Prognostic value of slow resolution of ST-segment elevation following successful direct percutaneous transluminal coronary angioplasty for recovery of left ventricular function

Incidence and Significance of Spontaneous ST Segment Re-elevation After Reperfused Anterior Acute Myocardial Infarction - Relationship With Infarct Size, Adverse Remodeling, and Events at 1 Year

BACKGROUND

Up to 25% of patients with ST elevation myocardial infarction (STEMI) have ST segment re-elevation after initial regression post-reperfusion and there are few data regarding its prognostic significance.Methods and Results:A standard 12-lead electrocardiogram (ECG) was recorded in 662 patients with anterior STEMI referred for primary percutaneous coronary intervention (PPCI). ECGs were recorded 60-90 min after PPCI and at discharge. ST segment re-elevation was defined as a ≥0.1-mV increase in STMax between the post-PPCI and discharge ECGs. Infarct size (assessed as creatine kinase [CK] peak), echocardiography at baseline and follow-up, and all-cause death and heart failure events at 1 year were assessed. In all, 128 patients (19%) had ST segment re-elevation. There was no difference between patients with and without re-elevation in infarct size (CK peak [mean±SD] 4,231±2,656 vs. 3,993±2,819 IU/L; P=0.402), left ventricular (LV) ejection fraction (50.7±11.6% vs. 52.2±10.8%; P=0.186), LV adverse remodeling (20.1±38.9% vs. 18.3±30.9%; P=0.631), or all-cause mortality and heart failure events (22 [19.8%] vs. 106 [19.2%]; P=0.887) at 1 year.

CONCLUSIONS

Among anterior STEMI patients treated by PPCI, ST segment re-elevation was present in 19% and was not associated with increased infarct size or major adverse events at 1 year.

Pre-angiography total ST-segment resolution is not a reliable predictor of an open infarct-related artery

BACKGROUND

While the cutoffs of predictive value for ST-segment elevations resolution (STSR) following thrombolysis and/or primary PCI were well documented, the impact of pre-angiography STSR has not been established yet.

OBJECTIVES

The aim of this study is to assess prognostic utility of pre-angiography STSR to predict pre-procedural TIMI flow in the infarct-related artery (IRA) and infarct size in STEMI patients undergoing primary PCI.

METHODS

A prospective study was performed, including 310 patients, admitted within 12h of symptom onset and who underwent primary PCI. ST-segment elevations were measured in: (1) qualifying ECG, (2) ECG before angiography, and (3) ECG post PCI. STSR was defined as: total (≥70%), partial (between 70% and 30%) and none (<30%). Relationships between pre-angiography STSR, initial TIMI flow and troponin T level (TnT) were analyzed.

RESULTS

Pre-angiography STSR correlated with initial TIMI flow in the IRA (rS=0.619; p<0.001). Pre-angiography total STSR was observed in 23.2% patients. It was noted in 79.2% of patients with pre-procedural TIMI flow ≥2 and in 20.8% with TIMI flow ≤1 (p<0.001). Although the sensitivity of pre-angiography total STSR to detect pre-procedural TIMI flow ≥2 was 93%, its specificity was only 56% and the likelihood ratio was 2.1. Pre-angiography total STSR was associated with lower peak TnT level (2.2±2.5ng/ml vs. 6.4±5.0ng/ml, p<0.0001) when compared to the remaining patients.

CONCLUSIONS

1. Pre-angiography STSR correlates with preprocedural TIMI flow. 2. The sensitivity of pre-angiography total STSR in detection of pre-procedural TIMI flow ≥2 is high, but low specificity of only 56% makes it an unreliable predictor of an open IRA.

Predictive value of ST resolution analysis performed immediately versus at ninety minutes after primary percutaneous coronary intervention

ST segment resolution (STR) predicts epicardial and microvascular reperfusion after primary percutaneous coronary intervention (PPCI) or thrombolysis for ST-elevation myocardial infarction. Immediate restoration of epicardial coronary flow, with improved microvascular perfusion, is much more likely with PPCI. However, the predictive value of immediate STR compared to 90 minutes after PPCI remains unknown. In 622 consecutive patients with ST-elevation myocardial infarction (mean age 59 +/- 13 years), 217 had complete STR immediately after PPCI (group A), 188 had complete STR only at 90 minutes (group B), and 217 had incomplete STR at either point (group C). The primary end point was mortality and adverse cardiovascular events ([MACE] death, nonfatal repeat myocardial infarction, and heart failure). Group A had a greater left ventricular ejection fraction (53%, 47%, and 46%, p <0.001) and lower all-cause mortality (1.8%, 3.2%, and 6%, p = 0.07), lower heart failure (1.8%, 4.3%, and 7.8%, p <0.001), and MACE (5.1%, 9.6%, and 16.1%, p = 0.001) at 30 days compared to groups B and C, respectively. The rate of MACE at 1 year was 7.6%, 17.1%, and 20.2% in groups A, B, and C, respectively (p <0.001). Immediate STR independently predicted MACE (adjusted hazard ratio 0.36, 95% confidence interval 0.21 to 0.61, p = 0.001, group A vs C), and STR at 90 minutes did not. In conclusion, STR analysis performed immediately after PPCI provided superior differentiation for adverse cardiovascular events compared to STR at 90 minutes. Immediate STR should be the contemporary goal of reperfusion with PPCI.

Maximum persisting single lead ST elevation after primary angioplasty: a good predictor of left ventricular dilatation assessed by magnetic resonance imaging

AIMS

To determine the frequency and predictors of left ventricular dilatation assessed by magnetic resonance imaging among patients with a first acute myocardial infarction treated with successful primary angioplasty and stent.

METHODS AND RESULTS

Cine magnetic resonance imaging and late enhancement imaging were prospectively performed in 42 patients 1 month and more than 1 year after successful early reperfusion of a first acute ST elevation myocardial infarction (age 61 +/- 13 years, 76% men, 55% anterior myocardial infarction, and mean symptom-to-balloon time 199 +/- 130 min). Both at the 1-month and at the 15-month magnetic resonance imaging examinations, 57% of patients had left ventricular dilatation (end-systolic volume indexed > 36 ml/m2, values above the upper 95th percentile based on magnetic resonance imaging reference values for left ventricular size in normal participants). The most accurate predictor of left ventricular dilatation was maximum persisting single lead ST elevation 60 min after reperfusion (area under the curve 0.81, P = 0.001). Maximum single lead ST elevation was significantly and independently associated with larger end-systolic volume indexed (beta = 0.35, P = 0.040) after adjusting for muscle and brain isoenzyme of creatine kinase and echocardiographic wall motion score index.

CONCLUSION

More than half of patients with a first acute myocardial infarction have left ventricular dilatation despite successful primary coronary angioplasty. Maximum persisting single lead ST elevation 60 min after mechanical reperfusion represents a simple tool for predicting left ventricular dilatation.

Effects of abciximab as adjunctive therapy in primary percutaneous coronary intervention patients (results from the DANAMI-2 trial)

INTRODUCTION

Successful reperfusion at the epicardial level is not always accompanied by reperfusion of the microvasculature. Therapies targeted against 'no-flow' are often employed in patients receiving primary percutaneous coronary intervention (pPCI) after acute myocardial infarction.

HYPOTHESIS

Abciximab as adjunctive to pPCI will improve ST-segment resolution used as a surrogate for optimal microvascular reperfusion, and improve prognosis.

METHODS

In the DANAMI-2 trial 309/790 (39%) patients treated with pPCI received abciximab at physician discretion. SigmaST-segment elevation at baseline, 90 min, 4 h, 12 h, 24 h after pPCI and at discharge was measured and ST-segment resolution grouped as: Complete (> or = 70 %); Partial (> or = 30 to < 70%); No (< 30%). Clinical endpoints were death, re-infarction and disabling stroke.

RESULTS

Abciximab prescription varied from 24.4-60.3% in the different hospitals. Patients receiving abciximab had a higher risk profile. ST-segment resolution at 90 min and 24 h was identical in the two groups, but at 4 h and 12 h partial ST-segment resolution was more pronounced in patients receiving abciximab (P = 0.001, P = 0.026). In a multivariate analysis, adjusting for baseline differences abciximab was associated with improved partial ST-segment resolution at 12 h. Patients treated with abciximab had no re-infarction at 30 days (0% versus 2.8%, P = 0.003), but increased disabling stroke rate (2.3% versus 0.4%; P = 0.019) driven by cerebral infarctions, and not intracranial hemorrhage. There were no differences in death rates.

CONCLUSIONS

In the DANAMI-2 trial with no age limit, the decreased re-infarction rates in patients receiving abciximab was offset by increased disabling stroke rates. Abciximab in conjunction with pPCI is associated with more pronounced partial ST-segment resolution after 4 h to 12 h suggesting improved microvascular reperfusion.

Potential significance of spontaneous and interventional ST-changes in patients transferred for primary percutaneous coronary intervention: observations from the ST-MONitoring in Acute Myocardial Infarction study (The MONAMI study)

AIMS

In patients with ST-elevation myocardial infarction (STEMI) scheduled for primary percutaneous coronary intervention (primary PCI), acute risk-assessment may be valuable for tailoring of adjunctive therapy at the time of coronary intervention. The present study was designed to quantify pre-, per-, and post-interventional ST-changes, to evaluate whether a pre-specified continuous ST-monitoring classification provides potential prognostic information in the pre- and per-interventional phase, and to compare post-interventional ST-resolution parameters derived from continuous ST-monitoring and snapshot ECGs, respectively.

METHODS AND RESULTS

In 92 STEMI patients, continuous ST-monitoring was initiated in the pre-hospital phase and continued during and 90 min following PCI. Patients were divided into three groups: (A) patients achieving spontaneous ST-resolution before PCI; (B) patients with preserved ST-elevation immediately before PCI and with no increase in ST-elevation during PCI; and (C) patients with preserved ST-elevation immediately before PCI and with increase in ST-elevation during PCI. Groups A (n=22), B (n=43), and C (n=27) differed in peak level of troponin-T (1.4, 4.7, and 7.2 microg/L, P<0.001), creatinine kinase MB isoenzyme (35, 150, and 325 microg/L, P<0.001), and N-terminal pro-brain natriuretic peptide (Nt-pro-BNP) (183, 175, and 269 pmol/L, P=0.084) during admission, and left ventricular ejection fraction evaluated within 2 h of PCI (0.53, 0.48, and 0.45, P=0.047) and after 3 months (0.58, 0.54, and 0.45, P<0.001). Groups B and C also differed in time from first balloon inflation to > or =70% resolution of ST-elevation (14 vs. 42 min, P=0.002), whereas no differences were observed in traditional 90 min ST-resolution analysis or angiographically assessed parameters.

CONCLUSION

STEMI patients transferred for primary PCI are heterogeneous with respect to pre- and per-interventional ST-changes, and a pre-specified ST-monitoring classification seems useful for stratification of patients at time of PCI into groups with low, intermediate, and high risk profile. Furthermore, post-interventional ST-monitoring indicates that traditional 90 min ST-resolution analysis may have limited value in the era of primary PCI.

Intracoronary ST segment evolution during primary coronary stenting predicts infarct zone recovery

In patients with acute myocardial infarction (AMI), early ST segment elevation resolution on ECG predicts myocardial reperfusion and LV recovery. Intracoronary ECG is more sensitive than surface ECG to detect regional ischemia. In patients undergoing primary percutaneous coronary intervention (PCI), we investigated if failed myocardial reperfusion, despite successful infarct vessel recanalization, could be rapidly and easily identified by intracoronary ST segment monitoring from guidewire recording. We recorded intracoronary and standard ECG during primary coronary stenting (PCI) in 50 patients with AMI (59 +/- 11 years; anterior AMI in 66%). All patients had a successful PCI and underwent 2D echocardiography soon after PCI and 6 months later. Following PCI, intracoronary ST resolution >/= 50% from baseline was documented in 39 patients (78%; group A; from 11 +/- 8 to 1 +/- 2 mm) but not in 11 (22%; group B; from 11 +/- 8 to 8 +/- 5 mm). Group A had slightly shorter ischemic time (202 +/- 94 vs. 238 +/- 112 min in B; P = 0.2) and smaller peak CK values (2,752 +/- 2,038 vs. 4,802 +/- 3,671 U/L in B; P = 0.02). After PCI, ST resolution was found on standard ECG in 34 (87%) group A and in 3 (27%) group B patients. At 6-month follow-up, left ventricular ejection fraction was greater in group A (47% +/- 8% vs. 39% +/- 8% in B; P < 0.001) with improved wall motion score index (from 2.2 +/- 0.3 to 1.7 +/- 0.3 in A; from 2.3 +/- 0.4 to 2.1 +/- 0.4 in B; P < 0.001). There were no significant differences between intracoronary and standard ECG for sensitivity (92% vs. 86%) and specificity (62% vs. 57%) to predict improved infarct zone recovery after 6 months. ST elevation resolution on intracoronary recording during PCI predicts infarct zone recovery. Monitoring ST segment evolution by intracoronary ECG allows prompt and inexpensive identification in the catheterization laboratory of those patients without myocardial reperfusion, who may require adjunctive therapeutic interventions after successful infarct vessel recanalization.

Prognostic implication of ST-segment resolution following primary percutaneous transluminal coronary angioplasty for ST-elevation acute myocardial infarction

BACKGROUND

ST-segment changes have been shown to correlate with myocardial tissue perfusion. Complete ST-segment resolution after thrombolysis in acute myocardial infarction is associated with lower mortality and better left ventricular function. Primary percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction restores better epicardial coronary flow to the infarct-related artery than thrombolysis. However, ST changes may persist and flow can remain poor despite a patent vessel.

AIM

To examine the prognostic implication of ST-segment resolution immediately following primary and rescue PTCA for ST-elevation acute myocardial infarction (STEMI).

METHODS

Records of 201 consecutive primary and rescue PTCA performed at Westmead Hospital for STEMI from January 2000 to December 2001 were reviewed. ST-segment elevation (taken 20 ms after the end of the QRS complex) was measured immediately before and after the procedure. ST-segment resolution of greater than 70% after the procedure was considered as -'complete' ST-segment resolution, whereas ST-segment resolution of less than 70% was considered as 'incomplete' ST-segment resolution.

RESULTS

Of the 201 patients, 117 (58%) had complete ST-elevation resolution and 84 (42%) did not. There was a significant difference in survival free of major adverse cardiovascular events; 60% of those with complete ST-segment resolution were event-free at 2 years compared with 35% of those patients without complete ST-segment resolution.

CONCLUSION

ST-segment resolution after primary and rescue PTCA for STEMI is associated with significantly higher event-free survival. The goal of primary angio-plasty should be the restoration of normal epicardial flow with normalization of ST-segments.

Relation between different methods for analysing ST segment deviation and infarct size as assessed by positron emission tomography

OBJECTIVE

To study the relation between resolution of ST segment deviation and infarct size using positron emission tomography.

METHODS

45 patients with ST segment elevation acute myocardial infarction treated with thrombolysis or percutaneous coronary intervention were studied prospectively. An ECG was taken before and at (mean (SD)) 100 (45) min after reperfusion therapy. ECGs were analysed by three methods. Residual ST segment deviation, obtained from the ECG immediately after completion of reperfusion therapy, was defined by summation for each of the three methods. Relative resolution of ST segment deviation was defined as the absolute resolution divided by the ST segment deviation score at baseline x 100 (%). After 29 (14) hours, myocardial blood flow was measured with 13NH3. For each patient, the regions with a myocardial blood flow < 80% of normally perfused myocardium ( = hypoperfusion) and < 50% ( = no reflow) were automatically delineated.

RESULTS

Substantial differences were found between different ECG analysis methods. There were moderate correlations between the area with myocardial hypoperfusion and ST segment deviation scores at baseline and after reperfusion therapy. After reperfusion therapy, residual ST segment deviation in the single lead with maximum ST segment deviation was as good at discriminating between tertiles of myocardial damage as summed ST segment elevation. Relative ST segment resolution did not discriminate between different degrees of myocardial damage.

CONCLUSIONS

In the individual patient, residual ST segment deviation after reperfusion in the single lead with maximum ST segment deviation is at least as good as summed ST elevation in predicting final myocardial damage.

New support for clarifying the relation between ST segment resolution and microvascular function: degree of ST segment resolution correlates with the pressure derived collateral flow index

OBJECTIVE

To investigate the relation between the degree of ST segment resolution (STR) after thrombolysis and the pressure derived collateral flow index (CFIp), determined using an intracoronary pressure measurement technique in patients with recent myocardial infarction.

METHODS

33 patients were studied. TIMI grade III flow was achieved in the infarct related artery by thrombolysis. A surface ECG was obtained on admission and 90 minutes later. The sum of ST segment elevations was measured by summing all leads with ST elevation on the baseline ECG and on the 90 minute ECG (after thrombolysis) and calculating the percentage recovery. The study population was divided into two groups, with good STR (> or = 50%; group 1) or poor STR (< 50%; group 2). After angiography, a fibreoptic pressure monitoring guidewire was advanced to the stenosis to be dilated. The CFIp was determined as the ratio [coronary wedge pressure - central venous pressure]/[mean aortic pressure - central venous pressure].

RESULTS

The mean STR on the surface ECG was 54.6% and mean (SD) CFIp was 0.25 (0.12) (range 0.10-0.41). There was an inverse correlation between the individually calculated percentage of STR and CFIp (r = -0.64, p < 0.01). The mean CFIp was lower in patients with a good STR than in those with a poor STR (0.18 (0.07) v 0.27 (0.10), p < 0.02).

CONCLUSIONS

Although TIMI grade III flow was achieved after thrombolysis, a worse STR on the surface ECG was associated with higher CFIp measured in the infarct related artery. CFIp appears to reflect the degree of microvascular obstruction by quantifying impedance of the microvasculature.

Primary percutaneous transluminal coronary angioplasty accelerates early myocardial reperfusion compared to thrombolytic therapy in patients with acute myocardial infarction

BACKGROUND

Successful early reperfusion of the infarcted myocardium as indicated by complete resolution of ST-segment elevations has been shown to be associated with an improved outcome in patients with acute ST-elevation myocardial infarction (AMI). The aim of this study was to compare early ST resolution in patients treated with primary percutaneous transluminal coronary angioplasty (PTCA) or thrombolytic therapy for AMI.

METHODS

A total of 1379 patients with AMI whose symptoms began <6 hours previously were enrolled in the Evaluation of the Safety and Cardioprotective effects of eniporide in Acute Myocardial Infarction (ESCAMI) trial and treated with primary PTCA (n = 528) or thrombolytic therapy (n = 851). Twelve-lead electrocardiograms (ECG) were obtained at baseline, directly after PTCA and at 90 minutes after the initiation of thrombolytic therapy.

RESULTS

There were no differences with respect to clinical or ECG baseline variables between the 2 groups. The time intervals between hospital admission and ECG 2 (obtained 0-30 min after PTCA and 90 min after start of thrombolysis) were 121 +/- 62 minutes in the PTCA group and 137 +/- 57 minutes in the thrombolysis group, respectively. In ECG 2, complete (> or =70%) ST resolution was observed more often in the PTCA treated patients (35 vs 27%, P =.003). The incidence of congestive heart failure until 6 weeks was lower in the PTCA group (11.2% vs 17.6, P =.001). Mortality after 6 weeks (3.4% vs 5.6%, P =.07) and after 6 months (4.5% vs 7.1%, P =.06) tended to be lower in the PTCA group.

CONCLUSION

Primary PTCA compared to thrombolytic therapy is associated with an accelerated myocardial reperfusion within 90 minutes after the start of reperfusion therapy. This early advantage in myocardial reperfusion is associated with an improved clinical outcome.

Additional ST-segment elevation during thrombolytic therapy in patients with acute ST-elevation myocardial infarction: impact on myocardial salvage and final infarct size

The aim of the study was to investigate the clinical significance of additional ST-segment elevation that occurs during thrombolytic therapy. Therefore, we classified 153 patients with a first acute myocardial infarction (MI) into two groups: Group A, 55 patients with additional ST-segment elevation > or = 1 mm above the initial ST elevation during thrombolytic therapy and Group B, 98 patients without this electrocardiographic pattern. Among the patients with anterior MI, Group A (n = 33) had no reduction from ST-predicted to final QRS-estimated infarct size (+12% versus -27%; p = 0.0005) and a larger final infarct size (QRS-score: 18% versus 12%; p = 0.0002) than Group B (n = 41). Among the patients with inferior MI, Group A (n = 22) had a smaller reduction from ST-predicted to final QRS-estimated infarct size (-30% versus -53%; p = 0.03) and a larger final infarct size (QRS-score: 15% versus 9%; p = 0.03) than Group B (n = 57). The area under the curve (AUC) of CK and CK-MB was higher in patients from Group A compared with those from Group B (anterior MI: AUC-CK: 22,048 versus 19,490 U.h.l-1; p = 0.07; AUC-MB: 2227 versus 2016 U.h.l-1; p = 0.11; inferior MI: AUC-CK: 17,206 versus 11,004 U.h.l-1; p = 0.01; AUC-MB: 2193 versus 1046 U.h.l-1; p = 0.007). Both global left ventricular function and ST-segment elevation resolution were significantly better in Group B. Two and three vessel disease was observed more frequently in Group A. Additional ST-segment elevation during thrombolytic therapy suggests reduced myocardial salvage by thrombolytic therapy and thus may result in larger final infarct size.

Effect of preinfarction angina pectoris on ST-segment resolution after primary coronary angioplasty for acute myocardial infarction

The presence of preinfarction angina has been shown to exert a favorable effect on left ventricular function after acute myocardial infarction (AMI). Whether or not preinfarction angina is beneficial for myocardial tissue reperfusion, however, remains to be determined. We sought to evaluate the influence of preinfarction angina on resolution of ST-segment elevation, which could be affected by microcirculatory damage after recanalization therapy. We studied 96 patients with a first AMI in whom Thrombolysis In Myocardial Infarction (TIMI)-3 flow in the infarct-related artery was established by primary angioplasty. Percent reduction in the sum of ST elevation from baseline to 1 hour after angioplasty (percent delta summation operator ST) was examined. Poor ST resolution, defined as percent delta summation operator ST <50%, was observed in 25 patients, who had a worse clinical outcome, larger infarct size, and poorer left ventricular function. On multivariate analysis, the absence of preinfarction angina, as well as anterior wall infarction, were major independent predictors of poor ST resolution, whereas age, sex, coronary risk factors, ischemic time, Killip class on admission, multivessel disease, initial TIMI flow grade, and extent of collaterals were not significant. Patients with preinfarction angina had a greater degree of ST-segment resolution than those without angina (71 +/- 21% vs 49 +/- 43%, p = 0.02). Additional ST elevation after reperfusion was noted exclusively in patients without preinfarction angina (p = 0.02). Preinfarction angina is associated with a greater degree of ST-segment resolution in patients with TIMI-3 flow after primary angioplasty, suggesting a protective effect of preinfarction angina against microcirculatory damage after reperfusion.

Time to treatment influences the impact of ST-segment resolution on one-year prognosis: insights from the assessment of the safety and efficacy of a new thrombolytic (ASSENT-2) trial

BACKGROUND

Early ST resolution after reperfusion is a prognostic indicator in acute myocardial infarction. Little information exists regarding the prognostic utility of ST resolution beyond 4 hours after fibrinolysis. Furthermore, the relation between time to treatment, ST resolution at 24 to 36 hours, and 1-year outcome has not been well studied. Accordingly, we undertook a prospective ECG substudy in the Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT-2) trial to examine this.

METHODS AND RESULTS

Patients (n=13 100) were stratified into 3 ST-resolution categories, based on baseline and 24- to 36-hour ECGs: complete resolution (>/=70%) in 6698 (51.1%) patients, partial resolution (30% to 70%) in 4610 (35.2%) patients, and no resolution (<30%) in 1792 (13.7%) patients; 1-year mortality rate was 5.1%, 8.0%, and 9.7%, respectively (P<0.001). Among patients treated <2 hours after symptom onset, 55.6% had complete ST resolution, whereas 52.1% and 43% of patients treated between 2 to 4 hours and 4 to 6 hours, respectively, had complete ST resolution (P<0.001). Within each category of ST resolution, patients treated <2 hours had lower 1-year mortality rates as compared with patients treated between 2 to 4 hours or >4 hours (3.8% versus 5.2% and 6.6%, P=0.002 in complete ST resolution; 5.7% versus 8.4% and 9.9%, P=0.001 in partial ST resolution; 7.1% versus 8.7% and 13%, P=0.006 in no resolution). The extent of ST resolution was closely and inversely correlated with 1-year mortality rates (r=-0.963, P<0.001).

CONCLUSIONS

ST resolution at 24 to 36 hours after fibrinolysis is influenced by time to treatment and inversely related to 1-year mortality rates. Time to treatment further differentiates between high- and low-risk patients and further highlights the importance of reducing time delay to initiation of fibrinolysis in acute myocardial infarction.

Extent of ST-segment deviation in a single electrocardiogram lead 90 min after thrombolysis as a predictor of medium-term mortality in acute myocardial infarction

BACKGROUND

In evolving myocardial infarction, assessment of the sum of early resolution of ST-segment elevation (sumSTR) has become an established method to predict outcome. We have found previously that mortality is predicted more accurately by the existing ST-segment deviation in the single electrocardiograph (ECG) lead with maximum deviation (maxSTE) 90 min after start of thrombolysis. This report compares the power to predict medium-term mortality by these two approaches.

METHODS

An ST-segment resolution substudy was done in conjunction with the Intravenous nPA for Treatment of Infarcting Myocardium Early (InTIME) II Study, which compared mortality in patients with acute myocardial infarction randomly assigned lanoteplase or alteplase. In 2719 patients, a 12-lead ECG was assessed at baseline and 90 min after the start of thrombolytic therapy.

FINDINGS

MaxSTE achieved a better combination of sensitivities and specificities for mortality prediction than sumSTR. The area under the receiver-operating characteristic curves for 180-day mortality prediction was 0.680 for maxSTE and 0.622 for sumSTR (difference 0.058; 95% CI 0.027-0.088). Risk groups categorised at low, medium, or high risk by maxSTE comprised 43%, 32%, and 24% of patients and those by complete, partial, or no sumSTR comprised 40%, 36%, and 24% of all patients. The 180-day mortality rates for the three maxSTE risk groups were 3.1%, 7.1%, and 16.2%, and those for the sumSTR groups were 4.8%, 8.1%, and 11.7%. The 12-month Kaplan-Meier estimates were 4.1%, 8.8%, and 18.6%, and 5.9%, 9.9%, and 13.7%, respectively.

INTERPRETATION

MaxSTE predicts early and medium-term mortality more accurately than does sumSTR. The prognosis for an individual patient can be accurately estimated simply by the ST-segment deviation present in one ECG lead recorded 90 min after thrombolysis.

Early identification of impaired myocardial reperfusion with serial assessment of ST segments after percutaneous transluminal coronary angioplasty during acute myocardial infarction

To evaluate the relation between ST-segment analysis and microvascular reperfusion in patients with acute myocardial infarction (AMI), we studied 51 patients with first AMI who were successfully treated by percutaneous transluminal coronary angioplasty (PTCA). The lead showing the greatest ST-segment elevation on the 12-lead electrocardiogram (ECG) was serially investigated until 24 hours after PTCA. Successful reperfusion was determined by technetium-99m tetrofosmin single-photon emission computed tomography. Impaired reperfusion (group 1: < 4 change in the sum of the defect score from before to immediately after PTCA) was observed in 24 patients, and successful reperfusion (group 2) was observed in 27 patients. Although ST-segment elevation was reduced significantly at 30 minutes after PTCA in group 2 (2.2 +/- 1.4 to 1.7 +/- 1.3 mm, p = 0.01), there was no significant change in group 1 (1.9 +/- 1.9 to 2.4 +/- 1.7 mm). Ten of 14 patients (71%) with persistent ST-segment elevation (DeltaST > 0 mm change in ST segment from before to 30 minutes after PTCA > 0) were in group 1, whereas 23 of 37 patients (62%) with ST-segment resolution (DeltaST < or = 0) were in group 2. The sensitivity and specificity of persistent ST-segment elevation for predicting impaired microvascular reperfusion were 42% and 85%, respectively. Thus, persistent ST-segment elevation 30 minutes after primary PTCA was a highly specific electrocardiographic marker of impaired reperfusion in patients with AMI.

ST segment resolution as a tool for assessing the efficacy of reperfusion therapy

Rapid, simple and inexpensive measures are needed to assess the efficacy of reperfusion therapy both in clinical practice and in clinical trials testing novel reperfusion regimens. In the last decade, several observations have led to a favorable reappraisal of the utility of ST segment monitoring as a simple means of assessing reperfusion in patients receiving fibrinolytic therapy for acute ST elevation myocardial infarction, and ST resolution is being used increasingly in clinical practice and in clinical research. This review focuses on four interrelated roles for ST segment monitoring: the assessment of epicardial reperfusion and the identification of candidates for rescue percutaneous coronary intervention; the evaluation of microvascular and tissue-level reperfusion; the determination of prognosis early after fibrinolytic therapy; and the use of ST segment resolution to compare different reperfusion regimens.

ST-Segment resolution as a marker of epicardial and myocardial reperfusion after thrombolysis: insights from the TIMI 14 and in TIME-II trials

Patients with persistent ST segment elevation after fibrinolysis are at high risk for death and congestive heart failure, even if normal epicardial flow has been restored. In the TIMI 14 trial, combination therapy with abciximab plus reduced-dose alteplase enhanced the speed and efficacy of epicardial reperfusion. We also found that combination therapy provided an additional benefit in terms of myocardial reperfusion, as evidenced by greater ST resolution on serial 12-lead electrocardiograms. Specifically, the proportion of patients with complete (> or =70%) ST resolution was higher among patients receiving combination therapy than in those treated with alteplase alone (59% vs 37%; p < 0.0001). Even among patients with normal (TIMI grade 3) epicardial blood flow, combination therapy was associated with a significantly greater likelihood of complete ST resolution than was fibrinolysis alone (69% vs 44%; p = 0.0002). In conclusion, combination reperfusion therapy improved myocardial (microvascular) reperfusion, independent of epicardial flow, suggesting an additional mechanism by which abciximab may improve outcomes in patients with acute MI.

Abciximab and early adjunctive percutaneous coronary intervention are associated with improved ST-segment resolution after thrombolysis: Observations from the TIMI 14 Trial

BACKGROUND

Percutaneous coronary intervention (PCI) improves clinical outcomes in selected patients with failed thrombolysis but has not been proven to benefit patients who achieve a patent infarct-related artery. Even after successful epicardial reperfusion, myocardial perfusion may be inadequate. We sought to evaluate whether a strategy that uses a reperfusion regimen containing abciximab and a reduced-dose thrombolytic agent (combination therapy), followed by early adjunctive PCI, would result in improved myocardial perfusion, as assessed by ST-segment resolution.

METHODS

ST resolution from 90 to 180 minutes after therapy was calculated for all 410 patients from the TIMI 14 trial who had evaluable electrocardiograms at both time points and who were treated with alteplase or reteplase. Patients were grouped according to whether they were treated with combination therapy or full-dose thrombolytic agent alone and whether they underwent PCI between the 90- and 180-minute electrocardiographic measurements.

RESULTS

Among 105 patients who underwent adjunctive PCI between 90 and 180 minutes, mean ST resolution from 90 to 180 minutes was significantly greater in those who had received combination therapy versus those who had received full-dose thrombolytic alone (54% vs 8%; P =.002). Among 241 patients with TIMI grade 3 flow in the infarct-related artery at 90 minutes, adjunctive PCI significantly improved mean ST resolution in patients who had been treated with combination therapy (57% [PCI] vs 24% [no PCI]; P =.006), but PCI did not have this effect in patients who had received thrombolytic therapy alone (1% [PCI] vs 10% [no PCI]; P =.70). In a multivariate model controlling for factors that would be expected to independently influence 90- to 180-minute ST resolution, abciximab treatment remained significantly associated with greater ST resolution (P =.008).

CONCLUSIONS

A strategy that uses a combination reperfusion regimen that includes abciximab, followed by early adjunctive PCI, is associated with greater ST-segment resolution, which may reflect enhanced tissue level and microvascular perfusion. Future studies should evaluate prospectively the clinical efficacy of this strategy.

Comparison of a 60- versus 90-minute determination of ST-segment resolution after thrombolytic therapy for acute myocardial infarction. In TIME-II Investigators. Intravenous nPA for Treatment of Infarcting Myocardium Early-II

Determination of ST-segment resolution 60 minutes after the administration of thrombolytic therapy allows accurate risk stratification for mortality and congestive heart failure. Patients with complete ST resolution at 60 minutes tended to be at lower risk for 30-day mortality than patients with complete ST resolution at 90 minutes.

ST-segment resolution and infarct-related artery patency and flow after thrombolytic therapy. Thrombolysis in Myocardial Infarction (TIMI) 14 investigators

Because patients who fail to achieve reperfusion after thrombolytic therapy remain at high risk for morbidity and mortality, noninvasive measures of infarct-related artery (IRA) patency are needed to identify candidates for rescue interventions. We prospectively studied 444 patients from the Thrombolysis In Myocardial Infarction (TIMI) 14 trial with interpretable baseline and 90 minute 12-lead electrocardiograms. The percent resolution of ST-segment deviation from baseline to 90 minutes was compared with 90-minute IRA TIMI flow grade, as determined in an angiographic core laboratory. Patients with complete (> or = 70%) ST resolution (n = 208; 47%) had a patency (TIMI 2 or 3 flow) rate of 94%, a TIMI 3 flow rate of 79%, and a 30-day mortality rate of 1.0%. Patients with partial (30% to 70%) or no (< or = 30%) ST resolution had significantly lower rates of patency (72% and 68%; p < 0.0001 vs complete ST resolution) and TIMI 3 flow (50% and 44%; p < 0.0001 vs complete ST resolution), and higher 30-day mortality (4.2% and 5.9%; p = 0.01 vs complete ST resolution). With use of electrocardiographic criteria alone, approximately 50% of patients can be classified as having a high (94%) probability of IRA patency and a very low risk for mortality. Angiography to determine patency of the IRA may be unnecessary in these patients. In patients without complete (> or = 70%) ST resolution, the IRA is still likely to be patent, and additional information from clinical variables or serum markers may help to identify candidates for coronary angiography. Patients with persistent ST elevation despite a patent IRA are at increased risk for mortality, likely due to extensive microvascular and tissue injury.

Abciximab improves both epicardial flow and myocardial reperfusion in ST-elevation myocardial infarction. Observations from the TIMI 14 trial

BACKGROUND

In the presence of ST-elevation myocardial infarction, patients with successful epicardial reperfusion (TIMI 3 flow) but persistent ST elevation on a 12-lead ECG are at high risk for subsequent death and left ventricular dysfunction. In the TIMI 14 trial, a dose-ranging angiographic study, combined therapy with abciximab plus reduced-dose tPA enhanced the speed and efficacy of epicardial reperfusion. We determined whether the combination of abciximab plus reduced-dose tPA provided additional benefit in terms of myocardial reperfusion, as evidenced by greater resolution of ST elevation.

METHODS AND RESULTS

All 346 patients with interpretable baseline and 90-minute ECGs, treated with either tPA alone or abciximab plus reduced-dose tPA (combination therapy), were included. Patients receiving combination therapy (n=221) had a 59% rate of complete (>/=70%) ST resolution at 90 minutes versus 37% in those treated with tPA alone (n=125) (P<0.0001). When the analysis was limited to patients with TIMI 3 flow, patients treated with combination therapy (n=151) remained significantly more likely to achieve complete ST resolution than those receiving tPA alone (n=80) (69% versus 44%; P=0.0002).

CONCLUSIONS

Combination therapy with abciximab and reduced-dose tPA improves myocardial (microvascular) reperfusion, as reflected in greater ST-segment resolution, in addition to epicardial flow. This finding may translate into improved clinical outcomes by enhancing myocardial salvage.