Transient ischaemia refractory to conventional medical treatment in unstable angina: angiographic correlates and prognostic implications

Antithrombotic treatment tailoring and risk score evaluation in elderly patients diagnosed with an acute coronary syndrome

Age is an important prognostic factor in the outcome of acute coronary syndromes (ACS). A substantial percentage of patients who experience ACS is more than 75 years old, and they represent the fastest-growing segment of the population treated in this setting. These patients present different patterns of responses to pharmacotherapy, namely, a higher ischemic and bleeding risk than do patients under 75 years of age. Our aim was to identify whether the currently available ACS ischemic and bleeding risk scores, which has been validated for the general population, may also apply to the elderly population. The second aim was to determine whether the elderly benefit more from a specific pharmacological regimen, keeping in mind the numerous molecules of antiplatelet and antithrombotic drugs, all validated in the general population. We concluded that the GRACE (Global Registry of Acute Coronary Events) risk score has been extensively validated in the elderly. However, the CRUSADE (Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA Guidelines) bleeding score has a moderate correlation with outcomes in the elderly. Until now, there have not been head-to-head scores that quantify the ischemic versus hemorrhagic risk or scores that use the same end point and timeline (e.g., ischemic death rate versus bleeding death rate at one month). We also recommend that the frailty score be considered or integrated into the current existing scores to better quantify the overall patient risk. With regard to medical treatment, based on the subgroup analysis, we identified the drugs that have the least adverse effects in the elderly while maintaining optimal efficacy.

Association between comorbidities and absence of chest pain in acute coronary syndrome with in-hospital outcome

BACKGROUND

To evaluate the impact of comorbidities on the management and outcomes of acute coronary syndrome (ACS) patients without chest pain/discomfort (i.e. ACS without typical presentation).

METHODS

Of the 11,458 ACS patients, enrolled by the International Survey of Acute Coronary Syndrome in Transitional Countries (ISACS-TC; ClinicalTrials.gov: NCT01218776), 8.7% did not have typical presentation at the initial evaluation, and 40.2% had comorbidities. The odds of atypical presentation increased proportionally with the number of comorbidities (odds ratio [OR]: 1, no-comorbid; OR: 1.64, 1 comorbidity; OR: 2.52, 2 comorbidities; OR: 4.57, ≥3 comorbidities).

RESULTS

Stratifying the study population by the presence/absence of comorbidities and typical presentation, we found a decreasing trend for use of medications and percutaneous intervention (OR: 1, typical presentation and no-comorbidities; OR: 0.70, typical presentation and comorbidities; OR: 0.23, atypical presentation and no-comorbidities; OR: 0.18, atypical presentation and comorbidities). On the opposite, compared with patients with typical presentation and no-comorbidities (OR: 1, referent), there was an increasing trend (p<0.001) in the risk of death (OR: 2.00, OR: 2.52 and OR: 4.83) in the above subgroups. However, after adjusting for comorbidities, medications and invasive procedures, atypical presentation was not a predictor of in-hospital death. Independent predictors of poor outcome were history of stroke (OR: 2.04), chronic kidney disease (OR: 1.57), diabetes mellitus (OR: 1.49) and underuse of invasive procedures.

CONCLUSIONS

In the ISACS-TC, atypical ACS presentation was often associated with comorbidities. Atypical presentation and comorbidities influenced underuse of in-hospital treatments. The latter and comorbidities are related with poor in-hospital outcome, but not atypical presentation, per se.

Does continuous ST-segment monitoring add prognostic information to the TIMI, PURSUIT, and GRACE risk scores?

BACKGROUND

Recurrent ischemia is frequent in patients with non-ST-elevation acute coronary syndromes (NST-ACS), and portends a worse prognosis. Continuous ST-segment monitoring (CSTM) reflects the dynamic nature of ischemia and allows the detection of silent episodes. The aim of this study is to investigate whether CSTM adds prognostic information to the risk scores (RS) currently used.

METHODS

We studied 234 patients with NST-ACS in whom CSTM was performed in the first 24 hours after admission. An ST episode was defined as a transient ST-segment deviation in ≥1 lead of ≥ 0.1 mV, and persisting ≥1 minute. Three RS were calculated: Thrombolysis in Myocardial Infarction (TIMI; for NST-ACS), Platelet glycoprotein IIb/IIIa in Unstable angina: Receptor Supression Using Integrilin (PURSUIT; death/MI model), and Global Registry of Acute Coronary Events (GRACE). The end point was defined as death or nonfatal myocardial infarction (MI), during 1-year follow-up.

RESULTS

ST episodes were detected in 54 patients (23.1%) and associated with worse 1-year outcome: 25.9% end point rate versus 12.2% (Odds Ratio [OR]= 2.51; 95% Confidence Interval [CI], 1.18-5, 35; P = 0.026). All three RS predicted 1-year outcome, but the GRACE (c-statistic = 0.755; 95% CI, 0.695-0.809) was superior to both TIMI (c-statistic = 0.632; 95% CI, 0.567-0.694) and PURSUIT (c-statistic = 0.644; 95% CI: 0.579-0.706). A GRACE RS > 124 showed the highest accuracy for predicting end point. The presence of ST episodes added independent prognostic information the TIMI RS (hazard ratio [HR]= 2.23; 95% CI, 1.13-4.38) and to PURSUIT RS (HR = 2.03; 95% CI, 1.03-3.98), but not to the GRACE RS.

CONCLUSIONS

CSTM provides incremental prognostic information beyond the TIMI and PURSUIT RS, but not the GRACE risk score. Hence, the GRACE risk score should be the preferred stratification model in daily practice.

Timing and duration of myocardial ischemia on Holter monitoring following percutaneous coronary intervention and their association with clinical outcomes (a PROTECT-TIMI 30 Substudy Analysis)

In patients with unstable angina, evidence of myocardial ischemia on Holter monitoring is associated with an adverse prognosis. However, the association of duration and timing of ischemia on Holter monitoring with outcomes after percutaneous coronary intervention (PCI) in patients with non-ST-segment elevation acute coronary syndromes (NSTEACSs) has not been systematically evaluated. PROTECT-TIMI 30 randomized 857 patients with NSTEACSs undergoing PCI to eptifibatide plus a heparin product or bivalirudin monotherapy. Patients underwent continuous Holter monitoring following PCI, and the association between ischemia and clinical outcomes was evaluated retrospectively. Forty-three patients (5.0%) had ischemia on Holter after PCI. Any ischemia was associated with a significant increase in the incidence of death or myocardial infarction (MI) within 48 hours (32.6% vs 6.1%, odds ratio 7.5, 95% confidence interval 3.70 to 15.10, p <0.001). In patients who developed ischemia, there was a 1.44-fold increase in the odds for death or MI for every 30 minutes of ischemia (95% confidence interval 1.12 to 1.84, p = 0.004). Duration of ischemic events was related to their timing, such that ischemic events that occurred within the first 4 hours after PCI (median duration 141 minutes, interquartile range 36 to 227.5) were significantly longer than events occurring 4 to 24 hours after PCI (median duration 32.8 minutes, interquartile range 17.5 to 118, p = 0.041). In conclusion, early ischemia after PCI for NSTEACS is of longer duration, and longer duration of ischemia recognized by Holter monitoring is associated with an increased incidence of death or MI. Holter monitoring may be a useful surrogate end point in clinical trials.

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.

Long-term prognostic value and therapeutic implications of continuous ST-segment monitoring in acute coronary syndrome

BACKGROUND

In patients with acute coronary syndromes (ACS), recurrent ischemia detected by continuous electrocardiographic monitoring portends a poor outcome. We sought to investigate (1) the additional long-term prognostic value of ST-segment monitoring beyond the validated Global Registry of Acute Coronary Events (GRACE) risk score in ACS and (2) whether ST-segment monitoring can identify patients who benefit from early revascularization.

METHODS

We determined the GRACE risk score (a validated predictor of inhospital mortality) in 681 non-ST-elevation ACS patients enrolled in the Integrilin and Enoxaparin Randomized Assessment of Acute Coronary Syndrome Treatment trial. Continuous ST-segment monitoring in the first 48 hours was analyzed by an automated algorithm and reviewed by a blinded cardiologist. Clinical outcomes were centrally adjudicated in a blinded fashion.

RESULTS

ST-segment shifts were present in 19.1% of 681 patients. After a median follow-up of 30 months, patients with ST-segment shifts had a higher risk of death (17.7% vs 5.8%, log-rank P < .001) and death or myocardial infarction (MI) (24.6% vs 11.1%, log-rank P < .001). In multivariable analysis adjusting for GRACE risk score, the presence of ST-segment shifts remained an independent predictor of death (adjusted hazard ratio = 2.37, 95% CI 1.38-4.09, P = .002) and death/MI (adjusted hazard ratio = 1.93, 95% CI 1.25-3.00, P = .003). Inhospital revascularization was independently associated with a lower risk of death/MI among patients with ST-segment shifts but not among those without (P for interaction = .02).

CONCLUSIONS

Continuous ST-segment monitoring provides incremental prognostic information beyond the validated GRACE risk score determined on presentation and identifies high-risk patients who benefit from early revascularization. This simple and valuable clinical tool may be useful in the routine management of ACS.

Relevance of multivessel disease in the development of in-hospital refractory angina and myocardial infarction in patients with unstable angina

We investigated the relationship between clinical, electrocardiographic and angiographic characteristics with development of refractory angina and acute myocardial infarction (AMI) in 976 consecutive patients with unstable angina (UA). AMI occurred in 63 (6%) and recurrent angina in 384 (39%), 201 of whom had >2 episodes (refractory, 21%). Patients with AMI were older (P<0.001) and had a higher rate of smoking (P<0.02), previous cerebrovascular accident (P<0.02), abnormal ST segment on admission (P<0.002), refractory angina (P<0.001) and multivessel disease (P<0.005) than those without AMI. Patients with refractory angina were older (P<0.001) and showed a higher incidence of abnormal ST segment on admission (P<0.001) and multivessel disease (P<0.001) than those without. A multivariate analysis, however, showed that refractory angina (P<0.0001), and multivessel disease (P<0.001) were the strongest predictors of AMI while age and multivessel disease were the strongest predictors of refractory angina (P<0.003). Thus, multivessel disease was the most frequent substrate of refractory angina and AMI in patients with UA. These findings may suggest that significant coronary stenosis in non-culprit arteries may facilitate recurrence of ischemia/AMI perhaps by reacting in concert with the culprit lesion and causing a further reduction of the ischemic threshold.

Low molecular weight heparin decreases rebound ischemia in unstable angina or non-Q-wave myocardial infarction: the Canadian ESSENCE ST segment monitoring substudy

OBJECTIVES

The goal of this study was to determine whether enoxaparin was more effective than heparin in reducing recurrent ischemic episodes.

BACKGROUND

Continuous ST segment monitoring is a simple tool for assessment of ischemia and identifies patients with a worse prognosis. Little is known about the impact of low molecular weight heparin on ST segment shift.

METHODS

Patients were randomized to receive enoxaparin or heparin (mean 3.4 days). Three-lead ST segment monitoring was performed for the first 48 h (n = 220) and an additional 48 h (n = 174) after intravenous study drug discontinuation (mean 1.9 days later).

RESULTS

During initial monitoring, ischemia rates were similar among the heparin and enoxaparin groups (27.2% vs. 22.6%, p = 0.44); however, the time to first ischemic episode was earlier among heparin-treated patients (11 +/- 11 vs. 25 +/- 18 min, p = 0.001). After drug discontinuation, ischemic episodes occurred more frequently (44.6% vs. 25.6%, p = 0.009), and the total ischemic duration was greater among heparin patients (18 +/- 39 vs. 5 +/- 12 min/24 h, p = 0.005). Recurrent ischemia occurred more frequently after discontinuation in the heparin (46% vs. 31%, p = 0.043), but not the enoxaparin, group (18.4% vs. 25%, p = 0.33). Regardless of treatment, patients with ischemia were more likely to die or experience (re)infarction at one year (18.4% vs. 8.3%, p = 0.023).

CONCLUSIONS

ST segment shift occurs frequently in unstable angina/non-Q-wave myocardial infarction despite antithrombotic therapy and is associated with worse one-year prognosis. Enoxaparin is a more effective antithrombotic treatment than unfractionated heparin and leads to greater prevention of rebound ischemia.

Pathophysiology of acute coronary syndromes leading to acute myocardial infarction

Acute coronary syndromes, including unstable angina, myocardial infarction, and sudden death, account for more than 250,000 deaths annually. They are the manifestation of a progressive atherosclerotic process, which culminates in the rupture of atherosclerotic plaques and the formation of mural thrombi. This article reviews recent and current research, which has shed light on key events and evolutionary processes leading to acute coronary syndromes. The article details the development of vulnerable plaques, factors that promote plaque rupture, and triggering events related to plaque rupture. Also discussed are sequelae of acute coronary syndromes, including Q wave and non-Q wave infarction and left ventricular remodeling.

Clinical predictors of in-hospital prognosis in unstable angina: ECLA 3. The ECLA Collaborative Group

OBJECTIVES

Because of recent changes in the treatment of unstable angina, we wanted to reassess the short-term prognostic value of clinical and echocardiographic variables.

METHODS

This was an observational, prospective study that included 1038 nonselected consecutive patients admitted to coronary care units for unstable angina.

RESULTS

Baseline characteristics were age 60.18 +/- 16 years, history of prior myocardial infarction in 336 patients (32%), and a history of previous angina in 817 patients (78.7%). Angina during the 48 hours before admission was observed in 1004 patients (96.7%) and ST-segment changes on admission electrocardiogram occurred in 385 patients (37%). In-hospital treatment consisted of nitrates in 81.4% of patients, aspirin in 88.6%, beta-blockers in 71%, intravenous heparin in 34.5%, subcutaneous heparin in 23%, and angioplasty or coronary artery bypass grafting in 25.1%. After admission, angina occurred in 443 patients (40.8%), refractory angina in 223 patients (21.5%), and death or myocardial infarction in 84 patients (8.1%). At admission, the independent predictors of myocardial infarction or death identified by multivariate logistic regression analysis were ST-segment depression (odds ratio [OR] 2.13, 95% confidence interval [CI] 1.23 to 3.68, P =.006), prior angina (OR 2.23, 95% CI 0.98 to 5.05, P =.05), number of episodes of angina within the previous 48 hours (OR 1.63, 95% CI 0.98 to 2.70, P =.05), and history of smoking (OR 0.69, 95% CI 0.56 to 0.85, P =.004). Age greater than 65 years (OR 1.49, 95% CI1.09 to 2.03, P = 0.03) was significantly related to in-hospital death. The area under the receiver operating characteristic curve for application of this model was 0.59. Sensitivity was 80% with a specificity of only 33%. Refractory angina after admission showed a strong relation with an adverse short-term outcome.

CONCLUSIONS

With current therapy, clinical and electrocardiographic variables provide useful information about the short-term outcome of unstable angina. However, this model has low specificity to identify high-risk patients. Future studies about the incremental value of the new serum markers such as troponin T and C-reactive protein to assist in identification of high-risk patients are necessary.

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.

A detailed angiographic analysis of patients with ambulatory electrocardiographic ischemia: results from the Asymptomatic Cardiac Ischemia Pilot (ACIP) study angiographic core laboratory

OBJECTIVES

The purpose of this Asymptomatic Cardiac Ischemia Pilot (ACIP) data bank study was to characterize angiographic features of coronary pathology of patients enrolled in the ACIP study.

BACKGROUND

Ischemia during ambulatory electrocardiographic (AECG) monitoring is associated with increased morbidity and mortality. Reports relating AECG ischemia to severity or complexity of coronary artery disease are few in number and small in size and have produced conflicting results.

METHODS

Coronary angiograms from patients with asymptomatic AECG ischemia enrolled in the ACIP study were reviewed at a central core laboratory. Quantitative measurement of percent stenosis and Thrombolysis in Myocardial Infarction flow grades were used to assess the severity of coronary artery disease. Lesions were also evaluated for the presence of intracoronary thrombus, ulceration and lumen contour as indicators of stenosis complexity. In addition, comparisons were made with 27 patients screened for the ACIP study, but who were found ineligible because they did not have AECG ischemia on 48-h Holter monitoring.

RESULTS

A total of 329 (75%) of 439 patients with AECG ischemia had multivessel coronary artery disease. Proximal stenoses > or = 50% diameter reduction were common in patients with AECG ischemia (62.2%), as were proximal stenoses > or = 70% (38.7%). Features suggesting complex plaque were found in 50.1% of patients with AECG ischemia.

CONCLUSIONS

Multivessel coronary artery disease, severe proximal stenoses and features of complex plaque were observed frequently in patients who exhibited AECG ischemia. The presence of severe and complex coronary artery disease may explain, in part, the increased risk for adverse outcome associated with ischemia during activities of daily life.

Prognostic significance of transient ischemic episodes: response to treatment shows improved prognosis. Results of the Total Ischemic Burden Bisoprolol Study (TIBBs) follow-up

OBJECTIVES

The Total Ischemic Burden Bisoprolol Study (TIBBS) follow-up examined cardiac event rates in relation to transient ischemia and its treatment.

BACKGROUND

It is unclear whether transient ischemia on the ambulatory electrocardiogram has prognostic implications in stable angina and whether medical treatment can improve the prognosis.

METHODS

The TIBBS trial was an 8-week, randomized, controlled comparison of the effects of bisoprolol and nifedipine on transient ischemic episodes in patients with stable angina pectoris. Of the 545 patients screened, 520 (95.4%) could be followed up. Rates of cardiac and noncardiac death, nonfatal acute myocardial infarction, hospital admission for unstable angina and need for coronary artery bypass graft surgery or percutaneous transluminal coronary angioplasty were recorded.

RESULTS

A total of 145 events occurred in 120 (23.1%) of 520 patients. Patients with more than six episodes had an event rate of 32.5% compared with 25.0% for patients with two to six episodes and 13.2% for patients with less than two episodes (p < 0.001). Hard events (death, acute myocardial infarction, hospital admission for unstable angina pectoris) were more frequent in patients with two or more ischemic episodes (12.2% vs. 4.7%, p = 0.0049). Patients with a 100% response rate of transient ischemic episodes during the TIBBS trial had a 17.5% event rate at 1 year compared with 32.3% for non-100% responders (p = 0.008). Patients receiving bisoprolol during the TIBBS tria had a lower event rate (22.1%) at 1 year than patients randomized to nifedipine (33.1%, p = 0.033).

CONCLUSIONS

In patients with stable angina pectoris, frequent episodes of transient ischemia are a marker for an increased event rate. A 100% response to medical treatment reduces the event rate. The greater reduction of ischemia with bisoprolol than nifedipine during the TIBBS trial translated into an improved outcome at 1 year.

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.

Low molecular weight heparin versus regular heparin or aspirin in the treatment of unstable angina and silent ischemia

OBJECTIVES

This study was designed to test the hypothesis that low molecular weight heparin may lessen the severity of ischemic events in patients with unstable angina.

BACKGROUND

Unstable angina is a thrombotic process that requires intensive medical treatment. Although current treatments can reduce the number of complications, serious bleeding continues to occur. Nadroparin calcium, a low molecular weight heparin, seems to be a safe therapeutic agent that does not require laboratory monitoring.

METHODS

A total of 219 patients with unstable angina entered the study at a mean time of 6.17 h after the last episode of rest pain. Patients were randomized to receive aspirin (200 mg/day [group A]), aspirin plus regular heparin (400 IU/kg body weight per day intravenously and titered by activated partial thromboplastin time [group B]) and aspirin plus low molecular weight heparin (214 UIC/kg anti-Xa twice daily subcutaneously [group C]). The major end points determined for the in-hospital period were 1) recurrent angina, 2) myocardial infarction, 3) urgent revascularization, 4) major bleeding, and 5) death. Minor end points were 1) silent myocardial ischemia, and 2) minor bleeding. Event rates were tested by chi-square analysis.

RESULTS

Recurrent angina occurred in 37%, 44% and 21% of patients in groups A, B and C, respectively, and was significantly less frequent in group C than in either group A (odds ratio 2.26, 95% confidence interval [CI] 1 to 5.18, p = 0.03) or group B (odds ratio, 3.07, 95% CI 1.36 to 7.00, p = 0.002). Nonfatal myocardial infarction was present in seven patients in group A, four in group B and none in group C (group B vs. A, p = 0.5; group C vs. A, p = 0.01). Urgent revascularization was performed in nine patients in group A, seven in group B and one in group C (C vs. A, p = 0.01). Two episodes of major bleeding occurred in group B. Silent myocardial ischemia was present in 38%, 41% and 25% of patients in groups A, B and C, respectively, and was significantly less frequent in group C than group B (odds ratio 2.12, 95% CI 0.97 to 4.69, p = 0.04). Minor bleeding was detected in 10 patients in group B, 1 patient in group C (B vs. C, p = 0.01) and no patient in group A (A vs. B, p = 0.003).

CONCLUSIONS

In this study, treatment with aspirin plus a high dose of low molecular weight heparin during the acute phase of unstable angina was significantly better than treatment with aspirin alone or aspirin plus regular heparin.

Angiographic stenosis progression and coronary events in patients with 'stabilized' unstable angina

BACKGROUND

Recent studies suggest that angiographically complex coronary stenoses are associated with an adverse short-term outcome. It is not known, however, if this applies to unstable angina patients who stabilize on medical therapy.

METHODS AND RESULTS

We prospectively studied 85 consecutive patients with unstable angina who stabilized on medical therapy but were found to require angioplasty for treatment of obstructive coronary disease. Angiography was carried out at admission, and patients were restudied 8 +/- 4 months (mean +/- SD) after the first angiogram. Ischemia-related stenoses were identified and classified as "complex" (irregular borders, overhanging edges, or thrombus) or "smooth" (absence of complex features). Stenosis progression (> or = 20% diameter reduction or new total occlusion) was assessed by automated edge detection. At initial angiography, there were 198 stenoses (> or = 50%, 102), of which 85 (54 complex and 31 smooth) were ischemia related. At restudy, 21 ischemia-related stenoses and 8 non-ischemia-related stenoses progressed (25% versus 7%, P = .001). Seventeen of the 21 ischemia-related stenoses that progressed developed into total occlusion compared with 3 of the 8 non-ischemia-related stenoses (P = .02). Changes in average stenosis severity and in absolute stenosis diameter were significantly larger in ischemia-related stenoses than in non-ischemia-related stenoses (P = .03). Eighteen (34%) complex stenoses progressed, compared with 3 (10%) smooth lesions (P = .02). During follow-up, 1 patient died (myocardial infarction) and 25 patients had nonfatal coronary events that were associated with progression of ischemia-related stenoses in 14 (56%).

CONCLUSIONS

In unstable angina patients who stabilize medically, subsequent short-term stenosis progression and coronary events are common. The unstable coronary lesion (particularly complex stenoses) is often not stabilized and will continue to progress over the ensuing months.

Relation of severity of symptoms to transient myocardial ischemia and prognosis in unstable angina

OBJECTIVES

This study was undertaken to compare the relative power of the severity of angina versus that of any other clinical, electrocardiographic (ECG) and angiographic findings in predicting the risk of subsequent in-hospital coronary events in patients admitted to the coronary care unit for treatment of unstable angina.

BACKGROUND

The presence or absence of chest pain has traditionally been used to guide management and therapy of unstable angina. However, recent studies raised the possibility that the cumulative duration of ischemia may be an additional index of prognosis.

METHODS

We studied 104 consecutive patients admitted to the coronary care unit because of unstable angina. Diaries of symptoms were accurately kept. All patients underwent Holter ambulatory ECG monitoring during the 1st 24 h and angiography within 1 week of admission.

RESULTS

During the hospital stay, 41 patients (group 1) had subsequent coronary events; the remaining 63 patients (group 2) had a good clinical outcome. Recurrence of chest pain after admission was observed in 76% of patients: 36 of the 41 group 1 patients (sensitivity 88%) and 43 of the 63 group 2 patients (specificity 32%). Anginal scores (frequency and persistence of pain, duration of each single episode and pain-free interval) showed high specificity but low sensitivity for detecting evolution toward subsequent coronary events. On Holter monitoring, the duration/24 h of the total number of ischemic episodes was consistently greater in group 1 than in group 2. A cumulative duration of ischemia > or = 60 min/24 h was observed in 34 of the 41 group 1 patients (sensitivity 83%) but in only 16 of the 63 group 2 patients (specificity 75%). High risk coronary artery lesions (left main coronary artery disease or complex stenosis) were detected in 36 of the 41 group 1 patients and in 26 of the 63 group 2 patients.

CONCLUSIONS

Transient myocardial ischemia detected by Holter monitoring, but not chest pain, is the best predictor of unfavorable short-term clinical outcome. The decision to perform early angiography and revascularization cannot be based on symptoms alone.

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)

Lewis A. Conner Memorial Lecture. Mechanisms leading to myocardial infarction: insights from studies of vascular biology

Myocardial infarction is the most frequent cause of mortality in the United States as well as in most western countries. In this review, the processes leading to myocardial infarction are described based on the most recent studies of vascular biology; in addition, evolving strategies for prevention are outlined. The following was specifically discussed. (1) Five phases of the progression of coronary atherosclerosis (phases 1 to 5) and eight morphologically different lesions (types I, II, III, IV, Va, Vb, Vc, and VI) in the various phases are defined. (2) The present understanding of the pathogenesis of each of the phases of progression and of the various lesion types preceding myocardial infarction is described; particular emphasis is placed on the physical, structural, cellular, and chemical characteristics of the "vulnerable or unstable plaques" prone to disruption (types IV and Va lesions). (3) The fate of plaque disruption (type VI lesion) in the genesis of the various coronary syndromes and especially acute myocardial infarction is defined; particular emphasis is placed on the combination of plaque disruption and a high thrombogenic risk profile--local factors (ie, degree of plaque disruption, exposure of lipid-macrophage-rich plaque, etc) and systemic factors (ie, catecholamines, RAS, fibrinogen, etc)--in the genesis of myocardial infarction. (4) Strategies of regression or stabilization of "vulnerable or unstable plaques" for prevention of myocardial infarction are presented within the context of recent favorable experience with risk factor modification and lipid-modifying angiographic trials, beta-blockade and angiotensin-converting enzyme inhibition, antithrombotic strategies, and the possible role of estrogens. The recent past has been very fruitful in yielding a better understanding of the processes leading to myocardial infarction, and the near future appears very promising in terms of preventing the number 1 killer in the western world.

Angioscopic versus angiographic detection of intimal dissection and intracoronary thrombus

OBJECTIVES

This study was undertaken to compare coronary angioscopy with angiography for the detection of intimal dissection and intracoronary thrombus.

BACKGROUND

It has been demonstrated previously that coronary angioscopy provides more intravascular detail than cineangiography. Both imaging methods have to be compared directly to assess the additional diagnostic value of angioscopy.

METHODS

The angiograms and videotapes of 52 patients who had undergone angioscopy were reviewed independently by two observers unaware of other findings. Classic angiographic definitions were used for dissection and thrombus. Angioscopic dissection was defined as visible cracks or fissures on the lumen surface or mobile protruding structures that are contiguous with the vessel wall. Angioscopic thrombus was defined as a red, white or mixed red and white intraluminal mass.

RESULTS

Angiography and angioscopy were in agreement in 40.4% of cases in the absence of thrombus and in 11.5% in the presence of thrombus. No fewer than 25 (48.1%) angioscopically observed thrombi remained undetected at angiography. With angioscopy as the standard, although the specificity of angiography for thrombus was 100%, sensitivity was very low at 19%. Angioscopic dissection was present in 40 patients (76.9%) versus angiographic dissection in 15 patients (28.8%). With regard to dissection, there was no correlation between the two imaging methods (r phi = 0.15, p = 0.29).

CONCLUSIONS

Coronary angiography underestimates the presence of intracoronary thrombus. Angioscopy and angiography are complementary techniques for detecting and grading intimal dissections.

Effects of treatment on outcome in mildly symptomatic patients with ischemia during daily life. The Atenolol Silent Ischemia Study (ASIST)

BACKGROUND

Detection of asymptomatic ischemia in patients with coronary artery disease has been associated with increased risk for adverse outcome, but treatment of patients with asymptomatic ischemia remains controversial. Accordingly, the purpose of this study was to determine if treatment reduces adverse outcome in patients with daily life ischemia.

METHODS AND RESULTS

A multicenter, randomized, double-blind, placebo-controlled study of asymptomatic or minimally symptomatic outpatients with daily life silent ischemia due to coronary artery disease was conducted. The primary outcome measure was event-free survival at 1 year by Kaplan-Meier analysis. Events were death, resuscitated ventricular tachycardia/fibrillation, myocardial infarction, hospitalization for unstable angina, aggravation of angina, or revascularization. The secondary outcome was ischemia during ambulatory ECG monitoring at 4 weeks. Three hundred six outpatients with mild or no angina (Canadian Cardiovascular Society class I or II), abnormal exercise tests, and ischemia on ambulatory monitoring were randomized to receive either atenolol (100 mg/d) or placebo. After 4 weeks of treatment, the number (mean +/- SD, 3.6 +/- 4.2 versus 1.7 +/- 4.6 episodes, P < .001) and average duration (30 +/- 3.3 versus 16.4 +/- 6.7 minutes, P < .001) of ischemic episodes per 48 hours of ambulatory monitoring decreased in atenolol- compared with placebo-assigned patients (4.4 +/- 4.6 to 3.1 +/- 6.0 episodes and 36.6 +/- 4.1 to 30 +/- 5.5 minutes). Event-free survival improved in atenolol-treated patients (P < .0066), who had an increased time to onset of first adverse event (120 versus 79 days) and fewer total first events compared with placebo (relative risk, 0.44; 95% confidence intervals, 0.26 to 0.75; P = .001). There was a nonsignificant trend for fewer serious events (death, resuscitation from ventricular tachycardia/fibrillation, nonfatal myocardial infarction, or hospitalization for unstable angina) in atenolol-treated patients (relative risk, 0.55; 95% confidence intervals, 0.22 to 1.33; P = .175). The most powerful univariate and multivariate correlate of event-free survival was absence of ischemia on ambulatory monitoring at 4 weeks. Side effects were mild and generally similar comparing atenolol- and placebo-treated patients, although bradycardia was more frequent with atenolol.

CONCLUSIONS

Atenolol treatment reduced daily life ischemia and was associated with reduced risk for adverse outcome in asymptomatic and mildly symptomatic patients compared with placebo.

The Asymptomatic Cardiac Ischemia Pilot (ACIP) study: design of a randomized clinical trial, baseline data and implications for a long-term outcome trial

OBJECTIVES

The primary objectives of the Asymptomatic Cardiac Ischemia Pilot were 1) to compare the 12-week efficacy of three treatment strategies to suppress cardiac ischemia, and 2) to assess the feasibility of a prognosis trial in patients with asymptomatic cardiac ischemia.

BACKGROUND

Cardiac ischemia has been associated with increased morbidity and mortality. However, most cardiac ischemia is asymptomatic, and although therapeutic strategies ranging from no medication to revascularization are being used to treat ischemia, no prospective study evaluating different treatment strategies has been reported.

METHODS

Patients with angiographically documented coronary artery disease and ischemia on exercise and ambulatory electrocardiogram (ECG) in 11 clinical units were randomized to receive angina-guided medical therapy, angina-guided plus ambulatory ECG ischemia-guided medical therapy or revascularization (coronary angioplasty or bypass surgery). Patients were also randomized to receive either diltiazem plus isosorbide dinitrate or atenolol plus nifedipine when possible. After anti-ischemic medication adjustment to control angina, blinded medication was adjusted in the medical therapy groups to eliminate ischemia in the ischemia-guided group. The primary outcome was the absence of ischemia at 12 weeks. Follow-up was scheduled for 1 year.

RESULTS

A total of 1,959 patients were screened by ambulatory ECG monitoring; 982 (49%) had asymptomatic ischemia, and 618 (65%) were enrolled in the study. Most patients were men, were > 60 years old and had two or more ischemic episodes, early positive exercise tests and multivessel disease.

CONCLUSIONS

Design and baseline data for a pilot study of ischemia treatment strategies are described.

Silent myocardial ischemia

The documentation of abnormalities related to myocardial ischemia, whether symptomatic or silent, is of central importance. Whenever this information is available, it should be used in the overall assessment of the patient at risk for adverse outcome. The level of concern for treatment of CAD should be based on the risk implications associated with the ischemia-related abnormalities detected during objective testing rather than on the presence or absence of pain. The exercise stress test is still the single most useful test to begin the evaluation of a patient with an analyzable ST segment. In persons suspected of having CAD, the detection of ischemic-type ST-segment depression, at a low workload (e.g., < 120 beats/min or < 6.5 METS) of > 2 mm magnitude or persisting for more than 6 min implies high risk for adverse outcome. Asymptomatic ischemia during everyday activities, detected by Holter monitoring, in the high-risk patient, most probably adds additional risk beyond the risk of an abnormal stress test alone. Left ventricular imaging by two-dimensional echocardiography, RNA, angiogram, vest, etc, showing an ejection fraction > or = 40%, reversible wall motion abnormalities in multiple regions and redistribution defects or a failure to increase ejection fraction during exercise even if the patient remains asymptomatic, also imply high risk. The presence of any of these abnormal findings, regardless of symptoms, should therefore prompt as high a degree of concern as with ischemia-related signals associated with pain. Thus any therapy chosen should be directed toward elimination of transient ischemia, not just relief of symptoms that may or may not be ischemia related. If this course is chosen, the efficacy of the therapeutic regimen and possible progression of CAD should be assessed with follow-up testing for ischemia. We believe that risk factor modification and aspirin should be considered for most, if not all, patients in whom ischemia, silent or symptomatic, is suspected or detected. If symptoms or ischemia suggesting low risk is present, anti-ischemic medical therapy may be considered, but follow-up is advised. If a high-risk ischemic signal, even without symptoms, is detected, medical therapy should be used to attempt to modify the signal. If the ischemic signal suggesting high risk persists despite medical therapy, revascularization should be considered. Until additional data from large clinical trials are available, this approach appears to have the greatest likelihood of modifying the adverse outcome of CAD.