Clinical and laboratory signs of reperfusion: are they reliable?

Antistreptokinase antibodies and the response to thrombolysis with streptokinase in patients with acute ST elevation myocardial infarction

BACKGROUND AND OBJECTIVE

A large number of patients with ST elevation myocardial infarction (STEMI) continue to receive streptokinase (SK) in the developing countries. High levels of antistreptokinase (ASK) antibodies can result in failure of thrombolysis. This study was conducted to assess the presence of ASK antibodies in the general population and its effect on the outcome of thrombolysis with SK.

DESIGN

Prospective observational study.

SETTING

A tertiary care medical institute in Vellore, India.

PATIENTS

148 patients presenting with STEMI undergoing thrombolysis with SK were recruited.

MAIN OUTCOME MEASURES

The response to SK was assessed by reperfusion markers in the patients and they were categorised as good responders, probable responders and non-responders. Those who responded to SK and probable responders were considered to have benefited from thrombolysis.

RESULTS

60 patients (40%) had ASK antibody titres higher than the median. In patients with a window period <6 h, 73% of patients who benefited from thrombolysis had low ASK titres while 100% of the patients who did not benefit had high ASK titres (p=0.001). Similarly, in patients with a window period >6 h, 89% of patients who benefited from thrombolysis had low ASTK titres while 54% of those who did not benefit had high ASK titres (p=0.002).

CONCLUSIONS

ASK antibodies are present in significant titres in a large proportion of patients in developing countries, which leads to failure of thrombolysis in such patients. In endemic areas with high endemic streptococcal infection, alternative agents should be used for thrombolysis in STEMI.

One year results of the Middlesbrough early revascularisation to limit infarction (MERLIN) trial

OBJECTIVE

To report one year results of the MERLIN (Middlesbrough early revascularisation to limit infarction) trial, a prospective randomised trial comparing the strategy of coronary angiography and urgent revascularisation with conservative treatment in patients with failed fibrinolysis complicating ST segment elevation myocardial infarction (STEMI). The 30 day results have recently been published. At the planning stage of the trial, it was determined that follow up of trial patients would continue annually to three years to determine whether late benefit occurred.

SUBJECTS

307 patients who received a fibrinolytic for STEMI but failed to reperfuse early according to previously described ECG criteria and did not develop cardiogenic shock.

METHODS

Patients were randomly assigned to receive either emergency coronary angiography with a view to proceeding to urgent revascularisation (rescue percutaneous coronary intervention (rPCI) arm) or continued medical treatment (conservative arm). The primary end point was all cause mortality at 30 days. The secondary end points included the composite end point of death, reinfarction, stroke, unplanned revascularisation, or heart failure at 30 days. The same end points were evaluated at one year and these results are presented.

RESULTS

All cause mortality at one year was similar in the conservative arm and the rPCI arm (13.0% v 14.4%, p = 0.7, risk difference (RD) -1.4%, 95% confidence interval (CI) -9.3 to 6.4). The incidence of the composite secondary end point of death, reinfarction, stroke, unplanned revascularisation, or heart failure was significantly higher in the conservative arm (57.8% v 43.1%, p = 0.01, RD 14.7%, 95% CI 3.5% to 25.5%). This was driven almost exclusively by a significantly higher incidence of subsequent unplanned revascularisation in the conservative arm (29.9% v 12.4%, p < 0.001, RD 17.5%, 95% CI 8.5% to 26.4%). Reinfarction and clinical heart failure were numerically, but not statistically, more common in the conservative arm (14.3% v 10.5%, p = 0.3, RD 3.8%, 95% CI -3.7 to 11.4, and 31.2% v 26.1%, p = 0.3, RD 5.0%, 95% CI -5.1 to 15.1). There was a strong trend towards fewer strokes in the conservative arm (1.3% v 5.2%, p = 0.06, RD -3.9%, 95% CI -8.9 to 0.06).

CONCLUSION

At one year of follow up, there was no survival advantage in the rPCI arm compared with the conservative arm. The incidence of the composite secondary end point was significantly lower in the rPCI arm, but this was driven almost entirely by a highly significant reduction in the incidence of further revascularisation.

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.

Early noninvasive detection of failed epicardial reperfusion after fibrinolytic therapy

Available noninvasive techniques for identifying patients with failed epicardial reperfusion after fibrinolytic therapy are limited by poor accuracy. It is unknown whether combining multiple noninvasive predictors would improve diagnostic accuracy and facilitate identification of candidates for rescue percutaneous coronary intervention. In the Thrombolysis In Myocardial Infarction (TIMI) 14 trial, we evaluated the ability of ST-segment resolution (n = 606), chest pain resolution (n = 859), and the ratio of 60-minute/baseline serum myoglobin (n = 308) to identify patients with angiographic evidence of failed reperfusion 90 minutes after fibrinolysis. Three criteria were prospectively defined: <50% ST resolution at 90 minutes, presence of chest pain at the time of angiography, and myoglobin ratio <4. Patients who met any individual criterion were more likely to have less than TIMI 3 flow and an occluded infarct-related artery (TIMI 0/1 flow) than those who did not meet the criterion (p <0.005 for each). When the 3 criteria were used together (n = 169), patients who satisfied 0 (n = 29), 1 (n = 68), 2 (n = 51), or 3 (n = 21) of the criteria had a 17%, 24%, 35%, and 76% probability of failing to achieve TIMI 3 flow (p <0.0001 for trend), a 0%, 6%, 18%, and 57% probability of an occluded infarct-related artery (p <0.0001 for trend), and a 0%, 1.5%, 2.0%, and 9.5% rate of 30-day mortality (p = 0.05 for trend), respectively. Use of the criteria in combination increased positive predictive values without decreasing negative predictive values. In conclusion, ST-segment resolution, chest pain resolution, and early washout of serum myoglobin can be used in combination to aid in the early noninvasive identification of candidates for rescue percutaneous coronary intervention.

The use of the electrocardiogram to identify epicardial coronary and tissue reperfusion in acute myocardial infarction

The standard 12-lead electrocardiogram (ECG) gives us crucial information concerning myocardial perfusion and the success of reperfusion therapy for ST elevation acute myocardial infarction. Continuous monitoring has advantages over repeated snapshot recordings. There are four electrocardiographic markers for prediction of the perfusion status of the ischemic myocardium: (1) ST-segment measurements, (2) T-wave configuration, (3) QRS changes, and (4) reperfusion arrhythmias. Complete and stable (> or = 70%) resolution of ST-segment elevation is associated with better outcome and preservation of left ventricular function than partial (30 to 70%) or no (<30%) ST-segment resolution. Early inversion of the T waves after initiation of reperfusion therapy is another marker of myocardial reperfusion and a good prognostic sign. Using standard 12-lead ECG, dynamic changes in Q-wave number, amplitude, and width; R-wave amplitude; and S-wave appearance are detected during reperfusion therapy. However, the significance of these changes has not been clarified. Reperfusion arrhythmias, especially bradycardia and accelerated idioventricular rhythm, are detected occasionally during reperfusion therapy, but the value of reperfusion arrhythmias as a marker of coronary artery patency is still debatable. Dynamic changes in the QRS complexes, ST segments and T waves occur during reperfusion therapy and the days after. Whereas changes in ST-segment amplitude have been extensively studied, the significance of QRS-complex and T-wave changes is less clear, and especially whether changes in the QRS complex and T wave may be complementary and additive to ST-segment monitoring. It has remained unclear whether electrocardiographic signs of reperfusion and reischemia should be used for therapeutic decision making in the clinical setting.

Failed thrombolysis in myocardial infarction

Prompt treatment with thrombolytic therapy in acute myocardial infarction has been proven to reduce infarct size and mortality. However, reperfusion fails to occur in 30-50% of patients, either due to impaired epicardial artery flow or microvascular occlusion, with these patients experiencing a higher morbidity and mortality. We review the diagnosis and management of failed thrombolysis in acute myocardial infarction.

The use of the electrocardiogram to identify epicardial coronary and tissue reperfusion in acute myocardial infarction

The standard 12-lead ECG gives us crucial information concerning myocardial perfusion and the success of reperfusion therapy for ST-elevation acute myocardial infarction. Continuous monitoring has advantages over repeated snapshot recordings. There are four electrocardiographic markers for prediction of the perfusion status of the ischemic myocardium: 1) ST-segment measurements; 2) T-wave configuration; 3) QRS changes; and 4) reperfusion arrhythmias. Complete and stable (> or = 70%) resolution of ST-segment elevation is associated with better outcome and preservation of left ventricular function than partial (30% to 70%) or no (< 30%) ST-segment resolution. Early inversion of the T-waves after initiation of reperfusion therapy is another marker of myocardial reperfusion and a good prognostic sign. Using standard 12-lead ECG, dynamic changes in Q-wave number, amplitude and width, R-wave amplitude and S-wave appearance are detected during reperfusion therapy. However, the significance of these changes have not been clarified. Reperfusion arrhythmias, especially bradycardia and accelerated idioventricular rhythm are detected occasionally during reperfusion therapy, but the value of reperfusion arrhythmias as a marker of coronary artery patency is still debatable. Dynamic changes in the QRS complexes, ST-segments and T-waves occur during reperfusion therapy and the days after. While changes in ST-segment amplitude have been extensively studied, the significance of QRS-complex and T-wave changes are less clear, and especially whether changes in the QRS-complex and T-wave may be complementary and additive to ST-segment monitoring. It has remained unclear whether electrocardiographic signs of reperfusion and re-ischemia should be used for therapeutic decision-making in the clinical setting.

Failure of thrombolysis by streptokinase: detection with a simple electrocardiographic method

OBJECTIVE

To determine whether simple, readily applicable ECG criteria will allow early prediction of inadequate (< TIMI 3) flow in the infarct related vessel in patients receiving thrombolytic treatment for acute myocardial infarction; and to determine the success of streptokinase in achieving adequate antegrade flow in the infarct related vessel two hours after starting treatment.

DESIGN

Cohort study.

SETTING

Regional cardiothoracic unit.

PATIENTS

100 sequential patients with acute myocardial infarction.

INTERVENTIONS

Coronary angiography two hours after the initiation of thrombolytic treatment, proceeding to rescue angioplasty for inadequate flow in the infarct related vessel where appropriate.

MAIN OUTCOME MEASURES

Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of six ECG criteria for the detection of inadequate antegrade flow in the infarct related vessel.

RESULTS

The ECG test that performed best as a positive test for < TIMI 3 flow in the infarct related vessel was < 50% resolution of the ST segment elevation in the worst lead and no accelerated idioventricular rhythm. This had a sensitivity of 81%, specificity of 88%, positive predictive value of 87%, negative predictive value of 83%, and overall accuracy of 85%.

CONCLUSIONS

Sensitive, specific, and simple ECG criteria are defined for diagnosing failure of thrombolytic treatment with streptokinase. These allow the early detection of patients at high risk of further adverse events from a persistently occluded vessel. They may be used without recourse to sophisticated equipment or complex analyses. Such patients can then be considered for alternative treatments or enrollment into appropriate research protocols.

The role of coronary angioplasty and stenting in acute myocardial infarction

Despite the improvements in the pharmacological treatment of acute myocardial infarction, it is recognised that thrombolysis fails to reproduce reperfusion in a significant proportion of patients. Coronary interventional techniques have been shown to offer an alternative reperfusion strategy. There is increasing evidence that mechanical reperfusion may offer significant advantages over established thrombolytic therapy.

The role of antegrade and collateral flow in relation to left ventricular function post-thrombolysis

The aim of the study was to analyze the relationship between antegrade and collateral flow degree to the "culprit" coronary artery, and between both variables and left ventricular systolic function. We analyzed five hundred patients with acute myocardial infarction, treated prospectively and consecutively within 6 h of evolution with intravenous streptokinase. The degree of antegrade (0-3) and collateral blood flow (0-3) were correlated with 18 other variables.

RESULTS

(a) By simple regression analysis, antegrade flow degree correlated positively (p < 0.0001), and collateral flow degree negatively (p = 0.0073) with left ventricular ejection fraction; (b) By multiple regression analysis, antegrade flow degree (p = 0.0032), but not collateral flow degree (p > 0.1), correlated independently with left ventricular ejection fraction; (c) In the subgroup of patients with occluded "culprit" coronary artery, the mean ejection fraction was significantly higher for those with collateral flow 3 (60.2% +/- 13.3 in relation to those with collateral flow < 3 (53.9% +/- 13.1, p = 0.032, 95% CI. 11.96 to (0.53%). In conclusion, antegrade coronary flow degree, but not collateral flow degree, correlated significantly and independently with left ventricular ejection fraction. However, in the subgroup of patients with occluded "culprit" coronary artery, collateral flow 3 led to better left ventricular systolic function, in relation to collateral flow < 3.

Diltiazem improves left ventricular systolic function following acute myocardial infarction treated with streptokinase. The Calcium Antagonist in Reperfusion Study (CARES) Group

The role of diltiazem on left ventricular systolic function was analyzed in 101 patients with acute myocardial infarction treated with streptokinase, being obtained, for the total of the population, higher LV global ejection fraction (p = 0.022), LV regional shortening (p = 0.046) and LV global shortening (p = 0.064) for the treated group, relative to the placebo group; the p values were, respectively, 0.005, 0.009, and 0.012, for patients that achieved TIMI-3 antegrade coronary flow. It is concluded that diltiazem is useful as adjuvant to streptokinase, especially when antegrade coronary blood flow TIMI-3 is obtained.

Q-wave regression unrelated to patency of infarct-related artery or left ventricular ejection fraction or volume after anterior wall acute myocardial infarction treated with or without reperfusion therapy

We examined the relation of Q-wave regression to left ventricular (LV) indexes in acute anterior wall myocardial infarction (AMI) in relation to reperfusion therapy. A total of 94 patients with their first anterior wall AMI (segment 6 or 7 occlusion according to the American Heart Association classification) were examined. The follow-up period with 12-lead electrocardiograms ranged from 6 to 60 months (mean 24 +/- 18). An abnormal Q wave was defined as > 40 ms and > 25% of the R-wave amplitude. Q-wave regression was defined as Q-wave disappearance and r-wave regression > 0.1 mV in > or = 1 lead. Contingency tables with the chi-square test and analysis of variance were used for assessment of the relation between Q-wave regression and angiographic and clinical indexes. Q-wave regression in > or = 1 lead was found in 77% of the patients. The incidence of Q-wave regression in patients with patent infarct-related artery (81%) was not significantly different from that in those with an occluded lesion (67%). Q-wave regression appeared within 1 month in 60% of patients with a patent infarct-related artery but in 25% of those with an occluded lesion. No difference in the incidence of Q-wave regression was seen between patients with lesions at segments 6 (81%) and 7 (70%), or between those with (75%) and without (77%) collateral circulation. Q-wave regression did not correlate with LV ejection fraction, LV end-diastolic or end-systolic volumes, or regional wall motion.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiographic diagnosis of reperfusion during thrombolytic therapy in acute myocardial infarction

Continuous 12-lead electrocardiographic monitoring was performed in 61 patients receiving thrombolytic therapy for an acute myocardial infarction. Coronary angiography within 90 minutes revealed a patent vessel (Thrombolysis in Myocardial Infarction [TIMI] trial 2 or 3) in 44 patients. Early signs of reperfusion were ST-segment normalization (likelihood ratio 16.0), development of terminal T-wave inversion (likelihood ratio 10.6), accelerated idioventricular rhythm (likelihood ratio 6.0), and a twofold increase in ventricular premature complexes (likelihood ratio 2.5). Relief of chest pain after 60 minutes was reported by 96%. During reperfusion of the infarct-related vessel, an increase in ST-segment deviation was recorded in 61% of the patients, whereas 69% had an increase in chest pain preceding the eventual decline.

Noninvasive assessment of reperfusion and reocclusion after thrombolysis in acute myocardial infarction

The clinical significance of ST-segment changes and of the time course of appearance in serum of different cardiac proteins has been reviewed for the diagnosis of coronary reperfusion and reocclusion after thrombolysis. In particular, the value of serial 12-lead electrocardiographic (ECG) studies, of Holter monitoring, and of continuous multilead computer-assisted ECG monitoring is compared. Regarding the serum proteins, the clinical significance of reperfusion indices described so far for serum creatine kinase (CK), its isoenzyme serum creatinine kinase MB, the CK isoforms, and myoglobin is reviewed. Emphasis is placed on (1) the calculation method used for deriving the reperfusion indices; (2) the sensitivity and the specificity of the reperfusion indices; (3) the minimum turn-around time needed to produce the reperfusion indices (depending on the practicability of the analytical and calculation methods and their applicability in an emergency laboratory); (4) the ability of the indices to produce reliable estimates of reperfusion efficacy of the thrombolytic agents under study; and (5) the ability of the marker proteins to detect reinfarction as well as the suitability of the markers to detect real-time necrosis.

Defibrotide versus heparin in the prevention of coronary reocclusion after thrombolysis in acute myocardial infarction

A multicenter controlled study versus heparin was conducted to explore the activity of defibrotide, a polydesoxyribonucleotide drug, in preventing reocclusion after urokinase thrombolysis in patients with acute myocardial infarction (AMI). The study involved 137 consecutive patients with AMI and a time from the onset of symptoms < or = 6 hours, treated with urokinase (1,000,000 U intravenous bolus followed by 1,000,000 U slow-drip infusion over 12 hours). Immediately after thrombolysis, patients were allocated to treatment with defibrotide (group D: day 0, 3.6 g by intravenous infusion in 12 hours; days +1 to +6, 800 mg tid intravenously; days +7 to +10/+12, 400 mg tid intramuscularly), or heparin (group H: day 0, 1000 IU/hour infused over 12 hours; days +1 to +10/+12, 5000 IU tid subcutaneously). Coronary angiography was done, whenever possible, at +10/+12 days. The following parameters were assessed: (a) noninvasive estimate of myocardial reperfusion, through the analysis of CPK time-activity curves; (b) incidence of infarct-related artery (IRA) patency (TIMI scores 2-3) at coronary angiography. A total of 125 patients had a complete enzymatic curve (63 in group D and 62 in group H) and 106 had coronary angiography as well. IRA patency (the main end point) was observed in 63% of group D versus 43% of group H patients (p = 0.07). No statistically significant differences were found in the proportion of patients with indirect signs of early reperfusion (63% in group D versus 52% in group H patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute myocardial infarction treated with intravenous streptokinase: 6-year follow-up

Our objective was to investigate variables which, although occurring during the acute period, could influence the medium (1st year) and long-term (6th year) survival of infarcted patients. Of a total of 332 patients treated consecutively and prospectively according to the same protocol which included intravenous streptokinase, 305 survived the hospital phase and represent the study population. Mean patient age was 55.6 +/- 10 years and mean follow-up time was 3.33 years, with 1008.59 patient-years. The clinical course of the group was analyzed according to the following variables: left ventricle ejection fraction, hypotension per/peri streptokinase infusion, CK-MB peak, previous myocardial infarction, number of obstructed coronaries, reinfarction, sex, 'definitive' treatment, residual obstruction, age, pain/streptokinase infusion interval, patency of the 'culprit' coronary and infarct location. Overall, patient survival was 93.8 +/- 1.4% during the 1st year and 83.7 +/- 2.6% at the 6th. The following groups showed significantly different (log-rank) survivals: (a) 1st year: 94.6% for absence and 82.6% for presence of reinfarction (P = 0.0451); 97.9% for inferior and 91.4% for anterior infarct location (P = 0.044); 96.4% for ejection fraction > 50% and 90.6% for ejection fraction < or = 50% (P = 0.0187); 96.5% for angioplasty/surgery and 90.1% for clinical treatment (P = 0.0028); 95.5% for absence and 80.6% for presence of previous infarct (P = 0.0001). (b) 6th year: 88.3% for ejection fraction > 50% and 73.9% for ejection fraction < or = 50% (P = 0.028); 87.4% for < or = 65 and 66.4% for > 65 years (P = 0.0114); 89.6% for aggressive and 76.8% for conservative treatment (P = 0.013); 86.6% for absence and 60.7% for presence of previous infarct (P = 0.0009).

Time course and interrelation of reperfusion-induced ST changes and ventricular arrhythmias in acute myocardial infarction

With the increasing use of thrombolytic therapy, the presence and time course of reperfusion-induced ventricular arrhythmias and ST-segment changes have become of particular interest. Technical improvements in bipolar Holter monitoring offer the opportunity to record both parameters continuously and simultaneously. Time course and interaction of both parameters in dependence on the onset of thrombolysis and time of reperfusion were investigated in 30 patients with acute myocardial infarction. Reperfusion was achieved in 20 patients after 49 +/- 23 minutes and in another 2 patients after 120 minutes (73%, group A). Vascular occlusion persisted in 8 patients for greater than 24 hours (group B). Sudden ST-segment changes (greater than 0.2 mV/15 min) in the bipolar leads indicated reperfusion in 7 of 22 patients (32%). Idioventricular rhythms, most frequent in reperfused patients (group A: 18 of 22 patients, mean 121 beats/hour), were unspecific reperfusion markers (group B: 5 of 8 patients, 1 beat/hour) unless frequent (p less than 0.05) or longer lasting, repetitive (p less than 0.01) episodes were considered. Premature ventricular beats and couplets (p less than 0.05) were also most frequent in group A (peak frequency 3 to 5 hours after thrombolysis). Ventricular tachycardia observed in 21 of 22 patients (95%) in group A and in 3 of 8 (38%) in group B (p less than 0.01) attained their peak frequency 7 to 9 hours after thrombolysis. They occurred most often in anterior myocardial infarction and were often preceded by frequent singular premature beats (r = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)