European Heart Journal (1990) 11,328-333
R. K E L L Y , M. M C G U I R E , J. HEALEY, H. G I B B S AND M .
O'ROURKE
Medical Professorial Unit, University of New South Wales, St. Vincent's Hospital, Sydney, New South Wales, Australia KEY W O R D S : Thrombolysis, Selvester score, infarct size, rt-PA, alteplase. Serial 12-lead surface electrocardiograms (ECGs) were analysed in 110 patients with first evolving myocardial infarction entered in a double-blind placebo-controlled trial of intravenous rt-PA within 2-5 h (mean l-9±0-5 (SD)) of pain onset. ECG analysis was performed by two 'blinded' analysts. QRS scoring (by the modified Selvester method) was used as an index of myocardial necrosis. Patient results were analysed according to infarct location. There was no difference between the two treatment groups in ST-segment elevation or QRS score at entry or up to 24 h after symptom onset. However from 24 h, QRS score was lower in patients with anterior infarction given rt-PA than in those given placebo: 5-4 ± 2-8 vs 7-7 + 4-1 (P = 0-02) at 48 h; 4-7 ±3-2 vs 80±40 (P = 001) at 4-10 days; and 4-6±3-9 vs 7-5±3-9 (? = 0-01) at 21 days. For patients with inferior infarction, rt-PA treatment also resulted in a lower QRS score although this was not significantly different from the score of the placebo group (P = 0-07). Comparison of QRS scores with ejection fraction measured from the contrast ventriculogram taken at 21 days showed a moderate correlation (r = 0-46) in patients with anterior infarction but a poor correlation in patients with inferior infarction. These ECG results indicate that in evolving anterior myocardial infarction, there is limitation of infarct size from early rt-PA infusion. Introduction Recombinant tissue plasminogen activator (rt-PA) causes lysis of coronary thrombosis and has the potential for limiting the size of evolving myocardial infarction" 21 . Such limitation has not been apparent in patients entered relatively late after symptom onset121, has been equivocal in patients entered earlier131, but has been seen in groups of patients entered very early after symptom onset"-51. In all these studies, infarct size limitation was gauged on the basis of improved global left ventricular ejection fraction in contrast ventriculograms; in some cases early ventriculography may have confused reversibly damaged ('stunned') with infarcted myocardium =NS) and 15-9±43% vs 30-4±55% (P = score in each of these studies was found to correlate NS) at 21 days. This non-significant trend to more well with the percent of ventricle infarcted. ECG rapid resolution in ST-segment elevation in patients scores after the initial acute period of'stabilization' treated with rt-PA was not seen in patients with also show a good correlation with ventricular
Downloaded from https://academic.oup.com/eurheartj/article-abstract/11/4/328/537570 by university of winnipeg user on 23 January 2019
y« 61-8272 - l-3468x R'0-46
332 R. Kelly eta\.
consistent with the higher ejection fraction measured by contrast ventriculography'51. The only moderate correlation between angiographic data and QRS score for anterior infarcts and poorer correlation for inferior infarcts may be explained on the basis that the two different techniques are measuring different aspects of ventricular function. The lower ECG score with thrombolytic therapy suggests that at day 21 there is a 31 % overall reduction in infarcted myocardium (Fig. 3) in patients given rt-PA compared with the placebo group. This ECG evidence is supportive of the 41 % reduction in infarct size suggested by the lesser fall in ejection fraction (by contrast ventriculography) in patients given rt-PA, on average 1 -9 h after onset of symptoms'51. These estimates of reduction in infarct size Figure 3 Mean QRS score displayed as a deterioration from are consistent with previous results'171 which indithe normal value of 0, for all patients (left), patients with cate that, in humans, restoration of coronary flow anterior infarction (centre), and patients with inferior infarcafter 2 h occlusion results in limitation of infarct tion (right). No patient had a previous infarction so the QRS score is shown as a change from 0. A = active therapy; P = size by approximately 50%. Allowing for time from rt-PA administration to clot lysis and for a 70 to placebo. 80% recanalization rate, a reduction in infarct size of the order of 31-41% is just as expected. The abfunction in patients not undergoing thrombolytic solute amount of myocardium salvaged by early therapy113'4'. The Selvester scoring system has also rt-PA infusion is of course a smaller proportion of been reported to correlate well with anatomic total myocardium, possibly 5-7%. Salvage ofjeopardized myocardium by thromboinfarct size in inferior infarcts'151 although this has been challenged by a later study1'6' in which QRS lysis as indicated by improvement in R wave ampliscores corresponded poorly with enzymatic and tude and regression of Q waves was shown initially pathologic infarct size. This later study however in- in 15 patients following intracoronary strepto181 cluded a smaller number of patients drawn from kinase using a retrospective control group' . two different study groups in which not all subjects Previous studies of intravenous thrombolysis in had anatomic estimation of infarct size at autopsy. which ECG parameters were measured, did not In addition, ECG scoring was performed manually always use a placebo control group or continue 20 in one subgroup and by computer algorithm in the follow-up beyond 8 to 10 days'"- '. In one placeboother. Nevertheless, the sensitivity of standard controlled study of intravenous streptokinase ECG leads in detecting inferior infarction is administered within 6 h, preservation of R wave obviously a limiting factor in any ECG scoring sys- amplitudes and limitation of Q wave development 2 tem and may explain the fact that in this study the were not significant until 7 months' ''. In the present difference between treatment groups for inferior study, the early detection of limited infarct size by QRS scoring may be explained by both earlier interinfarcts did not reach statistical significance. In this study of patients having their first infarc- vention with thrombolysis and use of the better tion the modified ECG score was used as an inde- validated Selvester scoring technique. This study pendent indicator of myocardial salvage. The group appears to be the first showing a consistent receiving rt-PA intravenously was compared with a improvement in the Selvester ECG score following well-matched placebo-controlled group. The two thrombolytic therapy in a double-blind placebogroups remained homogeneous throughout the controlled trial. It shows that a simple, quick study because of a low incidence of progression to bedside evaluation of the ECG pattern can be used angioplasty, (three rt-PA, three placebo) or coron- as a clinical guide to salvage of myocardium by ary artery bypass surgery (four rt-PA, one placebo). thrombolytic therapy. Furthermore, the ECG scoring was performed by We acknowledge with thanks the contributions made observers blinded to patient treatment groups. The by Nursing and ECG staff of our Emergency Rooms and lower ECG score in patients receiving rt-PA is Coronary Care Wards. All coses
ZP
R. K E L L Y , M. M C G U I R E , J. HEALEY, H. G I B B S AND M .
O'ROURKE
Medical Professorial Unit, University of New South Wales, St. Vincent's Hospital, Sydney, New South Wales, Australia KEY W O R D S : Thrombolysis, Selvester score, infarct size, rt-PA, alteplase. Serial 12-lead surface electrocardiograms (ECGs) were analysed in 110 patients with first evolving myocardial infarction entered in a double-blind placebo-controlled trial of intravenous rt-PA within 2-5 h (mean l-9±0-5 (SD)) of pain onset. ECG analysis was performed by two 'blinded' analysts. QRS scoring (by the modified Selvester method) was used as an index of myocardial necrosis. Patient results were analysed according to infarct location. There was no difference between the two treatment groups in ST-segment elevation or QRS score at entry or up to 24 h after symptom onset. However from 24 h, QRS score was lower in patients with anterior infarction given rt-PA than in those given placebo: 5-4 ± 2-8 vs 7-7 + 4-1 (P = 0-02) at 48 h; 4-7 ±3-2 vs 80±40 (P = 001) at 4-10 days; and 4-6±3-9 vs 7-5±3-9 (? = 0-01) at 21 days. For patients with inferior infarction, rt-PA treatment also resulted in a lower QRS score although this was not significantly different from the score of the placebo group (P = 0-07). Comparison of QRS scores with ejection fraction measured from the contrast ventriculogram taken at 21 days showed a moderate correlation (r = 0-46) in patients with anterior infarction but a poor correlation in patients with inferior infarction. These ECG results indicate that in evolving anterior myocardial infarction, there is limitation of infarct size from early rt-PA infusion. Introduction Recombinant tissue plasminogen activator (rt-PA) causes lysis of coronary thrombosis and has the potential for limiting the size of evolving myocardial infarction" 21 . Such limitation has not been apparent in patients entered relatively late after symptom onset121, has been equivocal in patients entered earlier131, but has been seen in groups of patients entered very early after symptom onset"-51. In all these studies, infarct size limitation was gauged on the basis of improved global left ventricular ejection fraction in contrast ventriculograms; in some cases early ventriculography may have confused reversibly damaged ('stunned') with infarcted myocardium =NS) and 15-9±43% vs 30-4±55% (P = score in each of these studies was found to correlate NS) at 21 days. This non-significant trend to more well with the percent of ventricle infarcted. ECG rapid resolution in ST-segment elevation in patients scores after the initial acute period of'stabilization' treated with rt-PA was not seen in patients with also show a good correlation with ventricular
Downloaded from https://academic.oup.com/eurheartj/article-abstract/11/4/328/537570 by university of winnipeg user on 23 January 2019
y« 61-8272 - l-3468x R'0-46
332 R. Kelly eta\.
consistent with the higher ejection fraction measured by contrast ventriculography'51. The only moderate correlation between angiographic data and QRS score for anterior infarcts and poorer correlation for inferior infarcts may be explained on the basis that the two different techniques are measuring different aspects of ventricular function. The lower ECG score with thrombolytic therapy suggests that at day 21 there is a 31 % overall reduction in infarcted myocardium (Fig. 3) in patients given rt-PA compared with the placebo group. This ECG evidence is supportive of the 41 % reduction in infarct size suggested by the lesser fall in ejection fraction (by contrast ventriculography) in patients given rt-PA, on average 1 -9 h after onset of symptoms'51. These estimates of reduction in infarct size Figure 3 Mean QRS score displayed as a deterioration from are consistent with previous results'171 which indithe normal value of 0, for all patients (left), patients with cate that, in humans, restoration of coronary flow anterior infarction (centre), and patients with inferior infarcafter 2 h occlusion results in limitation of infarct tion (right). No patient had a previous infarction so the QRS score is shown as a change from 0. A = active therapy; P = size by approximately 50%. Allowing for time from rt-PA administration to clot lysis and for a 70 to placebo. 80% recanalization rate, a reduction in infarct size of the order of 31-41% is just as expected. The abfunction in patients not undergoing thrombolytic solute amount of myocardium salvaged by early therapy113'4'. The Selvester scoring system has also rt-PA infusion is of course a smaller proportion of been reported to correlate well with anatomic total myocardium, possibly 5-7%. Salvage ofjeopardized myocardium by thromboinfarct size in inferior infarcts'151 although this has been challenged by a later study1'6' in which QRS lysis as indicated by improvement in R wave ampliscores corresponded poorly with enzymatic and tude and regression of Q waves was shown initially pathologic infarct size. This later study however in- in 15 patients following intracoronary strepto181 cluded a smaller number of patients drawn from kinase using a retrospective control group' . two different study groups in which not all subjects Previous studies of intravenous thrombolysis in had anatomic estimation of infarct size at autopsy. which ECG parameters were measured, did not In addition, ECG scoring was performed manually always use a placebo control group or continue 20 in one subgroup and by computer algorithm in the follow-up beyond 8 to 10 days'"- '. In one placeboother. Nevertheless, the sensitivity of standard controlled study of intravenous streptokinase ECG leads in detecting inferior infarction is administered within 6 h, preservation of R wave obviously a limiting factor in any ECG scoring sys- amplitudes and limitation of Q wave development 2 tem and may explain the fact that in this study the were not significant until 7 months' ''. In the present difference between treatment groups for inferior study, the early detection of limited infarct size by QRS scoring may be explained by both earlier interinfarcts did not reach statistical significance. In this study of patients having their first infarc- vention with thrombolysis and use of the better tion the modified ECG score was used as an inde- validated Selvester scoring technique. This study pendent indicator of myocardial salvage. The group appears to be the first showing a consistent receiving rt-PA intravenously was compared with a improvement in the Selvester ECG score following well-matched placebo-controlled group. The two thrombolytic therapy in a double-blind placebogroups remained homogeneous throughout the controlled trial. It shows that a simple, quick study because of a low incidence of progression to bedside evaluation of the ECG pattern can be used angioplasty, (three rt-PA, three placebo) or coron- as a clinical guide to salvage of myocardium by ary artery bypass surgery (four rt-PA, one placebo). thrombolytic therapy. Furthermore, the ECG scoring was performed by We acknowledge with thanks the contributions made observers blinded to patient treatment groups. The by Nursing and ECG staff of our Emergency Rooms and lower ECG score in patients receiving rt-PA is Coronary Care Wards. All coses
ZP
