Relative contributions of a single-admission 12-lead electrocardiogram and early 24-hour continuous electrocardiographic monitoring for early risk stratification in patients with unstable coronary artery disease

Patients with unstable coronary syndromes are a heterogeneous group with varying degrees of ischemia and prognosis. The present study compares the prognostic value of a standard electrocardiogram (ECG) obtained at admission to the hospital with the information from 24-hour continuous electrocardiographic monitoring obtained immediately after admission. The admission ECGs and 24 hours of vectorcardiographic (VCG) monitoring from 308 patients admitted with unstable coronary artery disease were analyzed centrally regarding standard electrocardiographic ST-T changes, ST-vector magnitude (ST-VM), and ST change vector magnitude episodes. End points were death, acute myocardial infarction, and refractory angina pectoris within a 30-day follow-up period. ST-VM episodes (> or = 50 microV for > or = 1 minute) during VCG monitoring was the only independent predictor of death or acute myocardial infarction by multivariate analysis. ST-VM episodes during vectorcardiography was associated with a relative risk of 12.7 for having a cardiac event, hypertension was associated with a relative risk of 1.7, and ST depression on the admission ECG was associated with a relative risk of 5.7. Patients with ST depression at admission had an event rate (death or acute myocardial infarction) of 17% at 30-day follow-up. Patients without ST depression could further be risk stratified by 24 hours of VCG monitoring into a subgroup with ST-VM episodes at similar (8%) risk and a subgroup without ST-VM episodes at low (1%) risk (p = 0.00005). Continuous VCG monitoring provides important information for evaluating patients with unstable coronary artery disease. It is recommended that patients not initially estimated at high risk based on the admission ECG are referred for 24 hours of VCG monitoring for further risk stratification.     

Morphology of ambulatory ST segment changes in patients with varying severity of coronary artery disease. Investigation of the frequency of nocturnal ischaemia and coronary spasm

The frequency and magnitude of objectively determined myocardial ischaemia during normal daily activities of patients with varying severity of coronary artery disease are unknown. Furthermore, the incidence of nocturnal resting myocardial ischaemia and frequency of coronary spasm in patients with normal coronary arteries and chest pain are also not known. One hundred consecutive patients with chest pain referred for coronary angiography were therefore investigated with exercise testing and ambulatory ST segment monitoring. Fifty two of 74 patients with significant coronary artery disease and six of 26 with no significant coronary narrowing had episodes of ST segment change during 48 hours of ambulatory monitoring. Two patients, one with normal coronary arteries and localised spasm and one with three vessel disease, had episodes of ST segment elevation, whereas all other patients had episodes of ST segment depression. The frequency, duration, and magnitude of ST segment changes were greater in patients with more severe types of coronary artery disease. Thus more than six episodes of ST segment change per day occurred in patients with two or three vessel disease or left main stem stenosis and in the only patient with coronary spasm and normal coronary arteries. Nocturnal ischaemia occurred in 15% of patients with coronary artery disease and was almost an invariable indicator of two or three vessel coronary artery disease or left main stem stenosis. Episodes of ST segment change occurred most commonly during the morning hours and least commonly during the night, in parallel with changes in basal hourly heart rates. The heart rate at the onset of ST segment change tended to be lower in patients with coronary artery disease than in those with normal coronary arteries. The duration of exercise to ST segment depression tended to be shorter in patients with more severe disease, but it could not predict patients with nocturnal myocardial ischaemia, left main stem stenosis, or coronary spasm, whereas ambulatory ST segment monitoring was able to identify most of these patients.     

Morphology of ambulatory ST segment changes in patients with varying severity of coronary artery disease. Investigation of the frequency of nocturnal ischaemia and coronary spasm.

The frequency and magnitude of objectively determined myocardial ischaemia during normal daily activities of patients with varying severity of coronary artery disease are unknown. Furthermore, the incidence of nocturnal resting myocardial ischaemia and frequency of coronary spasm in patients with normal coronary arteries and chest pain are also not known. One hundred consecutive patients with chest pain referred for coronary angiography were therefore investigated with exercise testing and ambulatory ST segment monitoring. Fifty two of 74 patients with significant coronary artery disease and six of 26 with no significant coronary narrowing had episodes of ST segment change during 48 hours of ambulatory monitoring. Two patients, one with normal coronary arteries and localised spasm and one with three vessel disease, had episodes of ST segment elevation, whereas all other patients had episodes of ST segment depression. The frequency, duration, and magnitude of ST segment changes were greater in patients with more severe types of coronary artery disease. Thus more than six episodes of ST segment change per day occurred in patients with two or three vessel disease or left main stem stenosis and in the only patient with coronary spasm and normal coronary arteries. Nocturnal ischaemia occurred in 15% of patients with coronary artery disease and was almost an invariable indicator of two or three vessel coronary artery disease or left main stem stenosis. Episodes of ST segment change occurred most commonly during the morning hours and least commonly during the night, in parallel with changes in basal hourly heart rates. The heart rate at the onset of ST segment change tended to be lower in patients with coronary artery disease than in those with normal coronary arteries. The duration of exercise to ST segment depression tended to be shorter in patients with more severe disease, but it could not predict patients with nocturnal myocardial ischaemia, left main stem stenosis, or coronary spasm, whereas ambulatory ST segment monitoring was able to identify most of these patients.     

How important is a history of chest pain in determining the degree of ischaemia in patients with angina pectoris?

Since therapeutic decisions in patients with angina pectoris are usually based on the reported frequency of exertional and rest pain the relations between the historical frequency of chest pain and objective evidence of myocardial ischaemia during normal daily activity were investigated in 100 patients by 48 hour ambulatory ST segment monitoring. Of these 100 consecutive patients with chest pain, 91 had typical pain and nine some atypical features. Twenty six patients had normal coronary arteries and 52 of the 74 with significant coronary disease had ambulatory ST segment changes. There was no relation between the frequency of reported exertional or rest pain and (a) the severity of coronary artery disease or (b) the frequency of daytime or nocturnal ST segment changes. Twelve patients had nocturnal ST segment changes but only four complained of nocturnal angina. Most patients had both painful and painless episodes of ST segment changes, but a substantial number had either painless or painful episodes only. These differences were not related to the severity of coronary artery disease. Chest pain after the onset of ST segment change was perceived with wide interpatient and intrapatient variability. Thus the frequency of pain is a poor indicator of the frequency of significant cardiac ischaemia. Individual differences in the perception of pain may be more important.     

Continuous vectorcardiography in patients with chest pain indicative of acute ischemic heart disease.

To assess the clinical usefulness of continuous on-line vectorcardiography (VCG), we studied 61 patients admitted to the coronary care unit (CCU) with chest pain, supposedly ischemic. Continuous VCG was performed for 24 h, monitoring QRS vector difference (QRS-VD), ST-change vector magnitude (STC-VM) and ST vector magnitude (ST-VM) measured 20 and 60 ms after the termination of the QRS complex. The patients were divided into four groups based on the final diagnosis; group A, 15 patients with normal exercise tests and extracardiac causes of chest pain; group B, 15 patients with unstable angina; group C, 15 patients with non-Q-wave myocardial infarction (MI); group D, 16 patients with Q-wave MI. Treatment was given according to a normal routine. Of 31 patients with MI, 16 received treatment with streptokinase. Groups A and B showed no significant permanent changes in QRS-VD, STC-VM or ST-VM. However, group B showed a higher occurrence of transient episodes (duration: 2 min-6 h) of a significant change of QRS-VD by > 15 microVs and of STC-VM, ST-VM 20 and ST-VM 60 by > 0.1 mV. Groups C and D showed both permanent changes and transient episodes for the studied vector parameters. Transient episodes were significantly fewer in group D than in group B. In patients with MI, the permanent change of vector parameters evolved more rapidly and reached a plateau earlier in those treated with streptokinase (QRS-VD: 178 +/- 82 vs. 293 +/- 100 min, p < 0.001; ST-VM 20: 142 +/- 75 vs. 293 +/- 89 min, p < 0.005). The magnitude of the end value for QRS-VD correlated with infarct size estimated by the maximal value of creatine kinase (r = 0.89; p < 0.001). We conclude that in patients admitted to the CCU with chest pain, continuous VCG monitoring early differentiates patients suffering from ischemic heart disease (IHD) from patients without IHD. It also differentiates patients with unstable angina from patients with MI.     

How important is a history of chest pain in determining the degree of ischaemia in patients with angina pectoris?

Since therapeutic decisions in patients with angina pectoris are usually based on the reported frequency of exertional and rest pain the relations between the historical frequency of chest pain and objective evidence of myocardial ischaemia during normal daily activity were investigated in 100 patients by 48 hour ambulatory ST segment monitoring. Of these 100 consecutive patients with chest pain, 91 had typical pain and nine some atypical features. Twenty six patients had normal coronary arteries and 52 of the 74 with significant coronary disease had ambulatory ST segment changes. There was no relation between the frequency of reported exertional or rest pain and (a) the severity of coronary artery disease or (b) the frequency of daytime or nocturnal ST segment changes. Twelve patients had nocturnal ST segment changes but only four complained of nocturnal angina. Most patients had both painful and painless episodes of ST segment changes, but a substantial number had either painless or painful episodes only. These differences were not related to the severity of coronary artery disease. Chest pain after the onset of ST segment change was perceived with wide interpatient and intrapatient variability. Thus the frequency of pain is a poor indicator of the frequency of significant cardiac ischaemia. Individual differences in the perception of pain may be more important.     

The Sensitivity of the Symptom Angina Pectoris as a Marker of Transient Myocardial Ischaemia in Chronic Stable Angina Pectoris

ABSTRACT Therapeutic decisions in patients with angina pectoris are traditionally based on the history reported by the patient, since objective evidence of myocardial ischaemia during daily life is often not available. In this study, ambulatory ST segment monitoring was performed in 60 patients with a history of chronic stable angina pectoris, positive exercise test and/or positive coronary angiography, and a correlation was made between the episodes of chest pain and ST segment change. The patients were grouped according to the results of exercise testing and coronary arteriography, and one group was studied with and without antianginal medication. Overall, 195 episodes of angina were noted, only 94 of which (48%) were accompanied by ST segment depression. Pain and ST segment changes were best correlated in patients with a positive exercise test, positive angiography and who were not receiving antianginal medication. In 101 episodes of chest pain, ST segment change could not be identified; in 18 (18%) there was sinus tachycardia, in 12 (12%) ventricular premature beats, and in 71 (70%) sinus rhythm solely. Thus, anginal pain appears not to be the reliable indicator of transient myocardial ischaemia as was previously thought, a finding which supports the use of objective methods in identifying episodes of transient myocardial ischaemia in daily life.     

Syndrome X: the haemodynamic significance of ST segment depression

The relation between chest pain, ST segment depression, and changes in left ventricular function was assessed in six patients with angina, a positive exercise test, and normal coronary arteries as assessed by arteriography (syndrome X). In the six patients with syndrome X and in six controls there was no significant rise in pulmonary artery diastolic pressure during treadmill exercise, although there was ST segment depression (range 1-4.5 mm) in the patients with syndrome X. In 19 patients with coronary artery disease, however, the pulmonary artery diastolic pressure increased by a median 5 mm Hg (range 0-13.6 mm Hg) on treadmill exercise. In only one patient with coronary artery disease, who showed 1 mm ST segment depression, was there no rise in pulmonary artery diastolic pressure. During ambulatory monitoring in patients with syndrome X there were 12 episodes of ST segment depression (greater than 1 mm) (4 painful, 8 painless) in which there was no change in pulmonary artery diastolic pressure. In the patients with coronary artery disease there were 29 episodes of angina during ambulatory monitoring and during all of them pulmonary artery diastolic pressure rose by a median 7.5 mm Hg (range 1.8-19.7 mm Hg). Unlike the haemodynamic changes that usually occur during myocardial ischaemia in coronary artery disease, chest pain and ST segment changes in patients with syndrome X are not associated with impaired left ventricular function as assessed by ambulatory pulmonary artery pressure monitoring.     

Syndrome X: the haemodynamic significance of ST segment depression.

The relation between chest pain, ST segment depression, and changes in left ventricular function was assessed in six patients with angina, a positive exercise test, and normal coronary arteries as assessed by arteriography (syndrome X). In the six patients with syndrome X and in six controls there was no significant rise in pulmonary artery diastolic pressure during treadmill exercise, although there was ST segment depression (range 1-4.5 mm) in the patients with syndrome X. In 19 patients with coronary artery disease, however, the pulmonary artery diastolic pressure increased by a median 5 mm Hg (range 0-13.6 mm Hg) on treadmill exercise. In only one patient with coronary artery disease, who showed 1 mm ST segment depression, was there no rise in pulmonary artery diastolic pressure. During ambulatory monitoring in patients with syndrome X there were 12 episodes of ST segment depression (greater than 1 mm) (4 painful, 8 painless) in which there was no change in pulmonary artery diastolic pressure. In the patients with coronary artery disease there were 29 episodes of angina during ambulatory monitoring and during all of them pulmonary artery diastolic pressure rose by a median 7.5 mm Hg (range 1.8-19.7 mm Hg). Unlike the haemodynamic changes that usually occur during myocardial ischaemia in coronary artery disease, chest pain and ST segment changes in patients with syndrome X are not associated with impaired left ventricular function as assessed by ambulatory pulmonary artery pressure monitoring.     

Continuous vectorcardiographic monitoring of ischemia during coronary angioplasty in patients with bundle-branch block

BACKGROUND: Patients with the combination of bundle-branch block and ischemic heart disease have a poor outcome. There is no established criterion for detection of transient ischemia when bundle-branch block is present. OBJECTIVE: To elucidate vectorcardiographic changes during coronary angioplasty of patients with bundle-branch block. DESIGN AND METHODS: The QRS complex and ST-segment changes of 29 patients with bundle-branch block were studied during elective coronary angioplasty using continuous vectorcardiography. Data for the patients with bundle-branch block were compared with data for narrow-QRS-complex controls, matched for the vessel dilated, sex, and age. RESULTS: Patients with bundle-branch block were found to have more pronounced changes in the QRS-vector difference as a response to coronary occlusion than did controls. ST-vector magnitude responded in a similar way during coronary occlusion of patients with and without bundle-branch block but from different baselines. ST change-vector magnitude was found to be the most sensitive parameter for detection of ischemia in patients with bundle-branch block as well as for controls. CONCLUSION: Monitoring of transient ischemia during coronary angioplasty for patients with bundle-branch block is feasible using continuous vectorcardiography. A change in ST vector magnitude > 100 microV is suggested to indicate significant ischemia in the presence of bundle-branch block.     

Symptomatic and silent myocardial ischaemia in hypertensive patients with left ventricular hypertrophy.

OBJECTIVE--To assess the prevalence of symptomatic and silent myocardial ischaemia in patients with hypertensive left ventricular hypertrophy. DESIGN--Cross sectional study. SETTING--University department of medical cardiology. PATIENTS--90 patients (68 men and 22 women; mean age 57 (range 25 to 79)) with left ventricular hypertrophy due to essential hypertension. INTERVENTIONS--48 hour ambulatory ST segment monitoring (all patients), exercise electrocardiography (n = 79), stress thallium scintigraphy (n = 80), coronary arteriography (n = 35). RESULTS--43 patients had at least one episode of ST segment depression on ambulatory electrocardiographic monitoring. The median number of episodes was 16 (range 1 to 84) with a median duration of 8.6 (range 2 to 17) min. Over 90% of these episodes were clinically silent. 26 patients had positive exercise electrocardiography and 48 patients had reversible thallium perfusion defects despite chest pain during exercise in only five patients. 18 of the 35 patients who had coronary arteriography had important coronary artery disease. Seven of these patients gave no history of chest pain. CONCLUSIONS--Symptomatic and silent myocardial ischaemia are common in hypertensive patients with left ventricular hypertrophy, even in the absence of epicardial coronary artery disease.     

Effects of myocardial revascularisation in patients with effort angina and those with effort and nocturnal angina

The effects of coronary artery bypass graft operation were studied in 32 patients with daytime ambulatory ST segment changes and 14 patients with daytime and nocturnal angina and ST segment changes. Patients had ambulatory ST segment monitoring and exercise testing before and after operation and coronary arteriography was repeated in 34 patients after operation. Before operation, patients with daytime and nocturnal ischaemia tended to have more severe coronary artery disease, lower exercise tolerance, and more frequent ambulatory ST segment changes than those who had daytime ST segment changes only. After operation chest pain recurred in 22% of patients and ST segment depression during exercise testing or ambulatory ST segment monitoring recurred in 37% of the patients and was significantly more frequent in those with nocturnal ischaemia than in those with daytime ischaemia. Graft patency rates were similar in patients with and those without recurrence of ischaemia. After operation the frequency and magnitude of ST segment changes and exercise duration were improved in patients with preoperative daytime angina and also in those with daytime and nocturnal angina. The improvement was more pronounced in the latter groups. Thus, absence of postoperative angina is not a reliable indicator of the absence of reversible myocardial ischaemia. After revascularisation, patients with rest and nocturnal angina can expect relief from ischaemia, and if this recurs postoperatively, the threshold is improved and pain usually occurs only on exertion.     

Effects of myocardial revascularisation in patients with effort angina and those with effort and nocturnal angina.

The effects of coronary artery bypass graft operation were studied in 32 patients with daytime ambulatory ST segment changes and 14 patients with daytime and nocturnal angina and ST segment changes. Patients had ambulatory ST segment monitoring and exercise testing before and after operation and coronary arteriography was repeated in 34 patients after operation. Before operation, patients with daytime and nocturnal ischaemia tended to have more severe coronary artery disease, lower exercise tolerance, and more frequent ambulatory ST segment changes than those who had daytime ST segment changes only. After operation chest pain recurred in 22% of patients and ST segment depression during exercise testing or ambulatory ST segment monitoring recurred in 37% of the patients and was significantly more frequent in those with nocturnal ischaemia than in those with daytime ischaemia. Graft patency rates were similar in patients with and those without recurrence of ischaemia. After operation the frequency and magnitude of ST segment changes and exercise duration were improved in patients with preoperative daytime angina and also in those with daytime and nocturnal angina. The improvement was more pronounced in the latter groups. Thus, absence of postoperative angina is not a reliable indicator of the absence of reversible myocardial ischaemia. After revascularisation, patients with rest and nocturnal angina can expect relief from ischaemia, and if this recurs postoperatively, the threshold is improved and pain usually occurs only on exertion.     

Ergonovine--echo test to assess the significance of chest pain at rest without ECG changes

The aim of this study was to assess the feasibility and diagnosticrole of ergonovine maleate infusion under continuous two-dimensionalechocardiographic monitoring for the identification of vasospasticmyocardial ischaemia in patients with chest pain at rest notassociated with diagnostic ECG changes. One hundred and twenty-eight consecutive patients, selectedon the basis of absence of ischaemic ECG changes during anginaat rest before or during hospitalization, were enrolled in thestudy. Ergonovine maleate was i.v. administered in scaled doses(from 0.025 to 0.2 mg at 10 min intervals) under echocardiographic,electrocardiographs and systemic blood pressure monitoring.Wall motion asynergies were observed in 33 patients, accompaniedby typical chest pain in 24 patients and by ECG changes in 25(ST elevation in 13 patients, ST depression in seven, T wavechanges in five). AH patients were able to complete the test.Non life-threatening ventricular arrhythmias were observed infour patients exclusively in association with ischaemia. Inseven patients with a positive test, coronary artery spasm wasdocumented at angiography. In 16 patients with a positive test,the vasospastic event was reproduced by a hyperventilation—echotest or a second ergonovine maleate-echo test performed within3 days of the first examination. In none of the patients witha negative test was documentation of myocardial ischaemia dueto a primary reduction in coronary blood flow. Thus, in patientswho do not show ECG changes during chest pain at rest, the ergonovinemaleate-echo test is feasible and safe; it permits the recognitionof ischaemic episodes on the basis of wall motion abnormalitieswhen conventional 12-lead ECG-recorded chest pain is non-diagnostic.     

Prognostic value of maximum ST-vector magnitude during the first 24 h of vectorcardiographic monitoring in patients with unstable angina pectoris.

AIMS: To assess the prognostic importance of alternate ways of quantifying myocardial ischaemia by continuous ST analysis, the maximum ST vector magnitude and the area under the ST vector magnitude trend curve during the first 24 h of continuous ST monitoring. METHODS AND RESULTS: During a 22-month period from 1991 to 1993, 195 patients admitted to our CCU with suspected unstable angina pectoris, were included in the study. During the first 24 h the patients were monitored for ischaemic episodes with computerized vectorcardiography, using a MIDA 1000 system. Twenty seven (14%) of the 195 patients died or had a non-fatal myocardial infarction within 1 year and the maximum ST vector magnitude among those patients was, on average, 201 microV compared with 118 microV in patients who survived 1 year free of myocardial infarction (P<0.01). The area under the ST vector magnitude trend curve was, on average, 1598 microVmin compared with 164 microVmin (P<0.01). By multivariate analysis, the maximum ST vector magnitude emerged as a superior predictor of death or myocardial infarction, compared with the area under the ST vector magnitude trend curve and the number of ST vector magnitude and ST change vector magnitude episodes. The maximum ST vector magnitude and age were independent predictors of death or non-fatal myocardial infarction within 1 year. CONCLUSION: Maximum ST vector magnitude during the first 24 h of vectorcardiographic monitoring seems to be a strong predictor of subsequent death or non-fatal myocardial infarction.     

Continuous ST-segment monitoring of patients with left bundle branch block and suspicion of acute myocardial infarction

OBJECTIVES: Patients with left bundle branch block comprise 5-9% of all patients with acute myocardial infarction. Limited data exist on the usefulness of continuous electrocardiographic monitoring of these patients. We have investigated prospectively the usefulness of real-time continuous vectorcardiography for monitoring patients with left bundle branch block and suspicion of acute myocardial infarction. DESIGN: A prospective multi-centre study. SETTING: Fourteen Swedish coronary care units. SUBJECTS: Patients with left bundle branch block and suspicion of acute myocardial infarction with <6-h symptom duration were included. MAIN OUTCOME MEASURES: All patients were monitored with continuous vectorcardiography for 12-24 h. RESULTS: One hundred thirty-three patients were included, 47% had acute myocardial infarction. Patients with acute myocardial infarction showed a marked relative decrease in ST-vector than those without (P = 0.0002). These changes were most marked in the first 90 min. When comparing patients with acute myocardial infarction receiving thrombolytic therapy or not, those treated with thrombolytics showed more marked decline in ST-vector magnitude (P < 0.0001) and in shorter time (P = 0.0017). All patients showed STC-vector magnitude changes that were more marked in patients with acute myocardial infarction (P = 0.0002). An STC-vector magnitude cut-off value of 65 microV after 90 min of monitoring gave 54% sensitivity and 72% specificity for diagnosis of acute myocardial infarction. CONCLUSION: Real-time continuous vectorcardiographic monitoring of patients with left bundle branch and suspicion of acute myocardial infarction shows significant differences between those with and without acute myocardial infarction and could be of use for early diagnosis and subsequent monitoring.     

Symptomatic and silent myocardial ischaemia in hypertensive patients with left ventricular hypertrophy.

OBJECTIVE--To assess the prevalence of symptomatic and silent myocardial ischaemia in patients with hypertensive left ventricular hypertrophy. DESIGN--Cross sectional study. SETTING--University department of medical cardiology. PATIENTS--90 patients (68 men and 22 women; mean age 57 (range 25 to 79)) with left ventricular hypertrophy due to essential hypertension. INTERVENTIONS--48 hour ambulatory ST segment monitoring (all patients), exercise electrocardiography (n = 79), stress thallium scintigraphy (n = 80), coronary arteriography (n = 35). RESULTS--43 patients had at least one episode of ST segment depression on ambulatory electrocardiographic monitoring. The median number of episodes was 16 (range 1 to 84) with a median duration of 8.6 (range 2 to 17) min. Over 90% of these episodes were clinically silent. 26 patients had positive exercise electrocardiography and 48 patients had reversible thallium perfusion defects despite chest pain during exercise in only five patients. 18 of the 35 patients who had coronary arteriography had important coronary artery disease. Seven of these patients gave no history of chest pain. CONCLUSIONS--Symptomatic and silent myocardial ischaemia are common in hypertensive patients with left ventricular hypertrophy, even in the absence of epicardial coronary artery disease.     

Diagnostic and prognostic importance of ST recording after an episode of unstable angina or non-Q-wave myocardial infarction.

The diagnostic and prognostic value of ST recordings in unstable coronary artery disease were evaluated in 198 men below 70 years of age admitted to the coronary care unit because of chest pain due to myocardial ischaemia but without the development of Q-wave infarction. The ST recordings were performed for 24 h in bed in the CCU (n = 75) between 6 and 66 hours after the last episode of pain, before discharge during ambulation in hospital 4-6 days after admission (n = 198), and ambulatory out of hospital 1 month later (n = 109). The long-term ECG was registered from bipolar leads corresponding to V2 and V5 using two-channel FM-recorders. Significant ST episodes were defined as ST segment deviation greater than or equal to 0.1 mV from baseline and lasting for at least 1 min. During the recordings 85-90% of the patients were treated with betablockers and 27-41% also with calcium channel blockers. In the CCU recordings, ST depression occurred in 23% of the patients, 21% had asymptomatic and 7% symptomatic episodes. Before discharge the ST recordings showed ST depression in 18% of the patients, 16% asymptomatic and 7% symptomatic. Ambulatory monitoring after 1 month showed a higher occurrence of ST depressions--33% (P less than 0.01 compared to day 5), 26% had episodes without pain and 13% painful episodes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Silent myocardial ischaemia in chronic stable angina: a study of its frequency and characteristics in 150 patients.

One hundred and fifty unselected patients with documented coronary artery disease were studied to establish the frequency and characteristics of silent myocardial ischaemia. Patients underwent ambulatory ST segment monitoring off all routine antianginal treatment (total 6264 hours) and exercise testing (n = 146). Ninety one patients (61%) had a total of 598 episodes of significant ST segment change, of which 446 (75%) were asymptomatic. Twenty seven patients (18%) had only painless episodes; 14 (9%) patients only painful episodes; 50 patients (33%) had both painless and painful episodes. The mean number of ST segment changes per day was 2.58 (1.95 silent); however, 11 patients (7%) had 50% of all silent episodes, and 48 patients (32%) had 91% of all silent episodes. Fifty nine patients (39%) had no ST segment changes on ambulatory monitoring, and 73 patients (49%) had no evidence of silent ischaemia. Episodes of silent ischaemia occurred with a similar circadian distribution to that of painful ischaemia, predominantly between 0730 and 1930. There was a similar mean rise in heart rate at the onset of both silent and painful episodes of ischaemia. Silent ischaemia was significantly more frequent in patients with three vessel disease than in those with single vessel disease, and was also significantly related to both time to 1 mm ST depression and maximal exercise duration on exercise testing. There was a highly significant relation between the mean number and duration of episodes of silent ischaemia in patients with positive exercise tests when compared with those with negative tests. No episode of ventricular tachycardia was recorded in association with silent ischaemic change.     

Why is recurrent myocardial ischaemia a predictor of adverse outcome in unstable angina? An observational study of myocardial ischaemia and its relation to coronary anatomy.

OBJECTIVE: To establish why recurrent myocardial ischaemia predicts adverse outcome in patients with refractory unstable angina on maximal medical treatment. DESIGN: Prospective observational study in 101 patients with refractory unstable angina who underwent continuous ST-segment monitoring and kept detailed pain charts prior to cardiac catheterization.Setting Tertiary referral centre. RESULTS: Significant coronary disease was identified in 90 subjects with 74 (82%) having multivessel disease, 41 (46%) complex lesion morphology, and 10 (11%) subjects with definite features of intra-coronary thrombus. The frequency of complex lesions or intra-coronary thrombus did not differ in relation to the extent of coronary disease. Recurrent chest pain was present in 72 of the 90 (80%) subjects, while transient ischaemia was detected in 26 (29%). The presence of transient ischaemia was a powerful predictor of complex lesions or thrombus (odds ratio 7.1;P<0.001). Subjects with severe recurrent chest pain had a greater frequency of intracoronary thrombus (odds ratio 9.5;P<0.05). CONCLUSIONS: In unstable angina once the normal mechanisms causing myocardial ischaemia (i.e. increased myocardial demand and coronary vasoconstriction) have been treated using maximal antianginal treatment, the continued development of transient myocardial ischaemia is strongly associated with complex coronary lesion morphology and intracoronary thrombus. It is already known that patients with complex lesion morphology and intracoronary thrombus have an adverse outcome in unstable angina and therefore it is this association that explains why transient ischaemia is a predictor of poor outcome in unstable angina.