Usefulness of silent myocardial ischemia detected by ambulatory electrocardiographic monitoring in predicting new coronary events in elderly patients

Gender-Related Differences in Chest Pain Syndromes in the Frontiers in CV Medicine Special Issue: Sex & Gender in CV Medicine

Coronary artery disease (CAD) is the leading cause of morbidity and mortality among both women and men, yet women continue to have delays in diagnosis and treatment. The lack of recognition of sex-specific biological and socio-cultural gender-related differences in chest pain presentation of CAD may, in part, explain these disparities. Sex and gender differences in pain mechanisms including psychological susceptibility, the autonomic nervous system (ANS) reactivity, and visceral innervation likely contribute to chest pain differences. CAD risk scores and typical/atypical angina characterization no longer appear relevant and should not be used in women and men. Women more often have ischemia with no obstructive CAD (INOCA) and myocardial infarction, contributing to diagnostic and therapeutic equipoise. Existing knowledge demonstrates that chest pain often does not relate to obstructive CAD, suggesting a more thoughtful approach to percutaneous coronary intervention (PCI) and medical therapy for chest pain in stable obstructive CAD. Emerging knowledge regarding the central and ANS and visceral pain processing in patients with and without angina offers explanatory mechanisms for chest pain and should be investigated with interdisciplinary teams of cardiologists, neuroscientists, bio-behavioral experts, and pain specialists. Improved understanding of sex and gender differences in chest pain, including biological pathways as well as sociocultural contributions, is needed to improve clinical care in both women and men.

Gender in cardiovascular medicine: chest pain and coronary artery disease

Ischaemic heart disease (IHD) remains the leading cause of morbidity and mortality among women and men yet women are more often underdiagnosed, have a delay in diagnosis, and/or receive suboptimal treatment. An implicit gender-bias with regard to lack of recognition of sex-related differences in presentation of IHD may, in part, explain these differences in women compared with men. Indeed, existing knowledge demonstrates that angina does not commonly relate to obstructive coronary artery disease (CAD). Emerging knowledge supports an inclusive approach to chest pain symptoms in women, as well as a more thoughtful consideration of percutaneous coronary intervention for angina in stable obstructive CAD, to avoid chasing our tails. Emerging knowledge regarding the cardiac autonomic nervous system and visceral pain pathways in patients with and without obstructive CAD offers explanatory mechanisms for angina. Interdisciplinary investigation approaches that involve cardiologists, biobehavioural specialists, and anaesthesia/pain specialists to improve angina treatment should be pursued.

Treatment of stable angina pectoris

Management of stable angina pectoris includes antianginal medications, medications to prevent progression of atherosclerosis, and aggressive treatment of causative risk factors. Antianginal medications commonly used include nitrates, beta-blockers, calcium channel blockers, and ranolazine. Antiplatelet agents, statins, and angiotensin-converting enzyme inhibitors are used in patients with these problems to prevent progression of atherosclerosis and/or premature cardiovascular death. Aggressive risk factor control with diet; exercise; treatment of diabetes, hypertension, and dyslipidemia; and strategies to stop smoking and reduce weight should be a part of treatment strategy in all patients. Patients with stable angina who have symptoms refractory to medical treatment usually require coronary angiography, followed by either percutaneous or surgical revascularization. Recent mechanical techniques for the treatment of refractory angina include transmyocardial laser revascularization, enhanced external counterpulsation, and spinal cord stimulation.

Clinical and detailed angiographic findings in patients with ambulatory electrocardiographic ischemia without critical coronary narrowing: results from the Asymptomatic Cardiac Ischemia Pilot (ACIP) Study

BACKGROUND

Patients with ambulatory electrocardiographic (AECG) ST-segment depression and critical coronary narrowing are known to be at increased risk for adverse outcome, but little is known about patients with AECG ST-segment depression without critical coronary narrowing.

HYPOTHESIS

The objectives of this study were to characterize the coronary angiographic pathology in patients with AECG ST-segment depression but without critical (< 50% diameter stenosis) coronary narrowing and to compare demographic and clinical findings in these patients with those enrolled in the Asymptomatic Cardiac Ischemia Pilot Study with AECG ST-segment depression and critical (> or = 50% diameter stenosis) coronary narrowing.

METHODS

Coronary angiograms from patients with AECG ST-segment depression were reviewed in a central laboratory and quantitative measurement of percent stenosis was performed. Clinical and angiographic comparisons were made between patients with and without critical coronary narrowing.

RESULTS

Patients without critical coronary narrowing (n = 64) were younger (p = 0.02), less likely to be male (p < 0.001) or to have risk factors for coronary atherosclerosis or a history of myocardial infarction (p < 0.001), and had fewer ischemic episodes per 24 h on the screening AECG (p = 0.02) than patients with critical coronary narrowing (n = 441). Of patients without critical narrowing, one half had angiographic evidence for coronary artery disease (> or = 20% stenosis) and 60% had an ejection fraction > 70%.

CONCLUSIONS

Patients with AECG ST-segment depression without critical coronary narrowing are heterogeneous, with half having measurable coronary artery disease. Demographically and clinically, they appear to be different than patients with AECG ST-segment depression with critical coronary narrowing.

[Long term electrocardiography (Holter monitoring)]

During the past almost 50 years Holter monitoring has become an established non-invasive diagnostic tool in clinical electrophysiology. It allows ECG recording independent of stationary monitoring facilities during daily life and, therefore, contains much information. In the beginning the main interest was directed towards quantitative and qualitative assessment of arrhythmias, their circadian behaviour, and the circadian behaviour of the heart rate. With advances in technology the analysis spectrum of Holter monitoring expanded, and it was used also for detection of silent myocardial ischaemia. New digital recorders and computers with large capacities made it possible to measure every single heart beat very accurately, which was a prerequisite for heart rate variability and QT-interval analysis, which provided new knowledge about the autonomic modulation of the heart rate and the circadian dynamicity of the QT interval, respectively. Beyond arrhythmia analysis Holter monitoring was increasingly used to assess prognosis in different cardiac conditions. It can also be valuable in assessing transient symptoms possibly related to arrhythmias or device dysfunction, which will not necessarily be revealed by simple device control.

Randomized controlled trial of a psychoeducation program for the self-management of chronic cardiac pain

Cardiac pain arising from chronic stable angina (CSA) is a cardinal symptom of coronary artery disease and has a major negative impact on health-related quality of life (HRQL), including pain, poor general health status, and inability to self-manage. Current secondary prevention approaches lack adequate scope to address CSA as a multidimensional ischemic and persistent pain problem. This trial evaluated the impact of a low-cost six-week angina psychoeducation program, entitled The Chronic Angina Self-Management Program (CASMP), on HRQL, self-efficacy, and resourcefulness to self-manage anginal pain. One hundred thirty participants were randomized to the CASMP or three-month wait-list usual care; 117 completed the study. Measures were taken at baseline and three months. General HRQL was measured using the Medical Outcomes Study 36-Item Short Form and the disease-specific Seattle Angina Questionnaire (SAQ). Self-efficacy and resourcefulness were measured using the Self-Efficacy Scale and the Self-Control Schedule, respectively. The mean age of participants was 68 years, 80% were male. Analysis of variance of change scores yielded significant improvements in treatment group physical functioning [F=11.75(1,114), P<0.001] and general health [F=10.94(1,114), P=0.001] aspects of generic HRQL. Angina frequency [F=5.57(1,115), P=0.02], angina stability [F=7.37(1,115), P=0.001], and self-efficacy to manage disease [F=8.45(1,115), P=0.004] were also significantly improved at three months. The CASMP did not impact resourcefulness. These data indicate that the CASMP was effective for improving physical functioning, general health, anginal pain symptoms, and self-efficacy to manage pain at three months and provide a basis for long-term evaluation of the program.

Silent ischemia: silent after all?

OBJECTIVE

To examine the association of nonpain symptoms in men and women with exercise-related silent ischemia, as well as the independence of these findings from other clinical factors.

METHODS

A prospective study of 482 women and 425 men (mean age 58 years) undergoing exercise stress testing with myocardial perfusion imaging. Analyses were performed on 60 women and 155 men with no angina but medical perfusion imaging evidence of ischemia during exercise.

MEASURES

The presence of various non-pain-related symptoms. Ischemia is indicated by myocardial perfusion defects on exercise stress testing with single photon emission computed tomography.

RESULTS

Women reported more nonangina symptoms than men (P<0.05). They experienced fatigue, hot flushes, tense muscles, shortness of breath and headaches more frequently (P<0.05). Symptoms relating to muscle tension and diaphoresis were associated with ischemia after controlling for pertinent clinical covariates. However, the direction of association differed according to sex and history of coronary artery disease events or procedures. Sensitivity of the detection models showed modest improvements with the addition of these symptoms.

CONCLUSIONS

While patients who experience silent ischemia experience a number of nonpain symptoms, those symptoms may not be sufficiently specific to ischemia, nor sensitive in detecting ischemia, to be of particular help to physicians in the absence of other clinical information.

Increased prevalence of coronary artery disease, silent myocardial ischemia, complex ventricular arrhythmias, atrial fibrillation, left ventricular hypertrophy, mitral annular calcium, and aortic valve calcium in patients with chronic renal insufficiency

Cardiovascular morbidity and mortality is high in patients with chronic renal insufficiency. Patients with chronic renal insufficiency have an increased prevalence of coronary artery disease, silent myocardial ischemia, complex ventricular arrhythmias, atrial fibrillation, left ventricular hypertrophy, mitral annular calcium, and aortic valve calcium than patients with normal renal function. These risk factors for cardiovascular morbidity and mortality contribute to the increased incidence of cardiovascular morbidity and mortality seen in patients with chronic renal insufficiency.

Effect of aggressive versus moderate lipid-lowering therapy on myocardial ischemia: the rationale, design, and baseline characteristics of the Study Assessing Goals in the Elderly (SAGE)

BACKGROUND

Patients with stable CHD who experience episodes of ischemia during routine daily activities are at increased risk of coronary events. Older patients are at a particularly high risk. Few trials have specifically investigated the effects of lipid-lowering therapy with statins in older patients.

METHODS

The SAGE trial is a prospective, randomized, double-blind, parallel-arm study enrolling men and women with stable CHD at 192 centers worldwide. Qualifying participants (aged 65-85 years; low-density lipoprotein cholesterol 100-250 mg/dL) have had at least 1 episode of myocardial ischemia with total ischemia duration >or=3 minutes on 48-hour ambulatory electrocardiographic (AECG) monitoring performed during routine daily activities. Participants have been randomized to either atorvastatin 80 mg/day (aggressive lipid lowering) or pravastatin 40 mg/day (moderate lipid lowering). The primary efficacy measure is the absolute change in the total duration of myocardial ischemic events on 48-hour AECG monitoring from baseline to month 12.

RESULTS

SAGE is fully enrolled and 893 patients have been randomized. The majority of the study participants are white (97%) men (69%). The mean age of the participants is 72 years. Most participants (94%) have a history of angina. Other high-risk patient groups included in the study are patients with hypertension (65%), patients with diabetes (23%), and patients with peripheral vascular disease (12%).

CONCLUSIONS

SAGE will evaluate the effect of aggressive versus moderate lipid lowering on the total duration of myocardial ischemia in older ambulatory patients with CHD. It is likely to provide valuable data on the benefits of statins in this patient population.

Prevalence of and association between silent myocardial ischemia and new coronary events in older men and women with and without cardiovascular disease

OBJECTIVES

To investigate the prevalence of silent ischemia (SI) in older men and women detected by 24-hour ambulatory electrocardiograms (AECGs) and the association between SI and new coronary events.

DESIGN

In a prospective study, the prevalence of SI detected by 24-hour AECGs and the incidence of new coronary events in 915 older men and 1,874 older women with coronary artery disease (CAD); with hypertension, valvular disease, or cardiomyopathy without CAD; and with no cardiovascular disease were investigated.

SETTING

Large long-term healthcare facility.

PARTICIPANTS

Nine hundred fifteen men, mean age 80, and 1,874 women, mean age 81.

MEASUREMENTS

The prevalence of SI and the incidence of new coronary events in older men and women.

RESULTS

SI was present in 34% of men and 33% of women with CAD; 15% of men and 14% of women with hypertension, valvular disease, or cardiomyopathy without CAD; and 6% of men and 5% of women with no cardiovascular disease. At 45-month follow-up in men and 47-month follow-up in women, SI significantly increased the incidence of new coronary events by 2.0 times in men and women with CAD (P <.001); by 1.8 times in men and 1.7 times in women with hypertension, valvular disease, or cardiomyopathy without CAD (P <.001); and by 6.3 times in men (P =.018) and 4.4 times in women (P =.008) with no cardiovascular disease.

CONCLUSIONS

SI increases the incidence of new coronary events in older men and women with CAD, with hypertension, valvular disease, or cardiomyopathy without CAD, and with no cardiovascular disease.

Clinical manifestations of acute myocardial infarction in older patients

Coronary artery disease is the major cause of morbidity and mortality in the elderly in the United States. In this age group, the clinical presentation of coronary heart disease can be quite atypical. In general, the incidence of typical precordial chest pressure/pain denoting myocardial ischemia is less common, whereas dyspnea as an anginal-equivalent symptom is frequent. The diagnosis of ischemic cardiac pain is frequently confused by the many comorbid conditions present in the elderly. Even when classic ischemic precordial discomfort is present, it tends to be less severe and less well defined. The elderly appear to have reduced pain perception; as a result, silent myocardial ischemia is more common and carries a somewhat worse prognosis in the elderly than in younger age groups. Similarly, the presenting symptoms of acute myocardial infarction in the elderly can be nonspecific. The classic crushing substernal chest pain decreases with age, whereas the symptom of dyspnea gradually increases. Neurologic symptoms, confusional states, weakness, and worsening heart failure are common clinical presentations of an acute infarction in elderly patients. Silent (unrecognized) myocardial infarctions are common in the elderly and carry serious prognostic implications.

Diagnosis and management of myocardial ischemia (angina) in the elderly patient

Coronary artery disease is a major problem in the elderly population. Approximately 60% of all acute myocardial infarctions in the United States occur in people 65 years or older, and 30% occur in persons older than 75 years. Morbidity and mortality are high in elderly patients who sustain a myocardial infarction. Due to the atypical presentation of myocardial ischemia and absence of classic symptoms, coronary artery disease may not be diagnosed in many of these patients until an acute myocardial infarction occurs. Early diagnosis of coronary artery disease and reduction of all coronary risk factors are beneficial in reducing future coronary events in older as well as in younger patients. Many studies have shown that anti-ischemic and acute myocardial infarction therapies have been underutilized in the elderly population. The principles of drug therapy for myocardial ischemia are the same as those for younger patients. Aggressive therapy, including early coronary angiography and revascularization, has been found to be as beneficial in high-risk, unstable older patients as in younger patients. Therapy should be individualized according to the patient's clinical condition. On the basis of current knowledge, elderly, high-risk patients with acute coronary syndromes may be treated with a combination of intensive medical therapy and early coronary angiography with revascularization.

Silent ischaemia and hypertension

For many years now, silent ischaemia has been recognized as a distinct clinical entity, and its relevance in different patient groups has been established. However, a number of basic questions have not been answered. In explaining the pathophysiology of silent ischaemia, factors affecting both the demand and the supply side are now being recognized. With the exception of certain well-defined groups, it is not clear why some patients are mostly symptomatic, while other patients are predominantly asymptomatic. There appear to be many factors influencing the ischaemic pain threshold. Studies investigating the prevalence of silent ischaemia show a remarkably high prevalence of silent ischaemia in different patient groups. Patients with hypertension but without coronary artery disease form a specific and vulnerable high-risk population that is particularly prone to silent ischaemia. Since changes at the macrovascular level are not responsible, various factors negatively influencing either cardiac supply or demand have been investigated. A reduced coronary reserve is central in explaining the increased prevalence of silent ischaemia in hypertensives. Left ventricular hypertrophy renders meaningful detection of ST segment changes difficult, but a possible solution dealing with this problem is offered by applying more stringent criteria in terms of minimal ST depression in the definition of ischaemia. The treatment of silent ischaemia is largely the same as for angina pectoris, but whether therapy should be directed at elimination of all ischaemic episodes or only of symptomatic episodes depends on further prospective work addressing this question.

Silent myocardial ischaemia in the elderly

Coronary artery disease (CAD) is a leading cause of death and disability in the elderly. Several recent studies have shown that silent myocardial ischaemia (SMI) is a common manifestation of CAD, especially in the elderly. As many as 40% of elderly patients with no prior history of CAD may have underlying asymptomatic disease and up to 50% of elderly patients with known CAD might have evidence of SMI. The results of studies in elderly patients with CAD have also shown that SMI might exist despite antianginal therapy that is considered adequate for symptom control. In order to diagnose such residual SMI, the clinician would need to perform 24- to 48-hour Holter monitoring in the ambulatory setting while the patient is performing routine daily activities. Although a number of anti-ischaemic drugs have been evaluated for the treatment of SMI, available data suggest that beta-blocker given alone or in combination with a nitrate compound or calcium antagonist provides the best therapeutic choice. The long term benefit of SMI suppression in elderly patients has not been established. Future studies need to evaluate the clinical benefits of therapy given for SMI in the elderly.

Cost estimates for treatment of cardiac ischemia (from the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Costs for management of myocardial ischemia are enormous, yet comparison cost and outcome data for various ischemia treatment strategies from randomized trials are lacking and will require cost and resource utilization data from a large prospective trial. The Asymptomatic Cardiac Ischemia Pilot provided feasibility data for planning such a trial and an opportunity to estimate the long-term costs of different treatment strategies. Economic implications for ischemia management were compared in 558 patients with stable coronary artery disease and myocardial ischemia during both stress testing and daily life. Participants were randomized to 3 different initial treatment strategies and followed for 2 years. Based on cost trends over follow-up, costs for subsequent care were estimated. As expected, due to initial procedural costs, at 3 months, estimated costs for revascularization were approximately 10 times greater than costs for a medical care strategy. Extrapolated costs for anticipated resource consumption for care beyond 2 years, however, were approximately 2 times greater for an initial medical care strategy than for initial revascularization. This was due to increased need for drugs and hospitalizations for both late revascularizations and other ischemia-related events. Estimated costs for anticipated care in the medical strategies reached the anticipated cost of the revascularization strategy within 10 years. Because this cost-equal time period is well within the median life expectancy for such a patient population, these findings could have important public health implications and require testing in a full-scale prognosis trial. We anticipate that over the patients' life expectancy, early revascularization is likely to become either cost-neutral or cost-effective.

Angina-induced protection against myocardial infarction in adult and elderly patients: a loss of preconditioning mechanism in the aging heart?

OBJECTIVES

The present study examined whether angina 48 h before myocardial infarction provides protection in adult and elderly patients.

BACKGROUND

The mortality rate for coronary artery disease is greater in elderly than in young patients. In experimental studies, ischemic preconditioning affords an endogenous form of protection against ischemia-reperfusion injury in adult but not in senescent hearts. Angina before myocardial infarction, a clinical equivalent of experimental ischemic preconditioning, has a protective effect in adult patients. It is not known whether angina before myocardial infarction is also protective in aged patients.

METHODS

We retrospectively verified whether antecedent angina within 48 h of myocardial infarction exerts a beneficial effect on in-hospital outcomes in adult (< 65 years old, n = 293) and elderly (> or = 65 years old, n = 210) patients.

RESULTS

In-hospital death was more frequent in adult patients without than in those with previous angina (10% vs. 2.6%, p < 0.01), as were congestive heart failure or shock (10.7% vs. 3.3%, p < 0.02) and the combined end points (in-hospital death and congestive heart failure or shock) (20.7% vs. 5.9%, p < 0.0003). In contrast, the presence or absence of previous angina before acute myocardial infarction in elderly patients seems not to influence the incidence of in-hospital death (14.4% vs. 15.2%, p = 0.97), congestive heart failure or shock (11.0% vs. 11.9%, p = 0.99) and the combined end points (25.4% vs. 27.1%, p = 0.89). Logistic regression analysis models for in-hospital end points show that previous angina is a positive predictor in adult but not in elderly patients.

CONCLUSIONS

The presence of angina before acute myocardial infarction seems to confer protection against in-hospital outcomes in adults; this effect seemed to be less obvious in elderly patients. This study suggests that the protection afforded by angina in adult patients may involve the occurrence of ischemic preconditioning, which seems to be lost in senescent patients.

Relation between clinical, angiographic and ischemic findings at baseline and ischemia-related adverse outcomes at 1 year in the Asymptomatic Cardiac Ischemia Pilot study. ACIP Study Group

OBJECTIVES

We attempted to investigate the relation between patient characteristics and adverse outcome in patients with ischemia and clinically stable coronary artery disease (CAD).

BACKGROUND

Evidence suggests that cardiac ischemia, detected by exercise stress testing (ETT) and ambulatory electrocardiographic (AECG) monitoring during daily living, identifies a subgroup of patients at increased risk for adverse outcome, but the relation between these ischemia findings and clinical and angiographic characteristics is largely unknown.

METHODS

We examined the relation between clinical, angiographic and ischemia characteristics at entry with adverse outcome observed at 1 year in the 558 patients enrolled in the Asymptomatic Cardiac Ischemia Pilot (ACIP) study.

RESULTS

By the 12-month visit 13.1% of patients had an ischemia-related adverse clinical outcome that included death, nonfatal myocardial infarction or an ischemia-related hospital admission. Multivariate analysis identified only the number of AECG ischemic episodes at entry (odds ratio [OR] 1.06, 99% confidence interval [CI] 1.01 to 1.12, p = 0.002) as an independent predictor of outcome. Assignment to revascularization (as opposed to an initial medical treatment strategy) showed a trend (OR 0.56, 99% CI 0.26 to 1.2, p = 0.05). None of the other baseline clinical, exercise or angiographic variables examined provided additional information relative to adverse outcome.

CONCLUSIONS

Determinants of adverse outcome, among clinically stable patients with CAD and ischemia induced by stress and daily life were magnitude of AECG ischemia before treatment and, possibly, initial treatment assignment. Among the many other characteristics examined, including age, symptom status and angiographic and exercise variables, none contributed additional independent prognostic information. These two simple variables, which may be modifiable, need further study in a larger trial.

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.

Relation of patient characteristics to cardiac ischemia during daily life activity (an Asymptomatic Cardiac Ischemia Pilot Data Bank Study)

Cardiac ischemia during daily life activities, detected by ambulatory electrocardiographic (AECG) monitoring has been associated with increased risk for adverse outcomes. Because daily life ischemia is usually asymptomatic, prevalence and descriptive data of patients with asymptomatic cardiac ischemia (ACI) are not well defined. Accordingly, patients screened for the Asymptomatic Cardiac Ischemia Pilot (ACIP) trial by 48-hour AECG monitoring were investigated to identify factors associated with ACI. A total of 1,820 patients with ischemia on a screening stress test and/or known or suspected coronary artery disease underwent AECG monitoring. Their mean age was 61 years, range 33 to 89; 83% were men and 81% were white. On AECG monitoring, ACI occurred in 897 patients (49%). There was a modest trend (p = 0.04) between increasing age and ACI prevalence. Increased risk for ACI was observed in patients reporting angina 6 weeks before screening (odds ratio 1.38, 99% confidence interval 1.08 to 1.77, p = 0.0008). There was a positive association between increases in heart rate during daily life and ACI prevalence (p < 0.0001). No daily, monthly, or seasonal variation in ACI prevalence was found, although ACI was more prevalent in northern than southern sites. In this group of clinically stable patients, selected on the basis of high risk for coronary artery disease, the prevalence of ACI was higher than expected from previous reports. Several readily available clinical characteristics (i.e., advanced age, recent angina, increased heart rate change with daily activity) were associated with significantly increased probability of ACI.

Comparison of subgroups assigned to medical regimens used to suppress cardiac ischemia (the Asymptomatic Cardiac Ischemia Pilot [ACIP] Study)

This report focuses on the subset of 235 patients from the Asymptomatic Cardiac Ischemia Pilot (ACIP) study receiving randomly assigned medical therapy to treat angina and suppress ischemia detected on ambulatory electrocardiography: 121 patients received the sequence of atenolol and nifedipine, and 114 diltiazem and isosorbide dinitrate. After 12 weeks of therapy, the primary end point (absence of ambulatory electrocardiographic (ECG) ischemia and no clinical events) was reached in 47% of atenolol/nifedipine- versus 31% of diltiazem/isosorbide dinitrate-treated patients (adjusted p = 0.03). A trend to increased exercise time to ST depression was seen in the atenolol and nifedipine versus diltiazem and isosorbide dinitrate regimens (median treadmill duration 5.8 vs 4.8 minutes; p = 0.04). However, when adjusted for baseline imbalances in ambulatory ECG ischemia, the 2 medical combinations were similar in suppression of ambulatory ECG ischemia. In both medication regimens, an association between mean heart rate and ischemia on ambulatory electrocardiography after 12 weeks of treatment was observed so that patients on either regimen with a mean heart rate > 80 beats/min had ischemia detectable almost twice as often as those with a mean heart rate < 70 beats/min (p < 0.001).

Clinical manifestations and diagnosis of coronary artery disease

Coronary atherosclerosis is very common in the elderly population with autopsy studies demonstrating the prevalence to be at least 70% in persons over the age of 70. These autopsy findings may be coincidental, with the disease clinically silent throughout the person's life, although 20% to 30% of persons over age 65 years will demonstrate clinical manifestations of coronary heart disease (CHD). In most elderly persons, the disease will have manifested itself much earlier in their lives, however, in others the disease will be entirely silent until the person reaches his or her 70s or 80s. Unfortunately, even though CHD is prevalent in elderly persons, the disease is often not diagnosed or misdiagnosed in this age group. Failure to correctly diagnose the disease in the elderly may be due to the difference in the clinical manifestation in this age group compared with younger patients. Such differences may reflect a difference in the disease process between older and younger patients or it may be related to the superimposition of normal aging changes, plus the presence of concomitant diseases, which may mask the usual clinical manifestations.

Prognostic value of Holter monitoring in asymptomatic elderly subjects with sinus rhythm

Elderly people, even if asymptomatic and in apparently good cardiovascular condition, have a high incidence of cardiovascular events. Prognostic markers by noninvasive procedures would therefore be desirable. The aim of this study was to evaluate the prognostic usefulness of Holter monitoring in this setting. Holter findings in 50 asymptomatic elderly subjects with sinus rhythm were correlated with major clinical cardiovascular events occurring during a 5-year follow-up period (16% incidence). No significant association was found with any baseline arrhythmia category, even complex arrhythmias such as unsustained ventricular tachycardia, which had a 10% baseline prevalence. On the other hand, cardiovascular events were correlated (P < .01) with the presence of silent ST-segment depression (8% baseline prevalence), which seems to have an unfavorable clinical significance, in elderly, as well as younger, people. Holter monitoring, because of the benignity of high-prevalence findings and the very low incidence of unfavorable events, has an overall limited prognostic usefulness in asymptomatic elderly subjects with sinus rhythm. In a cost-conscious medical environment, its use seems to be justified only in selected cases.

Diagnostic and prognostic value of ambulatory electrographic monitoring in older patients

OBJECTIVE

To review the use of ambulatory electrocardiographic monitoring in detecting transient cardiac arrhythmias and myocardial ischemia in older patients and to determine the significance of these findings in predicting future cardiac events.

DATA SOURCES

Reports on ambulatory electrocardiographic monitoring's capabilities in the detection and quantification of arrhythmias and myocardial ischemia were identified by multiple searches on the MEDLINE database and citations from relevant articles.

STUDY SELECTION

Studies that demonstrated good research methodology were reviewed. Review was limited to studies that used reel-to-reel or cassette recorders (not reel-time monitors).

DATA EXTRACTION AND SYNTHESIS

Pertinent data were extracted from the studies, with specific emphasis on studies involving older patients. Prognostic findings were critically analyzed and compared between younger patients and older patients. Differences in prognoses younger patients with and without underlying heart disease were assessed.

CONCLUSION

Ambulatory electrocardiographic monitoring is a noninvasive procedure that is beneficial in stratifying older patients with heart disease into high and low risk groups for future cardiac events. The presence of complex ventricular arrhythmias or silent myocardial ischemia as documented on 24-hour monitoring, especially in combination with left ventricular dysfunction or left ventricular hypertrophy, is highly predictive of future cardiac events, including sudden cardiac death and total cardiac mortality. The use of preoperative, intraoperative, and postoperative electrocardiographic monitoring may also be beneficial in stratifying older surgical patients into high and low risks for postoperative cardiac events.

ST segment depression detected by continuous electrocardiography in patients with acute ischemic stroke or transient ischemic attack

BACKGROUND AND PURPOSE

Forty percent of patients with a history of ischemic stroke or transient ischemic attack (TIA) have concomitant coronary artery disease. ST segment depression, detected by continuous electrocardiography, is associated with increased cardiac morbidity and mortality in patients with known coronary artery disease. While electrocardiographic changes have been associated with acute stroke, the etiology and significance of these changes remain unclear. In this pilot study we report the prevalence of ST segment depression and ventricular arrhythmias in patients with acute ischemic stroke or TIA monitored by continuous electrocardiography. Clinical predictors of ST segment depression and ventricular arrhythmia are also identified.

METHODS

Consecutive patients presenting with acute ischemic stroke or TIA were enrolled within 72 hours of hospital admission and monitored by continuous electrocardiography for 48 hours. The electrocardiographic results were analyzed for periods of ST segment depression and ventricular arrhythmias.

RESULTS

Of 51 patients with ischemic stroke or TIA, 15 (29%) had episodes of ST segment depression (95% confidence interval, 15% to 43%), and 18 (35%) had ventricular arrhythmias (95% confidence interval, 21% to 49%). In logistic regression analysis, increasing age (P < .02) and a left-sided neurological event (P < .01) were significant predictors of ST segment depression. Increasing numbers of atherosclerotic risk factors, a history of cardiac disease, and increasing or decreasing mean arterial pressure were not predictive of ST segment depression.

CONCLUSIONS

Patients with acute ischemic stroke or TIA have a 29% prevalence of ST segment depression within the first 5 days after their event. In comparison, the prevalence of ST depression is 2.5% to 8% in asymptomatic adults and 43% to 60% in patients with symptomatic coronary artery disease. The association of ST segment depression with left-sided neurological events suggests that the electrocardiographic changes are in part neurologically mediated. Further study is necessary to better define the brain-heart interaction and to determine whether ST segment depression in patients with ischemic stroke or TIA reflects underlying coronary artery disease.

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.

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment

BACKGROUND

This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD).

METHODS AND RESULTS

The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels). During a mean follow-up of 29 months, there were 35 cardiac deaths or nonfatal myocardial infarctions. Multivariate Cox survival analysis showed the extent of thallium imaging abnormality and CAD to be independent predictors of prognosis. On the other hand, the treadmill exercise score was not a significant predictor even on univariate analysis. The results of thallium uptake were the strongest independent predictors of prognosis and in addition provided incremental prognostic power to coronary angiography (chi 2 = 29 for SPECT, 27 for coronary angiography, and 37 for both).

CONCLUSIONS

Thus exercise SPECT thallium imaging is significantly better than the treadmill exercise score in risk assessment. The size of the perfusion abnormality is an important predicator of prognosis.

[Silent ischemia]

Silent myocardial ischaemia is a very common phenomenon in patients with coronary artery disease. It may occur in patients with clinical manifestations of angina, be detected during the post-myocardial infarction period or in patients totally asymptomatic. Whatsoever, it is well demonstrated that silent myocardial ischaemia has a very potent prognostic value. Therapeutic implications are similar to those in symptomatic ischaemia. Indications for myocardial revascularization by mean of angioplasty or bypass grafting may be discussed and depend on ventricular function and extension of coronary lesions.

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.

Prognostic implications of myocardial ischemia during daily life in low risk patients with coronary artery disease

OBJECTIVES

The purpose of this study was to determine the incidence and prognostic importance of myocardial ischemia detected by ambulatory monitoring in low risk, medically managed patients with coronary artery disease.

BACKGROUND

Previous studies have demonstrated that certain high risk subsets of patients with coronary artery disease have improved survival with revascularization. The remaining low risk medically managed patients may still have episodes of silent ischemia during daily living, but the frequency and prognostic implications of such episodes in this group are unknown.

METHODS

We prospectively studied the incidence and prognostic significance of ST segment changes recorded during daily activities in 116 asymptomatic or mildly symptomatic low risk patients with native coronary artery disease who were followed up for 29 +/- 13 months. Low risk patients were selected after excluding patients with 1) left main disease; 2) three-vessel coronary artery disease and left ventricular dysfunction at rest; 3) three-vessel disease and inducible ischemia during exercise; and 4) two-vessel disease, left ventricular dysfunction and inducible ischemia.

RESULTS

Forty-five patients (39%) had transient episodes of ST segment depression during 48-h electrocardiographic (ECG) monitoring (total 217 episodes, lasting 7,223 min, 82% of episodes silent). There were eight acute cardiac events (seven myocardial infarctions, one episode of unstable angina) and nine patients underwent elective revascularization. Seven of the eight acute events occurred in patients without silent ischemia during monitoring. Kaplan-Meier survival analysis revealed no significant differences in event-free survival from either acute or total events in subgroups with or without silent ischemia during ambulatory ECG monitoring. None of the clinical, treadmill exercise, radionuclide ventriculographic or cardiac catheterization variables were predictive of outcome by Cox multivariate proportional hazard function analysis. Analysis of coronary arteriograms before and after acute cardiac events revealed that in five of the six patients studied, acute occlusion occurred in a coronary artery different from the artery with the severest stenosis on initial angiography.

CONCLUSIONS

In patients categorized as at low risk on the basis of the results of cardiac catheterization and stress testing, silent myocardial ischemia during daily life was not uncommon, and its presence failed to predict future coronary events.

Can we really justify the treatment of silent ischemia in 1992? No!

Since the advent of ambulatory ST-segment monitoring, it has been established that silent ischemia is common in patients with various coronary artery disease syndromes, and such silent episodes represent up to 80% of all ischemic episodes. It appears to be associated with an adverse prognosis when compared with similarly characterized patients without silent ischemia during daily life. Silent ischemia does not, however, bother the patients, by virtue of the fact that it is silent, and therefore treatment of such ischemia must be justified by an improved outlook for the patient, rather than symptom relief. There is no direct evidence to date that silent ischemia is associated with acute myocardial infarction or sudden cardiac death in a cause-and-effect relationship, or that reduction or eradication of silent ischemia will lead to an improved prognosis for the patient; indeed, we have been unable to demonstrate any significant improvement in outlook when using the various antianginal/antiischemic agents at our disposal. Until we can demonstrate a benefit to the patient by detecting and treating silent ischemia, we should not waste large resources attempting to eradicate something whose significance we do not understand.

Value of ambulatory ST segment monitoring in patients with chronic stable angina: does measurement of the "total ischaemic burden" assist with management?

OBJECTIVE

To assess the prognostic significance of transient ischaemic episodes during daily activities in patients with stable angina.

PATIENTS AND METHODS

172 patients with stable angina attending the cardiac outpatients departments of Hillingdon Hospital (n = 155) and the National Heart Hospital (n = 17) were prospectively studied by exercise testing and 48 hours of ambulatory ST segment monitoring, and followed for prognostic purposes for up to 39 months (mean 24.5 months). Patient inclusion depended on a clinical diagnosis of stable coronary artery disease which necessitated outpatient review (and antianginal treatment in 94% of patients). It was not dependent on objective evidence of reversible ischaemia. Events recorded during the follow up period included death, non-fatal myocardial infarction, unstable angina, and the requirement for revascularisation.

RESULTS

72 patients (42%) had transient ischaemic episodes during daily activities, and 104 patients (60.5%) had an ischaemic response to exercise. 63 patients (36%) had evidence of ischaemia on both investigations; with 59 (34%) having no documented ischaemia on either investigation. There were 27 patient events (15.7%) recorded over a mean 24.5 month follow up, including five deaths (2.9%) (three cardiac related (1.7%)), six non-fatal myocardial infarctions (3.5%), six admissions with unstable angina (3.5%), and 10 revascularisation procedures (5.8%). Of the nine "hard" or objective end points (cardiac death and non-fatal myocardial infarction), only two had evidence of transient ischaemia on ambulatory ST segment monitoring at initial investigation, with 10 of the 25 patients (38.5%) with any cardiac event having such episodes.

CONCLUSIONS

The outcome in patients with chronic stable angina receiving standard medical treatment was good over a mean two year follow up period. For the purpose of assessing prognosis over this time scale, there was no advantage to performing ambulatory ST segment monitoring in such patients.

Usefulness of echocardiographic left ventricular hypertrophy and silent ischemia in predicting new cardiac events in elderly patients with systemic hypertension or coronary artery disease

The authors performed a prospective study to correlate echocardiographic left ventricular hypertrophy (LVH) and silent ischemia (SI) detected by twenty-four-hour ambulatory electrocardiographic monitoring with new cardiac events in 355 patients, mean age eighty-two +/- eight years, with systemic hypertension or coronary artery disease (CAD). Cardiac events included myocardial infarction, primary ventricular fibrillation, or sudden cardiac death. Mean follow-up was thirty-one +/- seven months (range twelve to forty). Cardiac events occurred in 28 of 147 patients (19%) without LVH or SI (A), in 56 of 113 patients (50%) with LVH and no SI (B), in 16 of 29 patients (55%) with SI and no LVH (C), and in 52 of 66 patients (79%) with LVH and SI (D). Significant p values were p less than 0.001 comparing D with A, D with B, C with A, and B with A; and p less than 0.02 comparing D with C. These data indicate that echocardiographic LVH and SI detected by ambulatory electrocardiographic monitoring are independent risk factors for new cardiac events in elderly patients with systemic hypertension or CAD.