Character of transient ischemia in angina pectoris

There is growing interest in the possible therapeutic and prognostic significance of silent myocardial ischemia in coronary artery disease (CAD) and its detection by ambulatory electrocardiographic (ECG) monitoring. In 100 apparently healthy normal subjects (20 with angiographically normal coronary arteries), Holter monitoring revealed significant ST-segment depression in only 2 (both over 40 years, one with positive treadmill test, the other with risk factor for CAD). No significant ECG changes were found in those with normal coronary vessels. In 30 patients with documented CAD, significant ST-segment depression during 1,934 episodes over 446 days of monitoring over 18 months was found. Only 24% of the episodes were associated with angina. Asymptomatic and symptomatic episodes were associated with comparable changes in perfusion detected by positron emission tomography. Heart rate increases greater than 10 beats/min preceding the onset of the ST-segment changes occurred in only 23% of the episodes. There was considerable variability in the ST-segment changes in the same patient monitored serially over long periods of time. The data indicate that it is extremely uncommon for patients without CAD to exhibit silent myocardial ischemia, whereas patients with stable angina exhibit frequent, variable and often asymptomatic ECG evidence of myocardial ischemia rarely triggered by increases in heart rate. These findings are likely to be of therapeutic and prognostic significance.     

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.     

Transient ST-segment depression as a marker of myocardial ischemia during daily life

Patients with angina and coronary artery disease (CAD) have many episodes of transient ST-segment depression during ordinary daily life, and these are often asymptomatic. To investigate this signal as a marker of myocardial ischemia, 30 patients with chronic stable angina and CAD underwent positron tomography, recording the regional myocardial uptake of rubidium-82, pain and ST-segment changes before, during and after 59 technically satisfactory exercise tests, 35 cold pressor tests and 22 episodes of unprovoked ST depression. Exercise resulted in 53 episodes of ST depression with angina and in 5 episodes without pain. After cold pressor tests, there were 3 episodes of ST depression and pain and 12 of painless ST depression. Only 9 episodes of unprovoked ST depression were accompanied by pain. Tomography showed independent evidence of ischemia in 63 (97%) of the total 65 episodes of ST depression with angina and in all 30 episodes of painless ST depression. In each patient perfusion defects occurred in the same myocardial segment during painful and painless ST depression and responses were significantly different from those in 16 normal subjects studied in the same way. These findings support the use of transient ST depression in continuous monitoring to assess the activity of CAD, but only in patients with typical angina pectoris, ST depression during exercise and proved CAD. They strengthen the evidence derived from ambulatory monitoring for a wider picture of the disease than is generally appreciated, with more frequent episodes of silent myocardial ischemia than of angina pectoris.     

Hemodynamic and electrocardiographic correlates of symptomatic and silent myocardial ischemia: pathophysiologic and therapeutic implications

Numerous hemodynamic, electrocardiographic, metabolic and radionuclide measurements in various subsets of patients with coronary artery disease (CAD) reveal that ischemia does not always occur on the basis of increases in myocardial oxygen consumption. Continuous hemodynamic monitoring indicates that most episodes of myocardial ischemia are not preceded by increases in such major determinants of oxygen consumption as heart rate or blood pressure, but that these usually increase in response to the development of ischemia. The development of pain during ischemia is a late feature and most episodes are silent. There are no significant differences in the hemodynamic characteristics of symptomatic versus asymptomatic episodes of myocardial ischemia in patients with angina at rest or between those associated with ST-segment depression and those with ST-segment elevation. Continuous Holter recordings analyzed by compact analog technique in hospitalized and ambulatory patients with ischemic heart disease indicate that in both unstable and chronic stable angina, over two-thirds of myocardial ischemic episodes are clinically silent. Symptomatic and silent episodes do not differ significantly with respect to duration. Most symptomatic and asymptomatic episodes are not triggered by increases in the determinants of oxygen demand. Such episodes may arise on the basis of a critical reduction in the lumen of the diseased coronary artery leading to a primary reduction in blood flow. Intermittent obstruction due to changes in coronary vasomobility or possibly formation of thrombi may be a common mechanism for the pathogenesis of myocardial ischemia in patients with a varying spectrum of coronary artery lesions. At present, the precise clinical and prognostic significance of silent ischemia in CAD is not completely defined.(ABSTRACT TRUNCATED AT 250 WORDS)     

冠心病患者的无症状性心肌缺血

本文报道冠心病患者108例在日常活动情况下,采用Holter 24小时监测,发现60例(55.6%)有心肌缺血发作,总计发作244次,其中无症状性心肌缺血198次(81%)。心肌缺血发作时与发作前的心率比较无明显差异。无症状性心肌缺血发作时ST段下降程度与伴随有胸痛发作时比较,亦无明显差异。在上午6时至12时,无症状性心肌缺血发作频率最高,占55.1%。内服缓释硝酸异山梨酯(消心痛)可以减少心肌缺血发作。     

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.     

ST-segment depression in hypertensive patients is linked to elevations in blood pressure,pulse pressure and double product by 24-h Cardiotens monitoring

BACKGROUND: Various statements are made concerning peaks of heart rate (HR), blood pressure (BP) and double product (product of HR and systolic BP) as triggers for ST-segment depression. The aim of the present study was to identify determinants of ST-segment depression with a new ambulatory device for simultaneous 24-h electrocardiogram (ECG) and BP monitoring. METHODS: A total of 63 treated patients (63 +/- 9 years, 33 women and 30 men) with arterial hypertension and ischemic heart disease were studied with a new ambulatory 24-h BP measurement (ABPM) device evaluated according to the BHS protocol (Cardiotens, Meditech, Hungary). This device allows simultaneous ST-segment analysis with extra BP recordings triggered by episodes of ST-segment depression. RESULTS: ST-segment (Holter ECG) depression (> 1 mm and > 60 s) was demonstrated in 26 patients with a mean duration of 4.95 +/- 2.6 min and a peak in the early morning hours. All ST-segment depressions were silent and occurred during a significant increase of BP (15 +/- 11 mmHg systolic and 10 +/- 5 mmHg diastolic, compared with the mean ABPM values) and a significant increase of the double product from 10 921 +/- 2 395 (24-h mean) to 14 515 +/- 2329 (during ST-depression). The recorded systolic and diastolic BP (SBP, DBP) values from the pre ST-event were significant higher compared with 24-h values (153 +/- 19 versus 145 +/- 22 mmHg systolic, 83 +/- 12 versus 78 +/- 14 diastolic). The mean pulse pressure (PP) value in the group with ST-depression was significantly higher than in the group without ST changes (69 +/- 16 versus 58 +/- 10 mmHg; P < 0.005). A total of 73% of patients with ST-events compared with 35% without ST-events showed a PP >or= 60 mmHg (P = 0.025). CONCLUSION: Simultaneous ABPM and ST-segment analysis identifies episodes of silent myocardial ischemia during increases of BP and HR. Hypertensive patients with ischemic heart disease and ST events show higher mean pulse pressure values than are observed in patients without events. A PP of >or= 60 mmHg is linked to an increased risk of silent myocardial ischemias.     

Preoperative silent myocardial ischemia. Has it prognostic significance?

We studied the prognostic significance of preoperative silent myocardial ischemia in patients undergoing coronary artery bypass grafting (CABG). Nonfatal and fatal perioperative myocardial infarction were regarded as prognostically important endpoints. Ninety-five patients (9 women) with stable-effort angina pectoris were studied during their hospital stay in the surgery ward before CABG. Silent ischemia was detected using Holter monitoring; all patients had Holter monitoring 76 +/- 9 h before surgery using Marguette Laser Holter and Cardiodata Prodigy systems. Two-channel electrocardiographic recordings were used which included CM5 and a modified inferior lead. Effort was taken to avoid leads with pathological Q waves and resting ST segment abnormalities. The mean duration of the monitoring was 27.9 +/- 11.3 h. Three patients (3.2%) had angina pectoris during these observations, 1 of them with significant ST depression. Silent ST depression was found in 12 patients (12.6%). Twelve patients (12.6%) had perioperative myocardial infarction. Perioperative myocardial infarction was more common in patients with silent ischemia: 4/12 vs. 8/83; chi 2 = 4.48955, p = 0.0341. Our results suggest that Holter monitoring identifies a group of patients with a higher probability of perioperative myocardial infarction. In the future, it may be possible to study different methods to prevent this surgical complication.     

Coronariographic significance of heart rate variation related to ischemic episodes in patients undergoing peripheral vascular surgery.

OBJECTIVES: To evaluate the characteristics of myocardial ischemia during daily life and their coronariographic significance in a group of patients with proven coronary artery disease undergoing peripheral vascular surgery. SETTING: Department of Cardiology--Central Hospital--Lisbon. METHODS: In 14 patients undergoing peripheral vascular surgery and in whom coronariography revealed coronary significative lesions, Holter monitoring was performed during a 24-hour period. Two groups of ischemic episodes were considered: Group A constituted by 44 episodes detected in patients with left main or three vessel disease and group B by 12 episodes detected in patients with one ot two vessel disease. In each group the ischemic parameters were studied. RESULT: The incidence of myocardial ischemia was 64%. Statistically significant differences were observed between group A and B concerning the mean heart rate variation from two minutes before the onset of ST-segment depression to its onset (2.39 bpm vs 8.75 bpm; p < 0.05), from the onset of ST-segment depression to its maximal depression (4.43 bpm vs 16.67 bpm; p < 0.001) and from two minutes before St-segment depression to its maximal depression (6.82 bpm vs 25.4 bpm; p < 0.00001). No differences were found in duration and maximal ST-segment depression. CONCLUSION: Particular characteristics of heart rate variation related to the ischemic episodes seem to have a relation with the severity of coronary artery disease in patients undergoing peripheral vascular surgery.     

Diagnostic and prognostic value of ambulatory ECG (Holter) monitoring in patients with coronary heart disease: a review

Silent ischemia, the most common expression of atherosclerotic heart disease, affects approximately 30–50% of patients during their activities of daily living. The present review provides a comprehensive and practical summary of current knowledge on perioperative myocardial ischemia through MEDLINE searches up to June 2005, using keywords including “silent ischemia,” “transient ischemia,” and “Holter monitoring.” Holter monitoring (i.e., continuous ambulatory ST-segment monitoring) is an effective tool for assessing the frequency and duration of silent transient myocardial ischemia, particularly in patients who are post-acute myocardial infarction (MI), those with acute coronary syndromes (ACS), and in patients in the acute post-operative period. Holter monitoring allows for further risk stratification of patients who have a positive exercise ECG by collecting long-term ECG data on ischemic and arrhythmic events while patients perform routine activities. Both the presence and increased duration of transient ischemia as detected by continuous ST-segment Holter monitoring are associated with increased rates of coronary events and mortality. Holter monitoring may aid in the identification of patients and subgroups of patients with ACS who may derive the greatest benefit from antiplatelet and antithrombotic therapy. Indeed, many ongoing and upcoming trials of pharmacotherapy include ischemia on Holter monitoring as an endpoint.     

Effect of nipradilol on silent myocardial ischemia,plasma beta-endorphin,and bradykinin in chronic stable angina

Hypothesis: This study was undertaken to investigate the effect of nipradilol on the total ischemic burden and on plasma levels of beta-endorphin and bradykinin. Methods: Sixteen patients with chronic stable angina were subjected to exercise treadmill testing and 24-h ambulatory electrocardiogram (ECG). Results: Nipradilol significantly decreased both mean heart rate and mean pressure rate product at submaximal and maximal exercise. It significantly improved exercise-induced maximal ST-segment depression from ?2.7 ± 0.5 mm to ?1.3 ± 0.6 mm (p<0.05) and reduced the number of leads with significant ST-segment depression (4.0 ± 1.2 vs. 2.0 ± 1.8, p<0.05). Silent ischemic episodes recorded in 24-h ambulatory ECG were significantly decreased by nipradilol administration, concomitantly with a decrement of mean heart rate and observed maximal heart rate. Patients with exercise-induced silent myocardial ischemia showed significantly increased plasma levels of beta-endorphin during both the placebo and nipradilol phases of the study. However, during the nipradilol phase, bradykinin did not change significantly at rest and at peak exercise. Conclusion: Nipradilol effectively controls exercise-induced myocardial ischemia and silent myocardial ischemic episodes, and does not influence the response of plasma levels of beta-enduced silent myocardial ischemia.     

Painless myocardial ischemia in patients with stable stenocardia

24-hour Holter monitoring was performed in 58 patients with stable angina pectoris. Out of them, 70.7% were recorded to have painless ischemic ST-segment depression episodes which made up some half (45.7%) of the total number of myocardial ischemic episodes. The episodes of silent myocardial ischemia were characterized by various length, depending on the conditions of their occurrence. They were far short-term with physical activity and long-term at rest. An increase in the number of diseased coronary vessels in the patients undergoing coronary angiography was followed by a rise in the amount of episodes and ST-segment displacement amplitude. In patients who had an bicycle ergometric loading of 100 Wt or greater, the episodes of silent myocardial ischemia were observed twice more frequently than in patients who had a threshold loading of 25 to 50 Wt. Some proportion of the patients exhibited variations in the Holter monitoring and paired bicycle ergometric tests when finoptin and obsidan were evaluated for their antianginal effect. There was a significant decrease in obsidan's effect following 2-month continuous therapy. Despite the persistent growth of exercise tolerance as evidenced by bicycle ergometry, finoptin proved to be inefficient in 46.2% of the patients.     

ST segment analysis in 24-hour long-term ECG in patients with stable angina pectoris and angiographically detected coronary sclerosis

ST-segment analysis on 24-hour Holter ECG was performed in 64 patients with angiographically proven coronary artery disease, a positive exercise test and chronic stable angina. During 125 days of recording, 494 episodes of transient ST-segment depression were observed, at an average of 4.0 +/- 3.7 episodes (1-13 episodes, median: 3 episodes) per day. The duration of ST depression per episode was 13.2 +/- 14.4 min (1-90 min; median: 8 min). No episodes of ST-elevation were observed. Only 27 (5.5%) ischemic episodes occurred during the night, between midnight and 6:00 a.m., but they were frequently observed during the morning hours between 7:00 and 12:00 a.m. Nearly all episodes of ischemia were preceded by an increase in heart rate. However, heart rate at the onset of significant ST-segment depression was significantly lower during Holter monitoring than during exercise test (p less than 0.001); this indicates that factors additional to the increase in myocardial demand might be relevant for transient myocardial ischemia during daily life. 382 of the 494 episodes (77.3%) of ischemia were asymptomatic; heart rate at the onset of ST-segment depression was similar in symptomatic and asymptomatic episodes; however, in asymptomatic episodes, maximal heart rate was significantly lower (p less than 0.001) and the duration of the episodes significantly longer (p less than 0.001). The percentage of asymptomatic episodes was very high in patients with one-vessel disease, whereas the duration and amount of ST-segment depression, as well as heart rate, at the onset of ischemia, were not dependent on the extent of coronary artery disease.     

Coronary heart disease and silent myocardial ischemia]

Silent myocardial ischemia was studied in 100 patients with coronary heart disease (CHD), proved by the coronary arteriogram (at least one major coronary artery narrowed by > or = 50%). The study demonstrated that 51 of 100 patients with CHD had episodes of myocardial ischemia by Holter monitoring. In the 51 patients, during daily activities, through 24-hour Holter monitoring, 239 transient episodes of ST depression were detected, 161 of the total were asymptomatic (67.4%). There were no statistically significant differences in the heart rate and the product of heart rate and systolic blood pressure before ST depression between asymptomatic and symptomatic episodes. The heart rate at the time of maximal ST depression during both asymptomatic and symptomatic ischemia increased by 13 and 22 beats/min, respectively, over those before ST depression (P < 0.01); whereas the increase in heart rate during symptomatic ischemia was more significant than during asymptomatic ischemia (P < 0.01). The increase of product of heart rate and systolic blood pressure at the time of maximal ST depression during asymptomatic and symptomatic ischemia were 22.2 and 35.4, respectively, over those before ST depression (P < 0.01). The incidence of silent ischemic episodes in patients with single vessel disease was 81.7% and those with multivessel disease was 61.3% (P < 0.01). The frequency of silent ischemic episodes was maximal (36% of total number of ischemic episodes) between 6 a.m. and 12 a.m. during 24-hour, whereas the incidence of silent ischemic episodes in patients with single vessel disease was similar to that in patients with multivessel disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Silent myocardial ischemia: diagnosis, clinical significance and management

With the inception of continuous ECG monitoring with high-fidelity reproduction of the ST-segment, silent myocardial ischemia has been regarded with increasing importance in the detection and management of coronary artery disease. With the aid of a variety of invasive and noninvasive methods, the validity of ST-segment depression as indicative of myocardial ischemia, even in the absence of symptoms, has been adequately documented. In completely asymptomatic subjects with positive evidence of silent ischemia in the exercise ECG or Holter monitoring, the risk of developing a future manifestation of coronary artery disease may be up to ten-fold higher than in individuals with negative tests In patients with established coronary artery disease, concomitant use of continuous ECG monitoring and exercise testing, methods which complement each other rather than being mutually exclusive, a substantial number of patients with otherwise typical angina pectoris may be found to have silent ischemic episodes. An adequate differentiation between those with symptomatic and those who are asymptomatic based on characterization with respect to age, sex, hypertension, coronary anatomy, etc., has not been successful. Patients with silent ischemia during exercise may also exhibit more episodes of silent ischemia during daily activities and up to 75% of ischemic episodes may be asymptomatic. In general, however, silent ischemia during exercise appears more common than silent ischemia only during daily activities. In the latter case, since there is usually no increase in heart rate, the pathophysiology is regarded as dissimilar from that associated with exercise-induced ischemia. While the presence of silent ischemia appears quite common in patients after acute myocardial infarction, its occurrence, to date, has not been confirmed to carry additional risk, whereas in unstable angina, the association of silent ischemia is indicative of a higher probability of subsequent cardiac events.     

Silent myocardial ischaemia in patients with angiographically proven coronary artery disease

Twenty patients with angiographically proven coronary artery disease (CAD) were evaluated by Holter monitoring for assessment of total ischaemic burden during daily activities. Thirteen patients revealed ischaemia on Holter monitoring (symptomatic-2, silent-4 and both types-7). As compared to symptomatic ischaemia, the silent myocardial ischaemic episodes were more frequent (25 vs 10 episodes), longer in duration (15-53 minutes vs 8-45 minutes), occurred at lower heart rates (65-75/minute (mean 68) vs 70-90 per minute (mean 76) and silent ischaemic episodes exceeded symptomatic ones in both morning (10 vs 4) and evening (15 vs 6) peaks. Occurrence of symptomatic as well as silent ischaemia had no relation to rest, activity, left ventricular functions, and there was no difference in the extent (1-3mm) and type (horizontal or downsloping) of ST-segment depression. We conclude that in patients with significant coronary artery disease, silent myocardial ischaemia is more frequent than the symptomatic ischaemia during daily activities. It occurs at lower heart rates, lasts longer, and bears no relation to rest, activity or left ventricular function. Evening peaks may be as frequent or more than the morning peaks. Holter monitoring thus is helpful for assessment of total ischaemic burden in CAD patients.     

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.     

Painless episodes of ST segment displacement and the possibility of their prevention in patients with exertion-induced stenocardia

Sixty patients with stable exercise-induced angina were examined by 24-hour Holter monitoring. It was found that an average of 51.7% of significant episodes of ischemic ST-segment depression failed to be accompanied by anginal episodes during the whole day. The number and length of painless episodes of ST-segment depression exceeded those observed in painful episodes. The range in the values seen in ST-segment depression was great during the episodes, while its threshold values were far stable at the onset of pain. Usage of analyzing cardiac monitors with a signalling system switched on by the preset values of ST-segment depression prevented the evolution of myocardial ischemia and the development of exercise-induced anginal episodes.     

Usefulness of Holter monitoring to improve the sensitivity of exercise testing in determining the degree of myocardial revascularization after coronary artery bypass grafting for stable angina pectoris

To assess whether Holter monitoring improves the sensitivity of exercise testing in identifying incomplete myocardial revascularization, both tests were performed in 45 patients from 3 to 5 months after elective coronary artery bypass grafting (CABG) for stable angina pectoris. Coronary angiography revealed incomplete revascularization in 26 patients. Six of these 26 had 52 episodes of ST-segment depression during Holter monitoring and myocardial ischemia during exercise testing. Their exercise capacity was significantly lower than that of 10 other patients in whom the results of exercise testing only were positive (heart rate at 0.1 mV ST-segment depression 112 +/- 9 vs 123 +/- 15 beats/min, p less than 0.001). In the other 10 patients with incomplete myocardial revascularization the results of both investigations were negative. The graft patency rate was lower in patients with a positive response to exercise testing than in those with a negative response (52% vs 71%, p less than 0.005). Myocardial revascularization was angiographically complete in 19 patients. In 18 of these 19 patients the findings of both investigations were negative; in 1 patient Holter monitoring revealed episodes of ST-segment elevation suggestive of variant angina. Thus, after CABG for stable angina pectoris the results of Holter monitoring do not improve the sensitivity of exercise testing in identifying patients with angiographically incomplete myocardial revascularization because findings are positive only in patients with low exercise capacity. Both tests fail to show evidence of myocardial ischemia in most patients with angiographically complete myocardial revascularization.     

Frequency and significance of early postoperative silent myocardial ischemia in patients having peripheral vascular surgery

Coronary disease causes the majority of perioperative complications after peripheral vascular surgery. Twenty-four patients with stable coronary disease undergoing peripheral revascularization were studied using continuous electrocardiographic monitoring to determine the incidence of perioperative asymptomatic myocardial ischemia and its relation to postoperative clinical ischemic events. Patients were monitored preoperatively (17 +/- 1 hours), intraoperatively and postoperatively (29 +/- 2 hours) using 4-channel calibrated amplitude-modulated units. Fifteen patients (63%) had early postoperative silent ischemia; 3 also had preoperative silent ischemia and 5 intraoperative transient ischemia. Patients with and without silent ischemia had similar clinical characteristics, perioperative antianginal medications and postoperative episodes of hemodynamic instability. However, 8 of 15 patients (53%) with silent ischemia had postoperative clinical ischemic events (2 had myocardial infarction, 2 had new congestive heart failure and 4 had new rest angina), versus only 1 of 9 patients (11%) without silent ischemia who had angina (p less than 0.05). Early postoperative silent myocardial ischemia occurs frequently after vascular surgery and is associated with postoperative clinical ischemic events.