急性心肌梗死冠状动脉再通后ST段回落缓慢的意义

５４例急性心肌梗死患者溶栓或经皮冠状动脉腔内成形术后梗死相关冠状动脉再通，９０分钟时ＳＴ段上移总和回落，≥５０％为乙组。与乙组比较，甲组溶栓距发病时间及肌酸激酶峰值距发病时间延长。住院期间心脏事件发生率甲组显著高于乙组，而且出院前超声心动图检查显示，甲组收缩末期容量较乙组增大，射血分数减低。     

Unstable angina: ST segment depression with positive versus negative T wave deflections--clinical course, ECG evolution, and angiographic correlation

Thirty-two consecutive patients who initially had horizontal or downward-sloping ST segment depression confined to the precordial leads were studied. Patients were divided into two groups: group A included 21 patients with horizontal or downward-sloping ST depression with peaked positive T waves, and group B comprised 11 patients with peaked negative T waves and downward or horizontal ST depression. The incidence of acute myocardial infarction (AMI) was similar (group A 38.1% vs group B 36.4%; p greater than 0.05). In-hospital mortality was much more significant in group B (p = 0.03). Coronary arteriography was performed in 31 patients. Of the 10 patients in group B who were catheterized, seven (70%) had left main occlusion. Of the 21 patients in group A, none had a significant left main lesion (p = 0.001), although eight (38.1%) had single-vessel disease (p = 0.05). Thus the ECG pattern of horizontal or downward-sloping ST depression passing into a peaked negative T wave identifies a subgroup of high-risk patients in whom the prognosis is poor once AMI occurs. Early catheterization is recommended when this ischemic pattern is apparent on the ECG.     

Value of the exercise test in asymptomatic myocardial ischemia

To evaluate the predictive value of ischemic ST segment depression without associated chest pain during exercise testing, data were analyzed from 7305 studies. Two hundred thirty six patients were included in this study and were separated in 2 groups. Group A consisted of 169 patients without chest pain who, during exercise testing, showed a positive ST segment response (at least 1.5 mm of horizontal or downward ST segment depression for at least 0.08 second, compared with the resting baseline value), and Group B consisted of 67 patients who had both chest pain and a positive ST segment response. Selective coronary angiogram was performed on all patients. Each Group was separated into 3 sub-group according to the Cohn criteria: sub-group I (asymptomatic persons 8.3 vs 19.4%); sub-group II (patients with history of Myocardial Infarction 36.7% vs 19.4%); sub-group III (patients with chronic angina 55% vs 61.2%). The clinical characteristics, coronary risk factors, distribution of coronary artery disease, and exercise test response were similar in both groups. During treadmill exercise, the mean heart rate was 140.6 +/- 22 in group A versus 127.1 +/- 23 in the group B. The pressure-rate product was 2.4 +/- 0.8 versus 1.9 +/- 0.5, respectively (P less than or equal to 0.05). The predictive value for severe coronary artery disease of an exercise test in patients with asymptomatic ischemia was 77.5% as compared with 89.6% in the group with angina. This study confirms the high frequency of asymptomatic myocardial ischemia during exercise testing, compared with patients who had angina during exercise testing, with high percentage of prediction (77.5%) for coronary artery disease.     

Clinical evaluation of transient myocardial ischemia

Out of 432 patients with coronary heart disease, 106 (24.5%) were found to have transient myocardial infarction during ECG monitoring of ST segment for 10 hours of daily activity. High-grade ventricular arrhythmias were revealed in 74.6% of mainly male and middle-aged subjects. 63.4% of the patients exhibited congestive heart failure, 48.1% had postinfarct cardiosclerosis, and 25.5% presented with diabetes mellitus. Transient myocardial ischemia was more frequently detected during exercise and more rarely during emotional stress (21.7%), meal (19.8%), and smoking (7.8%). Asymptomatic episodes of ST segment elevation were recorded in 36.8%, while asymptomatic episodes of ST segment depression, in 29.2%. The duration of asymptomatic episodes of ST segment elevation and depression was twice and 1.5 times, respectively, less than that of symptomatic ones. Substantial myocardial perfusion and metabolic impairments were revealed with an asymptomatic ST segment depression frequency of at least one an hour, an amplitude of more than 2 mm, and a duration of no less than 40 min.     

Comparison of clinical and treadmill variables for the prediction of outcome after myocardial infarction

To assess the relative prognostic merits of 15 clinical and 10 predischarge exercise test variables, 226 patients who had sustained an acute myocardial infarction were studied. A submaximal treadmill test was performed on 205 patients to a mean work load of 5.7 +/- 2.9 METS. Testing was performed an average of 11.7 (range 6 to 33) days after myocardial infarction. During the first year of observation, major cardiac events were noted in 33 patients (16%), unstable angina in 7 (3.4%), recurrent myocardial infarction in 14 (6.8%) and death in 12 patients (5.9%). Cardiac mortality correlated with mean peak serum creatine kinase (CK) (p less than 0.05), history of previous myocardial infarction (p less than 0.01) and ST segment depression at rest (p less than 0.01). The only exercise variable that correlated with cardiac mortality was poor exercise endurance (p less than 0.05). Multivariate risk stratification of clinical and treadmill variables from these 205 patients using linear discriminant analysis produced a function that correctly classified 95% of those who were event-free and 80% of those who died. The first four discriminant variables that contributed independent information for the prediction of cardiac mortality were: 1) ST segment depression at rest; 2) CK greater than 1,280 IU/liter; 3) exercise duration less than 3 minutes; and 4) a history of previous myocardial infarction. ST segment depression on the predischarge treadmill test did not predict any event, nor did it improve the predictive accuracy of the clinical variables. It is concluded that a history of previous myocardial infarction and ST segment depression on the rest electrocardiogram indicate a poor prognosis after acute myocardial infarction. Poor endurance is the only exercise variable that suggests a future cardiac event. Prognosis after acute myocardial infarction is more accurately predicted by these clinical data than by variables derived from the predischarge treadmill test.     

Relationship between the QT indices and the microvolt-level T wave alternans in cardiomyopathy.

The relationship between the QT indices and microvolt-level T wave alternans (TWA) is unknown in cardiomyopathy, so the present study examined 86 patients with cardiomyopathy who experienced TWA during exercise testing (EXT). The QT interval (QT), duration from the Q wave to the peak of the T wave (QTp), duration from the peak to the end of the T wave and the dispersion of these parameters were measured by 12-lead electrocardiogram at rest and during EXT. In dilated cardiomyopathy (DCM), TWA was positive (TWA+) in 19 patients and negative (TWA-) in 17. No significant difference was observed between the TWA+ and TWA- groups in any parameter. In hypertrophic cardiomyopathy (HCM), TWA was positive in 24 patients and negative in 12. Max QTc, max QTpc and mean QTpc during EXT in the TWA+ group were significantly longer than those in the TWA- group. The sensitivity of TWA for ventricular tachycardia (VT) was high in DCM and HCM, and that of max QTc >500 ms during EXT for VT was high in HCM (93%). TWA is a useful predictor for VT in DCM and HCM, and prolonged max QTc during exercise has a prognostic value in HCM. Repolarization abnormality during exercise plays an important role in the genesis of VT in cardiomyopathy.     

Patients with symptomatic ischemia have larger thallium perfusion abnormalities and more adverse prognosis than patients with silent ischemia.

OBJECTIVE: To evaluate the mechanism for silent ischemia and the effect on prognosis. DESIGN: To test the hypothesis that patients with silent (compared with symptomatic) ischemia have less severe ischemia and a more favorable prognosis, the authors prospectively evaluated 152 consecutive patients with a positive exercise electrocardiogram with exercise thallium scintigraphy and followed them for two years. SETTING: Tertiary care university-based hospital. RESULTS: Asymptomatic patients during the exercise test had a greater exercise duration (9.4 +/- 3.1 versus 6.3 +/- 2.5 mins, P < 0.01), maximal heart rate (155 +/- 20 versus 136 +/- 20 beats/min, P < 0.01), systolic blood pressure (184 +/- 21 versus 176 +/- 23 mmHg, P < 0.05) and double product than patients who were symptomatic with chest pain. Although there was no difference in the magnitude of ST depression, time to ST depression was greater in the asymptomatic (5.6 +/- 2.7 mins), compared with symptomatic (4.6 +/- 2.6 mins), group (P < 0.01). Thallium ischemic score was smaller during asymptomatic ischemia (2.1 +/- 2.7) compared with symptomatic ischemia (3.9 +/- 3.1, P < 0.01). These findings were also demonstrated in a subgroup of 107 patients with both a positive exercise electrocardiogram and positive thallium scan. The patients with asymptomatic ischemia had a two-year cardiac event rate of 5.1% compared with 13.8% in the symptomatic patients (P = 0.065). CONCLUSIONS: Patients with asymptomatic ischemia have less severe myocardial ischemia and a better prognosis than patients with symptomatic myocardial ischemia during exercise testing.     

Comparison of propranolol, diltiazem, and nifedipine in the treatment of ambulatory ischemia in patients with stable angina. Differential effects on ambulatory ischemia, exercise performance, and anginal symptoms. The ASIS Study Group

Episodes of transient myocardial ischemia during ambulatory activities are common in patients with stable coronary artery disease and who are often asymptomatic. Selection of therapy for episodes of asymptomatic ischemia is limited by a lack of direct comparative studies. To determine the most effective monotherapy for patients with stable angina and a high frequency of asymptomatic ischemic episodes, propranolol-LA (mean daily dose, 293 mg), diltiazem-SR (mean daily dose, 350 mg), nifedipine (mean daily dose, 79 mg) were each compared with placebo, each for 2 weeks, in a randomized, double-blinded, crossover trial. Entry criteria were a positive exercise treadmill test during placebo therapy characterized by 1.0 mm or more ST segment depression and angina pectoris, and six or more episodes of transient ST segment depression of 1.0 mm or more on a 48-hour ambulatory electrocardiogram. One hundred ninety-four patients were screened, 63 were eligible and received randomized therapy, of which 56 patients completed at least two of the four treatment periods and were included in an intent-to-treat analysis. Fifty patients completed all four treatment phases and were included in the protocol-completed analysis. Anti-ischemia efficacy was assessed by 48-hour ambulatory electrocardiographic monitoring, exercise treadmill tests, and anginal diaries. Ninety-four percent of all episodes of ambulatory ischemia were asymptomatic. Compared with placebo, only propranolol was associated with a marked reduction in all manifestations of asymptomatic ischemia during ambulatory electrocardiographic monitoring (2.3 versus 1.0 episodes/24 hr; mean duration of ischemia per 24 hours, 43.6 versus 5.7 minutes; both p less than 0.0001). Diltiazem's reduction of the frequency of episodes compared with placebo (2.3 versus 1.9 episodes/24 hr) was associated with a trend (p = 0.08) in the protocol-completed analysis and with a significant reduction in the intent-to-treat analysis (p = 0.03). Nifedipine had no significant effect on any measured variable of ambulatory ischemia. The dosages of medication used may have been excessive for some patients, and a more beneficial effect may have been evident at a lower dose. In contrast to the marked effects of the active agents on ambulatory asymptomatic ischemia, the effects on exercise performance and angina pectoris were slight. The active agents modestly improved treadmill exercise duration time until 1 mm ST segment depression (3%), and only propranolol and diltiazem had significant effects. Only diltiazem significantly prolonged the total exercise time. Anginal frequency was significantly decreased by both propranolol and diltiazem.(ABSTRACT TRUNCATED AT 400 WORDS)     

墓碑形ST段抬高对心肌梗死范围及近期预后的影响

目的　探讨心电图墓碑形 ST段抬高对心肌梗死范围及预后的影响。方法　根据心电图 ST段抬高形式 ,将170例急性 ST段抬高型心肌梗死患者分为墓碑形组 5 2例 ,非墓碑形组 118例 ,比较两组心电图 ST段抬高振幅、QRS记分、血清肌酸激酶 (CK )及其同工酶 (CK - MB)峰值 ,并对其 4周内心脏事件进行分析。结果　墓碑形组 ST段抬高的振幅、QRS记分、CK和 CK- MB峰值均显著高于非墓碑形组 (P<0 .0 1)。墓碑形组心源性休克、心力衰竭、心室颤动和病死率分别为 11.5 4 %、4 2 .31%、2 6 .92 %和 19.2 3%,均高于非墓碑形组 2 .5 4 %、2 4 .5 8%、12 .71%和6 .78%(P<0 .0 5 )。 L ogistic回归分析结果显示 ,墓碑形 ST段抬高与心源性休克、心力衰竭、心室颤动和死亡危险独立相关 (OR分别为 1.880、1.5 73、2 .2 75和 3.0 6 4 ;均 P<0 .0 5 )。结论　墓碑形 ST段抬高提示心肌梗死范围大 ,是预后不良的独立预测指标。     

The threshold for myocardial ischemia varies in patients with coronary artery disease depending on the exercise protocol

It is generally accepted that angina pectoris and, presumably, myocardial ischemia occur at a fixed heart rate-systolic blood pressure product in a given patient. This concept of a fixed threshold has recently been challenged. To evaluate the effects of varying exercise intensity on the ischemic threshold, 33 patients with coronary artery disease and provokable myocardial ischemia, documented by thallium-201 myocardial perfusion imaging, underwent two exercise tests 2 to 7 days apart. A symptom-limited incremental treadmill exercise test was followed by a 20 min submaximal treadmill test at an intensity approximating 70% of the peak heart rate attained during the incremental test. During the incremental exercise test, angina pectoris developed in 16 patients and 17 patients were asymptomatic. At least 0.1 mV of ST segment depression developed in all subjects during the incremental exercise test at a mean exercise duration of 5.3 +/- 2.6 min, a rate-pressure product of 19,130 +/- 5,735 and oxygen uptake of 19.6 +/- 7.0 ml/kg per min. During the submaximal exercise test, 28 (85%) of the 33 patients had significant ST segment depression. Of these patients, 24 (86%) were asymptomatic, including 10 patients who had previously reported anginal symptoms during the incremental test. The average time to onset of 0.1 mV ST segment depression during the submaximal test was 8.1 +/- 4.5 min. These changes occurred at a rate-pressure product of 15,250 +/- 3,705 and an oxygen uptake of 14.3 +/- 5.9 ml/kg per min, and were significantly (p less than 0.001) lower than values observed during the graded exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection, frequency and clinical significance of silent myocardial ischaemia in patients with chronic stable angina

Forty-two patients (mean age 50 years) with chronic stable angina pectoris were subjected to exercise treadmill testing, coronary arteriography and left ventricular cineangiography. Twenty-one of these patients also underwent Holter monitoring for 24 hours. On exercise treadmill testing, angina was the endpoint in 24 (57%), while 18 (43%) developed significant ST segment depression without symptoms. Holter monitoring in 27 patients revealed a total of 248 episodes of myocardial ischaemia of which 210 (84%) were asymptomatic. ST segment depression at 80 mS from J point varied from 1 to 4 mm, and the average duration of ischaemic episodes during Holter monitoring was 9 minutes (range 30 seconds to 1 hour). Heart rate during the ischaemic episodes varied between 65-85 beats/minute. Coronary angiography revealed triple vessel disease in 22 (52%) and double vessel and single vessel involvement in 10 (24%) each. Left ventricular ejection fraction was less than 50% in only 3 (7%) patients. Thus silent myocardial ischaemia is detected frequently in patients with angina pectoris. It occurs during routine daily activity, and on exercise. Heart rate at which silent myocardial ischaemia occurs is much less during daily activity as compared to exercise induced ischaemia. All patients who were detected to have silent myocardial ischaemia had significant coronary artery disease. These findings are of prognostic and therapeutic value.     

吸烟量对急性心肌梗死墓碑形ST段患者临床预后的影响

目的 :探讨吸烟量对急性心肌梗死 （AMI）早期墓碑形ST段抬高患者发病年龄、临床险恶特点和心电图特征的影响。方法 :分析心电图检测AMI早期墓碑形ST段抬高患者 5 9例中不吸烟 11例 ,少量吸烟 18例 ,大量吸烟 30例的临床特点和心电图某些指标。结果 :吸烟患者占 81% ,其中大量吸烟患者占 6 3%。吸烟者AMI发病年龄提前 ,前壁或复合前壁多见 ,并发泵衰竭 ,恶性心律失常、MI扩展发生比例大 （P <0 .0 5 ）。 1周内病死率高 （P <0 .0 1） ,心电图指标PTFv1负值增大 ,QTc间期延长、ST段抬高 /振幅加大和血清肌酸激酶显著升高 （P <0 .0 5 ）均以大量吸烟居多。吸烟量越大时间越长 ,AMI病死率相对危险度越高。结论 :吸烟能影响墓碑形ST段抬高AMI患者的近期预后。     

Three-year follow-up of patients with right bundle branch block and ST segment elevation in the right precordial leads: Japanese Registry of Brugada Syndrome. Idiopathic Ventricular Fibrillation Investigators

OBJECTIVES: We sought to determine the prevalence of right bundle branch block (RBBB) and ST segment elevation in the working Japanese population, as well as the event rate during a three-year prospective follow-up period. BACKGROUND: A poor prognosis of RBBB and ST segment elevation has been reported in Europe and South America, even in asymptomatic patients; however, a large population of asymptomatic patients with sporadic RBBB and ST segment elevation has not been studied. METHODS: Ten thousand 12-lead electrocardiograms (ECGs) were obtained during annual check-ups of working adults in the Tokyo area. This three-year prospective follow-up study consisted of 105 patients, including 20 with ventricular fibrillation, 18 with syncope and 67 who were asymptomatic. They were registered from 46 institutions in Japan. RESULTS: The prevalence of ECG abnormalities in working adults was 0.16%. A coved-type ST segment elevation was related to a history of cardiac events, and 18% of registered patients had PR prolongation and 9.5% had left-axis deviation. The cumulative cardiac event-free rate was 67.6% in the symptomatic group and 93.4% in the asymptomatic group (p = 0.0004) after three years. CONCLUSIONS: The recurrence rate of cardiac events in symptomatic patients was similar to that reported previously, but it was very low in sporadic asymptomatic patients. The ECG findings may help us to select patients for further examination and more accurate evaluation of their prognoses.     

Autonomic Dysfunction and Silent Myocardial Ischaemia on Exercise Testing in Diabetes Mellitus

The incidence and mechanism of painless myocardial ischaemia on exercise testing in diabetic patients is not clear. Therefore, two studies were performed. Retrospectively, all exercise tests carried out in our hospital during the past 5 years were reviewed for silent ischaemia. Prospectively, diabetic patients with known or suspected coronary artery disease underwent autonomic function testing and a second exercise test. Of 1653 exercise tests reviewed, 247 were positive (ST depression > 0.1 mV). Of the 29 diabetic patients with positive tests 20 (69%) had painless ST depression, compared with 77 (35%) of the 218 non-diabetic patients (p < 0.001). The diabetic patients with painful and painless ST depression were comparable for age, sex, therapy, but the 20 with no pain on exercise testing had a longer duration of diabetes and a higher incidence of microvascular complications than the 9 with pain (70 vs 22%, p < 0.05). In the prospective study, 12 of 30 diabetic patients with positive exercise tests had pain in association with ST depression and 18 had no pain. Six patients had mild and 12 severe autonomic neuropathy on formal testing. Twelve had no autonomic dysfunction. Eleven (92%) of 12 patients with severe neuropathy had painless ST depression, compared with 7 (39%) of 18 without severe neuropathy (p < 0.01). Thus, silent myocardial ischaemia on exercise testing is common among patients with diabetes mellitus and is associated with severe autonomic dysfunction.     

Exercise performance-based outcomes of medically treated patients with coronary artery disease and profound ST segment depression

OBJECTIVES

We sought to determine the relationship between exercise duration and cardiovascular outcomes in patients with profound (≥2 mm) ST segment depression during exercise treadmill testing (ETT).

BACKGROUND

Patients with stable symptoms but profound ST segment depression during ETT are often referred for a coronary intervention on the basis that presumed severe coronary artery disease (CAD) will lead to unfavorable cardiovascular outcomes, irrespective of symptomatic and functional status. We hypothesized that good exercise tolerance in such patients treated medically is associated with favorable long-term outcomes.

METHODS

We prospectively followed 203 consecutive patients (181 men; mean age 73 years) with known stable CAD and ≥2 mm ST segment depression who are performing ETT according to the Bruce protocol for an average of 41 months. The primary end point was occurrence of myocardial infarction (MI) or death.

RESULTS

Eight (20%) of 40 patients with an initial ETT exercise duration ≤6 min developed MI or died, as compared with five (6%) of 84 patients who exercised between 6 and 9 min and three (3.8%) of 79 patients who exercised ≥9 min (p = 0.01). Compared with patients who exercised ≤6 min, increased ETT duration was significantly associated with a reduced risk of MI/death (6 to 9 min: relative risk [RR] = 0.25, 95% confidence interval [CI] 0.08 to 0.76; >9 min: RR = 0.14, 95% CI 0.04 to 0.53). This protective effect persisted after adjustment for potentially confounding variables. We observed a 23% reduction in MI/death for each additional minute of exercise the patient was able to complete during the index ETT.

CONCLUSIONS

Optimal medical management in stable patients with CAD with profound exercise-induced ST segment depression but good ETT duration is an appropriate alternative to coronary revascularization and is associated with low rates of MI and death.     

急性心肌梗死患者溶栓前ST段偏移总和值的预示价值

目的:探讨急性心肌梗死（AM I）患者溶栓前ST段偏移总和值对院内心功能情况的预示价值。方法:序贯入选我院心内科1997年2003年收治的首次发生AM I并接受溶栓治疗的患者,记录并对其临床资料进行回顾性分析。结果:符合入选标准的患者有136例,40例患者院内发生心功能不全,占29.4%。以溶栓前ST段偏移总和值将患者分为A组、B组、C组,组间比较:溶栓前ST段偏移总和值越高,患者院内心功能不全的发生率越高。Logis-tic多因素逐步回归分析显示:溶栓前ST段偏移总和值是该组患者院内发生心功能不全的独立危险因素,关联强度（OR值）为2.992（P=0.006）。结论:溶栓前ST段偏移总和值指标有助于早期识别发生院内心功能不全的高危AM I患者,以加强治疗,改善预后。     

Prognostic significance of transient myocardial ischaemia after first acute myocardial infarction: five year follow up study.

OBJECTIVE--To assess the five year prognostic significance of transient myocardial ischaemia on ambulatory monitoring after a first acute myocardial infarction, and to compare the diagnostic and long term prognostic value of ambulatory ST segment monitoring, maximal exercise testing, and echocardiography in patients with documented ischaemic heart disease. DESIGN--Prospective study. SETTING--Cardiology department of a teaching hospital. PATIENTS--123 consecutive men aged under 70 who were able to perform predischarge maximal exercise testing. INTERVENTIONS--Echocardiography two days before discharge (left ventricular ejection fraction), maximal bicycle ergometric testing one day before discharge (ST segment depression, angina, blood pressure, heart rate), and ambulatory ST segment monitoring (transient myocardial ischaemia) started at hospital discharge a mean of 11 (SD 5) days after infarction. MAIN OUTCOME MEASURES--Relation of ambulatory ST segment depression, exercise test variables, and left ventricular ejection fraction to subsequent objective (cardiac death or myocardial infarction) or subjective (need for coronary revascularisation) events. RESULTS--23 of the 123 patients had episodes of transient ST segment depression, of which 98% were silent. Over a mean of 5 (range 4 to 6) years of follow up, patients with ambulatory ischaemia were no more likely to have objective end points than patients without ischaemic episodes. If, however, subjective events were included an association between transient ST segment depression and an adverse long term outcome was found (Kaplan-Meier analysis; P = 0.004). The presence of exercise induced angina identified a similar proportion of patients with a poor prognosis (Kaplan-Meier analysis; P < 0.004). Both exertional angina and ambulatory ST segment depression had high specificity but poor sensitivity. The presence of exercise induced ST segment depression was of no value in predicting combined cardiac events. Indeed, patients without exertional ST segment depression were at increased risk of future objective end points (Kaplan-Meier analysis; P < 0.0045). These findings may be explained in part by a higher prevalence of left ventricular dysfunction in patients without ischaemic changes in the exercise electrocardiogram (P < 0.05). CONCLUSION--There seem to be limited reasons to perform ambulatory ST segment monitoring in survivors of a first myocardial infarction who can perform exercise tests before discharge. Patients at high risk of future myocardial infarction or death from cardiac causes are not identified. Ambulatory monitoring and exertional angina distinguish a small subset of patients who will develop severe angina pectoris demanding coronary revascularisation during follow up. Patients without exercise induced ST segment depression comprise a high risk subgroup in terms of subsequent objective end points. The role of ambulatory ST segment monitoring performed in unselected patients immediately after infarction when risk is maximal remains to be clarified.     

Prognostic value of an electrocardiogram at rest and exercise test in patients admitted with suspected acute myocardial infarction, in whom the diagnosis is not confirmed

The prognosis following discharge in 217 patients admitted with suspected acute myocardial infarction (AMI) due to chest pain, but in whom AMI was not confirmed, was related to the electrocardiogram (ECG) at rest and a symptom-limited exercise test. The patients were followed for 12 to 24 months, (median 14 months). The end-point was a cardiac event, i.e. non-fatal AMI or cardiac death. The prognosis after discharge was only slightly better than in a comparable group of patients with confirmed AMI (P = 0.05). The percentages without a cardiac event after one year were 91.3 and 86.1, respectively. Impaired prognosis was found in patients with negative T waves or ST depression at rest or with ST--T abnormalities or angina pectoris during exercise. Patients with ST depression or elevation, Q wave or intraventricular block at rest. ST abnormalities during exercise or both constituted a high-risk group. The prognosis was significantly better for patients without these entities. The percentage without a cardiac event after one year was 86.9 and 97.6, respectively. It is concluded that patients in whom AMI is not confirmed have a high risk of cardiac events following discharge. Signs of ischaemic heart disease in the ECG at rest and during exercise can be used to identify high and low risk patients.     

Value of the treadmill exercise test in asymptomatic and minimally symptomatic patients with chronic severe aortic regurgitation

The value of the graded treadmill exercise test was assessed in 19 asymptomatic and minimally symptomatic (13 NYHA class I and 6 NYHA class II) male patients with chronic severe aortic regurgitation. It was observed that, in 2 patients who showed significant ST segment depression at peak exercise, the total exercise duration was significantly shorter (P less than 0.001) than in the patients not showing such changes. During left ventricular and aortic root angiography (in both patients) and selective left coronary angiography (in one of them), ST segment changes similar to those seen during exercise testing were observed. The mean rise in left ventricular end-diastolic pressure after injection of contrast material was significantly more (P less than 0.001) in these 2 patients compared to the other 17 patients. Both patients had normal resting M-mode echocardiographic parameters. It is concluded that ST segment depression on exercise testing and reduced exercise capacity are indicants of exercise-induced left ventricular dysfunction in asymptomatic and minimally symptomatic patients with chronic severe aortic regurgitation. Furthermore, it is suggested that this simple and cheap test can be used for serial evaluation of such patients in the absence of the facility of radionuclide cineangiography.     

Predischarge maximal exercise test identifies risk for cardiac death in patients with acute myocardial infarction

A maximal exercise test was performed in 54 patients with acute myocardial infarction (AMI) before discharge and in 49 age-matched control subjects. The long-term prognosis was assessed after an average follow-up of 7.6 years in AMI patients and 5.8 years in control subjects. The maximal work capacity and systolic blood pressure increase in AMI patients was 59% that of control subjects (p less than 0.001). Seventeen AMI patients had significant ST-segment shifts, 13 with ST depression and 4 with ST elevation. In AMI patients experiencing a cardiac death during follow-up the maximal work capacity and systolic blood pressure increase were significantly lower than in survivors and those who died from noncardiac reasons (p less than 0.01; p less than 0.05), with no difference between these groups in the number of patients with ST-segment shifts. The average maximal work capacity of control subjects was 143 watts. A maximal work capacity half this (less than or equal to 72 watts) predicted long-term mortality in AMI patients (p less than 0.001). In addition a low increase in systolic blood pressure (less than 30 mm Hg) also predicted long-term mortality (p less than 0.005), whereas ST shifts were of no significant value. In this study maximal work capacity turned out to be the best single exercise variable for identifying groups of AMI patients with very low and relative high risk of cardiac death. When all 3 exercise variables were combined, the predischarge maximal exercise test was of great value in identifying AMI patients at low risk for cardiac death (predictive value of a negative test: 95%).