Noninvasive assessment of speed and stability of infarct-related artery reperfusion: results of the GUSTO ST segment monitoring study. Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries

Prognostic usefulness of serial C-reactive protein measurements in ST-elevation acute myocardial infarction

It has been reported that increased levels of C-reactive protein are related to adverse long-term prognosis in the setting of ST-segment elevation acute myocardial infarction (MI). In previous studies, the timing of C-reactive protein determination has varied widely. In the present study, serial high-sensitivity C-reactive protein (hsCRP) measurements were performed to investigate if any of the measurements is superior regarding long-term prognosis. A total of 861 consecutive patients admitted for ST-segment elevation MI and treated with intravenous thrombolysis within the first 6 hours from the index pain were included. HsCRP levels were determined at presentation and at 24, 48, and 72 hours. The median follow-up time was 3.5 years. New nonfatal MI and cardiac death were the study end points. By the end of follow-up, cardiac death was observed in 22.4% and nonfatal MI in 16.1% of the patients. HsCRP levels were found to be increasing during the first 72 hours. Multivariate Cox regression analysis demonstrated that hsCRP levels at presentation were an independent predictor of the 2 end points (relative risk [RR] 2.8, p = 0.002, and RR 2.1, p = 0.03, for MI and cardiac death, respectively), while hsCRP levels at 24 hours did not yield statistically significant results (RR 1.4, p = 0.40, and RR 1.1, p = 0.80, for MI and cardiac death, respectively). The corresponding RRs at 48 hours were 1.2 (p = 0.5) for MI and 3.2 (p = 0.007) for cardiac death and at 72 hours were 1.6 (p = 0.30) for MI and 3.9 (p <0.001) for cardiac death. In conclusion, hsCRP levels at presentation represent an independent predictor for fatal and nonfatal events during long-term follow-up. HsCRP levels at 48 and 72 hours, which are close to peak hsCRP levels, independently predict only cardiac death.

Patent coronary artery and myocardial infarction in the era of primary angioplasty: assessment of an old problem in a new setting with data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR)

AIMS

The purpose of this study was to evaluate factors that contribute to a patent IRA (infarct - related artery) and the prognostic impact of a patent IRA in patients with ST-elevation myocardial infarction.

METHODS AND RESULTS

Using the Swedish angiography and angioplasty registry (SCAAR) we included all patients with STEMI and one-vessel coronary artery disease who underwent primary PCI of the culprit lesion only from May 2005 to December 2007. A patent IRA was found in 1,104 of 3,284 patients. Patients with an occluded IRA had significantly increased 7-day mortality (HR, 3.03, 95% CI 1.68-5.46, P<0.001). The incidence of an occluded IRA increased with higher age, in patients over 80 years of age (OR, 1.23, 95% CI; 0.92-1.64), lower in patients on lipid-lowering drugs (OR, 0.68, 95% CI; 0.54-0.86) and lower in patients pre-treated with heparin (OR 0.71, 95% CI; 0.60-0.83) or GPIIb/IIIa receptor blockade (OR 0.77, 95% CI; 0.61-0.97). Treatment with acetylsalicylic acid or clopidogrel had no effect on IRA patency.

CONCLUSIONS

IRA patency was associated with a lower 7-day mortality. Older STEMI patients and patients not taking lipid-lowering drugs or pre-treated with heparin or GPIIb/IIIa receptor blockers seem to constitute risk groups for having an occluded IRA.

The significance of circulating levels of both cardiac troponin I and high-sensitivity C reactive protein for the prediction of intravenous thrombolysis outcome in patients with ST-segment elevation myocardial infarction

OBJECTIVES

To evaluate, using continuous 12-lead ECG ST-segment monitoring, the role of circulating levels of both cardiac troponin I (cTnI) and high-sensitivity C reactive protein (hs-CRP), on presentation, in the prediction of intravenous thrombolysis outcome in patients with ST-segment elevation myocardial infarction (STEMI).

DESIGN AND SETTING

Prospective observational study in a tertiary referral centre.

PATIENTS

786 consecutive patients with STEMI, who received intravenous thrombolysis in the first 6 h from index pain.

MAIN OUTCOME MEASURES

The incidence of failed thrombolysis and of cardiac death by 30 days. Failed thrombolysis was defined as the absence of abrupt and sustained > or =50% ST-segment recovery in the first 90 min after the initiation of intravenous thrombolysis.

RESULTS

The incidence of failed thrombolysis and 30-day cardiac death was 57.4% and 11.8%, respectively. By multivariate logistic regression analysis according to tertiles of both cTnI (RR, 1.5; 95% CI 1.1 to 1.8, p = 0.004 for highest vs middle third; 2.2, 1.9 to 3.5, p<0.001 for highest vs lowest third; 1.5, 1.2 to 1.8, p = 0.001 for middle vs lowest third) and hs-CRP (RR, 2.0, 95% CI, 1.6 to 2.2; p<0.001 for highest vs middle third; 2.6, 2.1 to 3.5, p<0.001 for highest vs lowest third; 1.3, 1.2 to 1.7, p = 0.02 for middle vs lowest third), were independently associated with failed thrombolysis. Moreover, by multivariate Cox regression analysis according to tertiles of both cTnI (HR 1.2, 95% CI 1.1 to 1.8, p = 0.03 for highest vs middle third; 1.5, 1.2 to 2.2, p = 0.004 for highest vs lowest third; 1.1, 0.6 to 1.4, p = 0.6 for middle vs lowest third) and hs-CRP (HR1.2, 95% CI 1.1 to 1.6, p = 0.04 for highest vs middle third; 1.7, 1.3 to 2.6, p = 0.001 for highest vs lowest third; 1.1, 0.9 to 2.1, p = 0.1 for middle vs lowest third), were independently related with an increased risk of 30-day cardiac death.

CONCLUSIONS

High circulating levels of both cTnI and hs-CRP are related with an independent increased risk of intravenous thrombolysis failure and 30-day cardiac death in patients who received intravenous thrombolysis in the first 6 h of STEMI.

Prediction of infarction-related artery occlusion and multivessel disease in postinfarction angina

CONDENSED ABSTRACT

To investigate the predictive value of clinical data for infarction-related artery (IRA) occlusion and multivessel coronary disease in postinfarction angina (PIA), we studied 181 consecutive patients presenting PIA following a first uncomplicated ST elevation AMI. Multivariate analysis showed ECG changes during PIA and the absence of thrombolytic therapy as independent predictors of IRA occlusion. Independent clinical predictors of multivessel coronary disease were age, previous history of angina and the number of cardiovascular risk factors. We conclude that reversible ECG changes during PIA correlated to IRA occlusion but failed to predict a multivessel coronary disease.

AIM

To identify clinical variables predictive of infarction-related artery (IRA) occlusion and multivessel coronary disease in patients with postinfarction angina pectoris (PIA) after a first uncomplicated acute myocardial infarction (AMI).

METHODS

We studied 181 consecutive patients with PIA following a first uncomplicated AMI. Clinical variables included cardiovascular risk factors, clinical history of angina before the event of inclusion, use of thrombolytic therapy in the previous AMI, ST-T changes during PIA, time to onset, number of episodes and delay to angiography after PIA. Angiographic variables were IRA TIMI flow, number of diseased vessels and ventricular function.

RESULTS

The IRA was occluded in 67 patients with PIA (37.0%). Reversible ECG changes during PIA were detected in 121 patients (67.0%): 79 cases (43.6%) with ST/T elevation and 42 cases (23.2%) with ST/T depression. Multivariate logistic regression analysis showed ECG changes during PIA (OR 3.12 CI 95% 1.48-6.54, p<0.01) and the absence of thrombolytic therapy (OR 2.21 95% CI 1.11-4.43, p<0.05) as independent predictors of IRA occlusion. We found multivessel coronary disease in 89 patients (49.2%) without any correlation to ECG changes during PIA. Independent clinical predictors of multivessel coronary disease were age (OR 1.03 95% CI 1.01-1.06, p<0.05), previous history of angina (OR 2.37 95% CI 1.06-5.28, p<0.05) and the number of cardiovascular risk factors (OR 1.37 95% CI 0.97-1.92, p=0.07).

CONCLUSIONS

ECG changes during PIA was correlated to IRA occlusion in spite of previous thrombolytic therapy but failed to predict a multivessel coronary disease in our patients.

AHA scientific statement: practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association Scientific Statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized electrocardiology and the American Association of Critical-Care Nurses

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas Computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide "best practices" for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, time frames, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

Continuous ST-segment monitoring of patients with right bundle branch block and suspicion of acute myocardial Infarction

BACKGROUND

Patients with right bundle branch block comprise 5-9% of all patients with acute myocardial infarction. In spite of this, limited data exist on early diagnosis or the usefulness of continuous electrocardiographic monitoring in these patients.

METHODS

A prospective multicenter study with 14 Swedish coronary care units. Patients with right bundle branch block and suspicion of acute myocardial infarction with less than 6 hours symptom duration were included. All patients were monitored with continuous vectorcardiography for 12-24 hours.

RESULTS

Seventy-nine patients were included, 43% had acute myocardial infarction. Patients with acute myocardial infarction had significantly higher initial ST-vector magnitude values (P = 0.0014) compared to patients without acute myocardial infarction. Patients with acute myocardial infarction also showed gradual regression of ST-vector magnitude over time that was not seen for patients without acute myocardial infarction (P = 0.005). ST-vector magnitude measured at the J-point differentiated best between patients with and without acute myocardial infarction. A cutoff value of 125 microV for initial ST-vector magnitude resulted in 55% sensitivity and 87% specificity for the diagnosis of acute myocardial infarction. Over time, patients with acute myocardial infarction showed greater changes in QRS-vector difference compared to patients without acute myocardial infarction (P = 0.052).

CONCLUSION

Vectorcardiographic monitoring shows good diagnostic abilities for patients with right bundle branch block and clinical suspicion of acute myocardial infarction and could be useful for continuous monitoring of these patients.

Practice Standards for Electrocardiographic Monitoring in Hospital Settings

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide ‘best practices’ for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, timeframes, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

[Prediction of outcome in ST elevation myocardial infarction by the extent of ST segment deviation recovery. Which method is best?]

Simple and rapid measures are needed for timely assessment of the quality of reperfusion therapy early after fibrinolysis in acute STEMI. Sum ST segment elevation resolution (sum STR) categorized into the three groups of low risk (complete ST resolution), medium risk (partial ST resolution), and high risk (no ST resolution) has become an established method to predict infarct size, left ventricular function, epicardial vessel patency, and mortality. However, measurement of the sum of ST elevation from all leads of repeated ECG's is time-consuming. For routine practice more simple measures are needed. This report summarizes recent findings on direct comparisons between different modes of evaluation of ST segment deviation recovery employed for risk stratification in large-scale mortality trials. With respect to predictive accuracy combined with simplicity, two methods were superior to the conventional model of sum STR: 1) ST segment deviation resolution in only the one ECG lead showing the maximal deviation (single lead STR), and 2) the existing ST segment deviation in the single ECG lead of maximum deviation present 90 or 180 min after start of fibrinolysis (max STE). In multivariate analyses the ST segment deviation recovery models including sum STR were significant independent predictors of short- and long-term mortality. In receiver-operating characteristic (ROC) curves for predicting mortality the analysis of single lead STR and max STE performed better than sum STR. After categorization into risk groups patients are best classified by max STE. With an ECG recorded at 90 min in 2719 patients, the proportion of patients of sum STR, single lead STR, and max STE were 40, 34, and 43% in the low risk groups, and 24, 31, and 25% in the high risk groups. Cardiac mortality rates at 30 days were 2.0, 1.2, and 1.0% in low risk versus 9.6, 10.3, and 12.8% in the high risk groups, respectively. Long-term mortality with a followup of 5 years was best predicted by max STE risk groups.

CONCLUSION

Single lead STR and max STE are very simple, inexpensive, non-invasive, and highly reliable measures which provide very strong early prognostic information. The relationship between degree of ST segment deviation recovery and subsequent mortality is remarkably consistent. Both methods perform better than sum STR in predicting mortality. They can be used for very early risk stratification and can form a basis for an individual treatment of patients after fibrinolysis for STEMI within 6 hours of symptom onset. Of the two methods max STE is even simpler to use and has better accuracy in predicting outcome.

Continuous ST-segment monitoring of patients with left bundle branch block and suspicion of acute myocardial infarction

OBJECTIVES

Patients with left bundle branch block comprise 5-9% of all patients with acute myocardial infarction. Limited data exist on the usefulness of continuous electrocardiographic monitoring of these patients. We have investigated prospectively the usefulness of real-time continuous vectorcardiography for monitoring patients with left bundle branch block and suspicion of acute myocardial infarction.

DESIGN

A prospective multi-centre study.

SETTING

Fourteen Swedish coronary care units.

SUBJECTS

Patients with left bundle branch block and suspicion of acute myocardial infarction with <6-h symptom duration were included.

MAIN OUTCOME MEASURES

All patients were monitored with continuous vectorcardiography for 12-24 h.

RESULTS

One hundred thirty-three patients were included, 47% had acute myocardial infarction. Patients with acute myocardial infarction showed a marked relative decrease in ST-vector than those without (P = 0.0002). These changes were most marked in the first 90 min. When comparing patients with acute myocardial infarction receiving thrombolytic therapy or not, those treated with thrombolytics showed more marked decline in ST-vector magnitude (P < 0.0001) and in shorter time (P = 0.0017). All patients showed STC-vector magnitude changes that were more marked in patients with acute myocardial infarction (P = 0.0002). An STC-vector magnitude cut-off value of 65 microV after 90 min of monitoring gave 54% sensitivity and 72% specificity for diagnosis of acute myocardial infarction.

CONCLUSION

Real-time continuous vectorcardiographic monitoring of patients with left bundle branch and suspicion of acute myocardial infarction shows significant differences between those with and without acute myocardial infarction and could be of use for early diagnosis and subsequent monitoring.

Vectorcardiography risk stratifies emergency department chest pain patients with left ventricular hypertrophy on the initial 12-lead ECG

BACKGROUND

Vectorcardiographic (VCG) measurements of ST-vector magnitude (VM) and QRS-vector difference (VD) have been demonstrated to be independent predictors of adverse outcome (AO) and acute myocardial infarction (AMI) in emergency department (ED) chest pain patients with absence of bundle branch block or left ventricular hypertrophy (LVH) on the initial 12-lead electrocardiogram (ECG). The prognostic value of ST-VM and QRS-VD in ED chest pain patients with LVH on the initial 12-lead ECG has not been previously investigated.

METHODS

A prospective observational study was performed in 196 consecutive ED chest pain patients with suspected AMI and presence of voltage criteria for LVH on initial ECG who underwent continuous VCG monitoring during the initial evaluation. The optimal baseline ST-VM value and 2-hour QRS-VD value were defined as the most accurate value on the receiver operator characteristic curve (value with lowest false-negative and false-positive rate). Thirty-day AO was defined as AMI, percutaneous coronary intervention, coronary artery bypass grafting (CABG), or cardiac death occurring within 30 days of initial ED visit.

RESULTS

Fourteen patients (7.1%) were diagnosed as 24-hour AMI and 28 patients (14.3%) experienced 30-day AO. The optimal cut-off value for predicting 30-day AO was > 124 microV for ST-VM and > 21.7 microV for QRS-VD. Patients with either a positive ST-VM or a positive QRS-VD had 8.8 times increased odds of AMI (95% confidence interval, CI, 1.9-40.3; P = 0.003); 4.3 times increased odds of 30-day PTCA/CABG (95% CI 1.3-13.8; P = 0.019); and 3.8 times increased odds of 30-day AO (95% CI 1.6-9.3; P = 0.003).

CONCLUSIONS

Baseline ST-VM and 2-hour QRS-VD risk stratifies ED chest pain patients with LVH voltage criteria on the initial 12-lead ECG.

Combining baseline clinical descriptors and real-time response to therapy: the incremental prognostic value of continuous ST-segment monitoring in acute myocardial infarction

BACKGROUND

Clinical descriptors and ST-segment recovery variables hold prognostic information for clinical outcome after thrombolysis for acute myocardial infarction (MI). We sought to define the incremental prognostic value of continuous 12-lead ST-segment monitoring variables to clinical risk descriptors identified by the Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries (GUSTO-I) trial 30-day mortality analysis.

METHODS

Of 1,777 patients enrolled in continuous ST-segment substudies from the Thrombolysis and Angioplasty in Myocardial Infarction (TAMI-9), GUSTO-I, Duke University Clinical Cardiology Study (DUCCS-II), Integrilin to manage Platelet Aggregation to Combat Thrombus in Acute Myocardial Infarction (IMPACT-AMI), Promotion of Reperfusion by Inhibition of Thrombin During Myocardial Infarction Evolution (PRIME), and Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction (PARADIGM) trials, 825 patients qualified for assessment of time to recovery. ST recovery variables analyzed were time to stable ST-recovery and late ST elevation. Patients who were at low clinical risk (n = 261) had no high-risk descriptors, and patients at high clinical risk (n = 564) had at least 1 of these high-risk descriptors: age >or=70 years, systolic blood pressure <or=110 mm Hg, heart rate >or=90 beats/min, anterior MI, or previous MI. High (n = 90), moderate (n = 318), and low (n =417) ST-risk groups were defined by the presence of both slow ST recovery and late ST elevation, one or the other, or neither, respectively. End points analyzed were inhospital death and combined death, reinfarction, or congestive heart failure.

RESULTS

There was a trend toward increased mortality rate in the high-clinical/high-ST-risk group. For the composite end point, ST subgrouping resulted in significant event stratification in both patients at low and high clinical risk. In multivariable analysis, age and heart rate were independent predictors of both mortality and the composite end point. Late ST elevation added incremental prognostic information.

CONCLUSION

Age, heart rate, and late ST elevation are powerful, independent predictors of adverse clinical outcome. Continuous monitoring allows noninvasive assessment of the response to therapy. Consequently, this technique will enhance the potential to risk-stratify individual patients in a real-time setting.

Early reperfusion and late clinical outcomes in patients presenting with acute myocardial infarction randomly assigned to primary percutaneous coronary intervention or streptokinase

BACKGROUND

Primary percutaneous coronary intervention (PCI) has become an alternative to thrombolytic therapy as a reperfusion strategy for ST-elevation acute myocardial infarction (AMI).

METHODS

The main goal of this study was to determine whether PCI and thrombolytic therapy achieve comparable reperfusion rates, as evidenced by ST-segment resolution. Secondary end points included infarct vessel patency rates before hospital discharge and short- and long-term outcomes. Patients with ischemic chest pain with duration < or =12 hours and no contraindication for thrombolytic therapy were included.

RESULTS

Between October 1993 and August 1995, 58 patients were randomly assigned to streptokinase (SK) and 54 patients to primary PCI. Baseline clinical characteristics and infarct location were well balanced in both groups. Median age (interquartile range) was 68 (58, 75) years, 29% were women, and 78% of the patients met at least one criterion for "not low risk" AMI (anterior location, age >70 years old, previous MI, systolic blood pressure <100 mm Hg, and/or heart rate >100 bpm). The median time from symptom onset to random assignment was 217 (139, 335) minutes in the PCI group and 210 (145, 334) minutes in the SK group. Median random assignment to balloon time was 82 (55, 100) minutes, and median random assignment to needle time was 15 (10, 26) minutes (P <.0001). TIMI grade 3 flow after primary PCI was obtained in 85% of patients. The proportion of patients with ST-segment resolution > or =50% at 120 minutes was 80% in the PCI group and 50% in the SK group (P =.001). The predischarge angiogram showed the presence of TIMI 3 flow in 96% of patients who received PCI and 65% of patients who received SK (P <.001). A composite of in-hospital death, reinfarction, severe heart failure, stroke, and major bleeding occurred in 15% of patients who received PCI and 21% of patients who received SK (P =.4). At 3 years, freedom from the composite end point of AMI, postdischarge revascularization, and death was 61% in the PCI group and 40% in the SK group (P =.025).

CONCLUSIONS

Our study shows that primary PCI, as compared with SK, is associated with more effective ST-segment resolution, higher patency rates in the infarct vessel at 7 days, and more favorable clinical outcomes at 3 years of follow-up.

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.

Relationship Between Collateral Blood Flow and Microvascular Perfusion After Reperfused Acute Myocardial Infarction

During acute occlusion of an epicardial vessel collaterals preserve the microvascular perfusion and limit the extent of myocardial damage. Pressure-derived collateral flow index (CFIp) assessed by intracoronary pressure measurement allow us to quantify collateral vessel development. The angiographic myocardial blush (MB) scores, based on the contrast dye density and washout in the infarcted myocardium, provide important information about microvascular perfusion after acute myocardial infarction (AMI). In this study we assessed the microvascular perfusion with MB and studied the relation between CFIp in patients with AMI who treated with thrombolytic therapy and TIMI grade III flow restored in the infarct related artery (IRA). Forty-one patients with AMI who were treated with thrombolytic therapy and underwent stent implantation (mean of 3 days after AMI) to the IRA were included in this study. After angiography, CFIp was calculated as the ratio of simultaneously measured coronary wedge pressure--central venous pressure (Pv) to mean aortic pressure--Pv. Myocardial blush was graded densitometrically based on visual assessment of the relative contrast opacification of the myocardial territory subtended by the infarct vessel. There was a statistically significant correlation between CFIp and post-stent myocardial blush grades (P < 0.01, r = 0.70). There was a significant difference in mean CFIp among myocardial blush grades implying that higher CFIp is associated with better MB (0.39 +/- 0.11 in grade 3, 0.32 +/- 0.10 in grade 2, 0.24 +/- 0.09 in grade 1, and 0.16 +/- 0.08 in grade 0, P < 0.01). Well developed collaterals can limit microvascular damage by preserving microvascular perfusion. A higher pressure-derived collateral flow index is associated with better tissue level perfusion as evidenced by the higher myocardial blush score.

Use of baseline ST-vector magnitude to identify electrocardiographic injury in patients with suspected acute myocardial infarction

No information is currently available regarding optimal cut-off values of the ST-vector magnitude (ST-VM) for predicting acute myocardial infarction (AMI) in emergency department (ED) chest pain patients undergoing vectorcardiographic (VCG) monitoring. A prospective observational study was performed in 1,722 chest pain patients with suspected acute coronary syndrome and absence of bundle branch block (BBB) and left ventricular hypertrophy (LVH) on initial ECG who underwent continuous VCG ST-segment monitoring during the initial ED evaluation. Three cut-off values for baseline ST-VM are reported and represent the smallest values in which the positive likelihood ratio (+LR) for AMI is greater than 5, 10, and 20, respectively. AMI occurred in 158 of 1,722 patients (9.2%) without BBB or LVH on initial ECG. Optimal cut-off values at the predetermined +LR values of 5, 10, and 20, were 121 microV (sensitivity, 41.8%; specificity, 92.0%), 151 microV (sensitivity, 29.1%; specificity, 97.1%), and 175 microV (sensitivity, 25.9%; specificity, 98.7%), respectively. Combining the earlier-mentioned cut-off values with physician judgment of initial pretest probability (high, intermediate, or low, respectively) resulted in a relative increase in identification of injury of 37.5% as compared with the ED physician's interpretation of initial ECG (41.8% v 30.4%; P <.0001), and 65.2% as compared with the official ECG interpretation (41.8% v 25.3%; P <.0001). Increasing ST-VM results in increasing likelihood of AMI. Clinical studies need to be performed to determine if ST-VM cut-off values of 121, 151, and 175 microV in conjunction with physician pretest probability of AMI can be used as criterion for emergent reperfusion therapy in patients without LVH or BBB on the initial ECG.

Clinical outcomes of patients with diabetes mellitus and acute myocardial infarction treated with primary angioplasty or fibrinolysis

OBJECTIVE

To compare the early and late outcomes of primary percutaneous transluminal coronary angioplasty (PTCA) with fibrinolytic treatment among diabetic patients with acute myocardial infarction (AMI).

DESIGN

Retrospective observational study with data obtained from prospective registries.

SETTING

Tertiary cardiovascular institution with 24 hour acute interventional facilities.

PATIENTS

202 consecutive diabetic patients with AMI receiving reperfusion treatment within six hours of symptom onset.

INTERVENTIONS

Fibrinolytic treatment was administered to 99 patients, and 103 patients underwent primary PTCA. Most patients undergoing PTCA received adjunctive stenting (94.2%) and glycoprotein IIb/IIIa inhibition (63.1%).

MAIN OUTCOME MEASURES

Death, non-fatal reinfarction, and target vessel revascularisation at 30 days and one year were assessed.

RESULTS

Baseline characteristics were similar in these two treatment groups except that the proportion of patients with Killip class III or IV was considerably higher in those treated with PTCA (15.5% v 6.1%, p = 0.03) and time to treatment was significantly longer (103.7 v 68.0 minutes, p < 0.001). Among those treated with PTCA, the rates for in-hospital recurrent ischaemia (5.8% v 17.2%, p = 0.011) and target vessel revascularisation at one year (19.4% v 36.4%, p = 0.007) were lower. Death or reinfarction at one year was also reduced among those treated with PTCA (17.5% v 31.3%, p = 0.02), with an adjusted relative risk of 0.29 (95% confidence interval 0.15 to 0.57) compared with fibrinolysis.

CONCLUSION

Among diabetic patients with AMI, primary PTCA was associated with reduced early and late adverse events compared with fibrinolytic treatment.

Celebrating the 100th Birthday of the Electrocardiogram: Lessons Learned From Research in Cardiac Monitoring

The electrocardiogram continues to be the gold standard for the diagnosis of cardiac arrhythmias and acute myocardial ischemia. The treatment of arrhythmias in critical care units has become less aggressive during the past decade because research indicates that antiarrhythmic agents can be proarrhythmic, causing malignant ventricular arrhythmias such as torsade de pointes. However, during the same period, the treatment of acute myocardial ischemia has become more aggressive, with the goal of preventing or interrupting myocardial infarction by using new antithrombotic and antiplatelet agents and percutaneous coronary interventions. For this reason, critical care nurses should learn how to use ST-segment monitoring to detect acute ischemia, which is often asymptomatic, in patients with acute coronary syndromes. Because the electrocardiographic lead must be facing the localized ischemic zone of the heart to depict the telltale signs of ST-segment deviation, the challenge is to find ways to monitor patients continuously for ischemia without using an excessive number of electrodes and lead wires. The current trend is to use reduced lead set configurations in which 5 or 6 electrodes, placed at convenient places on the chest, are used to construct a full 12-lead electrocardiogram. Nurse scientists at the University of California, San Francisco, School of Nursing are at the forefront in developing and assessing the diagnostic accuracy of these reduced lead set electrocardiograms.

Failed reperfusion after thrombolytic therapy: recognition and management

BACKGROUND

Failed reperfusion after thrombolysis occurs in as many as 30% of patients with acute myocardial infarction (MI). Furthermore, some patients have incomplete tissue perfusion despite reperfusion of the infarct-related artery. Close assessment of the efficacy of thrombolytic administration in people with evolving acute MI is necessary, particularly with regard to myocardial perfusion status, because some patients may benefit from incremental pharmacologic or invasive reperfusion strategies.

PURPOSE AND METHOD

This article reviews a number of strategies to assess infarct-related artery patency and myocardial tissue perfusion. These include coronary angiography, continuous ST-segment monitoring, serial electrocardiography, obtaining serial serum biochemical markers of myocardial necrosis, monitoring for reperfusion arrhythmias, and assessment of changes in chest pain intensity.

CONCLUSION

The early detection of failed reperfusion is critical if incremental strategies to enhance myocardial salvage are to be considered. Continuous ST-segment monitoring is a relatively inexpensive, reliable, and accurate tool for assessing real-time myocardial perfusion.

Multicenter, dose-ranging study of efegatran sulfate versus heparin with thrombolysis for acute myocardial infarction: The Promotion of Reperfusion in Myocardial Infarction Evolution (PRIME) trial

BACKGROUND

Adjunctive therapies that increase the incidence of normal reperfusion after thrombolysis for acute myocardial infarction (MI) could enhance clinical outcomes. Direct thrombin inhibitors may offer an advantage over standard adjunctive therapies.

METHODS

We randomized 336 patients with acute MI at 33 sites to receive 1 of 5 doses of efegatran sulfate, a direct thrombin inhibitor, or heparin for 72 to 96 hours, both with accelerated alteplase and aspirin. The primary end point was the incidence of thrombolytic failure (death, reinfarction, or TIMI grade 0-2 flow in the infarct artery from 90 minutes to discharge or 30 days, whichever occurred earlier).

RESULTS

Significantly more patients randomized to efegatran had evidence of heart failure at admission. The lowest-dose efegatran arm was terminated at 15 patients because of unacceptably increased thrombolytic failure. The primary end point occurred in 53.0% of patients treated with heparin, in 53.8% of patients treated with efegatran overall (P =.90), and in 55.4% of patients given intermediate-dose efegatran (P =.74). These findings were unaffected after adjustment was done for baseline differences. Most bleeding was minor; major bleeding and the use of blood transfusions did not differ significantly by treatment. Three patients in the high-dose efegatran group had intracranial hemorrhage, as did 1 patient in the heparin group. Continuous ST monitoring showed a shorter time to recovery for the efegatran group (median 107 minutes) compared with the heparin group (154 minutes; P =.025).

CONCLUSIONS

Efegatran sulfate appeared to offer no clear advantage over heparin as an adjunct to thrombolysis for acute myocardial infarction, although there may be a modest improvement in time to 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.

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.

A randomized double-blind trial of intravenous trimetazidine as adjunctive therapy to primary angioplasty for acute myocardial infarction

BACKGROUND

Despite high patency rates, primary angioplasty for myocardial infarction does not necessarily result in optimal myocardial reperfusion and limitation of infarct size. Experimentally, trimetazidine limits infarct size, decreases platelet aggregation, and reduces leukocyte influx into the infarct zone. To assess trimetazidine as adjunctive therapy to primary angioplasty for acute myocardial infarction a prospective, double-blind, placebo-controlled pilot trial was performed.

METHODS

94 patients with acute myocardial infarction were randomized to receive trimetazidine (40 mg bolus followed by 60 mg/day intravenously for 48 h) (n=44) or placebo (n=50), starting before recanalization of the infarct vessel by primary angioplasty. Patients underwent continuous ST-segment monitoring to assess return of ST-segment deviation to baseline and presence of ST-segment exacerbation at the time of vessel recanalization. Infarct size was measured enzymatically from serial myoglobin measurements. Left ventricular angiography was performed before treatment and repeated at day 14.

RESULTS

Blinded ST segment analysis showed that despite higher initial ST deviation from baseline in the trimetazidine group (355 (32) vs. 278 (29) microV, P=0.07), there was an earlier and more marked return towards baseline within the first 6 h than in the placebo group (P=0.014) (change: 245 (30) vs. 156 (31) microV respectively, P=0.044). There was a trend towards less frequent exacerbation of ST deviation at the time of recanalization in the trimetazidine group (23.3 vs. 42.2%, P=0.11). There was no difference in left ventricular wall motion at day 14, or in enzymatic infarct size. There was no side effect from treatment. Clinical outcomes were similar between groups.

CONCLUSION

Trimetazidine was safe and led to earlier resolution of ST-segment elevation in patients treated by primary angioplasty for acute myocardial infarction.

Shifting the open-artery hypothesis downstream: the quest for optimal reperfusion

Successful reperfusion after acute myocardial infarction (MI) has traditionally been considered to be restoration of epicardial patency, but increasing evidence suggests that disordered microvascular function and inadequate myocardial tissue perfusion are often present despite infarct vessel patency. Thus, optimal reperfusion is being redefined to include intact microvascular flow and restored myocardial perfusion, as well as sustained epicardial patency. Coronary angiography has been used as the gold standard to define failed reperfusion, according to the Thrombolysis In Myocardial Infarction (TIMI) flow grades. However, new angiographic techniques, including the corrected TIMI frame count and myocardial blush grade, have been used to show that epicardial TIMI flow grade 3 may be an incomplete measure of reperfusion success. Furthermore, evolving noninvasive diagnostic techniques, including measurement of infarct size with cardiac marker release patterns or technetium-99m-sestamibi single-photon emission computed tomographic imaging and analysis of ST segment resolution appear to be useful complements to angiography for the assessment of myocardial tissue reperfusion. Promising adjunctive therapies that target microvascular dysfunction, including platelet glycoprotein IIb/IIIa inhibitors, and agents designed to improve tissue perfusion and attenuate reperfusion injury are being evaluated to further improve clinical outcomes after acute MI. To accelerate development of these new reperfusion regimens, an integrated approach to phase II clinical trials that incorporates multiple efficacy variables, including angiography and noninvasive biomarkers of microvascular dysfunction, should be considered. Thus, as the reperfusion era moves into the next millennium, the open-artery hypothesis is expected to shift downstream and guide efforts to further improve myocardial salvage and clinical outcomes after acute MI.

[ST-segment and myocardial enzymes evolution during myocardial infarction after fibrinolysis therapy and its relation with postinfarction angina, Killip class and mortality in intensive unit care]

INTRODUCTION

The prognostic value of enzyme peaks, the sum of the ST segment and reperfusion arrythmias during myocardial infarction remains unclear.

AIM

The aim of this study was to relate the early enzymatic peaks, the sum of the ST segment and reperfusion arrythmias after thrombolytic therapy with postinfarction angina, Killip class and mortality during the acute phase of myocardial infarction.

PATIENTS AND METHODS

Of 187 patients receiving fibrinolytic therapy, 169 were consecutively and prospectively included in the study. The following myocardial enzymes were determined: CK, MB, TGO, LDH. Electrocardiograms were performed prior to and 2, 6, 12 and 24 hours after the administration of the fibrinolytic drug.

RESULTS

The mean age of the patients was 60.12 +/- 11.3 years, with 138 (81.7%) being males. Myocardial infarction was anterior in 74 (43.7%) and inferior in 95 cases (56.3%). Reperfusion arrythmias were observed in 65 cases (38.5%). One hundred thirty-one (77.5%) were Killip class I, 12 (7.1%) presented postinfarction angina, and 8 (4.7%) died. A peak was observed in MB at 6 hours in cases of anterior myocardial infarction and the sum of the ST segment decreased less than 50% in the first 2 hours. No statistically significant correlation was observed between the enzymatic peaks, the reperfusion arrythmias, Killip class, postinfarction angina or early mortality. The greater the ST segment sum, the greater the severity according to the Killip class. On multivariate analysis no model was found to be related to postinfarction angina. However, age was related to mortality and sex and age were associated with heart failure.

CONCLUSIONS

In our population, the variables studied were not found to be useful to determine the prognosis during the early phase of acute myocardial infarction.

Considerable time from the onset of plaque rupture and/or thrombi until the onset of acute myocardial infarction in humans: coronary angiographic findings within 1 week before the onset of infarction

BACKGROUND

It has been thought that the thrombi and bleeding in plaques that occur after plaque rupture or endothelial damage from vessels with mild stenosis suddenly occlude the lumen and cause acute myocardial infarction (AMI). However, our hypothesis is that thrombi and bleeding may not suddenly occlude the lumen.

METHODS AND RESULTS

The study group consisted of 20 patients who had coronary angiograms performed within 1 week (3+/-3 days) before AMI and 20 control patients who had coronary angiograms performed 6 to 18 months (282+/-49 days) before AMI. The features of infarct-related coronary segments (IRCS) at 3 days before AMI were the presence of a significant stenosis of >50% (95% in incidence and 71+/-12% diameter stenosis) and Ambrose's type II eccentric lesions (plus multiple irregularities), an indicator of plaque rupture and/or thrombi (60% [70%]), and the features at 1 year before AMI were mild stenosis of <50% (95% incidence and 30+/-18% diameter stenosis) with rare Ambrose's type II eccentric lesions (plus multiple irregularities) (10% [10%]). The same relation was observed in each of the 4 subgroups with Q-wave infarction, non-Q-wave infarction, preceding effort angina within 1 month before AMI, and no preceding effort angina.

CONCLUSIONS

The appearance of marked progression and Ambrose's type II eccentric lesion on coronary angiograms 3 days before AMI suggests the presence of a considerable time from the onset of plaque rupture and/or thrombi until the onset of AMI. These features may be predictors of AMI. The concept provides new insight into the mechanism and prevention of human AMIs.

ST-Segment recovery adds to the assessment of TIMI 2 and 3 flow in predicting infarct wall motion after thrombolytic therapy

BACKGROUND

Early resolution of ST-segment elevation (ST-segment recovery) is associated with an improved outcome after infarction. Whether this relation is present in patients with Thrombolysis In Myocardial Infarction (TIMI) grade 2 or 3 flow (ie, patent) infarct-related arteries is not known.

METHODS AND RESULTS

To examine the associations between time to achieve stable 50% ST-segment recovery assessed by continuous ECG monitoring, infarct artery flow, and infarct zone wall motion (at 48 hours), we studied 134 patients who underwent angiography at 99 (interquartile range 92 to 110) minutes after commencing streptokinase, initiated within 12 hours of onset of symptoms of myocardial infarction. Patients with TIMI 2 or 3 flow who failed to achieve early stable ST-segment recovery (50% ST-segment recovery sustained for > or 4 hours with <100 microV change in the peak lead) by 60 or 90 minutes had a higher fraction of chords in the infarct zone >2 SD below normal wall motion (TIMI 2: 55.5% vs 15.3%, P=0.006; and 56.5% vs 26.8%, P=0.01, respectively; and TIMI 3: 48.8% vs 28.3%, P=0.07; and 51.8% vs 29.9%, P=0.03, respectively). Time to stable ST-segment recovery was a multivariate predictor of infarct zone wall motion (P=0.04) independent of TIMI flow grade and the time from symptom onset to streptokinase therapy.

CONCLUSIONS

In patients with TIMI 2 or 3 flow in infarct-related artery, early stable ST-segment recovery is associated with improved infarct zone wall motion at 48 hours. ST-segment recovery may provide additional information about the degree of myocyte reperfusion achieved in patients with a patent epicardial infarct-related artery after thrombolytic therapy.

Achieving tissue-level perfusion in the setting of acute myocardial infarction

Treatment for ST-elevation myocardial infarction (MI) has advanced rapidly in the last few years with improvements in early fibrinolytic therapy, primary percutaneous revascularization, and use of potent platelet glycoprotein IIb/IIIa inhibitors. It is now obvious that establishing epicardial patency after myocardial infarction is not synonymous with tissue-level perfusion. Techniques and therapies are now available that measure true tissue-level perfusion and that may improve tissue-level perfusion after myocardial infarction.

Myocardial ischemia correlates with reduced fibrinolytic activity following peripheral vascular surgery

STUDY OBJECTIVES

To evaluate the relationship between perioperative ischemia and serial concentrations of D-dimer, which is a sensitive and specific marker of fibrinolytic activity. Myocardial ischemia and infarction are well-recognized complications of peripheral vascular surgery. We hypothesized that patients at increased risk of perioperative myocardial ischemia might be identified preoperatively by abnormal hemostatic indices.

DESIGN

Prospective clinical outcomes study.

SETTING

A 1,124-bed tertiary care medical center.

PATIENTS

42 ASA physical status II, III, and IV patients undergoing peripheral vascular surgery.

INTERVENTIONS

Serial D-dimer concentrations were measured preoperatively, and at 24 and 72 hours postoperatively. Continuous 12-lead ST-segment monitoring (Mortara Instrument, Inc., Milwaukee, WI) was performed with the acquisition of a 12-lead ECG every 20 seconds for 72 hours.

MEASUREMENTS AND MAIN RESULTS

D-dimer measurements were performed in duplicate using the Dimer Gold assay (American Diagnostica, Greenwich CT). Ischemic episodes, as defined by continuous 12-lead ST-segment monitoring, occurred in 49% of patients. There were no demographic differences between ischemic and nonischemic groups. Although baseline D-dimer concentrations were not statistically significantly different between groups, patients experiencing perioperative myocardial ischemia generated significantly less D-dimer during the perioperative period (p = 0. 014).

CONCLUSIONS

PATIENTS with an impaired fibrinolytic response, as defined by reduced generation of D-dimer, experienced an increased incidence of perioperative myocardial ischemia.

Continuous ST-segment monitoring associated with infarct size and left ventricular function in the GUSTO-I trial

BACKGROUND

The aim of this study was to evaluate whether in patients with myocardial infarction, the intensity and duration of myocardial ischemia as measured by continuous ST monitoring are associated with infarct size and residual left ventricular function.

METHODS AND RESULTS

The analyses included patients with myocardial infarction, receiving thrombolytic therapy, who were enrolled in the electrocardiographic substudy of GUSTO-I, monitored by a vector-derived 12-lead electrocardiographic recording system, and in whom either infarct size (defined as cumulative release of alpha-hydroxybutyrate dehydrogenase activity per liter of plasma over a 72-hour period [Q(72)]) or left ventricular ejection fraction (LVEF) was determined. With the use of linear regression analysis, we investigated the association of various ST-trend characteristics with Q(72) (206 patients) and with LVEF (180 patients). A higher area under the ST trend since thrombolysis until 50% ST recovery and a higher area under recurrent ischemic episodes (ST reelevations) were significantly associated with a higher Q(72), whereas only a higher area under recurrent ischemic episodes was significantly associated with a lower LVEF. These associations remained after adjusting for other patient characteristics such as age, sex, infarct location, and time to treatment.

CONCLUSIONS

These findings support the physiologic hypothesis that both the intensity and duration of myocardial ischemia (both reflected by the estimated areas under the ST-trend curve) determine myocardial damage and thus are associated with infarct size and ejection fraction in patients with acute myocardial infarction who receive thrombolytic therapy.

Device implementation, validation, and application assessment of two continuous 12-lead ECG monitors during percutaneous transluminal coronary angioplasty: description of the validation method and implications for clinical trials

Comparability of clinical and research data sets may be undermined if the instruments used to acquire them vary. Even when standard 12-lead electrocardiographic formats are used for monitoring, proprietary signal processing techniques and sampling intervals may differ among devices. In order to directly compare the two commercially available standard 12-lead devices with monitoring capabilities, bifurcated wires from a single standard lead set were attached to each device in elective angioplasty patients. Neither device was used as a standard; rather, a method was designed to analyze the output from each device independently, and then, if results differed, data from both monitors were reviewed by consensus to determine the source of the differences. Analysis endpoints for each study included study quality, baseline ST-segment levels, the presence of ischemia, number of ischemic episodes, peak lead location, and peak lead amplitude. Sources of differences in these endpoints visible to consensus review included variations between devices in baseline stability, noise/artifact levels, stability of the QRS complex onset, and temporal sampling intervals.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

OBJECTIVES

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

BACKGROUND

Ischemic symptoms commonly recur after thrombolysis for acute myocardial infarction.

METHODS

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

RESULTS

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

CONCLUSIONS

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

Change in ST segment elevation 60 minutes after thrombolytic initiation predicts clinical outcome as accurately as later electrocardiographic changes

OBJECTIVE

To compare prospectively the prognostic accuracy of a 50% decrease in ST segment elevation on standard 12-lead electrocardiograms (ECGs) recorded at 60, 90, and 180 minutes after thrombolysis initiation in acute myocardial infarction.

DESIGN

Consecutive sample prospective cohort study.

SETTING

A single coronary care unit in the north of England.

PATIENTS

190 consecutive patients receiving thrombolysis for first acute myocardial infarction.

INTERVENTIONS

Thrombolysis at baseline.

MAIN OUTCOME MEASURES

Cardiac mortality and left ventricular size and function assessed 36 days later.

RESULTS

Failure of ST segment elevation to resolve by 50% in the single lead of maximum ST elevation or the sum ST elevation of all infarct related ECG leads at each of the times studied was associated with a significantly higher mortality, larger left ventricular volume, and lower ejection fraction. There was some variation according to infarct site with only the 60 minute ECG predicting mortality after inferior myocardial infarction and only in anterior myocardial infarction was persistent ST elevation associated with worse left ventricular function. The analysis of the lead of maximum ST elevation at 60 minutes from thrombolysis performed as well as later ECGs in receiver operating characteristic curves for predicting clinical outcome.

CONCLUSION

The standard 12-lead ECG at 60 minutes predicts clinical outcome as accurately as later ECGs after thrombolysis for first acute myocardial infarction.

Key factors in the identification of the high-risk patient with unstable coronary artery disease: clinical findings, resting 12-lead electrocardiogram, and continuous electrocardiographic monitoring

This article reviews a range of methods for identifying high-risk patients with unstable coronary artery disease, including clinical evaluation, the resting 12-lead electrocardiogram, continuous vectorcardiography, and a combined risk evaluation using continuous vectorcardiography and measurement of troponin-T. Clinical evaluation is not very accurate for identifying high-risk patients and modern techniques have not been fully validated in clinical trials. The combination of continuous vectorcardiography and biochemical monitoring is a very powerful method of identifying both very high- and very low-risk patients and may be increasingly used in the future.

Combined accelerated tissue-plasminogen activator and platelet glycoprotein IIb/IIIa integrin receptor blockade with Integrilin in acute myocardial infarction. Results of a randomized, placebo-controlled, dose-ranging trial. IMPACT-AMI Investigators

BACKGROUND

Platelet activation and aggregation may be key components of thrombolytic failure to restore and maintain perfusion in acute myocardial infarction. We performed a placebo-controlled, dose-ranging trial of Integrilin, a potent inhibitor of platelet aggregation, with heparin, aspirin, and accelerated alteplase.

METHODS AND RESULTS

We assigned 132 patients in a 2:1 ratio to receive a bolus and continuous infusion of one of six Integrilin doses or placebo. Another 48 patients were randomized in a 3:1, double-blind fashion to receive the highest Integrilin dose from the first phase or placebo. All patients received accelerated alteplase, aspirin, and intravenous heparin infusion; all but two groups also received an intravenous heparin bolus. The highest Integrilin dose group from the nonrandomized phase and the randomized patients were pooled for analysis and compared with placebo-treated patients. The primary end point was Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow at 90-minute angiography. Secondary end points were time to ST-segment recovery, an in-hospital composite (death, reinfarction, stroke, revascularization procedures, new heart failure, or pulmonary edema), and bleeding variables. The highest Integrilin dose groups had more complete reperfusion (TIMI grade 3 flow, 66% versus 39% for placebo-treated patients; P = .006) and a shorter median time to ST-segment recovery (65 versus 116 minutes for placebo; P = .05). The groups had similar rates of the composite end point (43% versus 42% for placebo-treated patients) and severe bleeding (4% versus 5%, respectively).

CONCLUSIONS

The incidence and speed of reperfusion can be enhanced when a potent inhibitor of the glycoprotein IIb/IIIa integrin receptor, such as Integrilin, is combined with accelerated alteplase, aspirin, and intravenous heparin.

Implications of the GUSTO trial for thrombolytic therapy

This article discusses the impact of previous clinical observations on the development of the GUSTO-I protocol, particularly the absence of a survival benefit of alteplase (rt-PA) over streptokinase in the GISSI-2/International Study Group and ISIS-3 trials in spite of a higher efficacy for clot lysis. The demonstrated superiority of front-loaded alteplase in this large trial is translated into useful guidelines for the practising clinician. Risk-benefit analysis indicates that, in general, this thrombolytic regimen is most indicated in patients presenting with large amounts of jeopardized ischaemic myocardium in the absence of a particularly increased risk of haemorrhagic stroke. Finally, the impact of this study for future development in the field of acute coronary syndromes is evaluated, more specifically for the design of new trials with new fibrinolytic and antithrombotic agents. These include mutants of alteplase, staphylokinase, direct antithrombins and inhibitors of the glycoprotein IIb/IIIa platelet receptor.

Time from symptom onset to treatment and outcomes after thrombolytic therapy. GUSTO-1 Investigators

OBJECTIVES

This study sought to examine the relations among patient characteristics, time to thrombolysis and outcomes in the international GUSTO-I trial.

BACKGROUND

Studies have shown better left ventricular function and decreased infarct size as well as increased survival with earlier thrombolysis, but the relative benefits of various thrombolytic agents with earlier administration are uncertain.

METHODS

We evaluated the relations of baseline characteristics to three prospectively defined time variables: symptom onset to treatment, symptom onset to hospital arrival (presentation delay) and hospital arrival to treatment (treatment delay). We also examined the relations of delays to clinical outcomes and to the relative 30-day mortality benefit with accelerated tissue-type plasminogen activator (t-PA) versus streptokinase.

RESULTS

Female, elderly, diabetic and hypertensive patients had longer delays at all stages. Previous infarction or bypass surgery was an additional risk factor for treatment delay. Early thrombolysis was associated with lower overall mortality rate (< 2 h, 5.5%; > 4 h, 9.0%), but no additional relative benefit resulted from earlier treatment with accelerated t-PA versus streptokinase (p = 0.38). Longer presentation and treatment delays were both associated with increased mortality rate (presentation delay < 1 h, 5.6% and > 4 h, 8.6%; treatment delay < 1 h, 5.4%, and > 90 min, 8.1%). As time to treatment increased, the incidence of recurrent ischemia or reinfarction decreased, but the rates of shock, heart failure and stroke increased.

CONCLUSIONS

Earlier treatment resulted in better outcomes, regardless of thrombolytic strategy. Elderly, female and diabetic patients were treated later, adding to their already substantial risk.

Heart rate variability assessment early after acute myocardial infarction. Pathophysiological and prognostic correlates. GUSTO ECG Substudy Investigators. Global Utilization of Streptokinase and TPA for Occluded Arteries

BACKGROUND

Diminished heart rate variability is associated with less favorable prognosis after myocardial infarction. However, the prognostic value of early (first 48 hours) measurement and the influence of thrombolytic strategies, myocardial infarction location, left ventricular function, ST-segment shift, and infarct-related artery patency on heart rate variability have not been examined comprehensively.

METHODS AND RESULTS

Heart rate variability and ST-segment analysis of 48-hour Holter tapes were performed with the use of a commercial system in 204 patients who were part of an ST-monitoring substudy of the Global Utilization of Streptokinase and TPA for Occluded Arteries (GUSTO-I) trial. Both time-domain measures (SD of the average normal RR interval for all 5-minute segments of a 24-hour ECG recording [SDANN] and percent difference between adjacent normal RR intervals > 50 ms computed over the entire 24-hour ECG recording [pNN50]) and frequency-domain measures (low frequency [LF], high frequency [HF], and LF/HF ratio) were assessed on days 1 and 2 after acute myocardial infarction. Coronary angiography performed within the first 24 hours was also available in 75% of the patients. All heart rate variability measures decreased between day 1 and day 2 (P = .001) except the LF/HF ratio. There was no difference in heart rate variability among groups assigned to one of four different thrombolytic treatment strategies (streptokinase/subcutaneous heparin, streptokinase/intravenous heparin, accelerated tissue plasminogen activator, and combination streptokinase/tissue plasminogen activator). Heart rate variability measures were lower in anterior versus nonanterior infarcts (SDANN, 53 +/- 21 versus 63 +/- 24 ms; P < .005) and increased with TIMI grade 3 flow (LF, 5.3 +/- 1.0 versus 4.8 +/- 1.2 ms2; P < .01) and better ejection fraction (r = .2, P < .03). An inverse correlation between the duration of ST shift and frequency domain measures was observed (LF, r = -.2, P < .009; HF, r = -2, P < .03). Lower LF/HF ratio by 24 hours after myocardial infarction was seen in those who ultimately died at 30 days (1.0 +/- 0.2 versus 1.3 +/- 0.2, P < .001) or at 1 year (1.17 +/- 0.14 versus 1.26 +/- 0.19, P = .05).

CONCLUSIONS

Changes in heart rate variability occurred early after thrombolysis and may be of prognostic value. Heart rate variability measures were improved in patients with better ejection fraction and greater angiographic patency. This suggests a possible mechanism for the enhanced survival observed with TIMI grade 3 flow in the GUSTO angiographic substudy. These data indicate that early heart rate variability assessment after myocardial infarction may be useful in noninvasive risk stratification.

Frequency, significance, and cost of recurrent ischemia after thrombolytic therapy for acute myocardial infarction. TAMI Study Group

Early postinfarction angina implies an unfavorable prognosis. Most published information on this outcome represents data collected in the prethrombolytic era, in which definitions and populations differed considerably. Our purpose was to evaluate the incidence and importance of recurrent ischemia after administration of thrombolytic therapy. We studied patients enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction studies. Patients were enrolled into 5 studies with similar entry criteria; 552 patients were treated with tissue plasminogen activator (t-PA), 293 were treated with urokinase, and 385 received both thrombolytic agents. Recurrent ischemia was defined as symptoms in association with electrocardiographic changes; reinfarction was defined as a reelevation of creatine kinase myocardial band isoenzyme in an appropriate clinical setting. Both recurrent ischemia and reinfarction occurred in 42 patients (3.4%), recurrent ischemia alone occurred in 226 (18%), whereas neither occurred in 964 (78%). Although baseline characteristics were similar among the 3 groups, in-hospital cardiac events (total 73 deaths, 253 heart failure episodes) were not: in-hospital mortality in patients with reinfarction was 21%; with recurrent ischemia, 11%; and with neither event, 4% (p < 0.0001). The in-hospital heart failure rate of patients with reinfarction was 50%; with recurrent ischemia alone, 31%; and with neither event, 17% (p < 0.0001). As expected, median in-hospital costs were highest in patients with reinfarction ($26,802), intermediate for those with recurrent ischemia alone ($18,422), and lowest in patients with neither event ($15,623). Recurrent myocardial ischemia after thrombolytic therapy is a frequent, important, and expensive adverse clinical outcome, making it a critical target for therapeutic intervention.