A metaanalysis of predischarge risk stratification after acute myocardial infarction with stress electrocardiographic, myocardial perfusion, and ventricular function imaging

Early computed tomography coronary angiography in adults presenting with suspected acute coronary syndrome: the RAPID-CTCA RCT

BACKGROUND

Acute coronary syndrome is a common medical emergency. The optimal strategy to investigate patients who are at intermediate risk of acute coronary syndrome has not been fully determined.

OBJECTIVE

To investigate the role of early computed tomography coronary angiography in the investigation and treatment of adults presenting with suspected acute coronary syndrome.

DESIGN

A prospective, multicentre, open, parallel-group randomised controlled trial with blinded end-point adjudication.

SETTING

Thirty-seven hospitals in the UK.

PARTICIPANTS

Adults (aged ≥ 18 years) presenting to the emergency department, acute medicine services or cardiology department with suspected or provisionally diagnosed acute coronary syndrome and at least one of the following: (1) a prior history of coronary artery disease, (2) a cardiac troponin level > 99th centile and (3) an abnormal 12-lead electrocardiogram.

INTERVENTIONS

Early computed tomography coronary angiography in addition to standard care was compared with standard care alone. Participants were followed up for 1 year.

MAIN OUTCOME MEASURE

One-year all-cause death or subsequent type 1 (spontaneous) or type 4b (stent thrombosis) myocardial infarction, measured as the time to such event adjudicated by two cardiologists blinded to the computerised tomography coronary angiography ( CTCA ) arm. Cost-effectiveness was estimated as the lifetime incremental cost per quality-adjusted life-year gained.

RESULTS

Between 23 March 2015 and 27 June 2019, 1748 participants [mean age 62 years (standard deviation 13 years), 64% male, mean Global Registry Of Acute Coronary Events score 115 (standard deviation 35)] were randomised to receive early computed tomography coronary angiography (n = 877) or standard care alone (n = 871). The primary end point occurred in 51 (5.8%) participants randomised to receive computed tomography coronary angiography and 53 (6.1%) participants randomised to receive standard care (adjusted hazard ratio 0.91, 95% confidence interval 0.62 to 1.35; p = 0.65). Computed tomography coronary angiography was associated with a reduced use of invasive coronary angiography (adjusted hazard ratio 0.81, 95% confidence interval 0.72 to 0.92; p = 0.001) but no change in coronary revascularisation (adjusted hazard ratio 1.03, 95% confidence interval 0.87 to 1.21; p = 0.76), acute coronary syndrome therapies (adjusted odds ratio 1.06, 95% confidence interval 0.85 to 1.32; p = 0.63) or preventative therapies on discharge (adjusted odds ratio 1.07, 95% confidence interval 0.87 to 1.32; p = 0.52). Early computed tomography coronary angiography was associated with longer hospitalisations (median increase 0.21 days, 95% confidence interval 0.05 to 0.40 days) and higher mean total health-care costs over 1 year (£561 more per patient) than standard care.

LIMITATIONS

The principal limitation of the trial was the slower than anticipated recruitment, leading to a revised sample size, and the requirement to compromise and accept a larger relative effect size estimate for the trial intervention.

FUTURE WORK

The potential role of computed tomography coronary angiography in selected patients with a low probability of obstructive coronary artery disease (intermediate or mildly elevated level of troponin) or who have limited access to invasive cardiac catheterisation facilities needs further prospective evaluation.

CONCLUSIONS

In patients with suspected or provisionally diagnosed acute coronary syndrome, computed tomography coronary angiography did not alter overall coronary therapeutic interventions or 1-year clinical outcomes, but it did increase the length of hospital stay and health-care costs. These findings do not support the routine use of early computed tomography coronary angiography in intermediate-risk patients with acute chest pain.

TRIAL REGISTRATION

This trial is registered as ISRCTN19102565 and Clinical Trials NCT02284191.

FUNDING

This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 37. See the NIHR Journals Library website for further project information.

Corrected calculation of the overestimated ejection fraction in valvular heart disease by phase-contrast cardiac magnetic resonance imaging for better prediction of patient morbidity

Background

To establish a more accurate technique for the assessment of the left ventricular function correlated with patients’ clinical condition avoiding the miscalculation of the ejection fraction in valvular regurgitation. A prospective study carried out between July 2018 and June 2019. The studied group included 35 subjects, 25 patients with valvular regurgitation, and 10 healthy control subjects. All subjects underwent cardiovascular magnetic resonance examination to evaluate the ejection fraction by two methods: the volumetric method which assesses stroke volume via subtraction of the end-systolic volume from the end-diastolic volume, and phase-contrast method which assesses the aortic stroke volume via a through-plane phase contrast across the aortic valve. The sensitivity, specificity, P value and the area under the curve of both methods were calculated.

Results

In the healthy group, using the volumetric method, the calculated mean ejection fraction was 62.44 ± 6.61, while that calculated by the phase-contrast method was 64.34 ± 5.33, with a non-significant difference (P = 0.62) showing the validity of the phase-contrast method. In the patients’ group, by using the volumetric method, the calculated mean ejection fraction was 47.17 ± 14.31%, which was significantly higher than that calculated by the phase-contrast method (29.39 ± 7.98%) (P = 0.02). According to the results of the calculation of the ejection fraction by the volumetric method, there were 18 patients (72%) having impaired cardiac function and 7 (28%) patients of normal function; while according to the phase-contrast method, all the 25 patients had impaired cardiac function. The current study shows that the phase-contrast cardiac magnetic resonance had 89.29% sensitivity and 85.7% specificity in diagnosing impaired cardiac function with the area under the curve of 0.87 (P = 0.00).

Conclusion

The phase-contrast cardiac magnetic resonance can provide a better assessment of the ejection fraction in valvular regurgitation.

Appropriate use of noninvasive ischemia testing to guide revascularization decision making following acute ST elevation myocardial infarction in Latin American countries: Results from an expert panel meeting of the International Atomic Energy Agency

Across Latin American and Caribbean countries, cardiovascular disease and especially ischemic heart disease is currently the main cause of death both in men and in women. For most Latin American and Caribbean countries, public and community health efforts aim to define care strategies which are both clinically and cost effective and promote primary and secondary prevention, resulting in improved patient outcomes. The optimal approach to deal with acute events such as ST-elevation myocardial infarction (STEMI) is a matter of controversy; however, there is an expanding role for assessing residual ischemic burden in STEMI patients following primary percutaneous coronary intervention. Although randomized clinical trials have established the value of staged fractional flow reserve-guided revascularization, the use of noninvasive functional imaging modalities may play a similar role at a much lower cost. For LAC, available stress imaging techniques could be applied to define residual ischemia in the non-infarct related artery and to target revascularization in a staged procedure after primary percutaneous coronary intervention The use of nuclear cardiac imaging, supported by its relatively wide availability, moderate cost, and robust quantitative capabilities, may serve to guide effective care and to reduce subsequent cardiac events in patients with coronary artery disease. This noninvasive approach may avert potential safety issues with repeat and lengthy invasive procedures, and serve as a baseline for subsequent follow-up stress testing following the index STEMI event. This consensus document was devised from an expert panel meeting of the International Atomic Energy Agency, highlighting available evidence with a focus on the utility of stress myocardial perfusion imaging in post-STEMI patients. The document could serve as guidance to the prudent and appropriate use of nuclear imaging for targeting therapeutic management and avoiding unnecessary invasive procedures within Latin American and Caribbean countries, where resources could be scarce.

Fuzzy Modeling to Predict Severely Depressed Left Ventricular Ejection Fraction following Admission to the Intensive Care Unit Using Clinical Physiology

Left ventricular ejection fraction (LVEF) constitutes an important physiological parameter for the assessment of cardiac function, particularly in the settings of coronary artery disease and heart failure. This study explores the use of routinely and easily acquired variables in the intensive care unit (ICU) to predict severely depressed LVEF following ICU admission. A retrospective study was conducted. We extracted clinical physiological variables derived from ICU monitoring and available within the MIMIC II database and developed a fuzzy model using sequential feature selection and compared it with the conventional logistic regression (LR) model. Maximum predictive performance was observed using easily acquired ICU variables within 6 hours after admission and satisfactory predictive performance was achieved using variables acquired as early as one hour after admission. The fuzzy model is able to predict LVEF ≤ 25% with an AUC of 0.71 ± 0.07, outperforming the LR model, with an AUC of 0.67 ± 0.07. To the best of the authors' knowledge, this is the first study predicting severely impaired LVEF using multivariate analysis of routinely collected data in the ICU. We recommend inclusion of these findings into triaged management plans that balance urgency with resources and clinical status, particularly for reducing the time of echocardiographic examination.

Admission glucose and left ventricular systolic function in non-diabetic patients with acute myocardial infarction

Carbohydrate metabolism disorder in patients hospitalized due to acute ST-segment elevation myocardial infarction (STEMI) is associated with poor outcome. The association is even stronger in non-diabetic patients compared to the diabetics. Poor outcome of patients with elevated parameters of carbohydrate metabolism may be associated with negative impact of these disorders on left ventricular (LV) function. The aim of the study was to determine the impact of admission glycemia on LV systolic function in acute phase and 6 months after myocardial infarction in STEMI patients treated with primary angioplasty, without carbohydrate disorders. The study group consisted of 52 patients (9 female, 43 male) aged 35-74 years, admitted to the Department of Cardiology and Internal Medicine, Collegium Medicum in Bydgoszcz, due to the first STEMI treated with primary coronary angioplasty with stent implantation, without diabetes in anamnesis and carbohydrate metabolism disorders diagnosed during hospitalization. Echocardiography was performed in all patients in acute phase and 6 months after MI. Plasma glucose were measured at hospital admission. In the subgroup with glycemia ≥7.1 mmol/l, in comparison to patients with glycemia <7.1 mmol/l, significantly lower ejection fraction (EF) was observed in acute phase of MI (44.4 ± 5.4 vs. 47.8 ± 6.3 %, p = 0.04) and trend to lower EF 6 months after MI [47.2 ± 6.5 vs. 50.3 ± 6.3 %, p = 0.08 (ns)]. Higher admission glycemia in patients with STEMI and without carbohydrate metabolism disturbances, may be a marker of poorer prognosis resulting from lower LV ejection fraction in the acute phase and in the long-term follow-up.

Impact of continuous positive airway pressure treatment on left ventricular ejection fraction in patients with obstructive sleep apnea: a meta-analysis of randomized controlled trials

BACKGROUND

It has been known for a long time that obstructive sleep apnea (OSA) is associated with a decreased left ventricular ejection fraction (LVEF). Continuous positive airway pressure (CPAP) is the gold standard treatment for OSA; however, it is unknown whether or not CPAP treatment will improve the LVEF. The aim of the current study was to assess whether or not CPAP treatment improves the LVEF. A meta-analysis was conducted to determine the effect of CPAP treatment on the LVEF among patients with OSA.

METHODS

A literature search of PubMed, the Web of Science, and Cochrane Collaboration's database were utilized to identify eligible reports for this trial. Ten randomized controlled trails were examined and the meta-analysis was performed using STATA 11.

RESULTS

A significant improvement in the LVEF was observed after CPAP treatment (weighted mean difference(WMD) = 3.59, 95% CI = 1.74-5.44; P<0.001). Subgroup analysis revealed that patients with OSA and heart failure had a significant improvement in the LVEF after CPAP treatment (WMD = 5.18, 95% CI = 3.27-7.08; P<0.001); however, the LVEF of patients with OSA only increased 1.11% and there was no statistical significance (WMD = 1.11, 95% CI = -1.13-3.35; P = 0.331). Furthermore, based on univariate meta-regression analysis, only the baseline AHI had a statistically significant correlation with the LVEF.

CONCLUSIONS

Our meta-analysis supports the notion that CPAP may improve the LVEF among patients with OSA.

Accuracy of multi-slice computed tomography for measurement of left ventricular ejection fraction compared with cardiac magnetic resonance imaging and two-dimensional transthoracic echocardiography: a systematic review and meta-analysis

BACKGROUND

Multi-slice computed tomography (MSCT) allows non-invasive assessment of the coronary arteries and simultaneously can provide measurement of left ventricular ejection fraction (LVEF). The accuracy of newer MSCT generations (64-slice or more) for assessment of LVEF compared with magnetic resonance imaging (MRI) and two-dimensional transthoracic echocardiography (TTE) has not been evaluated in a meta-analysis.

PURPOSE

To evaluate, via a systematic literature review and meta-analysis, whether MSCT can assess LVEF with high accuracy compared with MRI and TTE.

METHODS

Electronic databases and reference lists for relevant published studies were searched. Twenty-seven eligible studies provided mean LVEF% with its standard deviation (SD) measured by MSCT versus MRI and TTE. Meta-analysis of weighted mean difference (WMD) and Bland-Altman method were used to quantify the mean difference and agreement between MSCT compared with MRI and TTE.

RESULTS

The results of combining 12 studies showed no significant difference in LVEF% between MSCT and MRI with a WMD of -0.11 (-1.48, 1.26, 95% CI), p=0.88. Bland-Altman analysis showed excellent agreement between MSCT and MRI with a bias of 0.0 (-3.7, 3.7 ± 1.96SD) with 95% CI. The results of combining 15 studies showed no significant difference in LVEF between MSCT versus TTE measurements with a WMD of 0.19 (-1.13 to 1.50; 95% CI), p=0.87. Bland-Altman analysis showed excellent agreement between MSCT and TTE with a bias of 0.3 (-4.7, 5.7 ± 1.96SD) with 95% CI.

CONCLUSION

The newer MSCT generations can provide accurate LVEF measurement compared to MRI and TTE. MSCT represents a valid technique for the combined evaluation of LVEF and coronary artery disease.

Decreased concentration of adiponectin together with a selective reduction of its high molecular weight oligomers is involved in metabolic complications of myotonic dystrophy type 1

OBJECTIVE

The hormone adiponectin exerts beneficial pleiotropic effects on biological and metabolic processes. Although a well-recognized insulin sensitizer, its characteristic has yet to be clearly defined. Myotonic dystrophy type 1 (DM1) is a rare genetic disorder that features muscle wasting and metabolic comorbidity, and patients have an increased risk of developing type 2 diabetes. We analyzed circulating levels of adiponectin and its oligomers to determine whether their expression correlates with metabolic alterations in DM1 patients.

DESIGN AND METHODS

We measured the anthropometric and biochemical features and three insulin resistance (IR) indices (homeostasis model assessment, quantitative insulin sensitivity check index, and McAuley) of 21 DM1 patients and of 82 age-, sex-, and weight-matched controls. In the blood samples of patients and controls, adiponectin levels were measured by ELISA, and its oligomers were characterized by using western blotting and gel filtration. The adiponectin gene was molecularly analyzed in patients.

RESULTS

DM1 patients had significantly higher body mass index, waist circumference, triglycerides (TGs), glucose, tumor necrosis factor α, and IR; conversely, they had significantly lower concentrations of total serum adiponectin with a selective, pronounced decrease of its high molecular weight (HMW) oligomers. There was a strong negative correlation between adiponectin and TGs in DM1 patients.

CONCLUSIONS

Our results endorse the hypothesis that decreased expression of adiponectin together with a selective reduction of its HMW oligomers contributes to the worsening of IR and its metabolic complications in DM1 patients. These findings suggest that adiponectin and HMW oligomers may serve as biomarkers and are promising therapeutic agents for IR and its consequences in DM1.

Imaging techniques in coronary atherosclerotic disease: dobutamine stress echocardiography--evidence and perspectives

Dobutamine stress echocardiography is the most widely disseminated noninvasive technique for the assessment of coronary artery disease. Its results are important for clinical decisions. It is a versatile technique with high sensitivity and specificity for detecting viable myocardium at jeopardy. More recently, strain rate imaging has been applied to stress echocardiography. This approach relies on tissue Doppler or two-dimensional strain imaging to quantify myocardial deformation. The application of contrast echocardiographic techniques to stress echocardiography enables left ventricular opacification for border enhancement and myocardial perfusion imaging. Thus, this application is not limited to stress echocardiography, but has utility whenever image quality adversely affects wall motion assessment. Recently, three-dimensional stress echocardiography imaging has been proposed as an alternative approach to assess myocardial ischemia.

The 20 year evolution of dobutamine stress cardiovascular magnetic resonance

Over the past 20 years, investigators world-wide have developed and utilized dobutamine magnetic resonance stress testing procedures for the purpose of identifying ischemia, viability, and cardiac prognosis. This article traces these developments and reviews the data utilized to substantiate this relatively new noninvasive imaging procedure.

Tc-99m sestamibi single photon emission computed tomography for guiding percutaneous coronary intervention in patients with multivessel disease: a comparison with quantitative coronary angiography and fractional flow reserve

To evaluate the accuracy of myocardial perfusion SPECT (MPI) in the detection and allocation of vessel specific perfusion defects (PD) using standard distribution territories in a routine clinical procedure of patients with multivessel disease (MVD). Combined quantitative coronary angiography and fractional flow reserve (QCA/FFR) measurements were used as invasive reference standard. 216 vessels in 72 MVD patients (67 +/- 10 years, 28 female) were investigated using MPI and QCA. FFR of 93 vessels with intermediate stenoses was determined. MPI detected significant stenoses according to QCA/FFR findings with a sensitivity of 85%. However, vessel-based evaluation using standard myocardial distribution territories delivered a sensitivity of only 62% (28 MPI+ out of 45 (QCA/FFR)+ findings), with specificity, PPV and NPV of 90, 62 and 90%. 7/17 false positive and 7/17 false negative findings (41%) could be attributed to incorrect allocation of reversible PD to their respective coronary arteries. 6/17 (35%) perfusion territories were classified as false negative when additional fixed PD were present. MPI had reasonable sensitivity for the detection of significant coronary artery disease in patients with multivessel disease. However, sensitivity decreased markedly, when the significance of each individual stenosis was evaluated using standard myocardial supplying territories. In this setting, 41% of false negative and false positive MPI findings resulted from incorrect allocation of reversible perfusion defects to their determining supplying vessel.

Impact of contrast echocardiography on diagnostic algorithms: pharmacoeconomic implications

The major goal of medicine in the era of managed care is to control escalating costs and to attain a high level of quality health care. Capitation has limited access to expensive and unnecessary testing, placing an emphasis on the prudent use of available technology. A vast armamentarium of available diagnostic screening tests are available within cardiology. Routine two-dimensional (2-D) echocardiography is a high-quality, low-cost test that provides enhanced portability and real-time test interpretation over other noninvasive test modalities. The echocardiogram may cost up to 50% less than competitive nuclear single-photon emission computed tomography (SPECT) imaging. However, on average 10% of routine and 33% of stress echocardiograms are suboptimal (disproportionately affecting obese patients and those with lung disease). Myocardial contrast echocardiography has been shown to provide enhanced endocardial border delineation and left ventricular opacification, to enhance Doppler signal, and to provide information on myocardial perfusion. In several recent phase II and III studies, the use of a contrast agent has been shown to improve the diagnostic accuracy of echocardiography substantially. Improvements in the diagnostic capabilities of echocardiography have been shown to (1) impact upon downstream repetitive testing in patients with an initially nondiagnostic echocardiogram, (2) potentially increase laboratory throughput, and (3) reduce the rate of false-positive and negative tests as a result of improved image quality. As clinical and cost-effectiveness parallel one another, the use of myocardial contrast echocardiography in selected patient cohorts will result in improved diagnostic accuracy and a cost-effective pattern of care.

Prognostic evaluation by clinical exercise test scores in patients treated with primary percutaneous coronary intervention or fibrinolysis for acute myocardial infarction (a Danish Trial in Acute Myocardial Infarction-2 Sub-Study)

The prognostic accuracy of exercise testing after myocardial infarction is low, and different models have been proposed to enhance the predictive value for subsequent mortality. This study tested a simple score against 3 established scores. Patients with ST-elevation myocardial infarctions were randomized in the Danish Trial in Acute Myocardial Infarction-2 (DANAMI-2) to either primary percutaneous coronary intervention or fibrinolysis with predischarge exercise testing. Clinical and exercise test data were collected prospectively and were available for 1,115 patients. A simple score was derived, awarding 1 point for history or new signs of heart failure, 1 point for a left ventricular ejection fraction <40%, 1 point for age >65 years in men and age >70 years in women, and 1 point for exercise capacity <5 METs in men and exercise capacity <4 METs in women. This DANAMI score was compared with the Veterans Affairs Medical Center score, the Duke treadmill score, and the Gruppo Italiano per lo Studio Della Sopravvivenza nell'Infarto Miocardico-2 (GISSI-2) score in multivariate Cox models and receiver-operating characteristic plots. All scoring systems were predictive of adverse outcomes. The DANAMI score performed better, with greater chi-square values (142 vs 53 to 88 for the prediction of death). Areas under the receiver-operating characteristic curves were compared and were larger for the DANAMI score (C-statistic 0.79 vs 0.71 to 0.74 for the other tests regarding mortality). The DANAMI score stratified patients into a small high-risk group (8% of the population with 43% mortality in 6 years), an intermediate-risk group (13% with 16% mortality in 6 years), and a low-risk group (79% with 4% mortality in 6 years). In conclusion, a simple exercise test score composed of age, METs, heart failure, and a left ventricular ejection fraction <40% seems to outperform the Duke treadmill score, Veterans Affairs Medical Center score, and GISSI-2 score in risk stratifying patients after myocardial infarction and deserves further evaluation.

Pre-discharge exercise test for evaluation of patients with complete or incomplete revascularization following primary percutaneous coronary intervention: a DANAMI-2 sub-study

OBJECTIVES

It is unclear whether the completeness of revascularization impacts on the prognostic value of an exercise test after primary percutaneous coronary intervention (PCI).

METHODS

The DANAMI-2 trial included patients with ST elevation acute myocardial infarction randomized to primary PCI or fibrinolysis. Of the 790 patients randomized to primary PCI, 572 performed an exercise test. Prospectively, 310 patients were classified as having complete and 216 as having incomplete revascularization. Primary endpoint was a composite of reinfarction and/or death.

RESULTS

Patients with incomplete revascularization had lower exercise capacity [6.5 (95% CI: 1.9-12.8) vs. 7.0 (95% CI: 2.1-14.0) METs, p = 0.004] and more frequently ST depression [43 (20%) vs. 39 (13%), p = 0.02] compared to patients with complete revascularization. ST depression was not predictive of outcome in either groups, while multivariable analyses showed that exercise capacity was predictive of reinfarction and/or death in patients with incomplete revascularization [hazard ratio = 0.71 (95% CI: 0.54-0.93), p = 0.012] or of death alone [hazard ratio = 0.56 (95% CI: 0.41-0.77), p = 0.0003], which was not found in patients with complete revascularization.

CONCLUSIONS

Exercise capacity was prognostic of reinfarction and/or death in patients with incomplete revascularization, but not in completely revascularized patients. ST segment depression alone did not predict residual coronary stenosis or dismal prognosis.

Assessment of left ventricular function: comparison of cardiac multidetector-row computed tomography with two-dimension standard echocardiography for assessment of left ventricular function

OBJECTIVE

To compare global Left Ventricular (LV) systolic function assessment by 16-detector row Computed Tomography (MDCT) with Two-Dimensional Standard Echocardiography (2DSE) in a routine cardiology practice setting and to ascertain the degree of correlation between LV volumes and measurements obtained by 2DSE with those measured by MDCT.

METHODS

In 52 patients with suspected coronary artery disease, a contrast enhanced MDCT study was performed using retrospective gating without dose modulation for better endocardial delineation. Eight phases of the cardiac cycle were analyzed to identify the end-diastolic and end-systolic phases. 2DSE was performed on the same day. Left ventricular systolic and diastolic volumes and ejection fraction were calculated in 4-chamber, 2-chamber and biplane (average of the two) views. Endocardial tracing was used to measure ventricular volumes by area length method for CT and Simpson's method for echocardiography.

RESULTS

On MDCT, mean LV ejection fraction (LVEF) in 4-chamber, 2-chamber and biplane views were 58.4 +/- 12, 59.3 +/- 12 and 59.7 +/- 12% respectively. On 2DSE, mean LVEF in 4-chamber, 2-chamber and biplane views were 58 +/- 14, 57 +/- 16 and 58 +/- 13% respectively. LVEF correlated best using the biplane views (r = 0.59 and P < 0.01) compared to 2-chamber (r = 0.57 and P < 0.01) and 4-chamber views (r = 0.32 and P = 0.02). Biplane measurement by these two techniques correlated well for LV volumes in both diastole (r = 0.69 and P < 0.01) and systole (r = 0.73 and P < 0.01), although MDCT consistently gave higher values.

CONCLUSIONS

MDCT can be a useful tool to measure LVEF while patients are undergoing CT coronary angiography.

Electrocardiographic exercise stress testing: an update beyond the ST segment

Routine exercise testing is frequently ordered to evaluate a patient's cardiovascular performance. The test is more direct and less expensive than imaging technology, and derives valuable information. New variables such as dyspnea and heart rate recovery, as well as integrated scores, provide incremental value to conventional analysis of exercise-induced angina or electrocardiographic changes. Considerations relating to test accuracy in women need to be weighed. This paper seeks to make physicians aware of the current status of the test, and improve their understanding of and ability to integrate new variables and scores to more effectively manage their patients.

Prognostic value of stress myocardial perfusion imaging in patients with mildly impaired systolic left ventricular function or left ventricular asynergy without chest pain but with suspected coronary artery disease

BACKGROUND

The prognostic value of myocardial perfusion imaging (MPI) was investigated in patients with mildly impaired left ventricular (LV) function who had no chest pain but were suspected to have coronary artery disease (CAD).

METHODS AND RESULTS

Consecutive patients (n=72, mean age =67) who had no chest pain but with mildly impaired systolic LV function (mean LV ejection fraction =52%) or LV asynergy and suspected to have CAD were followed up for 4.9 years after stress MPI. The follow-up time was censored at the occurrence of cardiac death, hospitalization for congestive heart failure (CHF), acute coronary syndromes (ACS), or revascularization. Images were scored using a 20-segment model and a 0-4 scale, and then the summed stress, rest, and difference scores (SDS) were calculated. During follow-up, there were 2 cases of cardiac death, 8 of hospitalization for CHF, 4 of ACS and 2 of revascularization. Cox regression demonstrated that SDS >or=4 was an excellent predictor of cardiac events in all patients (hazard ratio =4.2, p=0.01), and especially in diabetic patients (hazard ratio =28.4, p=0.01).

CONCLUSION

Stress MPI is useful for predicting cardiac events and may be performed in patients without chest pain if they have mildly impaired systolic LV function or LV asynergy.

Exercise Intensity Prescription After Myocardial Infarction in Patients Treated With Beta-blockers

PURPOSE

The aim of our study was to answer the following questions: (1) Is it possible to estimate the exercise training intensity according to heart rate in patients treated with beta-blockers after myocardial infarction? and (2) Are there any other appropriate alternate possibilities to estimate the training intensity?

METHODS

This study involved 112 men (60.2 +/- 8.6 years) with a previous myocardial infarction treated with beta-blockers. Patients underwent exercise echocardiography and also completed a symptom-limited cardiopulmonary ramp test to determine peak exercise capacity, maximal heart rate, heart rate (HR) at the anaerobic threshold (AT), peak oxygen uptake (VO2peak) VO2 consumption at AT, and exercise capacity at AT.

RESULTS

The mean value of HR at AT was 104.7 +/- 13.3 bpm, corresponding to 81.0% +/- 8% of VO2peak and 87.9% +/- 5.6% of HRpeak. The mean HR at 80% HRpeak was 96 +/- 13.7 bpm, at 70% heart rate reserve (HRR) 103.3 +/- 13.1 bpm and at 80% HRR 108 +/- 14.4 bpm. A close correlation was observed between HR at AT and values at 80% HRpeak (r = 0.86, P < .01). A similar correlation was found also for 70% and 80% HRR (r = 0.87 and 0.88, respectively, P < .01). Exercise intensity at AT occurred close to the value of 1 W/kg(bodyweight).

CONCLUSIONS

As an upper limit in determining training intensities, the assessment of AT is the gold standard. However, findings suggest that %HRpeak, %HRR, and %VO2peak can be used alternatively. The use of workload expressed as in W/kg also appears useful.

Prognostic value of adenosine Tl-201 myocardial perfusion imaging after acute myocardial infarction: results of a prospective clinical trial

BACKGROUND

We have previously shown in retrospective studies that adenosine myocardial perfusion imaging (MPI) done after acute myocardial infarction (AMI) can effectively predict the risk of future cardiac events in these patients. The objective of this study was to validate these observations in a prospective clinical trial.

METHODS AND RESULTS

One hundred twenty-six stable patients underwent quantitative adenosine MPI at a mean of 4.5 +/- 2.9 days after AMI. On the basis of the MPI results, they were divided into 3 risk groups: low risk (< 20% perfusion defect), intermediate risk (> or = 20% perfusion defect with < 10% ischemia), and high risk (> or = 20% perfusion defect with > 10% ischemia). The patients were followed up for 11 +/- 5 months for the occurrence of cardiac events: death, myocardial infarction, unstable angina, or congestive heart failure. The actual event rates correlated very well with the prespecified risk groups (19% for the low-risk group, 28% for the intermediate-risk group, and 78% for the high-risk group; P < .001). The significant multivariate predictors for events were female gender (relative risk [RR], 2.90; P = .002), left ventricular ejection fraction (RR, 1.34; P = .04), and ischemic defect size (RR, 1.46; P = .001), with a global chi2 value of 26.7.

CONCLUSION

This study demonstrates, in a prospectively designed clinical trial, that quantitative adenosine MPI performed soon after AMI can effectively predict the risk of future cardiac events. These findings are currently being validated in an ongoing, large, multicenter, international clinical trial.

Stress echocardiography versus myocardial SPECT for risk stratification of patients with coronary artery disease

PURPOSE OF REVIEW

Diagnostic testing using noninvasive imaging has become an integral part of risk stratification in patients with coronary artery disease. It is important to understand the integral strengths and weaknesses between the different modalities of stress testing and to apply accurately the type of test the clinical scenario demands.

RECENT FINDINGS

There have been tremendous advances made in the field of cardiac imaging. Both myocardial perfusion imaging and stress echocardiographic techniques continue to evolve and play an important role in the assessment of patients with coronary artery disease.

SUMMARY

In this review the authors discuss the relative merits of both stress echocardiography and myocardial single photon emission computed tomographic imaging for diagnosis and risk stratification of patients with coronary artery disease.

Effect of pharmacological wash-out in patients undergoing exercise testing after acute myocardial infarction

STUDY OBJECTIVES

Pharmacological therapy can reduce diagnostic and prognostic accuracy of exercise stress testing. However, the risk of withdrawing drugs early after myocardial infarction (MI) has not been established. We assessed safety and clinical implications of drug withdrawal in patients undergoing stress testing after uncomplicated MI.

METHODS

A total of 362 MI patients underwent ECG Holter recording before and after withdrawing beta-blockers, calcium-antagonists and nitrates. QRS (QRS/h) and ventricular premature beats (VPB/h) count per hour, repetitive ventricular arrhythmias, ST segment changes and patient complaints were evaluated for reproducibility using kappa statistics and Bland-Altman method.

RESULTS

No major complications occurred. Forty-three patients complained of >1 symptom on and 37 off therapy. QRS/h and VPB/h count were significantly (p<0.0001) higher off therapy but correlated with the corresponding values on therapy. A mean heart rate increase of 8 beats/min (agreement range -8 to +14 beats/min) and a five-fold increase in VPB/h (agreement range -141 to +151) were observed after withdrawing therapy. Repetitive ventricular arrhythmias and ST changes were also more frequent off therapy but intra-patient reproducibility was poor: kappa 0.12 (95% confidence interval (CI) -0.01 to 0.25) for arrhythmias, -0.02 (95% CI -0.46 to 0.39) for ST depression and -0.01 (95% CI -0.66 to 0.64) for ST elevation.

CONCLUSIONS

The withdrawal of therapy is well tolerated soon after uncomplicated MI; however, a generic but not individual risk of ventricular arrhythmias and/or transient myocardial ischemia has to be taken into account.

Incremental prognostic value of left ventricular function by myocardial ECG-gated FDG PET imaging in patients with ischemic cardiomyopathy

BACKGROUND

The purpose of this study was to determine the independent value of left ventricular (LV) functional parameters derived from gated fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) to predict prognosis in patients with ischemic cardiomyopathy undergoing myocardial viability assessment.

METHODS AND RESULTS

We studied 90 consecutive patients with coronary artery disease and low LV ejection fraction (26% +/- 7%) undergoing gated FDG PET to assess myocardial viability for potential revascularization. The primary endpoint for this analysis was the occurrence of cardiac death, myocardial infarction, or worsening heart failure (HF) to New York Heart Association class IV. During follow-up (22 +/- 14 months), 21 patients had an event (17 died, 4 had myocardial infarctions, and 4 had worsening HF). On Cox regression analysis, the event-free survival rate at 2 years was lower for patients with an end-diastolic volume (EDV) of 260 mL or greater (relative risk, 2.7; P = .014), end-systolic volume (ESV) of 200 mL or greater (relative risk, 2.5; P = .021), and LV mass of 143 g or greater (relative risk, 1.6; P = .009). In a risk-adjusted model, EDV (chi 2 = 68, P < .0001) and ESV (chi 2 = 75, P = .035) added a significant amount in the estimation of events over the perfusion-FDG mismatch pattern (chi 2 = 40, P < .001). In a stratified Cox model, patients with PET mismatch, LV ejection fraction lower than 25%, and EDV of 260 mL or greater had the lowest survival rate (P = .006). These patients showed an apparent survival benefit with revascularization but without an improvement in HF symptoms.

CONCLUSION

LV functional parameters determined by gated FDG PET have incremental prognostic value over viability information in patients with ischemic cardiomyopathy. Our data suggest that patients with residual viability and advanced cardiac remodeling are at high clinical risk. In these patients the apparent survival benefit of revascularization may not be associated with a measurable improvement in HF symptoms.

Exercise electrocardiography after acute coronary syndromes: still the first testing modality?

Recent diagnostic and therapeutic advances have been questioning the role of exercise electrocardiography (ECG) for risk stratification of patients recovering from an acute coronary syndrome. The aim of this review was to verify whether evidence still exists supporting the use of exercise ECG as first choice stress testing modality in this clinical setting in the light of the most recent prognostic data and of cost effectiveness considerations. It was concluded that a large body of evidence supports the use of exercise ECG as a cost-effective tool for prognostic purposes and for quality of life assessment following acute coronary syndromes.

Prognostic value of exercise tests in male veterans with chronic coronary artery disease

PURPOSE

The authors evaluate the prognostic value of treadmill testing in a large consecutive series of patients with chronic coronary artery disease. Exercise testing is widely performed, but analyses of the prognostic value of test results have largely concentrated on patients referred for the diagnosis of coronary artery disease, patients after an acute coronary event or procedure, or patients with congestive heart failure.

METHODS

All patients referred for evaluation at two university-affiliated Veterans Affairs Medical Centers who underwent exercise treadmill tests for clinical indications between 1987 and 2000 were determined to be dead or alive using the Social Security Death Index after a mean 5.8-year follow-up. Patients without established heart disease and those with congestive heart failure were excluded, leaving the target population of those with a history myocardial infarction or coronary intervention. Clinical and exercise test variables were collected prospectively according to standard definitions; testing and data management were performed in a standardized fashion using a computer-assisted protocol. All-cause mortality was used as the endpoint for follow-up. Standard survival analysis was performed including Kaplan Meier curves and the Cox Hazard Model.

RESULTS

Of the 1,473 patients with coronary artery disease who had exercise testing, 273 (19%) patients had a revascularization procedure (Revascularization group); 813 (55%) had a history of myocardial infarction, diagnostic Q waves (MI group), or both; and 387 (26%) had a history of myocardial infarction or Q wave and revascularization (Combined group). Mean age of the patients was 61.8 +/- 9 years. A total of 401 deaths occurred during a mean follow-up of 5.8 years with an annual mortality rate of 4.5%. Only two variables, age and maximal exercise capacity, were independently and statistically associated with time to death in all three groups and were the strongest predictors of all cause mortality.

CONCLUSION

A simple score based on METs, age, and history of myocardial infarction or diagnostic Q waves can stratify prognosis in patients with chronic coronary artery disease. The score enabled the identification of a group at low risk (32% of the cohort) with an annual mortality rate of 2%, a group at intermediate risk (42% of the cohort) with an annual mortality rate of about 4%, and a group at high risk (26% of the cohort) with an average annual mortality rate of approximately 7%.

Risk of sudden versus nonsudden cardiac death in patients with coronary artery disease

BACKGROUND

Patients at high risk of sudden cardiac death, yet at low risk of nonsudden death, might be ideal candidates for antiarrhythmic drugs or devices. Most previous studies of prognostic markers for sudden cardiac death have ignored the competitive risk of nonsudden cardiac death. The goal of the present study was to evaluate the ability of clinical factors to distinguish the risks of sudden and nonsudden cardiac death.

METHODS

We identified all deaths during a 3.3-year follow-up of 30,680 patients discharged alive after admission to the cardiac care unit of a Seattle hospital. Detailed chart reviews were conducted on 1093 subsequent out-of-hospital sudden deaths, 973 nonsudden cardiac deaths, and 442 randomly selected control patients.

RESULTS

Patients who died in follow-up (suddenly or nonsuddenly) were significantly different for many clinical factors from control patients. In contrast, patients with sudden cardiac death were insignificantly different for most clinical characteristics from patients with nonsudden cardiac death. The mode of death was 20% to 30% less likely to be sudden in women, patients who had angioplasty or bypass surgery, and patients prescribed beta-blockers. The mode of death was 20% to 30% more likely to be sudden in patients with heart failure, frequent ventricular ectopy, or a discharge diagnosis of acute myocardial infarction. A multivariable model had only modest predictive capacity for mode of death (c-index of 0.62).

CONCLUSION

Standard clinical evaluation is much better at predicting overall risk of death than at predicting the mode of death as sudden or nonsudden.

Exercise-induced symptomatic ischaemia predicts a poor long-term prognosis after acute myocardial infarction

STUDY OBJECTIVES

To evaluate the long-term prognostic significance of symptomatic ischaemia during exercise testing performed 3 weeks after acute myocardial infarction (AMI).

DESIGN

A prospective study with long-term follow-up.

SETTING

A Cardiac Rehabilitation Clinic in a University Hospital.

SUBJECTS

A total of 446 patients were allowed to perform exercise testing 3 weeks after AMI and followed for 72 +/- 20 months.

MEASUREMENTS AND RESULTS

Patients were divided into three groups according to whether they had no ECG evidence of ischaemia during exercise testing (334 patients), silent ischaemia (90 patients) or symptomatic ischaemia (22 patients). Cardiac death was significantly more frequent in patients with symptomatic ischaemia when compared with silent ischaemia (31.8% vs. 7.8%, P < 0.01) or when compared with no ischaemia (31.8% vs. 10.2%, P < 0.01). The three groups had a low cardiac mortality during the first 48 months of follow-up. The prognosis of patients with symptomatic ischaemia worsens markedly thereafter. The results of exercise testing did not predict recurrence of myocardial infarction. Coronary revascularization was performed in 34.4% of those without ischaemia, 47.8% of those with silent ischaemia and 45.5% of those with symptomatic ischaemia (P < 0.01).

CONCLUSIONS

Patients with symptomatic ischaemia have a good prognosis during the first 4 years of follow-up. Their prognosis worsens thereafter as opposed to patients with or without silent ischaemia. This high-risk group of patients with symptomatic ischaemia deserves optimal management including revascularization when appropriate.

Risk assessment in patients with acute myocardial infarction treated with thrombolytic therapy

OBJECTIVE

Several noninvasive methods have prognostic information regarding mortality and new coronary events after an acute myocardial infarction (AMI). The practical for clinical decision-making in the immediate postmyocardial infarction (MI) period is, however, less evident. We investigated consecutive patients with AMI treated with thrombolysis to further clarify this issue.

DESIGN

A total of 100 patients (27% women) aged 64 +/- 9 years (mean +/- SD) were studied. Risk assessment based on a clinical score system, myocardial perfusion scintigraphy single photon emission computed tomography (SPECT) at rest and during adenosine stress, echocardiography, radionuclide angiography, symptom-limited exercise stress test, and 24-h Holter ECG recording with ST-analysis and analysis of heart rate variability (HRV) were performed 5-8 days after hospital admission. Mortality, nonfatal reinfarction, and the need for revascularization were followed during 12 months.

SETTING

A university hospital.

RESULTS

A total of 6 patients died, seven had a nonfatal reinfarction, and 23 were revascularized. Inability to perform an exercise test (P = 0.004) and an ejection fraction (EF) < 40% (P = 0.002) were the only parameters separating those who died from the survivors. No method could predict a nonfatal reinfarction. Patients suffering either death or nonfatal reinfarction had a clinical risk assessment score 2 points higher (8.8 vs. 6.7, P = 0.05) than the group without such events. A positive symptom-limited exercise stress test (P = 0.027), ST-depressions on Holter ECG (P = 0.04), and reversibility on myocardial perfusion scintigraphy (P = 0.029) predicted the need for revascularization.

CONCLUSION

Risk assessment based on clinical information, exercise stress testing, and an estimate of left ventricular function (e.g. via echocardiography) contribute with prognostic information in thrombolysed MI-patients. Additional noninvasive investigations such as adenosine-SPECT, analysis of HRV, and Holter-monitoring do not add to these commonly available tools in risk stratification of subjects at low to medium risk.

Later management of documented ischaemic heart disease: secondary prevention and rehabilitation

Patients may present with a variety of syndromes related to ischaemic heart disease. These include unstable or stable angina pectoris, acute myocardial infarction, and occasionally cardiac failure without prior anginal pain or infarction. For the purposes of this review, it will generally be assumed that the condition has been stabilised, though one important aspect of the rehabilitation process is the recognition of continuing or recurrent problems such as angina pectoris and cardiac decompensation. This should then be followed by appropriate intervention. The key components of post-hospital management of such patients are: (i) support; (ii) education; (iii) assessment; (iv) intervention (if necessary); (v) therapy; and (vi) lifestyle modification.

Anatomy of a meta-analysis: a critical review of "exercise echocardiography or exercise SPECT imaging? A meta-analysis of diagnostic test performance"

BACKGROUND

Accurate diagnosis of coronary heart disease has the potential to contribute substantially to cost-effective delivery of health services. Recent work by Fleischmann et al (JAMA 1998;280:913-20) represents an effort to summarize the accuracy of exercise echocardiography and exercise single photon emission computed tomography (SPECT).

METHODS AND RESULTS

A critique of the previous work was constructed, obtaining the 44 articles used. These articles were reviewed and summarized with established techniques for meta-analysis. The studies summarized by Fleischmann et al were found to be significantly heterogeneous (echocardiography and SPECT, both P<.001). In the SPECT cohort, combination of different radioisotopes and reading techniques, and inclusion of reports using experimental techniques, were sources of heterogeneity. In the echocardiography cohort, experimental techniques and an individual series were identified. When the sample was stratified for sources of heterogeneity, it was found that there was no significant difference in diagnostic accuracy between the echocardiography and SPECT techniques used in current clinical practice. Meta-regression with summary receiver operating characteristic curve techniques, after adjustment of the model for multicolinearity and outliers, revealed that there were no significant differences between SPECT as used in current clinical practice and echocardiography.

CONCLUSION

The report by Fleischmann et al contains serious flaws that limit its validity and generalizability.

Prognostic value of impaired myocardial fatty acid uptake in patients with acute myocardial infarction

Impaired cardiac fatty acid uptake, assessed by the radiolabelled fatty acid analogue beta-methyl-p-iodophenyl pentadecanoic acid (I-123-BMIPP), is observed in the myocardium following acute ischaemic events, but the long-term prognostic implication has not been established. This study aimed to determine the prognostic value of cardiac BMIPP uptake in patients with acute myocardial infarction. Following the assessment of thallium-201 and I-123-BMIPP uptake, 101 post-infarct patients were prospectively followed up with primary end points of cardiac death, heart failure and non-fatal infarction. During a mean follow-up of 28 months, three cardiac deaths, three non-fatal infarctions, 23 revascularizations and four recurrences of angina pectoris were observed. Multivariate analysis identified reduced uptake of BMIPP and perfusion, no beta-blocking treatment and greater thallium-BMIPP mismatch (i.e. larger BMIPP defect than thallium defect) as significant predictors for overall cardiac events. Prior myocardial infarction, reduced left ventricular ejection fraction and greater thallium-BMIPP mismatch were selected as independent predictors of harder cardiac events. Female patients, those with greater BMIPP defect or greater thallium-BMIPP mismatch showed worse clinical outcomes. The inclusion of BMIPP data improved the prognostic values of conventional significant predictors. In conclusion, impaired myocardial I-123-BMIPP uptake and perfusion-BMIPP mismatch are related to a high probability of fatal and non-fatal cardiac events, suggesting the aetiological relevance and prognostic value of impaired cardiac fatty acid metabolism in viable, but jeopardized, myocardium following acute myocardial infarction.