Prognostic significance of maximal exercise testing after myocardial infarction treated with thrombolytic agents: the GISSI-2 data-base. Gruppo Italiano per lo Studio della Sopravvivenza Nell'Infarto

Low exercise blood pressure and risk of cardiovascular events and all-cause mortality: systematic review and meta-analysis

OBJECTIVE

The independent prognostic significance of abnormally low systolic blood pressure (SBP) during exercise stress testing (LowExBP) across different clinical and exercise conditions is unknown. We sought by systematic review and meta-analysis to determine the association between cardiovascular/all-cause outcomes and LowExBP across different patient clinical presentations, exercise modes, exercise intensities and categories of LowExBP.

METHODS

Seven online databases were searched for longitudinal studies reporting the association of LowExBP with risk of fatal and non-fatal cardiovascular events and/or all-cause mortality. LowExBP was defined as either: SBP drop below baseline; failure to increase >10 mmHg from baseline or; lowest SBP quantile among reporting studies.

RESULTS

After review of 13,257 studies, 19 that adjusted for resting SBP were included in the meta-analysis, with a total of 45,895 participants (average follow-up, 4.4 ± 3.0 years). For the whole population, LowExBP was associated with increased risk for fatal and non-fatal cardiovascular events and all-cause mortality (hazard ratio [HR]: 2.01, 95% confidence interval [CI]: 1.59-2.53, p < 0.001). In continuous analyses, a 10 mmHg decrease in exercise SBP was associated with higher risk (n = 9 HR: 1.13, 95% CI: 1.06-1.20, p < 0.001). LowExBP was associated with increased risk regardless of clinical presentation (coronary artery disease, heart failure, hypertrophic cardiomyopathy or peripheral artery disease), exercise mode (treadmill or bike), exercise intensity (moderate or maximal), or LowExBP category (all p < 0.05). However, bias toward positive results was apparent (Eggers test p < 0.001 and p = 0.009).

CONCLUSION

Our data show that irrespective of clinical or exercise conditions, LowExBP independently predicts fatal and non-fatal cardiovascular events and all-cause mortality.

Comparison of cardiogoniometry and ECG at rest versus myocardial perfusion scintigraphy

BACKGROUND

Cardiogoniometry (CGM) is a novel resting electrocardiac method based on computer-generated three-dimensional data derived from cardiac potentials. The purpose of this study was to determine CGM's and electrocardiography's (ECG) accuracy for detecting myocardial ischemia and/or lesions in comparison with stress/rest myocardial perfusion scintigraphy (single photon emission computer tomography [SPECT]).

METHOD

A cohort of consecutively enrolled patients (n = 100) with suspected or known coronary artery disease (mean age 67.8 years, 52% female) were examined by CGM and resting ECG before stress/rest myocardial scintigraphy.

RESULTS

Pathological scintigraphy findings at adenosine stress perfusion (ASP) and/or rest were conclusively identified in 21 patients. Diagnostic sensitivity was 71% for CGM and 24% for ECG, specificity was 70% for CGM and 95% for ECG. Reversible ischemia was diagnosed in 16 of 21 patients with pathological scintigraphy results. In this subgroup, sensitivity was 67% for CGM and 25% for ECG.

CONCLUSIONS

At rest, the sensitivity of a CGM significantly surmounts that of a standard 12-lead ECG for detection of isolated myocardial ischemia or myocardial lesions revealed by scintigraphy/SPECT; specificity is in a reasonable range. CGM's ease of use and its considerable agreement with the results of myocardial scintigraphy, suggests a possible role for patient screening in the primary care setting.

Comparison of cardiogoniometry and electrocardiography with perfusion cardiac magnetic resonance imaging and late gadolinium enhancement

AIMS

Cardiogoniometry (CGM) is a spatio-temporal five-lead resting electrocardiographic method utilizing automated analysis. The purpose of this study was to determine CGM's and electrocardiography (ECG)'s accuracy for detecting myocardial ischaemia and/or lesions in comparison with perfusion cardiac magnetic resonance imaging (CMRI) and late gadolinium enhancement (LGE).

METHODS AND RESULTS

Forty (n= 40) patients with suspected or known stable coronary artery disease were examined by CGM and resting ECG directly prior to CMRI including adenosine stress perfusion (ASP) and LGE. The investigators visually reading the CMRI were blinded to the CGM and ECG results. Half of the patients (n= 20) had a normal CMRI while the other half presented with either abnormal ASP and/or detectable LGE. Cardiogoniometry yielded an accuracy of 83% (sensitivity 70%) and ECG of 63% (sensitivity 35%) compared with CMRI.

CONCLUSIONS

In this pilot study CGM compares more favourably than ECG with the detection of ischaemia and/or structural myocardial lesions on CMRI.

Long-term outcome of patients with chronotropic incompetence after an acute myocardial infarction

BACKGROUND AND AIM

chronotropic incompetence is risk marker of mortality in various populations, but its value in risk stratification of patients with a recent myocardial infarction (MI) is not known.

METHODS

a consecutive series of 494 patients with a recent MI underwent a symptom-limited bicycle ergometer test and echocardiography before discharge from the hospital. Cardiac death was the primary end-point and sudden cardiac death (SCD) the secondary end-point. Heart rate (HR) response to exercise was evaluated using maximal chronotropic response index (CRI = 100 × (peak HR - resting HR) × (220 - age - resting HR)(-1)).

RESULTS

during 8 years of follow-up, 40 patients (8.1%) experienced cardiac death, of whom 18 died suddenly (3.6%). Abnormal CRI (<39) was the most powerful predictor of the primary end-point with adjusted relative risk (RR) of 5.4 (95% CI 2.9-11.2; P < 0.001) and also a potent risk marker for SCD (adjusted RR 7.3; 95% CI 2.6-20.0; P < 0.001). Adjusted RR of decreased left ventricular ejection fraction (LVEF) (<45%) was 3.4 (95% CI 1.8-6.6; P < 0.001) for cardiac death. In the final predictive model of cardiac death, the removal of CRI decreased c-index from 0.817 to 0.778, whereas c-index was 0.791 after removal of LVEF.

CONCLUSIONS

chronotropic incompetence is a powerful predictor of cardiac mortality among post-MI patients.

Electrocardiologic and related methods of non-invasive detection and risk stratification in myocardial ischemia: state of the art and perspectives

Background: Electrocardiographic methods still provide the bulk of cardiovascular diagnostics. Cardiac ischemia is associated with typical alterations in cardiac biosignals that have to be measured, analyzed by mathematical algorithms and allegorized for further clinical diagnostics. The fast growing fields of biomedical engineering and applied sciences are intensely focused on generating new approaches to cardiac biosignal analysis for diagnosis and risk stratification in myocardial ischemia.

Objectives: To present and review the state of the art in and new approaches to electrocardiologic methods for non-invasive detection and risk stratification in coronary artery disease (CAD) and myocardial ischemia; secondarily, to explore the future perspectives of these methods.

Methods: In follow-up to the Expert Discussion at the 2008 Workshop on "Biosignal Analysis" of the German Society of Biomedical Engineering in Potsdam, Germany, we comprehensively searched the pertinent literature and databases and compiled the results into this review. Then, we categorized the state-of-the-art methods and selected new approaches based on their applications in detection and risk stratification of myocardial ischemia. Finally, we compared the pros and cons of the methods and explored their future potentials for cardiology.

Results: Resting ECG, particularly suited for detecting ST-elevation myocardial infarctions, and exercise ECG, for the diagnosis of stable CAD, are state-of-the-art methods. New exercise-free methods for detecting stable CAD include cardiogoniometry (CGM); methods for detecting acute coronary syndrome without ST elevation are Body Surface Potential Mapping, functional imaging and CGM. Heart rate variability and blood pressure variability analyses, microvolt T-wave alternans and signal-averaged ECG mainly serve in detecting and stratifying the risk for lethal arrythmias in patients with myocardial ischemia or previous myocardial infarctions. Telemedicine and ambient-assisted living support the electrocardiological monitoring of at-risk patients.

Conclusions: There are many promising methods for the exercise-free, non-invasive detection of CAD and myocardial ischemia in the stable and acute phases. In the coming years, these new methods will help enhance state-of-the-art procedures in routine diagnostics. The future can expect that equally novel methods for risk stratification and telemedicine will transition into clinical routine.

Cardiogoniometric parameters for detection of coronary artery disease at rest as a function of stenosis localization and distribution

Cardiogoniometry (CGM), a spatiotemporal electrocardiologic 5-lead method with automated analysis, may be useful in primary healthcare for detecting coronary artery disease (CAD) at rest. Our aim was to systematically develop a stenosis-specific parameter set for global CAD detection. In 793 consecutively admitted patients with presumed non-acute CAD, CGM data were collected prior to elective coronary angiography and analyzed retrospectively. 658 patients fulfilled the inclusion criteria, 405 had CAD verified by coronary angiography; the 253 patients with normal coronary angiograms served as the non-CAD controls. Study patients--matched for age, BMI, and gender--were angiographically assigned to 8 stenosis-specific CAD categories or to the controls. One CGM parameter possessing significance (P < .05) and the best diagnostic accuracy was matched to one CAD category. The area under the ROC curve was .80 (global CAD versus controls). A set containing 8 stenosis-specific CGM parameters described variability of R vectors and R-T angles, spatial position and potential distribution of R/T vectors, and ST/T segment alterations. Our parameter set systematically combines CAD categories into an algorithm that detects CAD globally. Prospective validation in clinical studies is ongoing.

Electrocardiographic change after recanalization in a patient with recent extensive anterior wall myocardial infarction

In a 66-year-old male with subacute extensive anterior wall myocardial infarction, we report a change in ST vector orientation from a basal anterior to a mid anterior after coronary artery recanalization of the proximal left anterior descending coronary artery with rotational atherectomy. The ST vector shift on the frontal plane after recanalization was consistent with a change toward more distal location of the ischemia on thallium-201 single photon emission computed tomography images compared to the findings during an exercise test before intervention. These findings may be correlated with local occlusion caused by distal microvascular embolization which was not visualized on coronary angiography following recanalization.

Impact of stress testing before percutaneous coronary intervention or medical management on outcomes of patients with persistent total occlusion after myocardial infarction: analysis from the occluded artery trial

BACKGROUND

In the Occluded Artery Trial (OAT), 2,201 stable patients with an occluded infarct-related artery (IRA) were randomized to percutaneous coronary intervention (PCI) or optimal medical treatment alone (MED). There was no difference in the primary end point of death, reinfarction, or congestive heart failure (CHF). We examined the prognostic impact of prerandomization stress testing.

METHODS

Stress testing was required by protocol except for patients with single-vessel disease and akinesis/dyskinesis of the infarct zone. The presence of severe inducible ischemia was an exclusion criterion for OAT. We compared outcomes based on performance and results of stress testing.

RESULTS

Five hundred ninety-eight (27%) patients (297 PCI, 301 MED) underwent stress testing. Radionuclide imaging or stress echocardiography was performed in 40%. Patients who had stress testing were younger (57 vs 59 years); had higher ejection fractions (49% vs 47%); and had lower rates of death (7.8% vs 13.2%), class IV CHF (2.4% vs 5.5%), and the primary end point (13.9% vs 18.9%) than patients without stress testing (all P < .01). Mild-moderate ischemia was observed in 40% of patients with stress testing and was not related to outcomes. Among patients with inducible ischemia, outcomes were similar for PCI and MED (all P > .10).

CONCLUSIONS

In OAT, patients who underwent stress testing had better outcomes than patients who did not, likely related to differences in baseline characteristics. In patients managed with optimal medical therapy or PCI, mild-moderate inducible ischemia was not related to outcomes. The lack of benefit for PCI compared to MED alone was consistent regardless of whether stress testing was performed or inducible ischemia was present.

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.

Prognostic value of cycle exercise testing prior to and after outpatient cardiac rehabilitation

BACKGROUND

The prognostic value of cycle exercise testing prior to and after outpatient cardiac rehabilitation (OCR) is not well established.

METHODS

2146 consecutive patients undergoing symptom-limited cycle exercise testing at OCR entry, of whom 1853 (86%) also had a test at end of OCR, were followed for a median of 33 months.

RESULTS

All-cause and cardiovascular annual mortality rates were 1.2% and 0.8%, respectively. At OCR entry, older age, diabetes, lower left ventricular ejection fraction (LVEF), calcium channel blocker use, and lower workload [hazard ratio (HR) 2.38 if < or = 105 W; p<0.001] were independent predictors of death. Diabetes, diuretic use, and lower workload [HR 3.53 if < or = 105 W; p=0.001] were independently associated with cardiovascular death. At end of OCR, older age, lower LVEF, lower workload (HR 2.34 if <140 W; p=0.009), and lower increase in peak heart rate from entry to end of OCR (HR 2.46 if <4 bpm; p=0.002) were independently associated with all-cause mortality. Older age, lower LVEF, lower increase in systolic blood pressure (HR 2.97 if <54 mm Hg; p=0.02), and lower increase in peak heart from entry to end of OCR (HR 2.72 if <4 bpm; p=0.013) were independently associated with cardiovascular mortality. Failure to undergo a test at end of OCR was an additional independent predictor of all-cause (HR 2.51; p<0.001) and cardiovascular mortality (HR 2.56; p=0.003).

CONCLUSION

Symptom-limited cycle exercise testing prior to and after OCR provides important prognostic information.

Prognostic significance of exercise stress echocardiography in 3329 outpatients (5-year longitudinal study)

BACKGROUND

Appraisal of the risk to which outpatients with chest pain are exposed is a major clinical problem. Up to now, there have been no reports on the prognostic significance of exercise stress echocardiography in this patient cohort.

PATIENTS AND METHODS

In order to investigate the prognostic significance of exercise stress echocardiography (SE) in outpatients only, 3329 patients were monitored during a long-term follow-up regarding the occurrence of hard events (cardiac death, myocardial infarction, revascularization). The patients came to the cardiology practice complaining of chest pain.

RESULTS

The sensitivity/specificity of SE for hard events was 81.1/92.8 in the first year, that of exercise ECG, 27.4/87.0. During the observation period (5.1+/-1.1 years (median 5.2, 3-7 years)), a total of 446 (13.4%) hard events occurred. In patients with positive SE findings, 262 (61.9%) hard events occurred, in patients with negative SE findings, hard events were rarer (184, 6.3%, p<0.001). In the multivariate analysis, the positive SE finding was the most unambiguous, significant independent predictor of hard events (HR 6.6, CI 5.21-8.25, p<0.001).

CONCLUSIONS

In outpatients with chest pains, exercise stress echocardiography is of major prognostic significance (independent of other parameters) and its prognostic reliability is clearly superior to that of the exercise ECG. SE should always be performed in cases with symptoms requiring clarification.

Physical activity and exercise performance predict long-term prognosis in middle-aged women surviving acute coronary syndrome

AIM

To evaluate the importance of exercise testing (ET) parameters and leisure time physical activity in predicting long-term prognosis in middle-aged women hospitalized for acute coronary syndrome (ACS).

METHODS AND RESULTS

Women aged <66 years recently hospitalized for ACS in the Greater Stockholm area in Sweden were recruited. All underwent baseline clinical examinations including ET and then were followed up for 9 years. Nonparticipation in ET had a hazard ratio of 4.26 (95% confidence interval 2.02-8.95) for total mortality and 3.03 (1.03-8.91) for cardiovascular mortality. All ET parameters were significantly different between survivors than nonsurvivors, except for chest pain and ST-segment depression during ET. Sedentary lifestyle and ET parameters were related to total mortality and cardiovascular mortality in a multivariate analysis adjusting for potential confounders. Predictors of total mortality were sedentary lifestyle 2.94 (1.31-6.62), exercise time 1.75 (1.07-2.87) and inadequate haemodynamic responses: low increase in pulse rate 2.04 (1.16-3.60) and systolic blood pressure (SBP) 1.88 (1.19-2.95) from rest to peak exercise. Parameters that predicted cardiovascular mortality were sedentary lifestyle 3.15 (1.13-8.74) and poor increase in SBP 2.76 (1.30-5.86) from rest to peak exercise. The relation of sedentary lifestyle to survival was substantially weakened when exercise parameters were added to the multivariate analysis model.

CONCLUSION

In female patients <66 years surviving ACS, important independent predictors of long-term all-cause mortality were sedentary lifestyle, low physical fitness and inadequate pulse rate and SBP increase during exercise. Predictors of cardiovascular mortality were sedentary lifestyle and inadequate blood pressure response during exercise.

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.

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.

Participation versus education: the GISSI story and beyond

Approximately 20 years ago, the Italian cardiology community realized the scientific importance and the potential impact on clinical practice of the new concept of evidence-based medicine and launched (without funds) a national megatrial, the Gruppo Italiano por lo Studio della Streptochinasi nell'Infarto Miocardico (GISSI) study. In the following 20 years, 4 GISSI trials have been carried out, and a fifth is underway. The conceptual process that followed this experience shaped the role of the medico-scientific society that sponsored these trials as an active player in research, with the public health as the common target. This process of getting together was founded on the basic principle that active participation can be much more effective and rewarding than education (a passive process). Accordingly, further studies were undertaken dealing with clinical epidemiology, observational outcome research introduced complementarily to develop lines of clinical investigation along 2 mainstreams: ischemic heart disease and heart failure. The original decision to directly sponsor countrywide research projects in critical and relevant areas of care had broader implications not only for the role of scientific societies, but more generally for the nurture of independent research, which is today widely recognized to be at risk. The articulation among experimental, observational, and evaluative protocols in which all caring physicians are allowed to be producers and authors and not simply users of knowledge can favor a cultural continuity that minimizes the risk of parallelisms and gaps between research and care.

Prognostic Value of Stress Testing in Patients Over 75 Years of Age With Chronic Angina

STUDY OBJECTIVES

To define the prognostic value of stress testing (STRT) in patients >or= 75 years of age.

DESIGN

Multicenter prospective randomized trial.

SETTING

Tertiary care centers.

PATIENTS

Two hundred ninety-two patients of the Trial of Invasive vs Medical Treatment of Elderly Patients aged >or= 75 years with chronic angina despite receiving two or more antianginal drugs were prospectively observed for 1 year.

INTERVENTION

STRT (88% exercise ECG; 12% pharmacologic stress imaging) was performed if possible, and ischemia was diagnosed using current guidelines. Death for any reason and nonfatal myocardial infarction were outcome events.

RESULTS

Patients who could perform STRT (148 patients) were younger, had a lower risk profile, received less medication, and had less severe angina than patients who could not perform STRT (144 patients). The 1-year mortality rate was only 1.4% in patients with negative STRT results (72 patients) compared to 5.3% in patients with positive STRT results (76 patients) and 13.7% in patients who had not undergone STRT due to unstable symptoms (95 patients). The corresponding 1-year rates of death/infarction were 2.8%, 15.8%, and 26.3%, respectively. After adjustment for baseline differences, mortality rates were no longer significantly different. However, compared to patients with negative STRT results, infarction and death/infarction rates remained higher in patients with provocable ischemia (hazard ratio [HR], 8.9 [p = 0.04]; HR, 6.1 [p = 0.02], respectively) and in patients without STRT due to unstable angina (HR, 11.8 [p = 0.02]; HR, 8.6 [p =.004], respectively).

CONCLUSIONS

STRT in elderly patients is feasible and provides important prognostic information for their future management. Patients with negative STRT results after receiving therapy have a good prognosis, and their conditions may be managed conservatively.

T-wave alternans for risk stratification and prevention of sudden cardiac death

Despite considerable progress in the management of ischemic heart disease, a substantial proportion of patients continue to experience life-threatening arrhythmic events. The Multicenter Automatic Defibrillator Implantation Trial 2 has recently shown the superiority of implantable cardioverter defibrillators (ICDs) over conventional strategies to prevent sudden death in patients with reduced ejection fraction, but at the expense of potentially unnecessary ICD implantation in a large percentage of patients. T-wave alternans (TWA), which reflects alternation of cellular repolarization, results in a substantial increase in dispersion of repolarization, a prerequisite for reentrant arrhythmias. Recent trials, cumulating close to 3000 patients, have established TWA analysis as a powerful tool for arrhythmia prevention. Based on the most recent estimates, at least one third of post-myocardial infarction patients are expected to be tested negative. With a negative predictive value greater than 90%, TWA might allow for targeting of patients most likely to benefit from ICD therapy. Accurate identification of high-risk patients by noninvasive TWA may allow for improved widespread screening for sudden death prevention in the general population.

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.

[The changing prognosis of myocardial infarction in the reperfusion era: implications for evaluation and management of ventricular arrhythmias]

The prognosis of patients with ischemic heart disease has improved markedly with the introduction of reperfusion therapy and with aggressive efforts to modify risk factors. Consequently, the rate of cardiovascular events after myocardial infarction has decreased to approximately 5% over a period of 2 years as compared with the 20% to 30% reported in the prethrombolytic era. In this context, it is unlikely that the results of previous studies in the prereperfusion era can be applied to this group of patients. Others have demonstrated that the identification of subgroups of patients at greater risk and the search for new risk markers can significantly improve survival of patients who are at high risk despite reperfusion therapy. For example, it was found in the GISSI-2 study that unsuitability for exercise stress testing was associated with a mortality of 7% at 6 months. Other factors that determine poor prognosis after myocardial infarction are transitory heart failure, left ventricular dysfunction, and advanced age. The active search for new risk markers has identified other factors such as nonresolution of ST-segment changes, impaired ventricular filling, anomalous baroreflex sensitivity, or T-wave alternans that may be of benefit in assessing risk. Also, the timing of risk stratification can be critical. Often, risk factors have been analyzed weeks or even months after infarction instead of before hospital discharge. Approximately 30% of patients have deterioration of left ventricular function in the next 2 or 3 months, whereas others have improvement, highlighting the difficulties in attempting to risk stratify at one point in time. Although nobody doubts the effect that coronary revascularization has had on the prognosis of ischemic heart disease or the effectiveness of aspirin, beta -blockers, lipid-lowering drugs, and angiotensin-converting enzyme inhibitors, the search for cardiac or noncardiac risk markers can contribute notably to increasing the survival of patients who have had myocardial infarction.

Relationship between exercise-induced ST segmental depression and myocardial ischemia assessed by technetium-99m tetrofosmin SPECT imaging in patients with inferior Q wave myocardial infarction

BACKGROUND

ST segment depression (STD) is a standard electrocardiographic sign of myocardial ischemia. Although STD may represent reciprocal changes in patients with previous myocardial infarction, studies of reciprocal changes during exercise testing are scarce.

METHODS

From December 1999 to December 2000, 160 patients (119 males, 41 females, mean age 54 +/- 8 years), undergoing, maximal or symptom-limited exercise treadmill test (Bruce-protocol), myocardial perfusion scintigraphy using technetium-99m tetrofosmin single photon emission computed tomography (SPECT) imaging, within 30 days of an uncomplicated inferior Q wave myocardial infarction. The location of STD at the electrocardiogram (ECG) was defined as anterior (V1-4), high lateral (I, aVL), and lateral (V5-6). Ischemia was defined as reversible perfusion abnormalities.

RESULTS

STD occurred in anterior leads in 29 patients (18.1%), in the lateral leads in 41 patients (25.6%), in the high lateral leads in 20 patients (12.5%). In 70 patients (43.8%) no significant STD occurred during the exercise test. ST segment elevation occurred in 28 patients (17.5%) in inferior leads. High lateral STD was associated with inferior ST elevation in 16 patients (80%), whereas only eight patients (19.5%) with lateral STD and nine patients (31%) with anterior STD were associated with inferior ST elevation. Ischemia was detected in 63 of 90 patients (70%) with and in 10 of 70 patients (14.3%) without STD (p < 0.0001). Patients with high lateral STD had a higher prevalence of fixed perfusion defects in the inferior wall (95 vs. 27.8%) and in posterolateral wall (75 vs. 18.9%) compared with other patients (p = 0.003 and 0.002, respectively). Ischemia was more prevalent in patients with lateral STD than without (87.8 vs. 14.3%, p < 0.0001).

CONCLUSION

In patients with inferior Q wave, the presence of exercise-induced STD in lateral and anterior leads appears to be a sign of myocardial ischemia, and may require invasive evaluation; on the other hand, the presence of STD in high lateral leads should be recognized as a reciprocal change for ST elevation in the inferior leads, and may not be an indication for invasive evaluation.

Angiographic and prognostic correlates of cardiac output by cardiopulmonary exercise testing in patients with anterior myocardial infarction

STUDY OBJECTIVE

To assess the diagnostic and prognostic value of cardiac output assessed by cardiopulmonary exercise testing in patients with anterior acute myocardial infarction (AMI) and left ventricular dysfunction.

PATIENTS AND SETTING

Forty-six patients with AMI (7 female patients; mean +/- SD age, 55 +/- 8 years; ejection fraction, 39 +/- 7%) underwent cardiopulmonary exercise testing and coronary angiography following hospital discharge.

MEASUREMENT AND RESULTS

Cardiac output was estimated from oxygen uptake (VO(2)) during exercise according to a method based on the linear regression between arteriovenous oxygen content difference and percent maximum VO(2). Angiograms were scored using Gensini and Duke "jeopardy" scores. Cardiac output at anaerobic threshold (COAT) < or = 7.3 L/min was the best cutoff value for identifying multivessel coronary artery disease (relative risk, 3.1). Angiographic scores were significantly higher in patients with COAT < 7.3 L/min as compared to those with COAT > 7.3 L/min (82 +/- 8 vs 53 +/- 7 and 6 +/- 2 vs 4 +/- 3, respectively; p < 0.05) and were inversely and significantly correlated to COAT. Conversely, no correlation was found with ECG changes. COAT, VO(2) at anaerobic threshold, and peak VO(2) were univariate prognostic indicators. However, using Cox's model, COAT was the only multivariate predictor of outcome (odds ratio, 0.28; 95% confidence interval [CI], 0.09 to 0.9). Moreover, COAT < 7.3 L/min was associated to an increased risk of further cardiac events (odds ratio, 5; 95% CI, 1.4 to 17) and provided a significant discrimination of survival for the combined end point of cardiac death, reinfarction, and clinically driven revascularization.

CONCLUSIONS

COAT is a safe and feasible tool providing additional diagnostic and prognostic information in patients with AMI.

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.

Incremental prognostic value of stress echocardiography as an adjunct to exercise electrocardiography after uncomplicated myocardial infarction

OBJECTIVE

To assess the prognostic value of stress echocardiography as an adjunct to exercise electrocardiography in patients with uncomplicated acute myocardial infarction.

DESIGN

496 patients underwent a maximum exercise ECG and pharmacological stress echocardiography (406 dobutamine and 90 dipyridamole) within 15 days of uncomplicated acute myocardial infarction and were followed for a mean of 25 months (range 1-74 months) for reinfarction, unstable angina, and cardiac death. Patients undergoing revascularisation were omitted.

RESULTS

Exercise ECG was positive in 162 patients (32.6%) and low threshold positive (< 100 W) in 91 (18%). Stress echocardiography was positive in 239 patients (48%) (194 with dobutamine and 45 with dipyridamole stress). The agreement between the two tests was 63% (kappa = 0.24, 95% confidence interval 0.15 to 0.33). Sixty nine spontaneous events occurred (14 cardiac deaths, 26 reinfarctions, and 29 with unstable angina requiring hospital admission), and 126 patients underwent revascularisation (39 coronary angioplasty and 87 bypass surgery). By receiver operating characteristic curve analysis, stress echocardiography provided incremental prognostic information compared with clinical data. A low threshold positive exercise ECG was associated with a worse outcome, but there was a fivefold increase in risk in patients with positive stress echocardiography who also had a high threshold (> 100 W) positive exercise ECG. Event-free survival of patients with both tests positive was significantly less than in patients with only one positive test or with both tests negative.

CONCLUSIONS

Stress echocardiography provides additional prognostic information after uncomplicated acute myocardial infarction, but the greatest gain is found in patients with a high threshold positive exercise ECG.

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.

Relationship between corrected TIMI frame counts at three weeks and late survival after myocardial infarction

OBJECTIVES

To evaluate the corrected Thrombolysis in Myocardial Infarction (TIMI) frame count (CTFC) as a predictor of late survival after myocardial infarction.

BACKGROUND

Thrombolysis in Myocardial Infarction flow grades predict late survival after myocardial infarction. The CTFC provides a more reproducible measurement of infarct-related artery blood flow than the TIMI flow grade, and has been linked to 30-day outcomes, but it has not yet been established how the CTFC correlates with late survival.

METHODS

Of 1,001 patients with acute myocardial infarction presenting within 4 h of symptom onset, 882 underwent angiography at approximately three weeks. Infarct artery flow was assessed, blinded to clinical outcomes, according to the CTFC and TIMI flow grade. Late cardiac mortality and survival were determined in 97.5% of patients.

RESULTS

The mean CTFC was 40 +/- 29 in 644 patent infarct arteries (median, 34 [interquartile range, 24 to 47]). The CTFC, assessed as a continuous univariate variable, was found to be a predictor of five-year survival, as was the TIMI flow grade (both p < 0.001). On multivariate analysis, factors associated with five-year survival included the ejection fraction or end-systolic volume index (both p < 0.001); exercise duration (p = 0.005), age (p = 0.008), diabetes (p = 0.02) and CTFC (p = 0.02) or TIMI flow (p = 0.02). The same factors, except for the CTFC and TIMI flow grade, were predictors of 10-year survival.

CONCLUSIONS

The CTFC three weeks after myocardial infarction was an independent predictor of five-year survival, but not 10-year survival. Although the CTFC provided additional prognostic information within TIMI flow grades, its superiority was not demonstrated.

Long-term value of exercise testing after acute myocardial infarction: influence of thrombolytic therapy

OBJECTIVES

To evaluate the long-term predictive value of exercise testing performed early after acute myocardial infarction (AMI) in patients receiving thrombolytic therapy.

DESIGN

Nonblinded prospective follow-up study.

SETTING

Cardiac rehabilitation unit in a 900-bed university hospital.

SUBJECTS

Four hundred forty-three patients allowed to perform exercise testing 3 weeks after AMI were followed for a median of 75 months; 183 received IV thrombolysis and 263 did not.

RESULTS

Cardiac death hazard ratios were significantly increased in the presence of reduced physical working capacity on exertion, left ventricular dysfunction, and > or = 1-mm (but < 2-mm) ST-segment depression on exertion. In the group receiving thrombolytic therapy, no patient with > or = 2-mm ST-segment depression on exercise died; this group was characterized by a high rate of revascularization, whereas the group with > or = 1-mm but < 2-mm ST-segment depression was not. No parameter related to clinical or exercise testing predicted recurrent infarction in the group receiving thrombolytic therapy. Among patients not receiving thrombolysis, cardiac death was significantly related to > or = 2-mm ST-segment depression on exertion, to reduced physical working capacity, and to the lack of revascularization during follow-up.

CONCLUSION

Exercise test-derived parameters have variable value in predicting long-term survival of patients performing exercise test after AMI depending on the following: (1) whether thrombolytic therapy was given or not; (2) the degree of ST-segment depression during exercise testing; and (3) the rate of revascularization.

Prognostic value of symptom limited versus low level exercise stress test before discharge in patients with myocardial infarction treated with thrombolytics

OBJECTIVE

To evaluate the benefits and risks of symptom limited exercise testing versus low level exercise testing soon after a thrombolytic treated acute myocardial infarction.

DESIGN AND PATIENTS

98 patients (71 men, 27 women), mean (SD) age 64 (9) years (range 45-75 years), were investigated 5-8 days after admittance to hospital. An ergometer cycle test was used, starting at 30 W with 10 W increments per minute. Each exercise test was interpreted at the symptom limited end point and a low level end point, which was defined as the point at which the patient rated exhaustion as 13 on the 6-20 point Borg scale for rating perceived exertion.

SETTING

A university hospital.

RESULTS

75 of the 98 patients were able to perform a predischarge exercise test. Of the remaining 23 patients who could not perform an early exercise test (because of unstable angina, heart failure, or thrombus detected at echocardiography), five died or had a myocardial infarction and six underwent bypass surgery or percutaneous transluminal coronary angioplasty (PTCA) during a follow up period of one year. There were no complications related to the symptom limited exercise tests. The test results were positive in 15 patients at the low level end point and in 39 patients (p < 0.001) at the symptom limited end point. During a follow up period of one year, six of the 75 patients died or had a myocardial infarction. Two of these six patients had a positive low level exercise test and four had a positive symptom limited exercise test. Twenty three of the 75 patients who performed an exercise test had a cardiac event within one year (death, myocardial infarction, bypass surgery or PTCA); of these, 19 had a positive symptom limited exercise test and nine had a positive low level exercise test (p = 0.025). Four of the 36 patients with a negative symptom limited test suffered cardiac events within a year (two patients had a myocardial infarction and two had bypass surgery).

CONCLUSION

Symptom limited exercise testing soon after thrombolytically treated myocardial infarction will identify more patients with exercise induced ST depression or chest pain than a low level test, and seems safe. A negative symptom limited test has a better negative predictive value (11% risk of an event within a year) than a negative low level (25% risk of an event within a year).

Survival 12 years after randomization to streptokinase: the influence of thrombolysis in myocardial infarction flow at three to four weeks

OBJECTIVES

The purpose of this study was to determine whether the mortality benefit of intravenous streptokinase administered within 4 h of the onset of acute myocardial infarction is maintained at 12 years, and whether Thrombolysis in Myocardial Infarction (TIMI) flow grades independently influence late survival.

BACKGROUND

Treatment with reperfusion therapies and achievement of TIMI 3 flow are associated with increased short- and medium-term survival after infarction. Whether infarct artery flow independently influences survival more than five years after infarction is unknown.

METHODS

The late survival of patients randomized to receive either streptokinase (1,500,000 IU over 30 to 60 min) or a matching placebo within 4 h of symptom onset in 1984-1986 was determined. Angiography was performed in surviving patients at three to four weeks, and TIMI flow grades were assessed blind to randomization and outcomes. The late vital status was determined in 99% of patients.

RESULTS

Patients randomized to receive streptokinase (n = 107) had improved survival compared with those randomized to placebo (n = 112) at five years (84% vs. 70%; p = 0.023) and 12 years (66% vs. 51%; p = 0.022). At five years 94% of patients with TIMI grade 3 flow, 81% of those with TIMI grade 2 flow and 72% of those with TIMI grade 0-1 flow survived (p = 0.005). At 12 years 72% of patients with TIMI 3, 67% of those with TIMI 2 and 54% of those with TIMI 0-1 flow survived (p = 0.023). Multivariate analysis identified the ejection fraction (p = 0.014), exercise duration (p = 0.013) and TIMI 3 flow (p = 0.04 compared with TIMI 0-2 flow) as important factors for five-year survival. At 12 years multivariate predictors of late survival were the ejection fraction (p = 0.006), exercise duration (p = 0.003) and myocardial score (p = 0.013). The end-systolic volume index was similar to the ejection fraction as a predictor of survival at five and 12 years.

CONCLUSIONS

The survival benefits of streptokinase persist for 12 years after infarction. TIMI flow at three to four weeks is an independent predictor of five-year survival.

The significance of stress-induced ST segment depression in patients with inferior Q wave myocardial infarction

OBJECTIVES

This study was conducted to evaluate the relationship between ST segment depression (STD) during dobutamine stress tests in different electrocardiogram (ECG) leads and myocardial ischemia assessed by simultaneous single photon emission computed tomography (SPECT) imaging in patients with inferior Q wave myocardial infarction.

BACKGROUND

STD is a standard electrocardiographic sign of myocardial ischemia. Although STD may represent reciprocal changes in patients with previous myocardial infarction, studies of reciprocal changes during stress tests are scarce.

METHODS

Dobutamine (up to 40 microg/kg/min) stress and rest myocardial perfusion scintigraphy using technetium SPECT imaging was performed in 125 patients >3 months after Q wave inferior myocardial infarction. The location of STD at the ECG was defined as anterior (V1-4), high lateral (I, aVL) and lateral (V5,6). Ischemia was defined as reversible perfusion abnormalities.

RESULTS

STD occurred in the high lateral leads in 20 patients, in the anterior leads in 12 patients and in the lateral leads in 2 patients. ST segment elevation occurred in 25 patients in the inferior leads. High lateral STD was associated with inferior ST elevation in 16 patients (80%). There was a significant inverse linear correlation between the magnitude of ST segment shift from rest to peak stress in the inferior and the high lateral leads (r = -0.8, p < 0.0005), whereas no significant correlation was found between ST segment shift in the inferior and the anterior leads (r = -0.1, p = NS) or between the inferior and the lateral leads (r = 0.15, p = NS). Ischemia was detected in 45% of patients with and in 42% of patients without high lateral STD (p = NS). Patients with high lateral STD had a higher prevalence of fixed perfusion defects in the inferior wall (100% vs. 70%) and in the posterolateral wall (55% vs. 29%) compared with other patients (both p < 0.05). Ischemia was more prevalent in patients with anterior STD than without (75% vs. 39%, p < 0.05).

CONCLUSIONS

In patients with inferior Q wave myocardial infarction, stress-induced STD in high lateral leads should be recognized as a reciprocal change for ST elevation in the inferior leads, and therefore, should be interpreted with the consideration of the significance of ST elevation if present, rather than being indicative of myocardial ischemia on its own. The STD found in the anterior leads appears to be a sign of myocardial ischemia. These findings should be considered in the definition of a positive ECG stress test and in establishing the criteria for the termination of stress test.

Prognostic significance of double product and inadequate double product response to maximal symptom-limited exercise stress testing after myocardial infarction in 6296 patients treated with thrombolytic agents. GISSI-2 Investigators. Grupo Italiano per lo Studio della Sopravvivenza nell-Infarto Miocardico

BACKGROUND

The aim of this study was to evaluate the prognostic significance of the pressure-rate product (PRP) obtained during exercise stress testing and of its change from rest to maximal exercise (dPRP) in a population of survivors of acute myocardial infarction treated with thrombolytic agents.

METHODS AND RESULTS

Survivors of acute myocardial infarction (n = 6251) from the GISSI-2 database, who underwent a maximal symptom-limited exercise test with either bicycle ergometer or treadmill, were followed up for 6 months. PRP and dPRP values were dichotomized (</=21,700 and >21,700, </=11, 600 and >11,600, respectively) and analyzed in a multivariate Cox model individually and simultaneously with other ergometric variables. Six-month mortality rate was 0.8% in the high PRP group and 2.0% in the low PRP group. Low PRP was an independent predictor of 6-month mortality rate (relative risk [RR] 1.97, 95% confidence interval [CI] 1.24 to 3.13). Patients with low dPRP had mortality rates higher than patients with high dPRP (2.1% vs 0.8%). At the multivariate analysis, low dPRP showed negative predictive value (RR 1.97, 95% CI 1.23 to 3.16). A further multivariate analysis was performed with PRP and dPRP, also adjusting for low work capacity, abnormal systolic blood pressure response to exercise, and symptomatic-induced ischemia. The results showed that low work capacity, low PRP, and symptomatic exercise-induced ischemia were still significantly associated with higher 6-month mortality rate (P =.04,.02, and.05; RR = 1.68, 1.71, and 1.78 respectively).

CONCLUSIONS

PRP is a predictive index to assess prognosis in survivors of acute myocardial infarction treated with thrombolytic agents able to perform an exercise test after acute myocardial infarction, but its usefulness appears to be limited, considering that these patients were at low risk.

[The prognostic factors after an acute myocardial infarct treated with fibrinolytics]

BACKGROUND

The usefulness of the exercise test in evaluating patients with an acute myocardial infarction treated with fibrinolytics is controversial. On the other hand, the prognostic value of a patent infarct-related artery has not been clearly established. The objectives of this study were to assess the validity of the exercise test and to study the prognostic value of the artery patency after a myocardial infarction.

MATERIAL AND METHODS

We studied 99 patients with a myocardial infarction treated with fibrinolytics, non-complicated. An exercise test and a cardiac catheterization were performed in the first month. The patients were followed-up for 2 years, recording the major cardiac events (death and reinfarction) and the minor events (angina class (II, left cardiac failure class (II or maintained ventricular tachycardia).

RESULTS

On multivariate analysis with Cox regression, a workload < 4 METS at the exercise test was the only independent prognostic factor of major events (RR 5.6; CI 95% 1.68-19). The independent prognostic factors of minor events were: multivessel disease (RR 3.36; CI 95% 1.56-7.24), anterior infarction (RR 3.15; CI 95% 1.3-7.6), abnormal exercise test (RR 2.98; CI 95% 1.46-6.09) and ejection fraction < or = 40% (RR 2.48; CI 95% 1.07-5.74). The patency of the infarct-related artery was not a predictor of events.

CONCLUSIONS

The exercise test is useful in predicting the prognosis in patients treated with fibrinolytics. An occluded infarct-related artery was not an independent predictor of cardiac events in 2 years of follow-up.