Prognostic importance of myocardial ischemia detected by ambulatory monitoring early after acute myocardial infarction

Long-term returns to local health-care spending

This paper investigates the effects of health-care spending on mortality rates of patients who experienced a heart attack. We relate in-hospital deaths to in-hospital spending and post-discharge deaths to post-discharge health-care spending. In our analysis, we use detailed administrative data on individual personal characteristics including comorbidities, information about the type of medical treatment and information about health-care expenses at the regional level. To account for potential selectivity in the region of health-care treatment we compare local patients with visitors and stayers with recent movers from a different region. We find that in regions with higher health-care spending mortality after heart attacks is substantially lower. From this we conclude that there are long-term returns to local health-care spending.

Relationship of Psychological Characteristics to Daily Life Ischemia: An Analysis From the National Heart, Lung, and Blood Institute Psychophysiological Investigations in Myocardial Ischemia

OBJECTIVE

Cardiac ischemia during daily life is associated with an increased risk of adverse outcomes. Mental stress is known to provoke cardiac ischemia and is related to psychological variables. In this multicenter cohort study, we assessed whether psychological characteristics were associated with ischemia in daily life.

METHODS

This study examined patients with clinically stable coronary artery disease (CAD) with documented cardiac ischemia during treadmill exercise (n = 196, mean [standard deviation] age = 62.64 [8.31] years; 13% women). Daily life ischemia (DLI) was assessed by 48-hour ambulatory electrocardiophic monitoring. Psychological characteristics were assessed using validated instruments to identify characteristics associated with ischemia occurring in daily life stress.

RESULTS

High scores on anger and hostility were common in this sample of patients with CAD, and DLI was documented in 83 (42%) patients. However, the presence of DLI was associated with lower anger scores (odds ratio [OR] = 2.03; 95% confidence interval [CI] = 1.12-3.69), reduced anger expressiveness (OR = 2.04; 95% CI = 1.10-3.75), and increased ratio of anger control to total anger (OR = 2.33; 95% CI = 1.27-4.17). Increased risk of DLI was also associated with lower hostile attribution (OR = 2.22; 95% CI = 1.21-4.09), hostile affect (OR = 1.92; 95% CI = 1.03-3.58), and aggressive responding (OR = 2.26; 95% CI = 1.25-4.08). We observed weak inverse correlations between DLI episode frequency and anger expressiveness, total anger, and hostility scores. DLI was not associated with depression or anxiety measures. The combination of the constructs low anger expressiveness and low hostile attribution was independently associated with DLI (OR = = 2.59; 95% CI = 1.42-4.72).

CONCLUSIONS

In clinically stable patients with CAD, the tendency to suppress angry and hostile feelings, particularly openly aggressive behavior, was associated with DLI. These findings warrant a study in larger cohorts, and intervention studies are needed to ascertain whether management strategies that modify these psychological characteristics improve outcomes.

Signal Quality Analysis of Ambulatory Electrocardiograms to Gate False Myocardial Ischemia Alarms

OBJECTIVE

The objective of this study is to propose and validate an alarm gating system for a myocardial ischemia monitoring system that uses ambulatory electrocardiogram. The PeriOperative ISchemic Evaluation study recommended the selective administration of β blockers to patients at risk of cardiac events following noncardiac surgery. Patients at risk are identified by monitoring ST segment deviations in the electrocardiogram (ECG); however, patients are encouraged to ambulate to improve recovery, which deteriorates the signal quality of the ECG leading to false alarms.

METHODS

The proposed alarm gating system computes a signal quality index (SQI) to quantify the ECG signal quality and rejects alarms with a low SQI. The system was validated by artificially contaminating ECG records with motion artifact records obtained from the long-term ST database and MIT-BIH noise stress test database, respectively.

RESULTS

Without alarm gating, the myocardial ischemia monitoring system attained a Precision of 0.31 and a Recall of 0.78. The alarm gating improved the Precision to 0.58 with a reduction of Recall to 0.77.

CONCLUSION

The proposed system successfully gated false alarms with future work exploring the misidentification of fiducial points by myocardial ischemia monitoring systems.

SIGNIFICANCE

The reduction of false alarms due to the proposed system will decrease the incidence of the alarm fatigue condition typically found in clinicians. Alarm fatigue condition was rated as the top patient safety hazard from 2012 to 2015 by the Emergency Care Research Institute.

The clinical significance of continuous ECG (ambulatory ECG or Holter) monitoring of the ST-segment to evaluate ischemia: a review

Silent ischemia is a common manifestation of coronary artery disease (CAD). Continuous ECG (cECG) monitoring is an effective tool for assessing the frequency and duration of silent ischemic episodes for patients with CAD and for risk stratifying asymptomatic patients or those after an acute coronary syndrome by identifying those at increased risk for future cardiovascular events or death. cECG also allows monitoring of the effectiveness of therapy in patients with CAD. Treatment strategies targeted toward the elimination of silent ischemia have shown that revascularization was better than medical therapy in eliminating silent ischemia, but large scale, prospective studies targeting silent ischemia as a treatment endpoint are still lacking. Future research is warranted to study the effects of newer medical agents or the selected use of revascularization in those patients with persistent silent ischemia despite current medical regiments.

24 hour ST segment analysis in transient left ventricular apical ballooning

Objective

The etiologic basis of transient left ventricular apical ballooning, a novel cardiac syndrome, is not clear. Among the proposed pathomechanisms is coronary vasospasm. Long-term ST segment analysis may detect vasospastic episodes but has not been reported.

Methods

30 consecutive patients with transient left ventricular apical ballooning, left ventricular dysfunction and normal or near-normal coronary arteries were investigated. A 24-hour Holter ECG was obtained after emergency admission. ST segment analysis was performed automatically in 2 leads and confirmed by visual inspection. Criteria for an ischemic event were: 1. ST elevation or 2. horizontal or down-sloping ST segments ≥1 min duration and ≥100 µV J+80 point deviation corrected for baseline ST-deviation.

Results

Patients presented with ST segment elevation (n = 19) and/or T wave inversion (n = 20) on admission ECG. Ejection fraction was 50±12%. No transient ST elevations were observed during Holter ECG analysis. In 3 patients, 8 transient episodes of ST depression were recorded. Durations of episodes varied between 75s and 790s (mean 229s). Maximal ST deviation averaged −191±71 µV. Ischemic burden was −1 to −22 mVs (mean −8 mVs). 27 patients showed no ischemic events.

Conclusions

ST segment analysis of 24 h Holter recordings revealed minor ischemic events in only 10% of patients with transient left ventricular apical ballooning. Overall, ST segment changes were not indicative of recurrent coronary spasm playing a major role in the genesis of transient left ventricular apical ballooning.

Comparison of outcomes of patients with painless versus painful ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention

There are few data available on the prognosis of painless ST-segment elevation myocardial infarction (STEMI). The aim of this study was to determine the incidence, clinical characteristics, and outcomes of painless STEMI. We analyzed the Korea Acute Myocardial Infarction Registry (KAMIR) study, which enrolled 7,288 patients with STEMI (61.8 ± 12.8 years old, 74% men; painless STEMI group, n = 763; painful STEMI group, n = 6,525). End points were in-hospital mortality and 1-year major adverse cardiac events (MACEs). Patients with painless STEMI were older and more likely to be women, nonsmokers, diabetic, and normolipidemic and to have a higher Killip class. The painless group had more in-hospital deaths (5.9% vs 3.6%, p = 0.026) and 1-year MACEs (26% vs 19%, p = 0.002). In Cox proportional hazards analysis, hypotension (hazard ratio [HR] 4.40, 95% confidence interval [CI] 1.41 to 13.78, p = 0.011), low left ventricular ejection fraction (HR 3.12, 95% CI 1.21 to 8.07, p = 0.019), and a high Killip class (HR 3.48, 95% CI 1.19 to 10.22, p = 0.023) were independent predictors of 1-year MACEs in patients with painless STEMI. In conclusion, painless STEMI was associated with more adverse outcomes than painful STEMI and late detection may have contributed significantly to total ischemic burden. These results warrant more investigations for methodologic development in the diagnosis of silent ischemia and painless STEMI.

Prognostic value of high sensitive C-reactive protein in subjects with silent myocardial ischemia

OBJECTIVES

The aim of this study was to evaluate the prognostic value of high sensitive C-reactive protein (CRP) in subjects with silent myocardial ischemia (SMI).

DESIGN

In total, 678 healthy men and women aged 55 to 75 years with no history of cardiovascular disease or stroke were included. High-sensitive CRP and 48-hour ambulatory ECG monitoring were performed. The primary endpoint was the combined endpoint of death and myocardial infarction.

RESULTS

The median follow-up time was 76 months. Seventy-seven subjects (11.4%) had SMI. The combined endpoint occurred in 26% of the subjects with SMI and 14% of the subjects without SMI (P = .005). SMI had a poor prognosis in the group with an elevated CRP ≥ 3.0 μg/mL (hazard ratio, 3.46; 95% confidence interval, 1.67-7.16; P = .001) compared with the group of subjects with SMI and a low CRP <3.0 μg/mL (hazard ratio, 1.37; 95% confidence interval, 0.63-2.98; P = .54).

CONCLUSIONS

In apparently healthy subjects, a low level of CRP <3.0 μg/mL selects a low-risk subgroup, despite the presence of SMI.

Silent myocardial ischemia

Although much progress has been made in reducing mortality from ischemic cardiovascular disease, this condition remains the leading cause of death throughout the world. This might in part be due to the fact that over half of patients have a catastrophic event (heart attack or sudden death) as their initial manifestation of coronary disease. Contributing to this statistic is the observation that the majority of myocardial ischemic episodes are silent, indicating an inability or failure to sense ischemic damage or stress on the heart. This review examines the clinical characteristics of silent myocardial ischemia, and explores mechanisms involved in the generation of angina pectoris. Possible mechanisms for the more common manifestation of injurious reductions in coronary flow; namely, silent ischemia, are also explored. A new theory for the mechanism of silent ischemia is proposed. Finally, the prognostic importance of silent ischemia and potential future directions for research are discussed.

Prognostic value of predischarge radionuclide ventriculography at rest and exercise after acute myocardial infarction treated with thrombolytic therapy or primary coronary angioplasty. The Zwolle Myocardial Infarction Study Group

BACKGROUND

Previous studies have demonstrated the prognostic value of radionuclide ventriculography at rest and exercise in patients post myocardial infarction (MI). The number of studies in patients treated with modern reperfusion techniques, including thrombolysis or primary angioplasty, however, is limited.

HYPOTHESIS

The aim of this study was to evaluate the prognostic significance of predischarge radionuclide ventriculography at rest and exercise in patients with acute MI treated with thrombolysis or primary angioplasty.

METHODS

A total of 272 consecutive patients with acute MI who were randomized to thrombolysis or primary coronary angioplasty underwent predischarge resting and exercise radionuclide ventriculography. Left ventricular ejection fraction at rest, decrease in ejection fraction during exercise > 5 units below the resting value, angina pectoris, ST-segment depression, and exercise test ineligibility were related to subsequent cardiac events (cardiac death, nonfatal reinfarction) during follow-up.

RESULTS

During a mean follow-up of 30 +/- 10 months, cardiac death occurred in 11 (4%) patients and nonfatal reinfarction in 14 (5%) patients. Resting left ventricular ejection fraction was the major risk factor for cardiac death. In patients with an ejection fraction < 40%, cardiac death occurred in 16% compared with 2% in those with an ejection fraction > or = 40% (p = 0.0004). In addition, cardiac death tended to be higher in patients ineligible than in those eligible for exercise testing (11 vs. 3%, p = 0.08). None of the other exercise variables (decrease in ejection fraction during exercise > 5 units below the resting value, angina pectoris or ST-segment depression) were predictive for cardiac death. When all exercise test variables in each patient were combined and expressed as a risk score, a low risk (n = 185) and a higher risk (n = 87) group of patients could be identified, with cardiac death occurring in 1 and 10%, respectively. As the predictive accuracy of a negative test was high, radionuclide ventriculography was of particular value in identifying patients at low risk for cardiac death. Radionuclide ventriculography was not able to predict recurrent nonfatal MI.

CONCLUSION

In patients with MI treated with thrombolysis or primary angioplasty, radionuclide ventriculography may be helpful in identifying patients at low risk for subsequent cardiac death. In this respect, left ventricular ejection fraction at rest was the major determinant. Variables reflecting residual myocardial ischemia were of limited prognostic value. Identification of a large number of patients at low risk allows selective use of medical resources during follow-up in this subgroup and has significant implications for the cost effectiveness of reperfusion therapies.

The electrocardiogram as a prognostic tool for predicting major cardiac events

Among patients with cardiac disease, the identification of those who are at low risk and those who are at high risk for major cardiac events is crucial for a rational clinical management of individual patients. A correct noninvasive risk stratification of cardiac patients, in particular, has relevant clinical implications because it would avoid unnecessary exposure to potentially risky invasive diagnostic or interventional procedures in low-risk patients, whereas it would allow an appropriate aggressive diagnostic and therapeutic approach in high-risk patients. Furthermore, the appropriate identification of low- and high-risk patients would also have social and economic implications by favoring optimization of resource distribution and costs. A large number of studies in previous decades provided evidence that several methods and variables derived from the analysis of the electrocardiogram (ECG) are powerful predictors of major cardiac events in several clinical conditions. Despite that, there has been limited attention about how several of these findings can be used in clinical practice. Furthermore, in recent years, most studies about risk stratification of cardiac patients have mainly been focused on the use of a number of serum/plasma biomarkers with reduced attention to ECG variables. Surprisingly, however, there have been few attempts to establish whether the various proposed risk markers add any significant information to that obtainable from ECG methods. In this article, the evidence for the prognostic value of variables derived from the assessment of the ECG signal by several methods and techniques will be briefly reviewed. Because of the largeness of the topic, this review will be necessarily incomplete. Because most of the clinical research in this field concerned risk stratification of patients with coronary artery disease, the article will be largely focused on this population of patients. The role of ECG methods in specific cardiac diseases and, in particular, in the general population of asymptomatic subjects will be briefly discussed when believed appropriate and helpful. Furthermore, only major clinical events (ie, cardiac death, arrhythmic events, acute myocardial infarction) will be taken into account as end points in this article. Minor clinical events (eg, coronary revascularization procedures, coronary artery restenosis, recurrences of symptoms) are indeed less robust as end points because they are widely biased by subjective judgments.

Prevalence and prognostic implications of ST-segment deviations from ambulatory Holter monitoring after ST-segment elevation myocardial infarction treated with either fibrinolysis or primary percutaneous coronary intervention (a Danish Trial in Acute Myocardial Infarction-2 Substudy)

Ambulatory Holter monitoring has been shown to be useful in stratifying cardiovascular risk after acute myocardial infarction. However, it remains unclear whether ST-segment deviations might predict clinical outcomes in a population treated with primary percutaneous coronary intervention (PCI) compared with thrombolysis. Holter monitoring was initiated at discharge from ST-segment elevation myocardial infarction in 958 patients followed for 2,773 patient-years, randomized to immediate revascularization with either fibrinolysis (n=474) or PCI (n=484). The primary end point was all-cause mortality, and the secondary end point was a composite of death, reinfarction, and disabling stroke. The prevalences of ST-segment depression (STd) and ST-segment elevation (STe) were similar in patients treated with fibrinolysis or PCI (both p=NS). During follow-up, 58 patients died (primary PCI vs fibrinolysis hazard ratio 0.74, p=0.25). The secondary end point was reached in 113 patients (primary PCI vs fibrinolysis hazard ratio 0.66, p=0.03). In fibrinolysis-treated patients, mortality and the secondary end point were significantly higher in patients with STe (both end points p<0.001), an association that remained statistically significant after adjustment for age, gender, anterior infarction, beta-blocker treatment, left ventricular systolic function, and STd (p=0.03 and p=0.005, respectively). Significant associations were not observed for STd. In PCI-treated patients, there was no association between either STe or STd and outcome. In conclusion, immediate revascularization with PCI during STe myocardial infarction does not affect the subsequent prevalence of ST-segment deviation compared with fibrinolysis. However, although STe is an independent predictor of mortality and nonfatal major cardiovascular events in patients treated with fibrinolysis, it does not predict outcome after PCI, perhaps because of more complete revascularization.

Daily sedative interruption in mechanically ventilated patients at risk for coronary artery disease*

OBJECTIVES

To determine the prevalence of myocardial ischemia in mechanically ventilated patients with coronary risk factors and compare periods of sedative interruption vs. sedative infusion.

DESIGN

Prospective, blinded observational study.

SETTING

Medical intensive care unit of tertiary care medical center.

PATIENTS

Intubated, mechanically ventilated patients with established coronary artery disease risk factors.

INTERVENTIONS

Continuous three-lead Holter monitors with ST-segment analysis by a blinded cardiologist were used to detect myocardial ischemia. Ischemia was defined as ST-segment elevation or depression of >0.1 mV from baseline.

MEASUREMENTS AND MAIN RESULTS

Comparisons between periods of awakening from sedation vs. sedative infusion were made. Vital signs, catecholamine levels, and time with ischemia detected by Holter monitor during the two periods were compared. Heart rate, mean arterial pressure, rate-pressure product, respiratory rate, and catecholamine levels were all significantly higher during sedative interruption. Eighteen of 74 patients (24%) demonstrated ischemic changes. Patients with myocardial ischemia had a longer intensive care unit length of stay (17.4+/-17.5 vs. 9.6+/-6.7 days, p=.04). Despite changes in vital signs and catecholamine levels during sedative interruption, fraction of ischemic time did not differ between the time awake vs. time sedated [median [interquartile range] of 0% [0, 0] compared with 0% [0, 0] while they were sedated [p=.17]). The finding of similar fractions of ischemic time between awake and sedated states persisted with analysis of the subgroup of 18 patients with ischemia.

CONCLUSIONS

Myocardial ischemia is common in critically ill mechanically ventilated patients with coronary artery disease risk factors. Daily sedative interruption is not associated with an increased occurrence of myocardial ischemia in these patients.

Revascularization Compared to Medical Treatment in Patients with Silent vs. Symptomatic Residual Ischemia after Thrombolyzed Myocardial Infarction – The DANAMI Study

AIMS

The aim was to compare the effect of revascularization to conservative treatment in patients with residual silent and with residual symptomatic ischemia following acute myocardial infarction (AMI). The study was a subanalysis of the DANAMI (DANish AMI) randomized study of invasive vs. conservative treatment in patients with inducible ischemia after thrombolysis in AMI.

METHODS AND RESULTS

One thousand and eight patients were randomized to invasive or conservative treatment, stratified by the type of ischemia: silent, i.e. ST depression during an exercise test prior to discharge in 56%, or symptomatic, i.e. chest pain occurring either spontaneously during admission or during the exercise test, with or without ST changes, in 44%. Compared to a conservative strategy, invasive treatment reduced the incidence of nonfatal reinfarction, after in median 2.4 years, in both symptomatic patients (13.3-7.2%, p < 0.006) and patients with silent ischemia (10.1 vs. 5.7%, p < 0.05), and of admissions with unstable angina in symptomatic (44.5-27.6%, p < 0.0001) and silent ischemia (21.6-13.3%, p < 0.0006).

CONCLUSIONS

Compared to conservative strategy, invasive treatment reduces the risk of nonfatal reinfarction and hospital admissions for unstable angina in thrombolyzed post-AMI patients with silent as well as symptomatic exercise-induced ischemia.

Prognostic value of continuous ST-segment monitoring in patients with non-ST-segment elevation acute coronary syndromes

BACKGROUND

Patients with non-ST-segment elevation acute coronary syndromes constitute a heterogeneous group concerning prognosis. The 12-lead ECG at rest is recommended for early risk stratification but is unable to reflect the dynamic nature of myocardial ischemia and coronary thrombosis. This study investigated whether continuous ST-segment monitoring provides early prognostic information in such patients.

METHODS

We prospectively studied 183 patients admitted due to chest pain at rest suggestive of an acute coronary syndrome. ST-segment monitoring was performed continuously for 24 hours from admission. Cardiac-specific troponin I levels were determined on admission and every 6 hours for the first 24 hours. The endpoint was defined as death or nonfatal myocardial infarction, whichever occurred first by 30 days follow-up.

RESULTS

ST episodes, defined as transient ST deviations of at least 0.1 mV, were detected in 50 patients (27.3%) and associated with worse 30-day outcome: 22.0% endpoint rate compared to 6.8% for patients without ST episodes (P = 0.003). In a multivariate analysis, the presence of ST episodes (hazard ratio, 3.07; 95% CI, 1.26 to 7.46; P = 0.014) and peak troponin I levels > 0.2 microg/L (hazard ratio, 2.65; 95% CI, 1.01 to 6.95; P = 0.048) were independent predictors of prognosis. The combination of ST-segment monitoring and peak troponin I identified patients at low (2.5%, n = 79), intermediate (14.5%, n = 76), and high (25.0%, n = 28) risk for the 30-day endpoint.

CONCLUSIONS

In patients with non-ST-segment elevation acute coronary syndromes, continuous ST-segment monitoring provides on-line early prognostic information, in addition to troponin I levels.

Value and limitations of ambulatory ECG monitoring for assessment of myocardial ischemia

Ambulatory ECG monitoring (AEM) is the only available method to assess the presence and severity of myocardial ischemia during daily life. Several investigators have shown that the recording systems currently used can detect ischemic changes with similar accuracy as treadmill exercise testing. Ischemic changes on AEM are, however, present in only 40%-60% of patients with coronary artery disease (CAD) and positive exercise tests. For this reason, and because of the high day-to-day variability in daily ischemic changes, AEM cannot be used as a screening tool for detecting CAD or for evaluating severity of ischemia in individual patients. In patients with proven CAD, ischemic changes on AEM are associated with an adverse outcome in patients with stable and unstable ischemic syndromes, and in postmyocardial infarction patients. Suppression of daily ischemia seems to be associated with improved outcome. The mechanism of daily ischemia is not identical to exercise-induced ischemia. In addition to increased demand, which is a major contributor to AEM detected-ischemia, increased coronary tone also seems to play a major role. AEM has been shown to be a useful and reliable tool to assess the efficacy of various antiischemic drugs.

Contemporary management of silent ischemia: the role of ambulatory monitoring

Silent ischemia is highly prevalent among patients with ischemic heart disease and is associated with a poor prognosis in moderate/high risk outpatients who either exhibit exercise- or pharmacological-induced myocardial ischemia, or in those patients who demonstrate silent ischemia following an acute coronary syndrome. Pharmacotherapy, including beta-blockers, angiotensin-converting enzyme inhibitors, statins, calcium channel antagonists and antiplatelet agents, have all demonstrated a reduction in silent ischemia and an improvement in cardiac prognosis. The management of patients with ischemic heart disease is currently based on patients' report of anginal symptoms: documentation of silent ischemia, usually using ambulatory electrocardiography, is not incorporated into the routine management of coronary artery disease. Yet studies comparing ambulatory electrocardiography with exercise testing have shown these tests to be complementary. We review the evidence concerning the prognostic value of ambulatory electrocardiography for monitoring silent ischemia and the prognostic value of attenuating silent ischemia. Mitigation of silent ischemia improves cardiac prognosis and ambulatory electrocardiographic monitoring before and after treatment of silent ischemia can play a valuable role in the management of coronary artery disease.

Differential prognostic significance of peri-infarction versus remote myocardial ischemia on stress technetium-99m sestamibi tomography in patients with healed myocardial infarction

Peri-infarction and remote myocardial ischemia involve different myocardial substrates, but their differential clinical implications have not been previously studied. We assessed the differential prognostic significance of peri-infarction and remote ischemia during long-term follow-up in patients with healed myocardial infarction. We studied 345 patients (59 +/- 12 years old; 282 men) with previous myocardial infarction who demonstrated reversible perfusion abnormalities on exercise or dobutamine stress technetium-99m sestamibi tomography. Follow-up events for 5.5 +/- 2.6 years were 60 deaths (17%; 40 cardiac deaths) and 25 reinfarctions (7%). Reversible perfusion abnormalities were detected in the remote region in 129 patients (37%), the peri-infarction region in 142 patients (41%), and in both regions in 74 patients (21%). The annual rates of cardiac death in these groups were 1.2%, 2.8%, and 2.9%, respectively (p <0.01). The annual rates of reinfarction were 1%, 1.5%, and 0.9%, respectively (p = NS). In a multivariate analysis model, independent predictors of cardiac death were history of heart failure (risk ratio [RR] 2.8, 95% confidence interval [95% CI] 1.2 to 7), diabetes mellitus (RR 4.1, 95% CI 1.9 to 8.9), summed score at rest (RR 1.4, 95% CI 1.1 to 3.1), and peri-infarction ischemia (RR 2.6, 95% CI 1.1 to 6.1). Predictors of reinfarction were age (RR 1.03, 95% CI 1.01 to 1.07) and diabetes mellitus (RR 3.3, 95% CI 1.2 to 9.1). Peri-infarction ischemia assessed by stress technetium-99m sestamibi tomography is associated with a greater risk of cardiac death than is remote ischemia. The risk of reinfarction is not related to the location of ischemia.

Diabetes mellitus and cardiovascular disease

Diabetes is associated with a high incidence and poor prognosis of cardiovascular disease, and with high short- and long-term mortality. Adequate treatment of cardiovascular disorders and aggressive management of coexisting risk factors have proved to be at least as effective in diabetic as in nondiabetic patients in randomized, controlled studies. Indeed, treating diabetic patients with cardiovascular disease results in a larger absolute risk reduction than in nondiabetic subjects. Nevertheless, diabetic patients often receive inadequate therapy, which may, to a certain extent, explain their poor prognosis. Recommendations for the treatment of diabetic patients with acute myocardial infarction should include beta-blockers, aspirin, and ACE-inhibitors in all patients in whom no specific contraindications exist. Fibrinolysis should be administered when indicated, and the benefits of improving glycemic control should not be forgotten either. In patients with multi-vessel disease who need revascularization, when selecting the type of procedure, the superiority of surgical revascularization over angioplasty should be borne in mind. Even heart transplantation should be included as a therapeutic option since there are no data to support the exclusion of patients on account of their diabetes. Finally, coexisting risk factors should be intensively treated through lifestyle intervention, with or without drug therapy, in order to achieve secondary prevention goals.

Diagnostic and prognostic value of Holter-detected ST-segment deviation in unselected patients with chest pain referred for coronary angiography: a long-term follow-up analysis

OBJECTIVE

To evaluate the diagnostic and prognostic significance of ST-segment deviation detected by ambulatory Holter monitoring in unselected chest pain patients referred for coronary angiography.

METHODS

Two hundred seventy-seven patients (71% were men) who underwent coronary angiography for evaluation of chest pain were studied with 24-h ambulatory Holter monitoring within 72 h of angiography. A lumen diameter reduction of > or = 50% was considered coronary artery disease. The ST-segment deviation was defined as > or = 1-mm deviation from the baseline lasting > or = 1 min separated by a minimum of 1 min. The patients were followed up for 65 +/- 21 months (mean +/- SD) for occurrences of death, myocardial infarction, hospitalization for unstable angina, and need for revascularization.

RESULTS

Of the 277 patients, 223 (80%) had coronary artery disease. The prevalence of coronary artery disease was not significantly different in patients with (43 of 48 patients; 90%) and without (180 of 229 patients; 79%) Holter-detected ST-segment deviation. The diagnostic accuracy of Holter-detected ST-segment deviation in predicting the presence of coronary artery disease was poor (33%), with a sensitivity of 19% and a specificity of 91%. The presence of Holter-detected ST-segment deviation was not predictive of future cardiac events or death.

CONCLUSION

The ST-segment changes detected on ambulatory Holter monitoring are of limited value in identifying coronary artery disease and predicting the future adverse cardiac events or death in unselected patients with chest pain.

Determinants of left ventricular systolic function after acute myocardial infarction: the role of residual myocardial ischaemia

BACKGROUND

Left ventricular systolic function (LVSF) is one of the major determinants of survival after acute myocardial infarction (AMI). Some factors such as the infarct size and localization, and the patency of the infarct-related artery are known determinants of LVSF. However, the long-term effect of myocardial ischaemia on LVSF has been poorly studied in clinical settings.

OBJECTIVES

To assess the acute and long-term effects of myocardial ischaemia on LVSF in patients recovering from an AMI.

METHODS

A cohort of 74 patients recovering from AMI was studied. Myocardial ischaemia was detected by means of ambulatory electrocardiogram (ECG) monitoring at recruitment (4+/-2 days after AMI), exercise ECG test and stress echocardiography at discharge (7+/-4 days after AMI). LVSF was studied by means of two-dimensional echocardiography at recruitment, at discharge, and at 1, 3, 6 and 12 months after AMI.

RESULTS

Patients with myocardial ischaemia on ambulatory ECG monitoring and stress echocardiography had worse LVSF at recruitment than those without ischaemia. The presence of myocardial ischaemia on ambulatory ECG monitoring was an independent determinant of LVSF at recruitment together with infarct localization and size (assessed by creatine kinase MB isoenzyme (CK-MB) levels). Patients with signs of myocardial ischaemia on ambulatory ECG monitoring and stress echocardiography had a progressive left ventricular dysfunction compared with those without ischaemia.

CONCLUSIONS

Residual ischaemia is an independent determinant of LVSF after AMI and its presence implied a progressive worsening of the LVSF. Because left ventricular systolic dysfunction is a major determinant of survival after AMI, its precursors, among them residual myocardial ischaemia, should be identified. Treatment of ischaemia is known to be associated with improved prognosis and improved LVSF.

Ten-year mortality rate in relation to observations at a bicycle exercise test in patients with a suspected or confirmed ischemic event but no or only minor myocardial damage: influence of subsequent revascularization

AIM

Our purpose was to describe symptoms and electrocardiographic findings at a bicycle exercise test 4 weeks after hospitalization for a suspected or confirmed acute ischemic event but either no or only minor myocardial necrosis and its relationship to long-term prognosis and subsequent revascularization.

METHODS

In all patients a symptom-limited bicycle exercise test was performed 4 weeks after discharge from the hospital. The total mortality rate over 10 years was registered.

RESULTS

In all, 770 patients participated in the evaluation. The median age was 63 years, and 34% were women. The most frequent reason for stopping the exercise test was fatigue (69%) followed by dyspnea (33%) and angina pectoris (15%). Angina pectoris was observed in 24% of the patients. ST-segment depression >or=1 mm was observed in 50% and ST-segment depression >or=2 mm was observed in 15% of the patients. The 10-year mortality rate in patients with ST-segment depression >or=2 mm was 24.7%, in patients with ST-segment depression 1.0 to 1.9 mm 33.5%, and in patients with ST-segment depression <1 mm 26.9% (not significant [NS]). Patients with symptoms of angina pectoris had a 10-year mortality rate of 29.4% compared with 27.9% among patients without such symptoms (NS). Patients who had either a drop in systolic blood pressure or failure to raise systolic blood pressure (13%) had a 10-year mortality rate of 36.2% compared with 27.2% among patients without such signs (NS). However, there was a significant association between maximum exercise capacity (in watts) and mortality (P < .0001): 53.8% in the lowest quartile (30-70 W) and 10.2% in the highest (>120 w). When clinical history was considered simultaneously, a low exercise capacity remained as a strong independent predictor of death together with age and a history of either acute myocardial infarction, smoking, or diabetes mellitus. Mechanical revascularization during the subsequent 5 years interacted only with angina pectoris and prognosis; thus patients who had angina during the exercise test had a worse prognosis than those without if they were not being revascularized.

CONCLUSION

Among patients hospitalized with a suspected or confirmed acute ischemic event but either no or only minor myocardial necrosis, we found the maximum working capacity at a symptom-limited bicycle exercise test to be independently associated with the long-term prognosis but not other signs of myocardial ischemia. Further predictors for long-term prognosis were age, a history of acute myocardial infarction, current smoking, and diabetes mellitus. Mechanical revascularization during the subsequent 5 years interacted with the influence of symptoms of angina during test and prognosis.

Which factors determine the long-term outcome among patients with a very small or unconfirmed AMI

AIM

To describe various factors associated with the very long-term prognosis for patients with a very small or an unconfirmed acute myocardial infarction (AMI).

METHODS

Patients below 76 years of age, hospitalized due to suspected AMI who either developed a very small AMI (enzyme elevation<twice upper normal limit and maximum serum (S) aspartate aminotransferase (S-ASAT)<1.4 ukat/l) or an unconfirmed AMI (a suspected ischemic event with no signs of myocardial necrosis) were evaluated at our out-patient clinic. The 10-year mortality was related to the clinical history, age and sex, metabolic factors, diagnosis at hospital discharge, various psychosocial factors, use of medication, current symptoms, underlying reason to the symptoms, maximal working capacity and other observations at bicycle exercise test including signs of myocardial ischemia.

RESULTS

In all, 714 patients (33% women) with a median age of 63 years were included in the analyses. The following appeared as independent risk indicators for 10-year mortality: S-gammaglutamyl transpeptidase (GT) (P<0.0001), age (P<0.0001), current smoking (P<0.0001), a history of previous AMI (P<0.0001), maximal working capacity at bicycle exercise test (P=0.002), and current treatment with digitalis (borderline significance; P=0.022).

CONCLUSION

Among patients with a suspected acute myocardial ischemic event with no or minimal myocardial necrosis, various factors reflecting their age, history of cardiac disease and smoking, liver function, working capacity and possibly use of medication affected their very long-term prognosis.

Correlation of ST-segment depression during ambulatory electrocardiographic monitoring with myocardial perfusion and left ventricular function

To assess the relation between silent ischemia and objective markers of ischemia we compared ambulatory electrocardiographic (AECG) monitoring, exercise stress testing, and technetium-99m methoxyisobutyl isonitrile single-photon emission computed tomography (SPECT) in 68 patients with coronary artery disease. ST-segment depression at AECG monitoring occurred in 40%, exercise testing was positive in 88%, and SPECT was abnormal in 98% of patients. Patients with ST-segment depression had a higher incidence of 3-vessel disease (70% vs 45%, p = 0.04), shorter duration of exercise (267 +/- 109 vs 416 +/- 167 seconds, p < 0.01), lower workload achieved (5.1 +/- 1.9 vs 7.6 +/- 2.8 METs, p < 0.0002), and a greater extent of ischemia at scintigraphy (p = 0.01). Patients with a total ischemic time of >30 minutes in a 24-hour period had a lower ejection fraction (48 +/- 21% vs 70 +/- 9%, p = 0.001), a higher perfusion index at rest (2.4 +/- 0.6 vs 1.6 +/- 0.6, p = 0.001), and a greater number of segments with fixed perfusion defects (4.1 +/- 3.7 vs 1.3 +/- 1.8, p = 0.02) in comparison with those who had a shorter ischemic time. We conclude that AECG monitoring fails to identify a substantial proportion of patients with objective markers of ischemia; however, ST-segment depression reflects more significant disease. Longer total ischemic time correlates with the area of myocardial damage but not with other markers of ischemia.

Randomized trial of a noninvasive strategy to reduce hospital stay for patients with low-risk myocardial infarction

OBJECTIVES

This study evaluated the feasibility, pertinence and psychosocial repercussions of a noninvasive reduced hospital stay strategy (three days) for low-risk patients with acute myocardial infarction using simple clinical criteria and predischarge 24-h ambulatory ST-segment ischemic monitoring.

BACKGROUND

Previous studies evaluating shorter stays for uncomplicated myocardial infarction have been limited by retrospective or nonrandomized design and overdependence on invasive cardiac procedures.

METHODS

One-hundred twenty consecutive patients admitted with an acute myocardial infarction fulfilling low-risk criteria were randomized 2:1 to a short hospital stay (80 patients) or standard stay (40 patients). Short-stay patients with no ischemia on ST-segment monitoring were discharged on day 3, returning for exercise testing a week later. All analyses were on an intention-to-treat basis.

RESULTS

Forty-one percent of all screened patients with acute myocardial infarction would have been medically eligible for the short-stay strategy. Seventeen patients (21%) were not discharged early because of ischemia on ST-monitoring or angina. Median initial hospital stay was halved from 6.9 days in the standard stay to 3.5 days in the short-stay group. At six months, median total days hospitalized were 7.5 in the standard stay and 3.6 in the short-stay group (p < 0.0001). Adverse events and readmissions were low and not significantly different, and there were 25% fewer invasive cardiac procedures in the short-stay group. Psychosocial outcomes, risk factor changes and exercise test results were similar in the two groups.

CONCLUSIONS

This reduced hospital stay strategy for low-risk patients with acute myocardial infarction is feasible and worthwhile, resulting in a substantial and sustained reduction in days hospitalized. It is without unfavorable psychosocial consequences, appears safe and does not increase the number of invasive cardiac procedures.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Cost estimates for treatment of cardiac ischemia (from the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Costs for management of myocardial ischemia are enormous, yet comparison cost and outcome data for various ischemia treatment strategies from randomized trials are lacking and will require cost and resource utilization data from a large prospective trial. The Asymptomatic Cardiac Ischemia Pilot provided feasibility data for planning such a trial and an opportunity to estimate the long-term costs of different treatment strategies. Economic implications for ischemia management were compared in 558 patients with stable coronary artery disease and myocardial ischemia during both stress testing and daily life. Participants were randomized to 3 different initial treatment strategies and followed for 2 years. Based on cost trends over follow-up, costs for subsequent care were estimated. As expected, due to initial procedural costs, at 3 months, estimated costs for revascularization were approximately 10 times greater than costs for a medical care strategy. Extrapolated costs for anticipated resource consumption for care beyond 2 years, however, were approximately 2 times greater for an initial medical care strategy than for initial revascularization. This was due to increased need for drugs and hospitalizations for both late revascularizations and other ischemia-related events. Estimated costs for anticipated care in the medical strategies reached the anticipated cost of the revascularization strategy within 10 years. Because this cost-equal time period is well within the median life expectancy for such a patient population, these findings could have important public health implications and require testing in a full-scale prognosis trial. We anticipate that over the patients' life expectancy, early revascularization is likely to become either cost-neutral or cost-effective.

[The clinical management guidelines of the Sociedad Española de Cardiología in acute myocardial infarct]

In the recent years, new possibilities have emerged in the diagnosis and management of acute myocardial infarction with ST segment elevation and its complications. Moreover, a deep transformation has taken place in the health care system organization, particularly in aspects related to care of patients presenting non-traumatic chest pain, both in pre-hospital and hospital areas. All these issues warrant a consensus document in Spain dealing with the role that these important changes should play in the whole management of myocardial infarction patients. This document revises and updates all the main clinical issues of acute myocardial infarction patients from the moment they contact with the health care system outside the hospital until they return home, after staying at the coronary care unit and the general hospitalization ward. All those aspects are considered not only in the uncomplicated myocardial infarction but also in the complicated one. This review also includes a set of recommendations on structural and organisational aspects, mainly referred to the prehospital and emergency levels.

ST-segment monitoring with continuous 12-lead ECG improves early risk stratification in patients with chest pain and ECG nondiagnostic of acute myocardial infarction

OBJECTIVES

The purpose of this study was to evaluate the prognostic importance of ischemic episodes detected by ST-segment monitoring with continuous 12-lead electrocardiography (ECG) in a nonselected coronary care unit (CCU) population with chest pain and ECG nondiagnostic of acute myocardial infarction (AMI).

BACKGROUND

Patients with chest pain and ECG nondiagnostic of AMI constitute a heterogeneous group concerning both diagnosis and prognosis. Continuous 12-lead ECG is a rather new method not thoroughly studied in this population.

METHODS

The ST-segment monitoring with continuous 12-lead ECG was performed for 12 h in 630 consecutive patients admitted to CCU due to chest pain and a nondiagnostic ECG, i.e., no ST-segment elevations. An ST-episode was defined as a transient ST-segment depression or elevation of at least 0.10 mV. The median follow-up time was six months.

RESULTS

A total of 176 ST-episodes occurred in 100 (15.9%) patients. The median duration and maximal ST-segment deviation in patients with ST-episodes were 80 min and 0.20 mV, respectively. Presence of ST-episodes predicted worse outcome concerning cardiac death and cardiac death or myocardial infarction (MI) (log-rank p < 0.001). At 30 day follow-up procedure, 10% versus 1.5% died from cardiac causes or had an MI in the group with and without ST-episodes, respectively. In a multivariate analysis, only troponin T > or = 0.10 microg/l and the presence of ST-episodes came out as independent predictors of cardiac death or MI.

CONCLUSIONS

Continuous 12-lead ECG monitoring provides prognostic information on-line and considerably improves early risk stratification in patients with ECG nondiagnostic of AMI and symptoms suggestive of acute coronary syndrome.

Three-year follow-up of patients with silent ischemia in the subacute phase of myocardial infarction after thrombolysis and early coronary intervention

In order to assess the prognostic value of silent myocardial ischemia in acute myocardial infarction after thrombolysis and early coronary angiography (14-48 h after start of thrombolysis) including percutaneous transluminal coronary angioplasty, if indicated, 126 patients underwent 24 h-Holter-monitoring in the early postinfarction period. The 24 h-Holter-recording was initiated directly after early coronary intervention (40+/-11 h after onset of symptoms). Of the 126 patients initially eligible for the study 29 had to be excluded from further analysis for clinical or methodical reasons. Of the remaining 97 patients, 10 (10%) had silent ischemia (group A) and 87/97 (90%) patients showed no significant ST-segment alterations. Both groups did not significantly differ from each other with regard to baseline clinical characteristics, severity of coronary artery disease and frequency of successful percutaneous transluminal coronary angioplasty. The left ventricular ejection fraction showed a trend towards lower values in patients with than in those without silent ischemia (47+/-15% vs. 55+/-13%, p=0.07). When both silent ischemia and left ventricular ejection fraction <40% were present, a subset of patients at high risk for cardiac death could be identified (specificity: 98%, positive predictive accuracy: 75%). By Kaplan-Meier analysis, significantly more cardiac deaths occurred in group A than in group B (30% vs. 6%, p<0.01) during the three-year follow-up (950+/-392 days) after acute myocardial infarction. Regarding the cardiac events during long-term follow-up (emergency percutaneous transluminal coronary angioplasty, coronary artery bypass grafting, non-fatal reinfarction, and cardiac death) there was no significant difference between both groups (30% vs. 18%, NS). In conclusion, Holter monitor-detected silent ischemia in the subacute phase of myocardial infarction after thrombolysis followed by early delayed coronary intervention occurs in 10% of the patients indicating either a residual ischemia in the infarcted zone despite a combined reperfusion strategy or a remote ischemic potential in case of multivessel disease. In this small selected group of infarct patients too, silent ischemia is to be considered as an important non-invasive parameter to predict cardiac death during long-term follow-up and provides valuable complementary information to left ventricular dysfunction, a well established prognostic marker in the postinfarction period.

The learning curve of an academic cardiac surgeon: use of the CUSUM method

BACKGROUND

Despite the sizeable volume of research on the determinants of outcome after cardiac operations, few articles have analyzed the learning curves of individual cardiac surgeons over time. The objective of our study was to analyze statistically the learning curve of an academic cardiac surgeon in reducing operative morbidity and mortality during a 10-year interval.

METHODS

The study cohort of 1347 consecutive and unselected patients undergoing cardiac surgical operations from October 1988 to September 1998 were grouped into five 2-year blocks (periods 1 to 5) according to the date of operation. The main outcome measures were operative mortality rate and standardized definitions of perioperative myocardial infarction, intra-aortic balloon pump use, reoperation for bleeding, stroke, sternal wound complications, sepsis, and respiratory insufficiency. Preoperative risk factors and operative results in periods 1 to 5 were compared statistically using a chi-square test for linear trend (categorical variables) or analysis of variance with linear contrast and lack of fit tests (continuous variables). In addition, the cumulative sum (CUSUM) method was used to determine the association among operative morbidity, mortality, and prespecified 80% alert and 95% alarm boundary lines in practice years 1, 5, and 9.

RESULTS

Of the preoperative risk factors, only patient age showed an important change during the 10 years of the study (61.3+/-0.7 to 64.3+/-0.6, p = 0.001). There were no statistically significant changes from periods 1 to 5 in overall operative mortality (4.0% to 2.2%, p = 0.56) or in the rates of perioperative stroke (1.8% to 3.8%, p = 0.33), sternal wound complications (0.4% to 0.8%, p = 0.97), sepsis (0.9% to 0.8%, p = 0.63), or respiratory failure (4.4% to 2.8%, p = 0.21). Decreases occurred in a linear fashion during periods 1 to 5 in mortality after coronary artery bypass grafting (5.1% to 1.3%, p = 0.012) and in the rates of perioperative myocardial infarction (7.0% to 2.2%, p = 0.005), intra-aortic balloon pump use (7.0% to 3.0%, p = 0.05), and reoperation for bleeding (8.4% to 2.2%, p = 0.001). The number of uneventful cases between a death or complication increased from 2.82+/-0.43 in period 1 to 6.44+/-1.10 in period 5 (p < 0.001). On CUSUM analysis, the cumulative failure rate in year 1 transgressed the upper 80% alert line after 56 cases and the upper 95% alarm line after 69 cases. During years 5 and 9 the failure rate gravitated around the 80% and 95% "reassurance" lines, respectively, indicating improved results as compared to year 1.

CONCLUSIONS

The mortality rate after coronary artery bypass grafting and select perioperative morbidity rates improved in a linear fashion from the onset of independent practice to year 10. The CUSUM method was helpful in identifying suboptimal results during the first year of practice and shows promise as a method of prospective quality control in cardiac surgery. These data support mentorship of new consultants by a senior surgeon during the first year or two of independent practice.

Serial Holter ST-segment monitoring after first acute myocardial infarction. Prevalence, variability, and long-term prognostic importance of transient myocardial ischemia

Based on serial Holter monitoring performed 7 times within 3 years after a first acute myocardial infarction, we assessed the prevalence, variability and long-term clinical importance of transient myocardial ischemia (TMI) defined as episodes of ambulatory ST-segment depression. In all, 121 consecutive male patients <70 years old were studied. The prevalence of TMI on different Holter recordings varied around 20% ranging between 18 and 27%. Fifty-five of the patients (46%) had TMI on at least 1 of the 7 Holter recordings. Considerable variability was found within and between patients for the presence of TMI. No high-risk group for cardiac death, nonfatal reinfarction or coronary revascularization during up to 10 years of follow-up could be identified by the detection of TMI. From these results we conclude that a routine search for TMI on serial Holter monitoring cannot be recommended in male survivors of an uncomplicated first acute myocardial infarction.

Improved hemodynamics shown by continuous monitoring of electrical impedance during external counterpulsation with the end-diastolic pneumatic boot and improved ambulatory EKG monitoring after 3 weeks of therapy

Six normal subjects and 12 patients with clinical angina and significant ST depressions during baseline ambulatory cardiac monitoring were given a single treatment with the end-diastolic pneumatic compression boot, the Circulator Boot. With the use of continuous electrical impedance measurements, multiple hemodynamic variables were followed in five situations: (1) baseline before pumping; during end-diastolic pumping (2) on both legs after every heartbeat, (3) on one leg after every heartbeat, and (4) on both legs on alternate beats; and (5) during pumping on both legs during every systole. Both an increase in venous return and a reduction in afterload likely contributed to significant increases in cardiac output (CO) (51.1 +/- 33.6%), stroke volume (SV) (52.1 +/- 35.6%), change in impedance over time (dZ/dT) (72.0 +/- 68.1%), cardiac index (CI) (51.2 +/- 33.8%), and acceleration index (50.7 +/- 62.2%) during end-diastolic pumping on both legs after every heartbeat. A crucial role for afterload reduction was implied by opposite effects observed on CO, CI, dZ/dT, and SV during systolic pumping. Again, reductions (or a lack of an increase) in ventricular ejection time and/or the preejection period suggested a decrease in afterload during end-diastolic pumping. Pumping on one leg after every beat and on both legs on alternate beats was also effective but less so. After the initial study, the patients were given 14 additional end-diastolic treatments to both legs over 3 weeks. A clinical benefit for the patients was shown by symptomatic improvement in all patients along with a significant reduction in the amount and duration of the RST abnormalities in their ambulatory heart monitoring (p = 0.012).

[Is the exercise test performed after myocardial infarct really useful in improving prognosis? Arguments contra]

Exercise testing is considered to play a major role in risk stratification after myocardial infarction. With the aim of improving prognosis, an exercise test should be able to identify patients at higher risk of coronary events. In this sense, its major limitation is a low positive predictive value, especially in patients who have been treated with thrombolytic agents. This fact limits its clinical value in the decision making process in individual patients. Finally, the decision to revascularize with angioplasty or surgery when only a positive exercise test result is taken into account, has not been proven to prolong life in these patients. All these considerations should make us think about some clinical attitudes that are taken for granted.

Attenuation of ischemia-induced activation of cardiac sympathetic afferents following brief myocardial ischemia in cats

OBJECTIVE

We have previously shown that brief myocardial ischemia impairs neural conduction in cardiac sympathetic efferent fibers. However, attenuation of the activity of afferent sympathetic nerves, which may contribute to impaired ischemic nociception and reflex hemodynamic responses, is not well understood. Therefore, we studied the electrophysiological effects of brief myocardial ischemia on the mechano-, chemo- and ischemia-sensitive properties of cardiac sympathetic afferent fibers.

METHODS

Single unit activity of sympathetic afferent A delta and C fibers innervating the left ventricle (LV) was recorded from the thoracic chain or rami communicantes in 16 anesthetized cats. We tested the response of impulse activity to (1) mechanical LV probing, (2) epicardial application of bradykinin (10 microg), H2O2 (1.5%) or adenosine (500 microg), and (3) 1 min of coronary occlusion. Repeat tests were performed in 11 of 16 fibers after 15 min of coronary occlusion and 15 min of reperfusion. Control responses were measured in five fibers before and after a 30-min interval without ischemia.

RESULTS

Afferent fibers responded with increased activity to LV probing (16/16 fibers), bradykinin (13/16 fibers), H2O2 (7/11 fibers), adenosine (1/11 fibers), and to a 60 s period of coronary occlusion (11/16 fibers). The unit impulse activity to 1 min of coronary occlusion was markedly attenuated after 15 min of myocardial ischemia and 15 min of reperfusion (P < 0.05). This attenuation was associated with reduced sensitivity to mechanical and chemical stimuli, while in separate time-control studies (n = 5) no attenuation was observed in absence of ischemia.

CONCLUSION

A brief period of myocardial ischemia is capable of attenuating mechano-, chemo- and ischemia-sensitive activity of cardiac afferent sympathetic nerves. This may have important implications for the mechanism of silent myocardial ischemia.

Heparin is more effective than inogatran, a low-molecular weight thrombin inhibitor in suppressing ischemia and recurrent angina in unstable coronary disease. Thrombin Inhibition in Myocardial Ischemia (TRIM) Study Group

Thrombin has been suggested as one of the main pharmacologic targets in unstable coronary syndromes. Electrocardiographic signs of ischemia during continuous monitoring convey prognostic information in these patients. This study assessed the anti-ischemic and clinical effects of the novel low-molecular weight thrombin inhibitor inogatran in patients with unstable angina and non-Q-wave infarction without persistent ST-segment elevation on hospital admission. Within 24 hours of the last episode of chest pain, 324 patients were randomized to 72 hours of treatment with inogatran or heparin. Continuous ST-segment analysis with computerized vectorcardiography was used to monitor ischemia for 24 hours. The occurrence of cardiac events during the first 7 days were studied and compared with ischemic episodes during the initial 24 hours. The heparin-treated patients had less episodes of ischemia (ST vector magnitude [ST-VM]: 1 +/- 2.6 vs 2 +/- 4.5, p < 0.001 and ST change vector magnitude [STC-VM]: 3 +/- 4.7 vs 6 +/- 7.6, p < 0.001) than the patients receiving inogatran. This was paralleled by a lower incidence of the combined end point of death, nonfatal infarction, refractory or recurrent angina during the first 7 days for the heparin-treated patients (35%) compared with the inogatran-treated patients (50%) (p < 0.05). Patients who had episodes of ischemia in spite of anti-ischemic therapy were at increased risk of all events studied. Heparin is more effective than inogatran in suppressing myocardial ischemia and clinical events at short-term follow-up. Continuous ST-segment monitoring with vectorcardiography identifies nonresponders who are at an increased level of risk.

Prognostic significance of ST segment shift early after resolution of ST elevation in patients with myocardial infarction treated with thrombolytic therapy: the GUSTO-I ST Segment Monitoring Substudy

OBJECTIVES

We sought to study the relation between recurrent ST segment shift within 6 to 24 h of initial resolution of ST elevation after thrombolytic therapy and 30-day and 1-year mortality.

BACKGROUND

Rapid and stable resolution of ST segment elevation in relation to thrombolytic therapy in patients with an acute myocardial infarction is an indicator of culprit artery patency. Whether recurrence of ST segment shift during continuous ST monitoring after initial resolution is related to poor prognosis has not been studied.

METHODS

ST segment monitoring was performed within 30 min after thrombolytic therapy for acute myocardial infarction. The predictive value of a new ST segment shift (assessed as > or = 0.1-mV deviation from the baseline) 6 to 24 h after thrombolytic therapy was studied with respect to 30-day and 1-year mortality.

RESULTS

Of 734 patients, 243 had a new ST segment shift (33%). The 30-day mortality rate in patients with an ST shift (7.8%) was significantly higher than that in patients without an ST shift (2.25%, p = 0.001), as was the 1-year mortality rate (10.3% vs. 5.7%, respectively, p = 0.025). Multivariable analysis revealed an independent predictive value of ST shift with respect to 30-day mortality (p = 0.008), even after consideration of multiple clinical risk factors in the overall Global Utilization of Streptokinase and TPA for Occluded Coronary Arteries (GUSTO)-I mortality model (p = 0.0001). Moreover, the duration of the ST shift bore a direct relation with 1-year mortality (p = 0.008).

CONCLUSIONS

Detection of ST segment shift early after thrombolytic therapy for acute myocardial infarction is a simple, noninvasive means of identifying patients at high risk and is superior to other commonly assessed clinical risk factors. Thus, patients with a new ST shift after the first 6 h, but within 24 h, represent a high risk group that may benefit from more aggressive intervention, whereas patients without evidence of an ST shift represent a low risk subgroup.

Recurrent ischemia after thrombolysis: importance of associated clinical findings. GUSTO-I Investigators. Global Utilization of Streptokinase and t-PA [tissue-plasminogen activator] for Occluded Coronary Arteries

OBJECTIVES

We sought to assess the incidence and clinical relevance of examination data to recurrent ischemia within an international randomized trial.

BACKGROUND

Ischemic symptoms commonly recur after thrombolysis for acute myocardial infarction.

METHODS

Patients (n = 40,848) were prospectively evaluated for recurrent angina and transient electrocardiographic (ECG) or hemodynamic changes. Five groups were developed: Group 1, patients with no signs or symptoms of recurrent ischemia; Group 2, patients with angina only; Group 3, patients with angina and ST segment changes; Group 4, patients with angina and hemodynamic abnormalities; and Group 5, patients with angina, ST segment changes and hemodynamic abnormalities. Baseline clinical and outcome variables were compared among the five groups.

RESULTS

Group 1 comprised 32,717 patients, and Groups 2 to 5 comprised 20% of patients (4,488 in Group 2; 3,021 in Group 3; 337 in Group 4; and 285 in Group 5). Patients with recurrent ischemia were more often female, had more cardiovascular risk factors and less often received intravenous heparin. Significantly more extensive and more severe coronary disease, antianginal treatment, angioplasty and coronary bypass surgery were observed as a function of ischemic severity. The 30-day reinfarction rate was 1.6% in Group 1, 6.5% in Group 2, 21.7% in Group 3, 13.1% in Group 4 and 36.5% in Group 5 (p < 0.0001); in contrast, the 30-day mortality rate was significantly lower (p < 0.0001) in Groups 1, 2 and 3 (6.6%, 5.4% and 7.7%, respectively) than in Groups 4 and 5 (21.8% and 29.1%).

CONCLUSIONS

Postinfarction angina greatly increases the risk of reinfarction, especially when accompanied by transient ECG changes. However, mortality is markedly increased only in the presence of concomitant hemodynamic abnormalities.