of acute myocardial infarction (AMI), and > 70% are found not to have had a cardiac event. This study evaluates the safety and efficacy of immediate exercise testing for patients admitted to the hospital for suspected AMI. Ninety-three nonconsecutive low-risk patients admitted to the hospital from the emergency department to rule out AMI underwent exercise treadmill testing using a modified Bruce protocol immediately on admission to the hospital (median time < 1 hour). Twelve patients had positive exercise electrocardiograms, 6 of whom had significant coronary narrowing by angiography. An uncomplicated non-Q-wave AMI was diagnosed in 1 patient. Fifty-nine patients had negative and 22 patients had nondiagnostic exercise electrocardiograms. Of these 81 patients, 44 were discharged immediately after exercise testing, 17 were discharged within 24 hours, and 20 were discharged after 24 hours of observation. There were no complications from exercise testing. There were 2 late noncardiac deaths and 1 late AMI. Thus, immediate exercise testing of low-risk patients with chest pain who are at sufficient risk to be designated for hospital admission is effective in further stratifying this group into those who can be safely discharged immediately and those who require hospitalization.

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.

Clinical features and prognostic implications of myocardial ischemia at rest in patients with exertional angina pectoris

The prognosis of patients with coronary artery disease (CAD) is mainly influenced by organic factors such as cardiac muscle loss and extent of CAD. The aim of this study was to investigate whether a functional factor--reversible myocardial ischemia at rest--plays an independent prognostic role. Thus, 2 groups of patients were studied and followed up for 46 +/- 32 months: 1 group (483 patients) had ischemic electrocardiographic changes only on effort and another group (224 patients) both on effort and at rest. The 2 groups did not differ significantly as to age, gender, coronary risk factors, baseline electrocardiographic abnormalities, incidence of previous myocardial infarction, angiographic left ventricular dysfunction, and extent of coronary stenoses (> or = 50% diameter reduction). There were 65 deaths (40 of which were from cardiac causes) during the 5-year follow-up. Despite the similar incidence of known predictors of prognosis, Kaplan-Meier survival analysis revealed a significantly lower 5-year survival rate in patients with mixed (84.4%) rather than exertional (92.1%) ischemia (p < 0.05 by Mantel-Haenszel test). If only cardiac causes of deaths were considered, the 5-year survival rate was still lower in patients with mixed (89.6%) rather than exertional (93.9%) ischemia. Finally, reversible ischemia at rest was an independent predictor of survival by Cox multivariate regression analysis, preceded only by the extent of CAD and left ventricular dysfunction. Thus, reversible ischemia at rest plays an independent negative role in the long-term clinical outcome of patients with CAD and positive exercise stress test results.