T wave normalization in infarct-related electrocardiographic leads during exercise testing for detection of residual viability: comparison with positron emission tomography

Transient deep and giant negative T waves in dogs with myocardial injury

INTRODUCTION

Although transient deep and giant negative T waves (NTWs) may develop during myocardial injury (MI) in humans, no data exist on this repolarization abnormality in canine MI. Therefore, this study aimed to describe the occurrence of transient deep/giant NTWs in dogs with MI.

ANIMALS, MATERIALS AND METHODS

Medical records were retrospectively searched to identify dogs with MI and transient deep/giant NTWs. Signalment, history, and selected diagnostic test results were reviewed. Data analysis was descriptive.

RESULTS

Six cases were diagnosed with MI associated with deep (n = 1) and giant (n = 5) transient NTWs. Myocardial injury was classified as acute in all cases and was due to snake envenomation (n = 3), sepsis (n = 2), and systemic inflammatory response syndrome (n = 1). At the time of deep/giant NTWs identification, all dogs had elevated cardiac troponin I and ≥1 echocardiographic abnormality of the left ventricular structure and/or function. Moreover, all dogs with giant NTWs had prolonged QT intervals. After the MI resolution, T-wave polarity and QT-interval duration became normalized in all dogs. Moreover, left ventricular morphological and functional parameters were completely normalized in four dogs. In contrast, ventricular echogenicity remained heterogeneous in two dogs, despite otherwise normalized ventricular parameters. Five dogs were still alive at the conclusion of the study.

CONCLUSIONS

Transient deep/giant NTWs may develop in dogs with acute MI and T-wave polarity changes seem to occur synchronously with the evolution of myocardial damage. Moreover, transient deep/giant NTWs seem associated with a favorable prognosis in canine MI.

Original Article--Value of Pathological Q Waves and Angiographic Collateral Grade in Patients Undergoing Coronary Chronic Total Occlusion Recanalization: Cardiac Magnetic Resonance Study

Background/aim

Successful coronary chronic total occlusion (CTO) revascularization was found by many studies to be associated with improved left ventricular (LV) systolic function and survival if evidence of viability is present. Little is known about the association of CTO revascularization in patients with electrocardiographic Q waves and improvement in angina burden as a measurement of health-related quality of life (HRQOL) afterwards.

Methods

In this study, 100 patients with single vessel CTO were included. Myocardial viability was tested by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) and 50 patients showed evidence of viability. Seattle Angina Questionnaire (SAQ) scores were used as a measure of HRQOL.

Results

Pathological Q waves were present in 48 patients (including 19 patients with viable CTO territory) out of 100 patients. Patients with Q waves tended to have worse Seattle Angina Questionnaire (SAQ) scores compared to those with no Q waves (31.2 ± 11.7 vs 45.3 ± 13.9 respectively, p = 0.002), worse LV systolic function and wall motion score index (WMSI) on CMR. They also had significantly less prevalence of viability (p < 0.001). Patients with Q waves and positive viability had lower SAQ scores (37.2 ± 10.1 vs 52.7 ± 13.2 respectively, p = 0.02), higher LVEF and lower WMSI. They also had well developed collateral grade (2.1 ± 1.03 vs 0.7 ± 0.82 respectively, p < 0.001). After successful percutaneous coronary intervention (PCI), in the viable LV group, presence of Q waves was not associated with better LV functional recovery, while those with higher collateral grades were more likely to have better LV functional recovery post CTO-PCI. Patients with Q waves and viable CTO territory showed significantly better SAQ scores compared to pre-PCI (87.3 ± 12.2 vs 37.2 ± 10.1 respectively, p < 0.001). For angina frequency, post–PCI score was 80.2 ± 7.9 compared to 39.2 ± 7.1 before PCI, p < 0.001). Multivariate regression analysis showed that pathological Q waves, Rentrop's collateral grade and the Canadian Cardiovascular Society (CCS) angina class before PCI were the most significant independent predictors of improved HRQOL as reflected by SAQ (OR for Q waves 7.83, 95% CI 1.62–18.91,p 0.003), (OR for Rentrop's collateral grade 8.31,95% CI 2.21–26.33, p < 0.001), (OR for CCS class 8.39, 95% CI 1.21–20.8, p 0.01).

Conclusion

Well-developed collateral circulation could independently predict LV functional recovery after CTO-PCI. Patients with Q waves and viable CTO territory tend to have higher CCS class before revascularization and get significant improvement of HRQOL after PCI. Other predictors of improved HRQOL are Rentrop's collateral grade and worse CCS class before PCI.

Myocardial Viability: From Proof of Concept to Clinical Practice

Ischaemic left ventricular (LV) dysfunction can arise from myocardial stunning, hibernation, or necrosis. Imaging modalities have become front-line methods in the assessment of viable myocardial tissue, with the aim to stratify patients into optimal treatment pathways. Initial studies, although favorable, lacked sufficient power and sample size to provide conclusive outcomes of viability assessment. Recent trials, including the STICH and HEART studies, have failed to confer prognostic benefits of revascularisation therapy over standard medical management in ischaemic cardiomyopathy. In lieu of these recent findings, assessment of myocardial viability therefore should not be the sole factor for therapy choice. Optimization of medical therapy is paramount, and physicians should feel comfortable in deferring coronary revascularisation in patients with coronary artery disease with reduced LV systolic function. Newer trials are currently underway and will hopefully provide a more complete understanding of the pathos and management of ischaemic cardiomyopathy.

Electrocardiogram for predicting cardiac functional recovery

To investigate if the 12-lead resting electrocardiogram (ECG) is a predictor of left ventricular (LV) functional recovery after revascularization of chronic total coronary artery occlusions (CTO). Revascularization was performed in 58 CTO patients who had impaired regional wall motion. The 12-lead resting ECG was used to evaluate Q-wave, QT dispersion, and other parameters. Pre- and postoperative LV regional wall motions were evaluated by real-time three-dimensional echocardiography (RT-3DE). In patients with non-Q-wave, the wall motion score index (WMSI) was dropped from 1.56 ± 0.31 to 1.12 ± 0.21 (P < 0.05), while there was no significant changes (1.73 ± 0.12 and 1.59 ± 0.23, P > 0.05) for WMSI in patients with Q-wave. Preoperative non-Q-wave at baseline was predicted recovery with 88 % sensitivity and 68 % specificity. Positive predictive value for recovery was 67 % in patients with non-Q-wave. The presence of Q-wave can predict non-recovery of the regional wall motion with 68 % sensitivity and 88 % specificity. For CTO patients treated by revascularization, recovery can be predicted reliably through the analysis of pathological Q-wave on the 12-lead resting ECG.

Event-free survival in patients after an acute coronary event with exercise-induced normalization of the T-wave

BACKGROUND

Risk stratification of patients with unstable angina or non-Q-wave myocardial infarction (MI) is an unresolved clinical problem. The prognostic value of T-wave normalization (TWN) during exercise has not been studied in this group of patients.

HYPOTHESIS

Event-free survival in clinically stable patients after an acute coronary event without ST-segment elevation can be predicted by the presence of exercise-induced TWN.

METHODS

Sixty-five patients (43 men and 22 women, mean age 62+/-10 years) entered the study. The diagnosis of unstable angina and non-Q-wave MI was made in 40 and 25 patients, respectively. A treadmill exercise test was performed in all patients after clinical stabilization. The patients were divided into three groups: those with negative baseline T waves and exercise-induced TWN (Group 1); those with negative baseline T waves, but without TWN (Group 2); and those with positive baseline T waves (Group 3). The patients were followed up for 6 months.

RESULTS

During follow-up, serious cardiovascular complications occurred in 15 (23%) patients. These included exacerbation of ischemic heart disease (14 patients) and acute MI (1 patient). Event-free survival was greater in patients in Group 1 (95%) than in those in Group 2 (68%, p < 0.034) or Group 3 (71%, NS). Among all patients studied, exercise-induced TWN was predictive of event-free survival with a sensitivity of 38% and a specificity of 93%.

CONCLUSIONS

In clinically stable patients after an acute coronary event without ST-segment elevation, exercise-induced TWN is a specific but n ot sensitive predictor of event-free survival after 6 months.

Receiver operating characteristic (ROC) curves and the definition of threshold levels to diagnose coronary artery disease on electrocardiographic stress testing. Part I: The use of ROC curves in diagnostic medicine and electrocardiographic markers of ischaemia

A common problem in diagnostic medicine, when performing a diagnostic test, is to obtain an accurate discrimination between 'normal' cases and cases with disease, owing to the overlapping distributions of these populations. In clinical practice, it is exceedingly rare that a chosen cut point will achieve perfect discrimination between normal cases and those with disease, and one has to select the best compromise between sensitivity and specificity by comparing the diagnostic performance of different tests or diagnostic criteria available. Receiver operating characteristic (or receiver operator characteristic, ROC) curves allow systematic and intuitively appealing descriptions of the diagnostic performance of a test and a comparison of the performance of different tests or diagnostic criteria. This review will analyse the basic principles underlying ROC curves and their specific application to the choice of optimal parameters on exercise electrocardiographic (ECG) stress testing. Part I will focus on theoretical description and analysis along with reviewing the common problems related to the diagnosis of myocardial ischaemia by means of exercise ECG stress testing. Part II will be devoted to applying ROC curves to available diagnostic criteria through the analysis of ECG stress test parameters.

Normalization of abnormal T-waves during stress testing does not identify patients with reversible perfusion defects

OBJECTIVE

To determine if T-wave normalization during exercise or dobutamine stress testing identified patients with myocardial ischemia as indicated by reversible perfusion defects.

METHODS

Exercise or dobutamine stress tests with perfusion scintigraphy were performed in 1,173 patients with abnormal T-waves on their baseline electrocardiograms. The results of perfusion scintigraphy were compared in patients with and without stress-induced T-wave normalization.

RESULTS

Only 33 of 270 patients with reversible perfusion defects (12.2%) had T-wave normalization during stress while 76.4% of 140 patients who had T-wave normalization during stress did not have a reversible perfusion defect. Results were similar for patients who did or did not reach 85% of their maximal predicted heart rate, for patients with and without Q-wave infarction on the baseline EKG and for patients who did or did not have ischemic ST-segment depression during stress.

CONCLUSIONS

T-wave normalization during stress testing has low sensitivity and poor positive predictive value for stress-induced reversible myocardial ischemia.

Resting 12-lead electrocardiogram as a reliable predictor of functional recovery after recanalization of chronic total coronary occlusions

BACKGROUND

A major goal of revascularization is the recovery of left ventricular (LV) function. Nuclear imaging techniques are widely used for detecting recovery of function with a good sensitivity, but only moderate specificity. Predictors of recovery in chronic total coronary occlusions (CTO) are not investigated.

HYPOTHESIS

The 12-lead-resting electrocardiogram (ECG) is a predictor of LV recovery after successful recanalization of CTO.

METHODS

Successful recanalization of CTO was performed in 127 patients. Of these, 62 patients, who constitute the study group, had impaired regional wall motion prior to recanalization. The 12-lead resting ECG was evaluated for Q-wave areas and parameters of QT dispersion. Impairment of regional wall motion was evaluated by LV angiogram at baseline and at follow-up.

RESULTS

Angiographic follow-up after 5 +/- 1.4 months documented reocclusion in eight patients. Complete follow-up with a patent coronary artery and an ECG without bundle-branch block was available in 43 patients. Wall motion severity index (WMSI) improved from -2.92 +/- 0.28 to -1.34 +/- 0.61 (p < 0.001) in patients without Q waves, whereas it was unchanged in patients with Q waves (-3.01 +/- 0.30 and -2.81 +/- 0.32). Absence of Q waves at baseline predicted recovery of regional wall motion with 89% sensitivity and 67% specificity. Positive predictive value for recovery was 68% in patients without Q waves, but only 11% in patients with Q waves. In multivariate analysis, only absence of Q waves predicted improvement in WMSI (p = 0.01).

CONCLUSIONS

In patients with recanalization of CTO, recovery of regional wall motion is reliably predicted by analysis of the resting 12-lead ECG for pathologic Q waves.

Determinants of persistent negative T waves and early versus late T wave normalisation after acute myocardial infarction

OBJECTIVE

To determine whether persistent versus early or delayed T wave normalisation of negative T waves after acute myocardial infarction is determined by the myocardial state, the treatment strategy, or both.

DESIGN

127 consecutive patients with a first acute myocardial infarction and > or = 2 negative T waves on the 24-36 hour ECG were studied. They underwent dobutamine stress echocardiography and coronary angiography during the first week. ECG was recorded at hospital discharge and at a mean (SD) of 4 (1) months.

SETTING

University hospital.

RESULTS

T wave normalisation was observed in 88 patients (early at discharge in 19 and delayed at four months in 69). Early T wave normalisation was associated with sustained contractile reserve during dobutamine stress (13 of 19 (68%)), whereas delayed T wave normalisation was observed mainly in patients with an ischaemic response (49 of 69 (71%)). The persistence of negative T waves was associated with an ischaemic response (21 of 39 (54%)) or persistent akinesis (17 of 39 (44%)). Among patients with an ischaemic response to dobutamine, in-hospital elective angioplasty was an independent determinant of delayed T wave normalisation (39 of 49 v 4 of 21 patients with persistent negative T waves at four months, p < 0.0001).

CONCLUSIONS

Early T wave normalisation is associated with dobutamine induced, sustained improvement indicating myocardial stunning. Delayed normalisation is observed mainly in patients with ischaemic myocardium who have undergone revascularisation. Persistent negative T waves correspond to either extensive necrosis or non-revascularised, jeopardised myocardium.

Early negative T waves and viable myocardium in patients with a first ST-elevation acute coronary syndrome

Deep negative T waves (NTW) are a frequent finding following acute ST-segment elevation coronary syndromes but its possible relation with the status of regional contractility remains unclear. We studied 52 patients with a first ST-elevation acute coronary syndrome with or without NTW in anterior leads (> or =3 mm in > or=3 leads) and assessed the ejection fraction and regional myocardial contractility by contrast left ventriculography at baseline and during a low-dose dobutamine test (10 microg/kg per minute). Ejection fraction and regional contractility tended to be more preserved in patients with NTW, but dobutamine increased regional contractility in the jeopardized area in most patients with or without NTW and the improvement was similar in those either with or without enzyme elevation. In conclusion, deep NTW after ST-elevation acute coronary syndromes tends to be associated with a more preserved myocardium but it is neither a sensitive nor a specific marker of viable myocardium.

Normalization of negative T waves in the chronic stage of Q wave anterior myocardial infarction as a predictor of myocardial viability

We investigated whether spontaneous normalization of negative T waves (TWN) on infarct-related ECG leads (IRLs) in the chronic phase of Q wave anterior myocardial infarction (MI) could be a predictor of residual viability in infarct areas. We prospectively studied 35 patients (age 60 +/- 8.6 years) in the chronic phase of Q wave anterior MI. Spontaneous TWN (group A, n = 23) were defined as negative T waves that became upright (> or =0.15 mV) in > or =2 IRLs. The presence of negative T waves (group B, n = 12) was defined as symmetric or biphasic negative T wave of > or =0.15 mV. All patients underwent same-day rest 201Tl-stress (99m)Tc sestamibi dual-isotope myocardial perfusion SPECT and 24-hour 201Tl reinjection imaging for ischemia and viability analysis. On scintigraphic examination, ischemic or viable myocardial segments were found in 18 patients (78%) with TWN and 4 patients (33%) of group B (p = 0.013). The use of TWN as a parameter had a marked influence on the sensitivity (82%), specificity (62%), positive (78%) and negative (67%) predictive values and accuracy (74%) of the diagnosis of viable myocardium. If we add the criterion of positive T waves in aVR with negative T waves to our criteria, we found that sensitivity (90%), positive (80%) and negative (80%) predictive values and accuracy (80%) increased. The results of our study suggest that analysis of TWN on IRLs is an accurate marker of residual viability and/or persistent peri-infarct ischemia in patients in the chronic stage of Q wave anterior MI, and therefore optimizes the diagnostic and therapeutic strategies after MI.

Contribution of the sST elevation/T-wave normalization in Q-wave leads during routine, pre-discharge treadmill exercise test to patient management and risk stratification after acute myocardial infarction: a 2.5-year follow-up study

OBJECTIVES

This study investigated whether ST-segment elevation and T-wave normalization (TWN) in Q-wave leads on pre-discharge exercise electrocardiogram (ECG) can contribute to patient management after a recent myocardial infarction (MI).

BACKGROUND

The clinical relevance of these exercise ECG changes remains controversial despite accumulating evidence of their association with myocardial viability. Because discrepancies of previous studies may depend on patient selection, the value of these ST/T abnormalities in the thrombolytic era should be better defined.

METHODS

One-hundred one patients, age 58 +/- 11 years, with a recent, first Q-wave MI (57% thrombolyzed, ejection fraction 43 +/- 7%) underwent pre-discharge, submaximal treadmill testing followed, in the absence of severe ischemia, by dobutamine stress echocardiography, thallium-201 single photon emission computed tomography, and coronary angiography.

RESULTS

ST elevation at peak exercise, but not TWN, was associated with more severe infarctions as indicated by higher peak creatine kinase (p < 0.05) and with a greater number of scarred segments both on echocardiography (p < 0.05) and scintigraphy (p < 0.01). However, the incidence of myocardial viability and ischemia did not differ between groups with or without these ST/T changes. Anterior infarction location and >or=3 echocardiographically scarred segments were among the independent predictors of ST elevation at peak ergometric exercise. During follow-up (31 +/- 13 months), the rate of hard events was low (8%) and similar between the study groups.

CONCLUSIONS

In patients after acute Q-wave MI without severe ischemia according to clinical and standard ECG criteria, exercise-induced ST elevation, but not TWN, is associated with larger infarctions. The contribution of these ST/T abnormalities toward identifying patients with myocardial viability or ischemia and determining risk stratification is poor. In-hospital management of such patients based on routine clinical practice is sufficient for selection of a population with a relatively low long-term risk.

Relationship between T-wave normalization on exercise ECG and myocardial functional recovery in patients with acute myocardial infarction

BACKGROUND

Several studies suggested that T-wave normalization (TWN) in exercise ECG indicates the presence of viable myocardium. But the clinical implication of this phenomenon in patients with acute myocardial infarction who received proper revascularization therapy was not determined. Precisely the aim of this study was to investigate the relationship between TWN in exercise ECG and myocardial functional recovery after acute myocardial infarction.

METHODS

We studied 30 acute myocardial infarction patients with negative T waves in infarct related electrocardiographic leads and who had received successful revascularization therapy. Exercise ECG was performed 10-14 days after infarct onset using Naughton protocol. Patients were divided into 2 groups according to presence (group I; n = 14) or not (group II; n = 16) of TWN in exercise ECG. Exercise parameters and coronary angiographic findings were compared between groups. Baseline and follow-up (mean 11 months) regional and global left ventricular function was analyzed by echocardiography.

RESULTS

Exercise parameters were similar between groups. There was no difference in baseline ejection fraction and wall motion score between group I and II (EF; 56 +/- 12% vs 52 +/- 11%, p = ns. WMS; 21 +/- 3 vs 23 +/- 4, p = ns) and it was improved at the tenth month by similar magnitude (group I/group II, EF% change = 12 +/- 12% vs 7 +/- 6%, p = ns, WMS% change = 6 +/- 6% vs 7 +/- 5%, p = ns). The finding of no relation between TWN and functional recovery was observed also when the patients were analysed according to infarct location and presence or absence of Q-waves.

CONCLUSION

As the exercise-induced TWN in patients with acute myocardial infarction was not related with better functional recovery of dysfunctional regional wall motion and ejection fraction, TWN does not appear to be an indicator of myocardial viability.

Accuracy of low load exercise-induced T wave normalization in predicting the presence of contractile reserve after an anterior myocardial infarction

BACKGROUND AND METHODS. Exercise-induced T wave normalization occurring at a low (less-than-or-equal50 watt) workload in infarct-related electrocardiographic leads was studied in 30 consecutive patients with a recent transmural anterior acute myocardial infarction. Patients underwent both ergometric stress testing (within 30 days after the infarction) and low dose dobutamine echocardiography. The T wave normalization was considered significant when it occurred in at least two infarct-related leads. A significant contractile reserve was considered present in an infarcted region when 50% or more of the dyskinetic segments functionally improved on exercise during dobutamine infusion. RESULTS. Eighteen patients showed exercise-induced T wave normalization (group 1), and 12 patients did not (group 2). Myocardial contractile reserve in the infarct area was detected in 16 patients of group 1 (88%) and in 3 patients (25%) of group 2 (p=0.004). The overall sensitivity, specificity, and diagnostic accuracy of T wave normalization, as it reflects contractile reserve in the infarct area, were 84%, 82%, and 83%, respectively. CONCLUSION. Low load exercise-induced T wave normalization in infarct-related leads appears to be an accurate marker of residual contractile reserve in the infarct area in patients with recent transmural acute anterior myocardial infarction. (c) 2000 by CHF, Inc.

Significance of both negative T waves and stress-induced normalization of the repolarization phase in infarcted patients: a positron-emission-tomography assessment of regulation of myocardial blood flow and viability of myocardium

BACKGROUND

The clinical correlation of stress-induced normalization of previously negative T waves (NNTW) to regulation of regional myocardial blood flow (MBF) and tissue viability is still being debated.

OBJECTIVE

To clarify its meaning.

METHODS

We studied 25 patients, who had previously suffered anterior myocardial infarction and for whom negative T waves were recorded on baseline electrocardiographic precordial leads, by means of positron emission tomography. We obtained MBF in the infarcted myocardial regions under resting conditions for all patients, during infusion of dipyridamole (17 patients) and dobutamine (20 patients), using [13N]-ammonia as a flow tracer.

RESULTS

During stress tests, 13 patients exhibited NNTW (group 1) whereas the remaining 12 presented persistent negative T waves (group 2). NNTW was observed in 18 stress studies (for 10 and eight patients during administration of dobutamine and dipyridamole, respectively) whereas persistent negative T waves occurred 19 times (for 10 patients during infusion of dobutamine and nine patients during administration of dipyridamole). A complete concordance of the modifications of the repolarization phase was observed for patients who were subjected both to dipyridamole and to dobutamine studies. Furthermore, we assessed viability of myocardium in 20 of 25 patients using [18F]-fluorodeoxyglucose. For the remaining five patients not subjected to metabolic imaging, a coronary reserve of 1.65 was considered a cut-off of viability. Resting MBF for patients in groups 1 and 2 were similar (0.53 +/- 0.20 versus 0.47 +/- 0.17 ml/min per g, respectively, NS) whereas during pharmacological stress, MBF of patients in group 1 was significantly higher than that for patients in group 2 (0.99 +/- 0.41 versus 0.56 +/- 0.26 ml/min per g, respectively, P < 0.0001). Coronary vasodilating capability, expressed as stress/resting MBF ratio, turned out to be 1.88 +/- 0.49 and 1.16 +/- 0.37 for patients in groups 1 and 2, respectively (P < 0.0001). We observed no difference in mean exercise work load (9.6 +/- 2.80 versus 8.46 +/- 2.18 min, NS) and rate- pressure product (24230 +/- 6425 versus 24207 +/- 8146 mmHg beats/ min, NS) at peak for the two categories of patients. All 13 patients in group 1 (100%) had viable myocardium in the anterior infarcted areas whereas only one of 12 patients in group 2 did (9%, P< 0.0001 versus group 1). Finally, a subanalysis for the specific pharmacological agent used was performed and it gave similar results.

CONCLUSION

Regardless of the specific stress test able to elicit the electrocardiographic sign, infarcted dysfunctional areas with stress-induced NNTW were demonstrated to have a higher coronary vasodilating capability and a greater probability of viability of myocardium than had persistent negative T wave regions. Therefore, detection of NNTW appears to be a cheap first-line method for the identification both of a better preserved coronary microcirculatory function and of the persistence of viability of myocardium in the infarcted areas.

Prognostic usefulness of dobutamine-induced ST-segment elevation and T-wave normalization after uncomplicated acute myocardial infarction

We followed 229 consecutive patients exhibiting negative T waves on infarct-related electrocardiographic leads; these patients underwent dobutamine stress echocardiography within 10 days after a first uncomplicated acute myocardial infarction. T-wave normalization, but not ST-segment elevation, recognized patients at higher risk of cardiac events and optimized the prognostic accuracy of both myocardial viability and ischemia, to which it was correlated and became an independent predictor in cases of subdiagnostic stress echocardiography.

Negative T waves shortly after ST-elevation acute myocardial infarction are a powerful marker for improved survival rate

BACKGROUND

Recent studies have reported that negative T waves in the setting of acute coronary events are associated with Thrombolysis In Myocardial Infarction flow grade 3 in the infarct-related artery and with improved parameters of ventricular function rather than with ischemia.

METHODS

Patients enrolled in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) angiographic substudy (ie, patients with acute infarction randomly assigned to one of 4 thrombolytic regimens who then underwent coronary angiography) were included in this study if they survived at least 24 hours and had no confounding electrocardiographic factors (n = 1505).

RESULTS

More patients had negative T waves develop (NT group, n = 938 [62%]) than not (PT group, n = 567 [38%]). Peak creatine kinase MB, time to thrombolysis, and randomization to accelerated alteplase were no different between the groups. Thirty days after admission, 12 patients in the NT group had died versus 25 patients in the PT group (1.3% vs. 4.4%; P <.001; odds ratio for negative T waves 0.28; 95% confidence interval 0.14-0.56). The difference persisted when only patients who survived at least 3 days were analyzed. After adjusting for relevant covariates (including presence of new Q waves in the follow-up electrocardiogram), negative T waves were an independent predictor for survival (P =. 007; odds ratio for negative T waves 0.38; 95% confidence interval 0. 18-0.78). Patients in the NT group were 35% more likely to have achieved patency of the infarct-related artery, although this difference was not statistically significant.

CONCLUSIONS

Negative T waves shortly after acute myocardial infarction treated with thrombolysis were markers for improved 30-day survival rate. This finding merits prospective testing.

Enhanced detection of ischemic but viable myocardium by QT interval dispersion on treadmill exercise electrocardiograms of patients with healed anterior wall myocardial infarcts

BACKGROUND

The presence of ischemic but viable myocardium in infarcted areas is an important indication for coronary revascularization, but is often difficult to detect with the use of treadmill exercise electrocardiography (ECG).

HYPOTHESIS

QT interval dispersion (QTd) is a sensitive method for detecting myocardial ischemia and may improve the accuracy of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarcted areas.

METHODS

Forty-five patients with Q-wave anterior wall myocardial infarctions who underwent treadmill exercise ECG, exercise reinjection thallium-201 (201Tl) scintigraphy, radionuclide angiocardiography, and coronary angiography 1 month after infarction were enrolled in this study. The presence of viable myocardium in the infarct area was determined by exercise reinjection 201Tl scintigraphy. Patients who had no redistribution in the infarct area after reinjection were included in Group 1, and those with redistribution were included in Group 2.

RESULTS

QTd immediately after exercise, and the difference between QTd before and immediately after exercise, were significantly greater in Group 2 than in Group 1. The sensitivity, specificity, and accuracy of conventional ST-segment depression criteria for detecting viable myocardium in the infarct area were 48, 64, and 56%, respectively. The measurement of QTd immediately after exercise (abnormal: > or = 70 ms; normal: < 70 ms) improved the sensitivity, specificity, and accuracy to 78, 82, and 80%, respectively.

CONCLUSIONS

This novel diagnostic method using QTd-based criteria significantly improves the clinical usefulness of treadmill exercise ECG testing for detecting ischemic but viable myocardium in infarct areas in patients with healed Q-wave anterior wall myocardial infarctions.

Significance of spontaneous normalization of negative T waves in infarct-related leads during healing of anterior wall acute myocardial infarction

This study was conducted to elucidate the significance of spontaneous normalization of negative T waves in infarct-related leads during the chronic phase of anterior wall acute myocardial infarction. Results of this study indicate that patients with spontaneous normalization of negative T waves in infarct-related leads between 1 and 6 months after anterior wall acute myocardial infarction have smaller infarct size, decreased left ventricular dysfunction, and greater improvement in left ventricular wall motion in the infarct area, suggesting that T-wave normalization represents functional recovery of viable myocardium in the infarct area.

Significance of T-wave changes during early dobutamine stress echocardiography in patients with Q-wave acute myocardial infarction

The relation between T-wave changes and regional contraction during dobutamine stress echocardiography at low (5 to 10 microg/kg/min) and high (20 to 40 microg/kg/min) doses in 43 consecutive patients, early (7+/-2 days) after first recent Q-wave acute myocardial infarction has been evaluated. T-wave changes detected in > or =2 infarct-related electrocardiographic leads during dobutamine infusion were defined as follow: (1) negative T waves becoming positive, (2) positive T waves becoming upright > or =2 mm, and (3) negative T waves becoming upright > or =2 mm from baseline. Wall motion score index (WMSI) was defined as the sum of the echocardiographic scores of 16 segments divided by total segments considered at baseline, and at low and peak doses of dobutamine. Patients were classified according to the absence or presence of dobutamine T-wave changes. Those without T-wave changes had a significantly higher WMSI at rest (1.68+/-0.23 vs 1.50+/-0.21; p <0.05) and at peak (1.77+/-0.34 vs 1.51+/-.30 p <0.05) of dobutamine stress testing, without higher incidence of viability, homozonal, and heterozonal ischemia and chest pain. The angiographic patterns were similar between groups. Regression analysis showed a significant correlation between WMSI and T-wave amplitude at baseline (R = 0.38, p = 0.01) and at peak dobutamine stress testing (R = 0.50, p = 0.0006). The sensitivity sensitivity, specificity, and accuracy of T-wave changes to detect myocardial viability were 0.27, 0.84, and 0.70, respectively. The sensitivity, specificity, and accuracy of T-wave changes to detect homozonal ischemia were 0.76, 0.27, and 0.46, respectively. In conclusion, dobutamine-induced T-wave changes are associated with a greater extent of wall motion abnormalities both at rest and at peak stress echocardiography, but they are of little value in predicting myocardial viability when analyzed early after myocardial infarction.