Altered myocardial perfusion in patients with angina pectoris or silent ischemia during exercise as assessed by quantitative thallium-201 single-photon emission computed tomography

The extent of abnormally perfused myocardium was compared in patients with and without chest pain during treadmill exercise from a large, relatively low-risk consecutive patient population (n = 356) referred for quantitative thallium-201 single-photon emission computed tomography (SPECT). All patients had concurrent coronary angiography. Patients were excluded if they had prior coronary angioplasty or bypass surgery. Tomographic images were assessed visually and from computer-generated polar maps. Chest pain during exercise was as frequent in patients with normal coronary arteries (12%) as in those with significant (greater than 50% stenosis) coronary artery disease (CAD) (14%). In the 219 patients with significant CAD, silent ischemia was fivefold more common than symptomatic ischemia (83% versus 17%, p = 0.0001). However, there were no differences in the extent, severity, or distribution of coronary stenoses in patients with silent or symptomatic ischemia. Our major observation was that the extent of quantified SPECT perfusion defects was nearly identical in patients with (20.9 +/- 15.9%) and without (20.5 +/- 15.6%) exertional chest pain. The sensitivity for detecting the presence of CAD was significantly improved with quantitative SPECT compared with stress electrocardiography (87% versus 65%, p = 0.0001). Although scintigraphic and electrocardiographic evidence of exercise-induced ischemia were comparable in patients with chest pain (67% versus 73%, respectively; p = NS), SPECT was superior to stress electrocardiography for detecting silent myocardial ischemia (52% versus 35%, respectively; p = 0.01). The majority of patients in this study with CAD who developed ischemia during exercise testing were asymptomatic, although they exhibited an angiographic profile and extent of abnormally perfused myocardium similar to those of patients with symptomatic ischemia. The prognostic significance of quantified perfusion defects detected by SPECT remains to be assessed.     

Electrocardiographically and symptomatically silent myocardial ischemia during exercise testing

Certain patients with coronary artery disease (CAD) may have neither ST depression nor chest pain during exercise despite the presence of myocardial ischemia. The frequency and characteristics of such electrocardiographically and symptomatically silent ischemia were studied in 171 patients with both angiographically documented CAD and scintigraphically documented ischemia. Fifty-six (33%) of 171 patients had neither ST depression nor chest pain (Group N), and 115 (67%) had ST depression and/or chest pain (Group P). The two groups were similar with respect to age, gender, the prevalence of prior infarction, and peak systolic blood pressure. Group N patients, however, had a higher mean peak heart rate and rate-pressure product, less severe scintigraphic ischemia, a lower lung thallium-201 uptake, and a smaller number of diseased vessels. Stepwise discriminant analysis showed a history of effort angina, lung thallium-201 uptake, and scintigraphic severity of ischemia to be significant discriminators between Groups N and P. In conclusion, electrocardiographically and symptomatically silent ischemia may be common during exercise in patients with CAD, and less severe ischemia may be one of important determinants.     

Silent myocardial ischemia in diabetic and nondiabetic patients with coronary artery disease

Background: Patients with diabetes mellitus are at increased risk for CAD; silent ischemia is reported to be frequent in diabetic populations. The aim of the present study was to evaluate the prevalence of silent ischemia in diabetic and nondiabetic patients with assessed CAD. Methods and results: We recruited a total of 618 patients with CAD: 309 were consecutive diabetic patients and 309 were age- and gender-matched nondiabetic patients. Myocardial ischemia was evaluated both during daily life and during exercise testing. Angina pectoris during daily life was more frequent in diabetic than in nondiabetic patients (80% vs. 74%, P<0.05). The anginal pain intensity either during daily life or acute myocardial infarction (MI), the prevalence of a previous MI, the extent of CAD and ergometric parameters were similar in diabetics and nondiabetics. Silent ischemia during exercise was documented in 179 (58%) diabetics and in 197 (64%) nondiabetics (nonsignificant, ns). Both diabetics and nondiabetics with silent exertional myocardial ischemia differed from symptomatic subjects in higher heart rate values (P<0.01), systolic blood pressure (P<0.01), rate–pressure product (P<0.001), work load (P<0.01) and maximum ST-segment depression at peak exercise (P<0.05). Conclusions: The incidence of silent myocardial ischemia during exercise was similar in diabetic and nondiabetic CAD patients. Surprisingly, diabetics showed a higher prevalence of angina pectoris during daily activity than nondiabetics. A significant association between the presence of symptoms during daily life and exercise was observed in both groups. Our results may contribute to the planning of the clinical management of diabetic CAD patients and confirm the individual attitude to pain of CAD patients independent of the presence of diabetes.     

Incidence of acute myocardial infarction in patients with exercise-induced silent myocardial ischemia

Fifty-five patients with angiographically proved coronary artery disease (CAD) underwent Bruce protocol exercise stress testing with thallium-201 imaging. Twenty-seven patients (group I) showed myocardial hypoperfusion without angina pectoris during stress, which normalized at rest, and 28 patients (group II) had a similar pattern of reversible myocardial hypoperfusion but also had angina during stress. Patients were followed for at least 30 months. Six patients in group I had an acute myocardial infarction (AMI), 3 of whom died, and only 1 patient in group II had an AMI (p = 0.05), and did not die. Silent myocardial ischemia uncovered during exercise stress thallium testing may predispose to subsequent AMI. The presence of silent myocardial ischemia identified in this manner is of prognostic value, independent of angiographic variables such as extent of CAD and left ventricular ejection fraction.     

Silent myocardial ischemia after acute myocardial infarction.

Silent ischemia after myocardial infarction has definite prognostic significance but should be interpreted within the context of other prognostic indicators. The rationale for therapeutic intervention is based on the prognostic implications of silent ischemia and the potentially deleterious effect of repeated episodes of ischemia on the integrity of the left ventricle. We measured parameters of ischemia in 20 patients who showed asymptomatic ischemic ST-T changes on exercise testing in the early phase after myocardial infarction. After diltiazem administration, a reduction of exercise-induced ST-T depression from 2.3 +/- 0.8 to 0.7 +/- 0.6 mm (p less than 0.01) occurred, and regional wall-motion score at exercise, determined by radionuclide angiography, improved significantly (p less than 0.02). These and other observations warrant further studies in which the duration, severity and frequency of the ischemic episodes should be quantified and correlated with prognosis after myocardial infarction.     

Painless myocardial ischemia. Comparison of 2 groups of patients with a positive exercise test after myocardial infarction

Myocardial ischemia usually presents with chest pain, the characteristics of which are well known. However, anginal pain may be absent during true ischemia, an entity known as painless or silent myocardial ischemia. Does this type of ischemia have special clinical, angiographic or ergometric characteristics after posterior myocardial infarction (MI)? In order to answer this question 183 consecutive patients with recent posterior MI who had undergone coronary angiography and who had positive exercise stress tests on bicycle ergometers were separated into two groups depending on whether they had experienced at least one episode of pain after the acute phase of myocardial infarction or during the exercise stress test (Group S: 83 patients, average age 54 +/- 10 years) or not (Group A: 100 patients, average 54 +/- 8 years). The following parameters were commoner in Group A: cigarette smoking, heart rate and load developed during exercise stress testing provoking electrical signs of ischemia, single vessel disease on coronary angiography, long-term medical treatment. On the other hand, the following parameters were statistically more frequent in Group S: hypercholesterolemia, preinfarction angina, degree of ST depression during exercise testing, reperfusion of the distal vessels of the occluded artery responsible for the infarct by a collateral circulation, triple vessel disease and surgical treatment. However long-term follow-up (average 3 years) shows that mortality and recurrence of MI are similar in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Silent myocardial ischemia during daily activities in asymptomatic men with positive exercise test responses

The usefulness of prolonged ambulatory electrocardiographic monitoring (AEM) for detecting ischemia was investigated in 17 asymptomatic men who had ischemic-type ST-segment depression (greater than or equal to 2.0 mm) during treadmill exercise testing. No patient took anti-ischemic medications and all patients underwent coronary angiography. A total of 1,154 hours (range 64 to 72 hours/patient) of high-quality AEM recordings was obtained. Silent ischemia (episodes of asymptomatic ischemic-type ST depression of 60 seconds or longer) occurred in 11 patients during daily activity detected by AEM. In 6 other patients, no myocardial ischemic episodes were found. But 1 of these patients withdrew after only 24 hours of AEM and the remaining 5 had no significant coronary artery disease (CAD). All 11 patients who had silent ischemia had significant CAD (at least 50% stenosis) on angiography. There was wide intrapatient variability in the frequency of silent ischemic episodes. Silent ischemia was identified in 6 of these 11 patients after 24 hours of AEM, in 2 after 48 hours and in 3 after 72 hours. Thus, asymptomatic men with positive exercise test responses and CAD have silent ischemic episodes during daily activity. AEM may be useful in helping to predict which patients with asymptomatic positive exercise test responses have CAD; however, extended AEM periods are required.     

Silent myocardial ischemia as a potential link between lack of premonitoring symptoms and increased risk of cardiac arrest during physical stress

The risk of cardiac arrest is increased during strenuous physical exercise in patients with stable coronary artery disease (CAD). Because premonitoring symptoms are rarely observed, silent myocardial ischemia may represent the pathophysiological basis for the induction of malignant ventricular arrhythmias. Holter monitoring was, therefore, performed in 40 consecutive patients entering a randomized intervention trial on progression of CAD. In 20 of 21 participants (95%) in the intervention program greater than or equal to 1 episode of silent myocardial ischemia was observed during the initial training session. The mean duration of silent myocardial ischemia per patient was 25 +/- 13 min/hr of training session. During normal daily activity only 5 patients (24%) experienced greater than or equal to 1 episode of silent myocardial ischemia (p less than 0.001) yielding a mean duration of 0.6 +/- 1.3 minutes of silent myocardial ischemia/hr of ordinary activity per patient (p less than 0.001 vs training session). During a control period of 24 hours without exercise training the incidence (33%) and mean duration of silent myocardial ischemia (0.8 +/- 2.1 min/hr/patient) were similar to those during normal daily activity on the day of the training session. During the training session the occurrence of frequent or repetitive ventricular arrhythmias was related to 10 silent myocardial ischemia episodes detected in 5 patients. During normal daily activity in 1 patient only was the onset of malignant ventricular arrhythmias associated with silent myocardial ischemia (p less than 0.05). Conditions and results of the Holter studies in the control group patients were comparable to those of the patients in the intervention group on the day without physical exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Characteristics of silent myocardial ischemia during out-of-hospital activities in asymptomatic angiographically documented coronary artery disease

Ambulatory electrocardiographic monitoring is useful in documenting characteristics of both painful and silent myocardial ischemia occurring during out-of-hospital activities in patients with angina and coronary artery disease (CAD), but few data are available concerning silent myocardial ischemia during ambulatory electrocardiographic monitoring in asymptomatic patients with CAD. Accordingly, 480 hours of ambulatory electrocardiographic monitoring were recorded in 10 asymptomatic patients with CAD not receiving cardiac drugs (48 hours/patient). All 10 patients had silent myocardial ischemia on treadmill exercise testing, with initial ST-segment depression at 2 to 6 minutes in 7 patients and more than 6 minutes in 3 patients. During ambulatory electrocardiographic monitoring, 64 episodes of silent myocardial ischemia (1 mm of ST-segment depression for at least 1 minute) were recorded, ranging from 1 to 17 episodes/patient/48 hours. Of the 64 silent myocardial ischemic episodes, 30 (47%) occurred between 6 am and noon. Duration of silent myocardial ischemia was 798 minutes (range 1 to 80). ST-segment depression ranged from 1 to 4.5 mm. Heart rate at onset of the episodes on ambulatory electrocardiographic monitoring ranged from 65 to 150 beats/min (mean 98), which was significantly less than that during treadmill exercise testing in the same patients (mean 120). At cardiac catheterization, 7 patients had 2- or 3-vessel CAD and 3 had 1-vessel CAD. Thus, silent myocardial ischemia is common during daily life in asymptomatic CAD patients with positive treadmill exercise tests.     

Prevalence and clinical significance of silent myocardial ischemia in exercise test

Prevalence of silent myocardial ischemia in exercise test was retrospectively reviewed from 749 tests performed for 513 patients with definite evidence of ischemic heart disease. The clinical significance was studied and absence of transient ischemia, occurrence of transient ischemia with and without pain were observed in 48%, 30% and 22% of the tests, respectively. Anginal pain was frequently observed in exercise tests for patients with severe coronary artery disease and low exercise tolerance. A large number of tests showing ischemic response were discontinued due to symptoms other than anginal pain and hence silent myocardial ischemia could be thought to be a result of ischemic state which does not reach the angina threshold. Silent myocardial ischemia was frequently observed during usual daily life. However, a definite correlation between severity of transient ischemia and presence or absence of chest pain in the same individuals was not obtained from the study. A day to day variation in the angina threshold might be responsible. In general, silent myocardial ischemia was not rare. However, the consistent condition was very unusual. In angina of effort (EA) and old myocardial infarction (OMI), 3.7% and 12.3% were silent, respectively. A higher incidence was obtained in OMI than in EA. This is important for the management of these patients. The mechanism of silent myocardial ischemia and the cause of the different incidence of this state between EA and OMI were not defined and remained to be further studied.     

Risk of developing an acute myocardial infarction or sudden coronary death in patients with exercise-induced silent myocardial ischemia. A report from the Coronary Artery Surgery Study (CASS) registry

To evaluate whether patients with silent myocardial ischemia during exercise testing are at increased risk for developing a subsequent acute myocardial infarction or sudden death, the data on 424 such patients with proven coronary artery disease (CAD) from the Coronary Artery Surgery Study (CASS) registry were analyzed. These patients (group 1) were compared with 456 other patients with CAD (group 2) who had both ischemic ST depression and angina pectoris during exercise testing and with 1,019 control patients without CAD. The probability of remaining free of a subsequent acute myocardial infarction or sudden death at 7 years was 80 and 91%, respectively, for group 1, 82 and 93%, respectively, for group 2 (difference not significant, compared with group 1), and 98 and 99%, respectively, for the control patients (p less than 0.001), compared with group 1 or 2). Among patients in group 1, the probability of remaining free of myocardial infarction and sudden death at 7 years was related to the severity of CAD and presence of left ventricular (LV) dysfunction, and ranged from 90% for patients with 1-vessel CAD and preserved LV function to 38% for patients with 3-vessel CAD and abnormal LV function (p less than 0.001). Thus, patients with either silent or symptomatic ischemia during exercise testing have a similar risk of developing an acute myocardial infarction or sudden death--except in the 3-vessel CAD subgroup, where the risk is greater in silent ischemia. The risk of patients with silent myocardial ischemia is based primarily on angiographic variables.     

Predictive value of differential pulse pressure in the diagnosis of silent myocardial ischemia in patients with type-2 diabetes

Silent myocardial ischemia occurs more frequently in diabetics. Differential arterial pulse pressure is a valuable predictor of cardiovascular disease. We studied 48 consecutive male patients with type-2 diabetes and no known history of ischemic heart disease. Ambulatory monitoring of arterial pressure was carried out and the presence of silent myocardial ischemia was studied using a protocol that involved: resting ECG, echocardiography, 24-hour Holter ECG, conventional exercise stress testing, and exercise testing with nuclear scanning. Nine patients (19%) had silent myocardial ischemia. Differential pulse pressure had good discriminative ability in identifying the presence of silent ischemia: the area under the receiver operating characteristic (ROC) curve was 0.83 (95% confidence interval [CI], 0.71-0.96; P=.002). This predictive ability was also observed on adjusted logistic regression modeling (odds ratio [OR], 1.24, 95% CI = 1.02-1.49). We found that the OR for the risk of silent ischemia for every 10-mmHg increase in differential pulse pressure was 8.5 (95% CI 1.7-31.2). Age and differential pulse pressure were the only independent predictors of silent myocardial ischemia found in this study.     

The safety and diagnostic accuracy of dipyridamole-loading myocardial tomography with thallium-201 in the elderly with coronary artery disease

To test the diagnostic accuracy and safety of dipyridamole-loading myocardial imaging with thallium-201 (T1) in the elderly, we performed myocardial tomography in 42 patients with coronary artery disease (CAD). While monitoring of ECG and blood pressure, dipyridamole was infused at a rate of 0.57 mg/kg body weight over 4 minutes, and 4 minutes later T1 (3 mCi) was injected. Five minutes later (initial) and 3 hours after T1 injection (redistribution) myocardial images were obtained from 32 projections by a rotating gamma camera. After low-pass filtering, images were reconstructed into short-axis, horizontal long-axis and vertical long-axis tomograms. Myocardial T1 distribution both on initial and redistribution images and myocardial T1 washout rate's (WOR) of the entire left ventricle were expressed into two-dimensional polar maps by using short-axis cuts (bull's-eye maps). In addition to visual interpretation, abnormal WOR (less than 18%) was used as a criteria of dipyridamole induced myocardial ischemia. Patients were divided into 2 groups. Group I consisted of 24 patients more than 70 years of age and Group II consisted of 18 patients less than 65 years of age. The clinical and coronary angiographic characteristics of the two groups did not differ. The sensitivity of this method for the detection of CAD was identical (83%) between the 2 groups, and the detection of coronary artery stenosis was 73% in Group I and 74% in Group II (NS).(ABSTRACT TRUNCATED AT 250 WORDS)     

Frequency and importance of silent myocardial ischemia identified with ambulatory electrocardiographic monitoring in the early in-hospital period after acute myocardial infarction

The incidence and clinical significance of silent myocardial ischemia occurring in the early period after acute myocardial infarction (AMI) was studied in 59 patients who had an uncomplicated early course after admission for AMI. Calibrated 2-lead ambulatory electrocardiographic monitoring performed for 39 +/- 2 hours starting 4 +/- 1 days after AMI identified silent myocardial ischemia, defined as greater than or equal to 1 mm ST-segment change lasting greater than or equal to 2 minutes, in 27 patients. These patients had 5 +/- 1 episodes lasting a median of 11 minutes/episode (range 2 to 36 minutes/episode). Patients with and without silent ischemia had comparable baseline demographics, were receiving similar anti-ischemic medications and had similar severity of coronary disease by angiography. No reinfarctions occurred during the in-hospital period. Fourteen of 27 patients (52%) with silent ischemia had greater than or equal to 1 in-hospital clinical ischemic event (pulmonary edema, n = 5, cardiac death, n = 1, and postinfarction angina, n = 11). In contrast, only 7 of 32 patients without silent ischemia (22%) had greater than or equal to 1 in-hospital event (pulmonary edema, n = 1, cardiac death, n = 1, and postinfarction angina, n = 6). The frequency of ischemic events was significantly greater in patients with silent ischemia compared to those without silent ischemia, p less than 0.02. Silent ischemia occurs frequently very early after AMI and identifies a group of patients who are at increased risk for adverse in-hospital clinical outcomes.     

Silent myocardial ischemia in middle-aged asymptomatic patients with type 2 diabetes in Turkish population

The authors investigated silent myocardial ischemia in unselected consecutive middle-aged asymptomatic patients with type 2 diabetes without any evidence of coronary heart disease documented by treadmill exercise test. Ninety asymptomatic patients with type 2 diabetes (48 men; mean age: 49 +/-6 years) were included in the study. Mean duration of diabetes in the study group was 4 +/-4.2 years (range 1 to 21 years); 38% of the study population, diabetes duration was only 1 year). All patients were subjected to treadmill exercise test with Bruce protocol. A positive test was noted in 4 of 90 (4%) study patients. Two male patients (4%) and 2 (4%) women patients developed exercise-induced ST-segment depression, but none had concomitant chest pain. Diabetics with silent myocardial ischemia were older (55 +/-3 years vs 49 +/-6 years, p = 0.04) than those without silent myocardial ischemia. Also, diabetics with silent myocardial ischemia had higher fibrinogen level (372 +/-51 vs 307 +/-71 mg/dL, p = 0.04) than diabetics without silent myocardial ischemia. In treadmill exercise test, diabetics with silent myocardial ischemia had lower total exercise time and peak workload (375 +/-30 vs 474 +/-115 seconds, p = 0.04; 7.3 +/-0.5 vs 8.9 +/-1.9, p = 0.04, respectively) than without silent myocardial ischemia. Insulin resistance is associated with a variety of atherosclerosis risk factors. Exercise test findings show increased cardiac sympathetic activity and parasympathetic withdrawal in increased insulin resistance.     

Detection of silent myocardial ischemia in diabetes mellitus

The prevalence of silent myocardial ischemia and its relation to autonomic dysfunction and pain threshold was studied in 58 men with diabetes mellitus and without cardiac symptoms. All patients underwent 48-hour ambulatory electrocardiographic monitoring and exercise testing after assessment of their autonomic function and pain threshold. Silent myocardial ischemia, defined as greater than or equal to 1 mm of ST-segment depression on either exercise testing or ambulatory electrocardiographic monitoring, was corroborated by exercise-induced reversible defect(s) on tomographic thallium scintigraphy. Autonomic function was assessed by heart rate response to: (1) Valsalva maneuver, (2) deep breathing, and (3) upright posture, as well as by diastolic blood pressure response to sustained handgrip and systolic blood pressure response to upright posture. Autonomic dysfunction was defined as greater than or equal to 2 abnormal responses. Pain threshold measurements were performed using electrical cutaneous stimulation of both forearms. Of the 58 diabetic patients, 21 were found to have autonomic dysfunction (36%). Silent myocardial ischemia was detected in 10 patients (17%), and was significantly more frequent in patients with than without autonomic dysfunction (38 vs 5%, p = 0.003). There was no difference in the electrical pain threshold or tolerance in subjects with and without silent myocardial ischemia. It is concluded that silent myocardial ischemia in asymptomatic diabetic men occurs frequently and in association with autonomic dysfunction, suggesting that diabetic neuropathy may be implicated in the mechanism of silent myocardial ischemia.     

Risk factors related to the occurrence of silent myocardial ischemia in Mexicans

BACKGROUND: Silent myocardial ischemia is a growing world health problem. It has been related to factors that promote an increase in myocardial oxygen demand or affect coronary vasomotor tone. Coronary artery disease has shown an increasing trend in Mexico in this century. HYPOTHESIS: The aim of the study was to estimate the strength of the association between some risk factors and the occurrence of silent myocardial ischemia. METHODS: A cross-sectional study was conducted and 249 individuals were screened by 24-h Holter electrocardiogram. Silent myocardial ischemia was diagnosed in patients with painless transient ST-segment depression. All subjects were interviewed for coronary risk factors and total serum cholesterol was measured. RESULTS: Silent ischemia was diagnosed in 115 patients (46%), who were older (59 +/- 9 vs. 57 +/- 11 years; p = 0.01). In a logistic regression analysis, a lower risk for silent ischemia was found in patients with thrombolysis [odds ratio (OR) 0.28; 95% confidence interval (CI 95%) 0.14-0.53], or those who followed their medical treatment (OR 0.16; CI 95% 0.04-0.68). The major risk factors were hypercholesterolemia (OR 1.6; CI 95% 0.9-2.9) and more severe coronary artery disease (OR 2.5; CI 95% 1.1-5.7). CONCLUSIONS: Some coronary risk factors are related to silent ischemia. It is still important to diagnose this entity, but modification of its related risk factors should be kept in mind to diminish its occurrence and its severe consequences.     

Percutaneous transluminal coronary angioplasty in patients with reduced left ventricular ejection fraction: effects on myocardial perfusion and left ventricular response to exercise

Many patients with coronary artery disease treated by percutaneous transluminal coronary angioplasty (PTCA) have a history of previous myocardial injury resulting in a reduced left ventricular ejection fraction (EF). The effects of successful PTCA on myocardial perfusion and left ventricular function in these patients were compared to treatment in patients with normal left ventricular EF. There were 21 patients with a normal EF (mean EF 59 +/- 2%) (Group I) and 15 patients with reduced EF (mean EF 43 +/- 1%) (Group II). Before PTCA a similar degree of reversible myocardial ischemia was present on thallium scintigraphy. At peak exercise left ventricular EF in the Group I patients decreased by 4 +/- 1% compared to 8 +/- 1% in Group II. At one month following successful PTCA there was resolution of reversible myocardial ischemia in both groups. No changes in EF at rest were observed. At the same level of exercise as before PTCA the mean EF was 5 +/- 1% higher than the pretreatment value in Group I and 10 +/- 1% higher in Group II. Thus in this study reversible myocardial ischemia was associated with severe compromise in the left ventricular response to exercise which was substantially improved by PTCA.     

The prevalence and prognosis of unrecognized myocardial infarction and silent myocardial ischemia in patients undergoing major vascular surgery

OBJECTIVE: The aim of this study is to determine the prevalence and prognosis of unrecognized myocardial infarction (MI) and silent myocardial ischemia in vascular surgery patients. METHODS: In a cohort of 1092 patients undergoing preoperative dobutamine stress echocardiography and noncardiac vascular surgery, unrecognized MI was determined by rest wall motion abnormalities in the absence of a history of MI. Silent myocardial ischemia was determined by stress-induced wall motion abnormalities in the absence of angina pectoris. Beta blockers and statins were noted at baseline. During follow-up (mean: 6+/-4 years), all-cause mortality and major cardiac events (cardiac death or nonfatal MI) were noted. RESULTS: The prevalence of unrecognized MI and silent myocardial ischemia was 23 and 28%, respectively. Both diabetes and heart failure were important predictors of unrecognized MI and silent myocardial ischemia. During follow-up, all-cause mortality occurred in 45% and major cardiac events in 23% of patients. In multivariate analysis, unrecognized MI and silent myocardial ischemia were significantly associated with increased risk of mortality [hazard ratio (HR), 1.86; 95% confidence interval (CI), 1.53-2.25 and HR, 1.74; 95% CI, 1.46-2.06, respectively] and major cardiac events (HR, 2.15; 95% CI, 1.59-2.92 and HR, 1.86; 95% CI, 1.43-2.41, respectively). In patients with unrecognized MI, beta-blockers and statins were significantly associated with improved survival. Statins improved survival in patients with silent myocardial ischemia. CONCLUSIONS: In patients undergoing major vascular surgery, unrecognized MI and silent myocardial ischemia are highly prevalent (23 and 28%) and associated with increased long-term mortality and major cardiac events.     

Symptomatic and silent myocardial ischemia during exercise testing in coronary artery disease

During exercise by patients with coronary artery disease (CAD), electrocardiographic evidence of myocardial ischemia may precede the onset of angina or may be unassociated with angina, even at peak levels of stress. However, neither the precise incidence of silent versus symptomatic ischemic episodes nor their interrelation in this setting has been clearly defined. The prevalence of silent and symptomatic myocardial ischemia during treadmill exercise testing was determined in 92 patients with angiographically documented CAD. The study group comprised 77 men (84%) and 15 women (16%) of mean age 57 years (range 32 to 79). Exercise testing resulted in ischemic ST-segment depression (greater than or equal to 1 mm for greater than or equal to 80 ms) only or in association with delayed (greater than or equal to 1 minute) angina in 39 patients (42%); angina only or in association with delayed ST-segment depression occurred in 42 patients (46%); and simultaneous occurrence of angina and ST-segment depression was noted in 11 patients (12%). Analysis of clinical, exercise and angiographic factors (age, sex, history of myocardial infarction, heart rate, maximal ST-segment depression, extent of CAD and left ventricular ejection fraction) revealed no significant correlation with the frequency of symptomatic and silent myocardial ischemia during exercise. Asymptomatic myocardial ischemia occurred commonly during exercise in patients with CAD, but there were no differences in the characteristics of patients with symptomatic and asymptomatic episodes.