Prognostic significance of silent myocardial ischaemia during maximal exercise testing after a first acute myocardial infarction

Clinical, exercise, and angiographic variables, and long-termfollow-up were compared in patients, who, during maximal Bruceexercise testing after a first acute myocardial infarction (AMI),had positive responses to exercise testing (n = 116, 38% of303) with (n % 23, group I) or without (n = 93, group II) angina.Group I patients more often (52 vs 19%, P < 0.001) had ahistory of pre-infarction angina. Group II had a greater proportion(75 vs 52%, P < 0.05) of inferior wall AMI, whereas groupI had a greater proportion (30 vs 19%, P < 0.01) of non-Qwave AMI. Total exercise duration was significantly (P <0.01) longer in group II (7.6 ± 3.2 vs 5.5 ± 3.1min). Maximal exercise heart rate (144 ± 22 vs 133 ±21, beats . min^–1 P < 0.05 was also higher in groupII. A greater proportion of group II patients (37 vs 9%, P <0.05) had single-vessel disease, whereas multivessel diseasewas more common (91 vs 63% P < 0.03) in group I. Left ventricularfunction was similar in both groups. During follow-up (48 ±22 months) the incidence of cardiac death (group I, 3.3%, groupII, 4.8%), of recurrent infarction (group I, 4.8%, group II3.3%), and of revascularization procedures (group I, 28.5%,group II, 19.8%) were similar in both groups. Although asymptomaticexercise-induced ischaemia was associated with better exerciseperformance and less extensive coronary disease than symptomaticischaemia, it had the same long-term prognostic implications.     

Thrombolysis significantly reduces transient myocardial ischaemia following first acute myocardial infarction.

In order to investigate whether thrombolysis affects residual myocardial ischaemia, we prospectively performed a predischarge maximal exercise test and early out-of-hospital ambulatory ST segment monitoring in 123 consecutive men surviving a first acute myocardial infarction (AMI). Seventy-four patients fulfilled our criteria for thrombolysis, but only the last 35 patients included received thrombolytic therapy. As thrombolysis was not available in our Department at the start of the study, the first 39 patients included were conservatively treated (controls). No significant differences in baseline clinical characteristics were found between the two groups. In-hospital atrial fibrillation and digoxin therapy was more prevalent in controls (P less than 0.05). During exercise, thrombolysed patients reached a higher maximal work capacity compared with controls: 160 +/- 41 vs 139 +/- 34 W (P less than 0.02). Thrombolysis resulted in a non-significant reduction in exercise-induced ST segment depression: prevalence 43% vs 62% in controls. However, during ambulatory monitoring the duration of transient myocardial ischaemia was significantly reduced in thrombolysed patients: 322 min vs 1144 min in controls (P less than 0.05). Thrombolysed patients reached a higher heart rate during transient ischaemic episodes: 114 +/- 17 vs 93 +/- 11 b.min-1 in controls (P less than 0.001). In conclusion, thrombolytic therapy administered for a first AMI significantly reduces the burden of transient myocardial ischaemia. This may explain the improvement in myocardial function during physical activities, which was also observed in this study.     

Changing circadian variation of transient myocardial ischemia during the first year after a first acute myocardial infarction.

In a consecutive series of 123 men (aged 55 +/- 8 years) with a recent first acute myocardial infarction (AMI), 24-hour ambulatory ST-segment monitoring was performed early after discharge (day 11 +/- 5), 6 months (day 185 +/- 6) and 1 year (day 368 +/- 8) after AMI. No difference in the prevalence of transient myocardial ischemia was found between the 3 recordings (17, 17 and 20%), and most ischemic episodes were silent (98, 100 and 97%). In the early postinfarction period, a peak of ischemic activity was demonstrated between 6 P.M. and midnight (40 of 93 episodes [43%]). Over time, the maximal occurrence of ischemia gradually advanced toward the morning hours with a peak activity between 6 A.M. and noon at 1-year follow-up (32 of 73 episodes [44%]). Significantly more patients (16 of 21 [76%]) had ischemia from 6 P.M. to midnight at discharge compared with the findings 1 year later (9 of 23 patients [39%]) (p < 0.03). An opposite trend was found regarding patients who exhibited ischemic episodes in the hours from 6 A.M. to noon: 10 of 21 patients (48%) early after discharge versus 17 of 23 patients (74%) at 1-year follow-up (p = not significant). Results from the 6-month recording displayed characteristics between the findings from discharge and 1-year ambulatory monitoring. The pathophysiologic processes underlying the observations from this study are unknown. The change in circadian periodicity could not be explained from differences in heart rate variation patterns or medical antianginal treatment among the 3 recordings.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transient myocardial ischaemia after acute myocardial infarction.

The prevalence and characteristics of transient myocardial ischaemia were studied in 203 patients with recent acute myocardial infarction by both early (6.4 days) and late (38 days) ambulatory monitoring of the ST segment. Transient ST segment depression was much commoner during late (32% patients) than early (14%) monitoring. Most transient ischaemia (greater than 85% episodes) was silent and 80% of patients had only silent episodes. During late monitoring painful ST depression was accompanied by greater ST depression and tended to occur at a higher heart rate. Late transient ischaemia showed a diurnal distribution, occurred at a higher initial heart rate, and was more often accompanied by a further increase in heart rate than early ischaemia. Thus in the first 2 months after myocardial infarction transient ischaemia became increasingly common and more closely associated with increased myocardial oxygen demand. Because transient ischaemic episodes during early and late ambulatory monitoring have dissimilar characteristics they may also have different pathophysiologies and prognostic implications.     

Prognostic significance of angina pectoris before first acute myocardial infarction

To delineate the clinical significance and prognostic importance of a history of chronic or new onset angina pectoris before acute myocardial infarction (AMI), 732 consecutive patients admitted for a first AMI were studied and divided into 3 groups. Two hundred patients (27%) had chronic angina before AMI (greater than 1 month); 247 patients (34%) had new onset angina before AMI (less than 1 month) and the 285 remaining patients (39%) never had angina before AMI. All clinical characteristics were similar in the group of patients with chronic angina and in the group of patients with new onset angina, including in-hospital mortality (10 vs 9%) and 3-year post-hospital mortality (16 vs 16%). Compared to the 285 patients without angina, the 447 patients with angina before AMI were older, more likely to be women, and had a higher frequency of anterior AMI and early post-infarction angina. Both groups had a similar in-hospital mortality (10 vs 8%, not significant), but patients with angina had a higher 3-year post-hospital mortality (16 vs 7%, p less than 0.001). In the group of patients with angina before AMI who were discharged from the hospital, the comparison of nonsurvivors and survivors showed that the patients who died were older, presented more frequently with a non-Q-wave myocardial infarct and more often had left ventricular failure and complete bundle branch block during hospital stay. Chronic and new onset angina before AMI have the same clinical characteristics and deleterious long-term prognostic significance.     

Antiphospholipid syndrome: five year follow up.

Nineteen patients out of 250 subjects with antiphospholipid antibodies, who had initially presented to the lupus clinic at St Thomas's Hospital, London five or more years ago with a history of venous/arterial occlusions, were entered into the study. The patients were divided into two main groups: I those who remained well without any further thromboembolic complications (n = 10); II those who developed recurrent thrombotic events in the five year period (n = 9). The patients were followed up to determine the relation between the level or the isotype of the anticardiolipin antibodies, or both, to the recurrent thromboembolic events, and the effect of a variety of treatments (corticosteroids, immunosuppression, anticoagulation) in the prevention of further vascular occlusions. Lupus activity over the five year period varied considerably between the two groups--those in group I tending to be relatively inactive compared with those in group II. For some patients in group II thromboembolic events seemed to occur at the time of lupus activity. Antiphospholipid antibodies remained positive in all patients, the levels remaining fairly constant. Levels fell in only one patient in group I and in two in group II. Patients in group II had more systemic lupus erythematosus related disease than those in group I; most were receiving concomitant steroid and immunosuppressive therapy, but this did not seem to protect against the development of further occlusions. All patients were given anticoagulation treatment (warfarin/heparin) or salicylates (low dose aspirin 75 mg daily), or both. Patients with deep vein thromboses developed more complications during anticoagulation therapy than those with cerebrovascular symptoms. Problems in anticoagulation control and recurrent thromboses consequent on warfarin withdrawal despite the administration of subcutaneous heparin were responsible for complications in most patients in group II.     

Prognostic cardiac catheterization variables in survivors of acute myocardial infarction: a five year prospective study

The prognostic variables from predischarge coronary angiography and left ventriculography in survivors of acute myocardial infarction during the years 1974 to 1978 were evaluated in 143 patients (less than or equal to 66 years of age) with documented myocardial infarction who were then followed up prospectively for 5 years. One half of the study population had triple vessel coronary disease (greater than or equal to 50% stenosis). However, only 7% of patients had severely depressed left ventricular function with an ejection fraction less than or equal to 29%. Evaluation of the contribution of many clinical and angiographic variables to a first cardiac event (death, nonfatal reinfarction or coronary artery bypass surgery) was considered with Kaplan-Meier actuarial curves and multivariate Cox's hazard function analysis. A risk segment was defined as an area of contracting myocardium supplied by a coronary artery with a greater than 50% stenosis. Multivariate analysis demonstrated that right plus left anterior descending coronary artery stenoses (p less than 0.01), ejection fraction (p less than 0.01) and the presence of risk segments (p less than 0.05) were significant predictors of outcome. Furthermore, on separate multivariate analyses, the angiographic variables added significantly to the clinical variables to predict cardiac events over 5 years of follow-up. Therefore, in survivors of acute myocardial infarction who undergo cardiac catheterization, additive prognostic information is obtained that can be used to stratify risk over 5 years.     

Prognostic significance of transient ST segment changes after coronary artery bypass surgery: a long-term (4-10 year) follow up study.

OBJECTIVE--To assess the long-term (four to 10 years) prognostic significance of transient ST segment changes on ambulatory ST segment monitoring after coronary artery bypass grafting (CABG). PATIENTS AND METHODS--76 patients (67 men, nine women) underwent CABG between 1982 and 1984 (n = 31) and between 1987 and 1988 (n = 45) and at a mean age of 57. All underwent 48 hours of ambulatory ST segment monitoring at a mean of 19 weeks after surgery. The results were available for assessment. All general practitioners were contacted and patients' notes reviewed. Patients were contacted by telephone. Details were recorded of intervening events (acute myocardial infarction, unstable angina, need for further revascularisation, and deaths). Event free survival curves were produced for those with and without transient ST segment changes during routine postoperative ambulatory ST segment monitoring. RESULTS--During 3213 hours of monitoring after CABG, 21 (27.6%) of 76 patients had transient ST segment changes, of which 70% were silent. Over a mean 70 month follow up period, patients with such ischaemic changes were no more likely to have either an objective (myocardial infarction or cardiac death) or subjective (unstable angina or another revascularisation) event than those patients without ischaemic changes. This finding was the same in patients operated on between 1987 and 1988 and between 1982 and 1984. CONCLUSIONS--Although ambulatory ST segment monitoring is becoming increasingly popular in some countries as a routine investigation for ischaemia in various coronary subgroups, the findings of such an investigation, when performed after CABG, do not help to identify a subgroup more likely to have an adverse outcome during up to 10 years of follow up. There seems to be no reason to perform this investigation after surgery, and particularly to refer patients for reinvestigation because of the detection of predominantly silent ST segment changes of uncertain relevance.     

Transient myocardial ischaemia after acute myocardial infarction

The prevalence and characteristics of transient myocardial ischaemia were studied in 203 patients with recent acute myocardial infarction by both early (6.4 days) and late (38 days) ambulatory monitoring of the ST segment. Transient ST segment depression was much commoner during late (32% patients) than early (14%) monitoring. Most transient ischaemia (greater than 85% episodes) was silent and 80% of patients had only silent episodes. During late monitoring painful ST depression was accompanied by greater ST depression and tended to occur at a higher heart rate. Late transient ischaemia showed a diurnal distribution, occurred at a higher initial heart rate, and was more often accompanied by a further increase in heart rate than early ischaemia. Thus in the first 2 months after myocardial infarction transient ischaemia became increasingly common and more closely associated with increased myocardial oxygen demand. Because transient ischaemic episodes during early and late ambulatory monitoring have dissimilar characteristics they may also have different pathophysiologies and prognostic implications.     

Prognostic significance of late ventricular potentials after acute myocardial infarction

The prognostic significance of late ventricular potentials recordedfrom the body surface using high-gain amplification and signalaveraging was assessed prospectively in 160 patients (mean age56±8.3 years) after recent acute myocardial infarction(median day of study 25.5). Late potentials were recorded in 81 out of 160 patients (50.6%);a duration of less than 20 ms was observed in 33 patients (20.6%),whereas late potentials of 20 ms duration or more were presentin 48 patients (30%). The mean duration of late potentials was27 ± 16.5 ms. There was no significant correlation withthe frequency and type of spontaneous ventricular arrhythmiasduring 10–24 h Holter monitoring. The follow-up period was 7.5±3.2 months (mean ±s.D.;maximum 15.8 months). In 136 patients (85%) the course afterdischarge was uneventful. Sudden cardiac death occurred in sevenpatients (4.4%) after 3.7± 3.4 months (range 0.7–8.3months). Sustained ventricular tachycardia was documented infour cases 2.9± 1.3 months after myocardial infarction,all having late potentials. The overall incidence of ventriculartachycardia in patients with late potentials of 20 ms durationand more was four out of 48 patients (8.3%) increasing to 16.6%(three out of 18 patients) if only patients with late potentialsgreater than 40 ms were considered. Sudden cardiac death occurredin three of 79 patients (3.8%) without late potentials. In patientswith late potentials less than 40 ms duration, the incidenceof sudden death was 3.2% (two out of 63 patients), but it increasedto 11.1% (two out of 18 patients) with late potentials of 40ms duration or more. Ventricular tachycardia or sudden deathoccurred in 21.7% of patients with late potentials and anteriorwall infarction compared to 5.4% in patients with late potentialsand inferior wall infarction (P<0.05). Only one of 79 patients(1.3%) without late potentials died non-suddenly from a cardiaccause (reinfarction) compared to three of 81 patients (3.7%)with late potentials irrespective of duration. Thus, this prospective multicentre pilot study suggests thataveraging might be a promising non- invasive technique for theidentification of patients prone to ventricular tachycardiaor possibly even sudden death after recent acute myocardialinfarction.     

Influence of coronary nursing management follow up on lifestyle after acute myocardial infarction.

OBJECTIVE: To examine the ability of a secondary prevention programme to improve the lifestyle in myocardial infarction patients aged 50-70 years. DESIGN: Habitual physical activity, food habits, and smoking habits were assessed from questionnaires at admission to hospital and at the one year follow up. Initially, all patients were invited to join an exercise programme and were informed about cardiovascular risk factors. Four weeks after discharge from the hospital, 87 patients were randomised to follow up at the coronary prevention unit by a special trained nurse (the intervention group), and 81 to follow up by their general practitioners (the usual care group). After randomisation, the intervention group was educated about the effects of smoking cessation, dietary management, and regular physical activity. The intervention group also participated in a physical training programme two to three times weekly for 10-12 weeks. MAIN RESULTS: 89% of the patients referred to the intervention group improved their food habits compared with 62% of the patients referred to the usual care group (P = 0.008). Furthermore, 50% of the smokers referred to the intervention group stopped smoking compared to 29% in the usual care group (P = 0.09). Changes in physical activity did not differ between the groups. CONCLUSIONS: This secondary prevention programme based on a nurse rehabilitator was successful in improving food habits in patients with acute myocardial infarction. Initiating the smoking cessation programme during the hospital stay followed by repeated counselling during follow up might have improved the results. The exercise programme had no advantage in supporting physical activity compared to usual care.     

Transient ischaemia after acute myocardial infarction: relationship to exercise ischaemia

To study the implications of transient myocardial ischaemia following acute myocardial infarction we compared ambulatory ST segment monitoring with exercise treadmill testing in 170 patients (mean age 58 years) at 4-8 weeks after admission. Ambulatory monitoring detected transient ischaemia (265 episodes; 249 (94%) silent) in 53/170 patients (31%) which was less frequent than ischaemia during exercise testing (90 patients; 53%) (P less than 0.0001). However, patients displaying transient ambulatory ischaemia (i) achieved less total exercise (248.7 +/- 17.2 vs 318.7 +/- 14.1 s; means +/- SEM) (P less than 0.006), (ii) developed exercise ST deviation earlier (172.4 +/- 14.3 vs 244.8 +/- 16.2 s) (P less than 0.0004) and (iii) had more widespread exercise ischaemia (3.8 +/- 0.3 vs 2.5 +/- 0.2 ECG leads) (P less than 0.005). Positive ambulatory ST segment monitoring was infrequently found (12/80 patients; 15%) in the presence of a negative exercise test but did identify the majority of patients (9/11 patients; 82%) with easily provoked exercise ischaemia and hence strongly positive exercise tests. These data suggest a limited role for routine 24 h ambulatory monitoring after myocardial infarction for the diagnosis of ongoing ischaemia but raise the possibility of an important place for this test in prognosis and risk stratification.     

Primary stenting in acute myocardial infarction: A 30-day follow up study

Primary coronary stenting is being increasingly used in patients undergoing primary coronary angioplasty for acute myocardial infarction. In this prospective study we evaluated our experience of direct angioplasty in 68 patients with acute myocardial infarction of whom 57 received intracoronary stents using high-pressure deployment (≥12 atmospheres) with adjunct aspirin and ticlopidine therapy without coumadin. All patients underwent pre-discharge follow-up angiography. Stent implantation was successful in all patients. Stent thrombosis was not seen in any patient. However, TIMI grade 3 flow was obtained in only 51 patients (89.6%) with evidence of slow flow present in remaining six patients. Follow-up angiograms showed no stent thrombosis but five out of the six patients (83%) with slow-flow phenomenon persisted to have slow flow. These patients had lower left ventricular ejection fraction as compared to patients with TIMI 3 flow at follow-up angiography (27.5 ± 10.2% vs. 42.1 ± 15.2%, P < .001) and a high mortality (two out of six) within 30 days. Primary stenting is safe and feasible in the majority of patients with good short-term outcomes, but persistent slow-flow phenomenon with adverse clinical outcome is seen in a small but significant number of patients. Cathet. Cardiovasc. Intervent. 46:4–10, 1999. © 1999 Wiley-Liss, Inc.     

Thrombolysis siginificantly reduces transient myocardial ischaemia following first acute myocardial infraction

In the second page of this paper, under the heading ‘Exercisetesting’, the second sentence should read: ‘A totalexercise time of 15 min was sought in each patient.’Insertionof the word ‘reached’ for ‘sought’ isa publisher's error, for which we apologise.     

Arterial counterpulsation in continuing myocardial ischaemia after acute myocardial infarction.

Twenty-six patients underwent arterial counterpulsation for refractory heart failure without shock complicating acute myocardial infarction. Patients were divided into a group of 12 with continuing myocardial ischaemia, evidenced by anginal pain associated with abnormal ST segment elevation, and a group of 14 without continuing ischaemia. Clinical features (apart from pain) and prognostic indices were similar in the two groups when counterpulsation was started but short- and long-term results were different. Hospital survival was 92 per cent (11/12) and 43 per cent (6/14), respectively, in the groups with and without ischaemia and four-year survival was 73 per cent and 7 per cent. Counterpulsation is of greatest value in acute infarction when used to relieve myocardial ischaemia.     

Prognostic significance of left ventricular ejection fraction after acute myocardial infarction. A bedside radionuclide study

The prognostic significance of left ventricular ejection fraction measurements obtained at the bedside was assessed in 171 patients as soon as possible after acute myocardial infarction. Ejection fraction was measured with a radionuclide first pass portable probe method within a mean of 24 hours of the onset of major symptoms. The results were related prospectively to the subsequent incidence of ventricular fibrillation in hospital, and to hospital and postdischarge deaths in a mean follow up period of 15 (range 9-21) months. All eight episodes of primary ventricular fibrillation, all 12 deaths due to pump failure in hospital, and also 12 out of 13 postdischarge deaths occurred in that minority of 81 patients whose initial postinfarction left ventricular ejection fraction was less than 0.35. Multivariate correlation with clinical, enzymatic, and electrocardiographic indicators of myocardial infarction showed that the prognostic significance of these indicators could largely be explained by their association with low left ventricular ejection fractions. Left ventricular ejection fraction measured within the initial 24 hours after acute myocardial infarction predicts prognosis throughout the subsequent year.     

Prognostic significance of ischemic mitral regurgitation after non-Q-wave acute myocardial infarction

BACKGROUND AND AIM OF THE STUDY: The development of mitral regurgitation (MR) soon after acute myocardial infarction (AMI) is a recognized and frequent complication. Its negative impact on survival has been observed after Q-wave AMI, even when of a mild degree, and independently of left ventricular systolic function. Few data exist regarding MR after non-Q-wave AMI (nQ AMI), however. Hence, the study aim was to investigate the incidence, clinical predictors and prognostic implications of MR in the setting of nQ AMI. METHODS AND RESULTS: A total of 99 consecutive patients (37 men, 62 women; mean age 72 +/- 13 years) who suffered a nQ AMI was studied. All patients underwent echocardiography during the first week after the nQ AMI. MR was detected in 34 patients (17 men, 17 women; mean age 76 +/- 10 years). Events during follow up were coded as death, AMI, unstable angina, or heart failure. The in-hospital outcome was not significantly different between patients with and without MR. The mean follow up period was 663 +/- 574 days. In the univariate analysis, freedom from hospital survival was significantly greater in patients without MR. However, multivariate analysis showed that MR was not an independent predictor of cardiovascular hospitalization or death. CONCLUSION: The incidence of MR is high among patients with nQ AMI but, unlike results found with Q-wave AMI, its presence does not add any prognostic significance to other known negative factors in the setting of nQ AMI.     

Prognostic significance of left ventricular ejection fraction after acute myocardial infarction. A bedside radionuclide study.

The prognostic significance of left ventricular ejection fraction measurements obtained at the bedside was assessed in 171 patients as soon as possible after acute myocardial infarction. Ejection fraction was measured with a radionuclide first pass portable probe method within a mean of 24 hours of the onset of major symptoms. The results were related prospectively to the subsequent incidence of ventricular fibrillation in hospital, and to hospital and postdischarge deaths in a mean follow up period of 15 (range 9-21) months. All eight episodes of primary ventricular fibrillation, all 12 deaths due to pump failure in hospital, and also 12 out of 13 postdischarge deaths occurred in that minority of 81 patients whose initial postinfarction left ventricular ejection fraction was less than 0.35. Multivariate correlation with clinical, enzymatic, and electrocardiographic indicators of myocardial infarction showed that the prognostic significance of these indicators could largely be explained by their association with low left ventricular ejection fractions. Left ventricular ejection fraction measured within the initial 24 hours after acute myocardial infarction predicts prognosis throughout the subsequent year.