Early ST-segment recovery, infarct artery blood flow, and long-term outcome after acute myocardial infarction

BACKGROUND

Early resolution of ST-segment deviation (ST recovery) on the postthrombolytic electrocardiograms and restoration of "normal" blood flow in the infarct-related artery are associated with improved outcomes after myocardial infarction (MI).

METHODS AND RESULTS

To evaluate the relationships between ST recovery, infarct-related artery flow, and late survival we studied 766 patients with electrocardiograms recorded at a median of 167 minutes after thrombolytic therapy. Angiography was performed at 3 weeks, and follow-up was done at a median of 6.3 years (interquartile range [IQR] 5.0-8.4). At 10 years, the survival rates were 55% (95% CI 43-70) in patients with <30% ST recovery in the single lead with maximum ST elevation, 71% (95% CI 64-79) in those with 30% to 70% ST recovery, and 74% (95% CI 68-82) in those with >70% ST recovery (P =.0005), whereas ST recovery measured as the sum of voltage changes of either ST deviation (elevation or depression) or ST elevation was not associated with 10-year survival (log-rank test, P =.06 and P =.34, respectively). In patients with Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow, ST recovery of >70% (vs <30% and 30% to 70%) in the lead with maximum ST elevation was associated with increased late survival (P =.04). On multivariate analysis, the predictors, at admission, of 5-year survival were age (P <.001), ST recovery (measured as a continuous variable, P =.001), diabetes (P =.003) and female gender (P =.02). When the ejection fraction (P =.003) and TIMI flow grade (P =.02) at 3 weeks were included in the analysis, the P value for ST recovery was.08.

CONCLUSIONS

ST recovery measured in the single lead with maximum ST elevation was a predictor of late survival, even in patients with TIMI grade 3 flow but ST recovery measured as the sum of voltage changes in all leads with ST deviation was not. This simple electrocardiographic parameter can identify patients with a reduced chance of survival who might benefit from additional therapies.

Corrected TIMI frame counts correlate with stenosis severity and infarct zone wall motion after thrombolytic therapy

BACKGROUND

The majority of patients with patent infarct-related arteries after thrombolytic therapy have slower than normal flow, which relates to myocardial perfusion.

METHODS

To evaluate the relationships between blood levels of creatine kinase (CK) and the corrected Thrombolysis in Myocardial Infarction (TIMI) frame count (CTFC), infarct artery stenosis, and left ventricular function, we studied 397 patients with a first myocardial infarction who underwent angiography at 3 weeks. TIMI flow grades, the CTFC, infarct artery stenosis, and infarct zone wall motion (by contrast ventriculography using the centerline method) were assessed, and CK levels (in units per liter) were measured hourly for the first 4 hours after streptokinase (1.5 x 10(6) U over 30-60 minutes) and then every 4 hours over the next 20 hours, all blinded to treatment and outcome.

RESULTS

Infarct artery stenosis and the CTFC, assessed as continuous variables, correlated in patients with patent infarct arteries (r = 0.33, P <.001). Also, there was a significant correlation between the CTFC and the sum of hypokinetic chords in the infarct zone (r = 0.15, P =.01). Patients with total occlusion or markedly slowed infarct artery flow (CTFC >100) had a higher fraction of chords with wall motion >2 SDs below normal (0.65 [0.41, 0.80] vs 0.37 [0.0, 0.67]) compared with patients with normal flow (CTFC < or =27) (P <.001). The rates of increase of median CK levels with respect to TIMI flow grades were 342 U/L/h for TIMI 3 versus 212 U/L/h for TIMI 2 versus 140 U/L/h for TIMI 0-1 (P <.0001).

CONCLUSIONS

Prolonged corrected TIMI frame counts correlate with stenosis severity in the infarct artery after infarction, infarct zone regional wall motion, and CK levels.

Angiographic findings and clinical correlates in patients with cardiogenic shock complicating acute myocardial infarction: a report from the SHOCK Trial Registry. SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK?

OBJECTIVES

We sought to delineate the angiographic findings, clinical correlates and in-hospital outcomes in patients with cardiogenic shock (CS) complicating acute myocardial infarction.

BACKGROUND

Patients with CS complicating acute myocardial infarction carry a grave prognosis. Detailed angiographic findings in a large, prospectively identified cohort of patients with CS are currently lacking.

METHODS

We compared the clinical characteristics, angiographic findings, and in-hospital outcomes of 717 patients selected to undergo angiography and 442 not selected, overall and by shock etiology: left or right ventricular failure versus mechanical complications.

RESULTS

Patients who underwent angiography had lower baseline risk and a better hemodynamic profile than those who did not. Overall, 15.5% of the patients had significant left main lesions on angiography, and 53.4% had three-vessel disease, with higher rates of both for those with ventricular failure, compared with patients who had mechanical complications. Among patients who underwent angiography, those with ventricular failure had significantly lower in-hospital mortality than patients with mechanical complications (45.2% vs. 57.0%; p = 0.021). Importantly, for patients with ventricular failure, in-hospital mortality also correlated with disease severity: 35.0% for no or single-vessel disease versus 50.8% for three-vessel disease. Furthermore, mortality was associated with the culprit lesion location (78.6% in left main lesion, 69.7% in saphenous vein graft lesions, 42.4% in circumflex lesions, 42.3% in left anterior descending lesions, and 37.4% in right coronary artery lesions), and Thrombolysis In Myocardial Infarction (TIMI) flow grade (46.5% in TIMI 0/1, 49.4% in TIMI 2 and 26% in TIMI 3).

CONCLUSIONS

Patients who underwent angiographic study in the SHOCK Trial Registry had a more benign cardiac risk profile, more favorable hemodynamic findings and lower in-hospital mortality than those for whom angiograms were not obtained. Patients with CS caused by ventricular failure had more severe atherosclerosis, and a different distribution of culprit vessel involvement but lower in-hospital mortality, than those with mechanical complications. Overall in-hospital survival correlates with the extent of coronary artery obstructions, location of culprit lesion and baseline coronary TIMI flow grade.

Impact of thrombolysis, intra-aortic balloon pump counterpulsation, and their combination in cardiogenic shock complicating acute myocardial infarction: a report from the SHOCK Trial Registry. SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK?

OBJECTIVES

We sought to investigate the potential benefit of thrombolytic therapy (TT) and intra-aortic balloon pump counterpulsation (IABP) on in-hospital mortality rates of patients enrolled in a prospective, multi-center Registry of acute myocardial infarction (MI) complicated by cardiogenic shock (CS).

BACKGROUND

Retrospective studies suggest that patients suffering from CS due to MI have lower in-hospital mortality rates when IABP support is added to TT. This hypothesis has not heretofore been examined prospectively in a study devoted to CS.

METHODS

Of 1,190 patients enrolled at 36 participating centers, 884 patients had CS due to predominant left ventricular (LV) failure. Excluding 26 patients with IABP placed prior to shock onset and 2 patients with incomplete data, 856 patients were evaluated regarding TT and IABP utilization. Treatments, selected by local physicians, fell into four categories: no TT, no IABP (33%; n = 285); IABP only (33%; n = 279); TT only (15%; n = 132); and TT and IABP (19%; n = 160).

RESULTS

Patients in CS treated with TT had a lower in-hospital mortality than those who did not receive TT (54% vs. 64%, p = 0.005), and those selected for IABP had a lower in-hospital mortality than those who did not receive IABP (50% vs. 72%, p < 0.0001). Furthermore, there was a significant difference in in-hospital mortality among the four treatment groups: TT + IABP (47%), IABP only (52%), TT only (63%), no TT, no IABP (77%) (p < 0.0001). Patients receiving early IABP (< or = 6 h after thrombolytic therapy, n = 72) had in-hospital mortality similar to those with late IABP (53% vs. 41%, n = 64, respectively, p = 0.172). Revascularization rates differed among the four groups: no TT, no IABP (18%); IABP only (70%); TT only (20%); TT and IABP (68%, p < 0.0001); this influenced in-hospital mortality significantly (39% with revascularization vs. 78% without revascularization, p < 0.0001).

CONCLUSIONS

Treatment of patients in cardiogenic shock due to predominant LV failure with TT, IABP and revascularization by PTCA/CABG was associated with lower in-hospital mortality rates than standard medical therapy in this Registry. For hospitals without revascularization capability, a strategy of early TT and IABP followed by immediate transfer for PTCA or CABG may be appropriate. However, selection bias is evident and further investigation is required.

Cardiogenic shock with non-ST-segment elevation myocardial infarction: a report from the SHOCK Trial Registry. SHould we emergently revascularize Occluded coronaries for Cardiogenic shocK?

OBJECTIVES

We sought to determine the outcomes of patients with cardiogenic shock (CS) complicating non-ST-segment elevation acute myocardial infarction (MI).

BACKGROUND

Such patients represent a high-risk (ST-segment depression) or low-risk (normal or nonspecific electrocardiographic findings) group for whom optimal therapy, particularly in the setting of shock, is unknown.

METHODS

We assessed characteristics and outcomes of 881 patients with CS due to predominant left ventricular (LV) dysfunction in the SHOCK Trial Registry.

RESULTS

Patients with non-ST-segment elevation MI (n = 152) were significantly older and had significantly more prior MI, heart failure, azotemia, bypass surgery, and peripheral vascular disease than patients with ST-elevation MI (n = 729). On average, the groups had similar in-hospital LV ejection fractions (approximately 30%), but patients with non-ST-elevation MI had a lower highest creatine kinase and were more likely to have triple-vessel disease. Among patients selected for coronary angiography, the left circumflex artery was the culprit vessel in 34.6% of non-ST-elevation versus 13.4% of ST-elevation MI patients (p = 0.001). Despite having more recurrent ischemia (25.7% vs. 17.4%, p = 0.058), non-ST-elevation patients underwent angiography less often (52.6% vs. 64.1%, p = 0.010). The proportion undergoing revascularization was similar (36.8% for non-ST-elevation vs. 41.9% ST-elevation MI, p = 0.277). In-hospital mortality also was similar in the two groups (62.5% for non-ST-elevation vs. 60.4% ST-elevation MI). After adjustment, ST-segment elevation MI did not independently predict in-hospital mortality (odds ratio, 1.30; 95% confidence interval, 0.83 to 2.02; p = 0.252).

CONCLUSIONS

Patients with CS and non-ST-segment elevation MI have a higher-risk profile than shock patients with ST-segment elevation, but similar in-hospital mortality. More recurrent ischemia and less angiography represent opportunities for earlier intervention, and early reperfusion therapy for circumflex artery occlusion should be considered when non-ST-elevation MI causes CS.

Prevalence of factor V Leiden and prothrombin variant G20210A in patients age <50 years with no significant stenoses at angiography three to four weeks after myocardial infarction

OBJECTIVES

We sought to determine the frequencies of factor V Leiden and prothrombin variant G20210A in patients age <50 years with no significant coronary stenoses three to four weeks after myocardial infarction (MI).

BACKGROUND

Factor V Leiden and prothrombin variant G20210A occur frequently in patients with venous thromboembolism. However, the contribution of these mutations to the development of MI requires clarification.

METHODS

The frequencies of factor V Leiden and prothrombin variant G20210A were determined in 41 patients age <50 years who had "normal" or "near normal" coronary arteries (no stenosis >50%) at angiography three to four weeks after MI (the study group) and compared with those in 114 patients who had at least one angiographic stenosis >50% after MI (the control group). Patients age > or =50 years with, or without, stenoses were also studied.

RESULTS

The frequency of factor V Leiden was 14.6% in patients age <50 years in the study group compared with 3.6% in patients in the control group (odds ratio [OR] 4.7 [95% confidence interval (CI) 1.3-17.7], p = 0.02). The frequency of the prothrombin variant G20210A was 7.3% in the study group compared with 1.8% in the control group (OR 4.4 [95% CI 0.7-27.5], p = 0.12). One or both mutations were present in 8 of the 41 patients (19.5%) age <50 years in the study group compared with 6 of the 114 patients (5.5%) in the control group (OR 4.4 [95% CI 1.4-13.5], p = 0.01). In all 271 patients (irrespective of age) with normal arteries, the frequency of factor V Leiden was 11.7% (7/60) compared with 4.3% (9/211) in patients with at least one >50% stenosis (OR 2.9 [95% CI 1.1-8.3], p = 0.04), and the frequency of prothrombin variant G20210A was 6.7% (4/60) compared with 1.4% (3/211) (OR 4.9 [95% CI 1.1-22.8], p = 0.04), respectively.

CONCLUSIONS

The frequencies of factor V Leiden and/or prothrombin variant G20210A are increased in patients age <50 years with normal or near normal coronary arteries after MI.

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.

Occluded infarct-related arteries and clinical events

Late patency of the infarct-related artery has been shown to be associated with improved long-term survival rates in observational cohort studies. However, there is a dearth of randomized trials correlating the opening of persistently occluded infarct-related arteries with clinical outcomes. Recent technological advances have improved the success and safety of percutaneous revascularization, resulting in lower restenosis and reocclusion rates. A large randomized trial is needed to evaluate clinical outcomes with percutaneous revascularization versus medical management of occluded infarct-related arteries in the absence of inducible ischemia.

Relationship between corrected TIMI frame counts at three weeks and late survival after myocardial infarction

OBJECTIVES

To evaluate the corrected Thrombolysis in Myocardial Infarction (TIMI) frame count (CTFC) as a predictor of late survival after myocardial infarction.

BACKGROUND

Thrombolysis in Myocardial Infarction flow grades predict late survival after myocardial infarction. The CTFC provides a more reproducible measurement of infarct-related artery blood flow than the TIMI flow grade, and has been linked to 30-day outcomes, but it has not yet been established how the CTFC correlates with late survival.

METHODS

Of 1,001 patients with acute myocardial infarction presenting within 4 h of symptom onset, 882 underwent angiography at approximately three weeks. Infarct artery flow was assessed, blinded to clinical outcomes, according to the CTFC and TIMI flow grade. Late cardiac mortality and survival were determined in 97.5% of patients.

RESULTS

The mean CTFC was 40 +/- 29 in 644 patent infarct arteries (median, 34 [interquartile range, 24 to 47]). The CTFC, assessed as a continuous univariate variable, was found to be a predictor of five-year survival, as was the TIMI flow grade (both p < 0.001). On multivariate analysis, factors associated with five-year survival included the ejection fraction or end-systolic volume index (both p < 0.001); exercise duration (p = 0.005), age (p = 0.008), diabetes (p = 0.02) and CTFC (p = 0.02) or TIMI flow (p = 0.02). The same factors, except for the CTFC and TIMI flow grade, were predictors of 10-year survival.

CONCLUSIONS

The CTFC three weeks after myocardial infarction was an independent predictor of five-year survival, but not 10-year survival. Although the CTFC provided additional prognostic information within TIMI flow grades, its superiority was not demonstrated.

New Q waves on the presenting electrocardiogram independently predict increased cardiac mortality following a first ST-elevation myocardial infarction

AIMS

The prognostic significance of pathological Q waves appearing in the acute phase of myocardial infarction has not been determined. We investigated whether new Q waves on the presenting electrocardiogram of patients with acute ST-segment elevation were independently associated with a worse outcome after a first myocardial infarction.

METHODS AND RESULTS

The presence or absence of new Q waves on the presenting electrocardiogram was assessed in 481 patients who presented within 4 h of symptom onset and were randomized to receive either captopril or placebo within 2 h of streptokinase therapy for myocardial infarction. Ventriculography was performed at 22+/-6 days and mortality status was obtained at a median follow-up of 5.6 years. New Q waves were associated with a lower ejection fraction (51+/-13% vs 61+/-12%, P<0.0001), a larger end-systolic volume index (37 ml vs 28 ml, P<0.001), and increased cardiac mortality at 30 days (7% vs 2%, P=0.01) and at follow-up (17% vs 7%, P=0.002). On multivariate analysis, age (P<0.01), new Q waves at presentation (P<0.01) and a history of angina (P=0.046) were independent predictors of cardiac mortality, whereas randomization to captopril and the time from symptom onset to streptokinase administration were not.

CONCLUSION

New Q waves at presentation are independently associated with a worse outcome after a first myocardial infarction. The presence of new Q waves on the presenting electrocardiogram allows very early identification of patients at risk of increased cardiac mortality.

Serum troponins T and I after elective cardioversion

AIMS

To describe the pattern of release of five myocardial proteins after elective cardioversion.

METHODS AND RESULTS

We measured serum levels of the myocardial proteins creatine kinase, creatine kinase MB mass, myoglobin, troponin T and troponin I serially from baseline to 24 h after 72 elective cardioversion attempts. The total energy used for attempted cardioversion was 408+/-318 J (range 50 to 1280 J). Maximal creatine kinase levels (median 232 IU x l(-1), interquartile range 91 to 1152 IU x l(-1)) occurred at 24 h and correlated with the total energy delivered (r=0.75, P<0.0001). The peak creatine kinase MB mass levels exceeded the discrimination level for myocardial injury (>/=5 microg x l(-1)) in seven patients (10%). The peak myoglobin levels were elevated (>85 microg x l(-1)) in 40 patients (56%) and correlated with the peak creatine kinase levels (r=0.83, P<0.0001). Troponin T reached the discrimination level (0.10 microg x l(-1)) in one patient with a serum creatinine level of 0.16 mmol x l(-1)and severe left ventricular impairment. Twelve patients had baseline troponin I levels above our prespecified discrimination level of 0.4 microg x l(-1)(range 0.4 to 3.1 microg x l(-1)), which did not increase after cardioversion. In two patients the levels rose from <0.4 microg x l(-1) to 0.5 microg x l(-1) and 0.6 microg x l(-1) respectively.

CONCLUSIONS

Troponin T levels do not rise after elective cardioversion. The minor increases in troponin I may reflect our choice of discrimination level. Cardiac troponins are useful in determining whether arrhythmias requiring emergency cardioversion are primary or secondary to myocardial infarction.

Direct thrombin inhibitors as adjuncts to thrombolytic therapy

Thrombolytic therapy aims to achieve rapid and sustained infarct-related artery patency, although this results in a procoagulant state. Heparin has limitations as an antithrombin agent, which has led to clinical investigation of alternative agents. Direct thrombin inhibitors, as adjuncts to thrombolytic therapy, have been shown to increase 90 minute Thrombolysis in Myocardial Infarction (TIMI)-3 flow rates and reduce reinfarction, when compared with heparin. These results have been achieved with an acceptable risk of bleeding, when administered in appropriate dosing regimens. When the direct thrombin inhibitor hirudin was administered at a mean of 34 and 50 minutes after thrombolytic therapy in large clinical trials, there was no reduction in mortality. In contrast, in several angiographic studies, direct thrombin inhibitors were administered prior to thrombolysis. The effect on mortality of the administration of hirulog prior to streptokinase is currently being examined.

Four-year survival of patients with acute coronary syndromes without ST-segment elevation and prognostic significance of 0.5-mm ST-segment depression

We prospectively evaluated all patients admitted to our coronary care unit during 1993 with ischemic chest pain but without ST-segment elevation on the presenting electrocardiogram, and determined the influence of the extent of ST-segment depression, measured using calipers and blinded to the outcome, on 4-year survival. The presenting symptoms of 367 patients (mean age 64 years) were coded according to the Braunwald classification, 86% being in class IIIB (primary unstable angina with rest angina within 48 hours) and 7.4% in class IIIC (postinfarction angina). Thirty-two patients (8.6%) had myocardial infarction at presentation (defined as a creatine kinase level exceeding twice the reference range within 18 hours). During hospitalization 97% of patients received aspirin, 67% received intravenous heparin, 37% underwent angiography, and 35% underwent revascularization. The vital status of 99% of the patients was determined after a median of 52 months (interquartile range 48 to 55). At follow-up, 88% of patients were taking aspirin, 45% were taking beta blockers, and 50% had undergone revascularization. The survival rate was 70% in patients with > or = 0.5-mm ST-segment depression (53%, 77%, and 82% survival for > or = 2-, 1-, and 0.5-mm ST-segment depression, respectively; p <0.0001). Patients with a normal electrocardiogram had a greater survival rate (94%) than that of patients with 0.5-mm ST-segment depression (82%, p = 0.020), but not significantly different from that of patients with T-wave inversion (84%, p = NS). Independent predictors of mortality (odds ratio [95% confidence interval]) were: age in yearly increments (1.05 [1.03 to 1.06], p = 0.003), revascularization during follow-up (0.40 [0.29 to 0.56], p = 0.006), pulmonary edema (3.45 [2.19 to 5.45], p = 0.007), and ST-segment depression (1.37 [1.20 to 1.55], p = 0.015). Thus, ST-segment depression of > or = 0.5 mm predicts 4-year survival in patients with acute ischemic syndromes.

Survival 12 years after randomization to streptokinase: the influence of thrombolysis in myocardial infarction flow at three to four weeks

OBJECTIVES

The purpose of this study was to determine whether the mortality benefit of intravenous streptokinase administered within 4 h of the onset of acute myocardial infarction is maintained at 12 years, and whether Thrombolysis in Myocardial Infarction (TIMI) flow grades independently influence late survival.

BACKGROUND

Treatment with reperfusion therapies and achievement of TIMI 3 flow are associated with increased short- and medium-term survival after infarction. Whether infarct artery flow independently influences survival more than five years after infarction is unknown.

METHODS

The late survival of patients randomized to receive either streptokinase (1,500,000 IU over 30 to 60 min) or a matching placebo within 4 h of symptom onset in 1984-1986 was determined. Angiography was performed in surviving patients at three to four weeks, and TIMI flow grades were assessed blind to randomization and outcomes. The late vital status was determined in 99% of patients.

RESULTS

Patients randomized to receive streptokinase (n = 107) had improved survival compared with those randomized to placebo (n = 112) at five years (84% vs. 70%; p = 0.023) and 12 years (66% vs. 51%; p = 0.022). At five years 94% of patients with TIMI grade 3 flow, 81% of those with TIMI grade 2 flow and 72% of those with TIMI grade 0-1 flow survived (p = 0.005). At 12 years 72% of patients with TIMI 3, 67% of those with TIMI 2 and 54% of those with TIMI 0-1 flow survived (p = 0.023). Multivariate analysis identified the ejection fraction (p = 0.014), exercise duration (p = 0.013) and TIMI 3 flow (p = 0.04 compared with TIMI 0-2 flow) as important factors for five-year survival. At 12 years multivariate predictors of late survival were the ejection fraction (p = 0.006), exercise duration (p = 0.003) and myocardial score (p = 0.013). The end-systolic volume index was similar to the ejection fraction as a predictor of survival at five and 12 years.

CONCLUSIONS

The survival benefits of streptokinase persist for 12 years after infarction. TIMI flow at three to four weeks is an independent predictor of five-year survival.

Waiting times and prioritization for coronary artery bypass surgery in New Zealand

OBJECTIVES

To review the New Zealand coronary artery bypass priority score instituted in May 1996, and specifically to determine whether it prioritizes patients at high risk of cardiac events while waiting. The New Zealand score is compared with the Ontario urgency rating score, and waiting times for surgery are compared with the maximum times recommended by the Ontario consensus panel.

DESIGN

Retrospective review of patients accepted for isolated coronary artery bypass surgery between 1 January 1993 and 31 January 1996.

SETTING

Green Lane Hospital, Auckland, New Zealand.

MAIN OUTCOME MEASURES

Waiting time, cardiac death, myocardial infarction, and cardiac readmission.

RESULTS

The median waiting times were five days for hospital cases (n = 721) and 146 days for out of hospital cases (n = 701). Of the latter group, 28% waited more than a year, 33% had their surgery expedited because of worsening symptoms, and 19% failed to meet the cut off point set by the New Zealand score for acceptance onto the list. Twenty two patients died, 18 on the outpatient waiting list (waiting list mortality 2.6%, risk 0.28% per month of waiting), and 132 were readmitted, 12% with myocardial infarction and 76% with unstable angina. Risk factors for a composite end point of death or myocardial infarction and/or cardiac readmission were: previous coronary artery bypass surgery (p = 0. 001), class III or IV angina (p = 0.002), and hypertension (p = 0. 005). The New Zealand score did not identify those at risk. Excluding hospital cases, 32% had surgery within the time recommended by the Ontario consensus panel.

CONCLUSIONS

Waiting times for coronary artery bypass surgery in New Zealand are considerably longer than those in Ontario, Canada. By using a numerical cut off point, implementation of the New Zealand priority scoring system has restricted access to coronary surgery on the basis of funding constraints rather than clinical appropriateness. The score does not add greatly to the clinicians' prioritization in predicting those patients who will suffer events while waiting.

Angiographic frame counts 90 minutes after streptokinase predict left ventricular function at 48 hours following myocardial infarction

OBJECTIVE

To assess whether the 90 minute corrected thrombolysis in myocardial infarction frame count (CTFC) in the infarct related artery predicts left ventricular function at 48 hours in patients with myocardial infarction treated with aspirin, streptokinase, and either heparin or Hirulog.

DESIGN AND SETTING

Analysis of 251 patients with acute myocardial infarction enrolled in the international, multicentre Hirulog early reperfusion/occlusion (HERO-1) trial, who underwent both 90 minute coronary angiography and 48 hour left ventriculography.

MAIN OUTCOME VARIABLES

The CTFC was determined in the infarct related artery 90 minutes after starting intravenous streptokinase (1.5 x 106 U over 30 to 60 minutes), and compared with indices of left ventricular function assessed by contrast ventriculography at 48 hours.

RESULTS

A CTFC of </= 27 frames (previously reported mean + 2 SD in coronary arteries of patients without acute infarction) occurred in 29% of infarct related arteries, and was associated with a lower infarct zone mean chord score (-2.06 v -2.54, p = 0.01), a lower fraction of chords > 2 SD below normal (37% v 51%, p = 0.005), and trends towards higher left ventricular ejection fractions (60.9% v 58.2%, p = 0.11) and lower end systolic volumes (50.1 ml v 55.9 ml, p = 0.23). A CTFC of </= 40 at 90 minutes occurred in 50% of infarct related arteries, and was associated with a significantly lower mean chord score (-2.20 v -2.60, p = 0.02), a smaller fraction of chords > 2 SD below normal (41% v 52%, p = 0.025), a smaller end systolic volume (49.1 ml v 59.3 ml, p = 0.02), and a higher left ventricular ejection fraction (60.4% v 56.5%, p = 0.03).

CONCLUSIONS

The 90 minute CTFC predicts left ventricular function at 48 hours following streptokinase. The CTFC associated with better ventricular function may be higher than values determined from a non-infarct population.

Usefulness of the presenting electrocardiogram in predicting successful reperfusion with streptokinase in acute myocardial infarction

The presenting electrocardiogram may contain information indicating the probability of successful reperfusion. The relation between 3 parameters in the presenting electrocardiogram (pathologic Q waves, T-wave inversion, and the slope of ST elevation) and Thrombolysis in Myocardial Infarction trial (TIMI) grade 3 flow in the infarct-related artery was assessed angiographically 90 minutes after beginning streptokinase in 362 patients. TIMI grade 3 flow was more common in patients without Q waves (55%) than in those with Q waves (35%; p <0.001), and more common in patients without T-wave inversion (50%) than in those with T-wave inversion (30%; p <0.002). There was no relation between the slope of the ST segment or the magnitude of its deviation and the achievement of TIMI grade 3 flow. Only 20% of the 59 patients with both Q waves and T-wave inversion had TIMI grade 3 flow, compared with 50% of the remaining patients (p <0.0001). Among patients treated within 3 hours, TIMI grade 3 flow was seen in 68% of those without versus 44% of those with Q waves (p <0.01), and in 62% of those without versus 43% of those with T-wave inversion (p = 0.06). Among patients treated after 3 hours, TIMI grade 3 flow was seen in 38% of those without versus 30% of those with Q waves (p = NS), and in 38% of those without versus 23% of those with T-wave inversion (p <0.05). On multivariate analysis, the absence of Q waves, the time from the onset of chest pain to treatment, and age were independent predictors of TIMI grade 3 flow. Pathologic Q waves in the presenting electrocardiogram provide valuable information as to the probability of achieving successful reperfusion following administration of streptokinase, and may be helpful for triage of patients to alternative reperfusion strategies, including percutaneous revascularization.

Effects of early captopril administration after thrombolysis on regional wall motion in relation to infarct artery blood flow

OBJECTIVES

To determine whether early administration of captopril lessens infarct zone regional wall motion abnormalities when infarct artery blood flow is abnormal.

BACKGROUND

The interaction between angiotensin-converting enzyme (ACE) inhibitor therapy, ventricular function and infarct artery blood flow has not been well described.

METHODS

A total of 493 patients aged < or = 75 years with first infarctions, presenting within 4 h of symptom onset, were randomized to receive 6.25 mg captopril, increasing to 50 mg t.d.s. or a matching placebo 2.1+/-0.4 h after commencing intravenous streptokinase (1.5 x 10(6) U over 30 to 60 min). Trial therapy was stopped 48 h prior to angiography at 3 weeks, to determine regional wall motion and infarct artery flow.

RESULTS

There were no differences in ejection fractions or end-systolic volumes between patients randomized to receive captopril and those randomized to receive a placebo. Among patients with anterior infarction (n = 216), randomization to captopril resulted in fewer hypokinetic chords (40+/-13; vs. 44+/-13; p=0.028) and a trend toward fewer chords >2 SD below normal (26+/-17 vs. 30+/-17; p=0.052) in the infarct zone. In patients randomized to receive captopril who had anterior infarction and Thrombolysis in Myocardial Infarction (TIMI) 0-2, flow there were fewer hypokinetic chords (44+/-12 vs. 50+/-9; p=0.043) and a trend toward fewer chords >2 SD below normal (33+/-15 vs. 39+/-13; p=0.057). Patients receiving captopril who had anterior infarction and corrected TIMI frame counts > 27 had fewer hypokinetic chords (42+/-13 vs. 46+/-12; p=0.015) and fewer chords >2 SD below normal (27+/-17 vs. 32+/-17; p= 0.047). Captopril had no effect in patients with inferior infarction. There were 20 late cardiac deaths (median follow-up 4 years) in the captopril group and 35 in the placebo group (p=0.036).

CONCLUSIONS

Randomization to receive captopril 2 h after streptokinase improved regional wall motion at 3 weeks. The greatest benefit was seen in patients with anterior infarction particularly when infarct artery blood flow is reduced.

Inadequate control of lipid levels in patients with a previous myocardial infarction

AIM

To access the current lipid management of late survivors of acute myocardial infarction.

METHODS

A systematic follow-up of all survivors who had previously been screened for enrolment into one of three randomised clinical trials in Auckland was undertaken from December 1995 to January 1997. All contacted survivors were asked to answer a questionnaire regarding their current therapy and were invited to undergo venepuncture for a lipid assay.

RESULTS

Of the 1036 patients with acute myocardial infarction screened for enrolment in the three trials there were 984 (95%) who survived 30 days. At a median of 5.5 years (interquartile range 3.2-8.5) follow-up, 641 (86%) survivors agreed to have a fasting lipid test. The mean total cholesterol level was 5.7 +/- 1.1 mmol/L high density lipoprotein cholesterol 1.1 +/- 0.3 mmol/L, low density lipoprotein cholesterol 3.8 +/- 0.9 mmol/L and triglyceride level 1.9 +/- 1.1 mmol/L. Two hundred and seven (32%) patients were treated with a lipid-modifying agent. Four hundred and forty-five (69%) patients had a cholesterol level > or = 5.2 mmol/L 381 (59%) patients had a level > or = 5.5 mmol/L and 72 (11%) patients had a level > or = 7.0 mmol/L of whom 62 patients were not being treated with a lipid-modifying agent. For the 107 patients with coronary artery bypass grafts, the mean cholesterol level was 5.4 mmol/L and the mean low density lipoprotein cholesterol level was 3.7 +/- 0.9 mmol/L, with 57 (53%) patients not being treated with a "statin" or "fibrate".

CONCLUSION

Lipid management is suboptimal in this high risk population of patients post-infarction and greater efforts need to be made to achieve better control. Diet is frequently inadequate in these patients at high risk and statin therapy is indicated.

Thrombolytic eligibility

The Fibrinolytic Therapy Trialists' Collaborative Group has demonstrated that patients without clear contraindications who present with ischaemic chest pain within 12 hours of the onset of symptoms and who have ST segment elevation or bundle branch block on their electrocardiogram (ECG), will benefit from thrombolytic therapy. Therefore the treatment of patients presenting with ischaemic chest pain is guided by the initial ECG. This paper addresses the question of thrombolytic eligibility in several subsets of patients who may benefit from treatment. It also explores the data which confirm the benefit for patients presenting with an inferior myocardial infarction and for those presenting from six-12 hours after the onset of symptoms. In conclusion, thrombolytic therapy should not be routinely withheld from diabetic or elderly patients, menstruating women and patients who have had cardiopulmonary resuscitation.

The corrected TIMI frame count. The new gold standard?

Over the last decade Thrombolysis in Myocardial Infarction (TIMI) flow grades have been the gold standard for the assessment of efficacy of infarct-artery reperfusion. However, with the introduction of core angiographic laboratories, the reproducibility of TIMI flow grades has been questioned. The corrected TIMI frame count (CTFC) has been developed as a more reproducible method of quantifying infarct artery blood flow after myocardial infarction (MI). We have utilised the CTFC in two studies to examine infarct-artery blood flow. In the Hirulog in Early Reperfusion and Occlusion (HERO 1) study, the CTFC was measured at 90-120 minutes after administration of aspirin, streptokinase and either Hirulog or heparin. Only 27% of patients had a normal CTFC (< or = 27) in the infarct-related artery. Patients with a prolonged CTFC (> 27) had more abnormal left ventricular function (LVF) as measured by the mean chord score in the 'area at risk' (-2.51 vs -2.06, p = 0.02), on left ventriculography. In a second study, infarct-artery flow was examined four weeks and one year after MI. At four weeks, only 43% of patients with patient infarct-related arteries had a 'normal' CTFC of < or = 27. A prolonged CTFC at four weeks was a univariate predictor of increased reocclusion at one year (p = 0.001). CTFCs are frequently abnormal in patent infarct-related arteries, and predict reocclusion. Whether frame counting is a better predictor of late clinical outcomes than the TIMI flow grade needs to be prospectively examined in large clinical trials.

Low molecular weight heparins in acute ischaemic syndromes

Thrombus formation and ongoing generation play a major role in the pathogenesis of unstable angina and myocardial infarction (MI). Unfractionated heparin is widely used as an adjunctive therapy in the management of acute ischaemic syndromes, but it has a number of limitations including inter-patient variability, need for monitoring, and the fact that its use may be associated with thrombocytopenia. Low molecular weight heparins have pharmacological and pharmacokinetic properties that may result in better clinical outcomes and safety. They are easy to administer and do not require monitoring. Low molecular weight heparins have been shown to reduce mortality and the incidence of MI and recurrent ischaemia compared with placebo in patients with unstable angina and non-Q-wave MI, and have a more predictable anticoagulant effect than standard unfractionated heparin. They also can be used long term in the outpatient setting, in the form of self-administered subcutaneous injections. The clinical relevance of these new developments is still being defined in ongoing clinical trials and cost-effectiveness analyses.

New antiplatelet agents

Aspirin is an established therapy for the management of acute myocardial infarction (AMI) and unstable angina. Secondary prevention with chronic aspirin therapy is also indicated for patients with stable angina. Aspirin inhibits cyclo-oxygenase-I, a key enzyme in the biosynthetic pathway leading to the production of thromboxane A2. It therefore inhibits only one of the many activation pathways leading to platelet aggregation. Other antiplatelet agents that have also been evaluated in clinical trials include ticlopidine and clopidogrel, which inhibit adenosine diphosphate-mediated platelet aggregation, but these agents are known to be effective against only one of the 90 known agonists that stimulate platelet aggregation. The final common pathway for platelet aggregation involves the glycoprotein IIb/IIIa receptor combining with fibrinogen. Several inhibitors of the glycoprotein IIb/IIIa receptor have been developed and have an important role as adjunctive therapy in angioplasty. Recent trials have been performed in patients with unstable angina, and trials of adjunctive therapy are currently underway in patients receiving thrombolysis for AMI, and for secondary prevention. These drugs have various different features, including specificity for blockade of the glycoprotein IIb/IIIa receptor, half life, duration of the haemostatic effect and potential for antigenicity. Recently concluded and ongoing trials of both intravenous and oral agents are expected to provide further support for the introduction of these agents into clinical management of patients with acute coronary syndromes.

Hirudin (desirudin) and Hirulog (bivalirudin) in acute ischaemic syndromes and the rationale for the Hirulog/Early Reperfusion Occlusion (HERO-2) Study

Unlike unfractionated heparin, direct thrombin inhibitors such as hirudin and Hirulog inhibit clot-bound as well as fluid-phase thrombin, escape neutralisation by platelet secretion products, do not require monitoring, and are unassociated with immune thrombocytopenia. They have been shown to have modest advantages over heparin when given after thrombolytic therapy, reducing reinfarction by 14%. In the Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO 2b) trial, patients treated with streptokinase and adjunctive hirudin had a reduction in death or myocardial infarction of 40% at 30 days (8.6% with hirudin versus 14.4% with heparin, p = 0.004). In the Hirulog Early Reperfusion/Occlusion (HERO 1) trial, 48% of patients who received Hirulog as adjunctive therapy with streptokinase had Thrombolysis in Myocardial Infarction (TIMI) trial grade 3 flow in the infarct-related artery, compared with 35% of patients who received heparin with streptokinase (p < 0.05). The HERO 2 study, involving 17,000 patients, will test the hypothesis that Hirulog and aspirin given before streptokinase will reduce mortality compared with aspirin plus heparin. Early administration of direct thrombin inhibitors may potentially improve the outcome of patients treated with thrombolytic therapy.

Results of percutaneous coronary angioplasty in patients <40 years of age

This study examined factors influencing the outcome of percutaneous transluminal coronary angioplasty (PTCA) in patients <40 years of age. We followed 86 patients (mean age 37 years) treated from 1982 to 1994. The primary procedural success was 90%. At follow-up of 83 patients (97%) at a mean of 48 +/- 33 months (range 5 to 147), there had been 3 late deaths. Actuarial survival at 5 and 10 years was 95% and 91%, respectively. At review only 5% of patients had class III angina and no patient had class IV angina. Repeat revascularization (PTCA alone in 21 [25%], surgery in 8 [10%], or both in 10 [12%] patients) was performed for restenosis in 29 patients (35%) and for disease progression at other sites in 10 patients (12%). On multivariate analysis, a history of diabetes mellitus (p <0.02) was the only factor associated with death or a subsequent cardiovascular event (myocardial infarction, stroke, or hospital admission with unstable angina). At follow-up, 20 patients (24%) still smoked, 64 (77%) had a total cholesterol level > or = 200 mg/dl, 20 (24%) had a body mass index > or = 30, and 15 (18%) were not taking aspirin. In conclusion, PTCA in adults <40 years of age has excellent early results with a low morbidity and mortality. The medium-term prognosis and control of symptoms was good, although by 5 years, further revascularization was required in almost half of the patients.

Early noninvasive identification of failed reperfusion after intravenous thrombolytic therapy in acute myocardial infarction

OBJECTIVES

This study sought to evaluate a biochemical approach to the early noninvasive assessment of reperfusion.

BACKGROUND

In patients with an acute myocardial infarction, a rapid noninvasive method of detecting failure of intravenous thrombolytic therapy to restore early Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow in the infarct-related artery (IRA) is needed.

METHODS

Serial blood samples were collected to assay creatine kinase-MB fraction (CKMB mass), cardiac troponin T and myoglobin concentrations in 105 patients with a myocardial infarction who underwent early angiography after intravenous streptokinase. The ratios of the 60- and 90-min concentrations to prethrombolytic values were used to determine an index that could identify failure to achieve TIMI grade 3 flow in the IRA at 90 min.

RESULTS

Significant increases in serum concentrations of markers at 60 min were more likely with TIMI grade 3 flow (59 patients) than with TIMI grade 0 to 2 flow (46 patients). Ratios < or = 5 at 60 min after thrombolysis detected failure to achieve 90-min TIMI grade 3 flow with 92% to 97% sensitivity, 43% to 60% specificity and 63% to 76% positive and 86% to 94% negative predictive values. Ratios < or = 10 at 90 min showed 88% to 95% sensitivity, 49% to 65% specificity and 61% to 69% positive and 86% to 94% negative predictive values for TIMI flow grade < 3. The overall predictive values were thus similar for all three markers.

CONCLUSIONS

In acute myocardial infarction treated with intravenous streptokinase, a simple measurement of increased serum concentrations of CKMB mass, cardiac troponin T or myoglobin at 60 and 90 min can accurately predict failure to achieve TIMI grade 3 flow in the IRA at 90 min.

The roles for coronary surgery and angioplasty in the management of patients with stable angina: evidence and decision making

Evidence from the randomized studies of coronary surgery suggests that patients who benefit from surgery in terms of improved survival are those with left main stem stenosis, triple vessel coronary artery disease, impaired left ventricular function or higher angina class. Patients currently undergoing surgery are in general older, with more severe angina, more comorbidity and more extensive coronary disease as compared with the population randomized in the earlier studies. Angioplasty has been shown to improve symptoms and to reduce the need for surgery in certain patients. Recent changes in procedural techniques and adjunctive therapies have reduced the number of acute complications and the rate of restenosis. However, recent evidence suggests that some patients with mild angina (< class 2) or good exercise tolerance may not benefit as much from angioplasty as other patients with more severe angina.

Abnormal coronary flow in infarct arteries 1 year after myocardial infarction is predicted at 4 weeks by corrected Thrombolysis in Myocardial Infarction (TIMI) frame count and stenosis severity

Because 24% to 30% of patent infarct-related arteries occlude in the year following thrombolytic therapy for acute myocardial infarction, angiographic factors including corrected Thrombolysis in Myocardial Infarction (TIMI) frame count which may predict abnormal infarct-artery flow, require definition. We examined changes in coronary flow and infarct-artery lesion severity by computerized quantitative angiography over 1 year in 154 patients with a patent infarct-related artery 4 weeks after myocardial infarction. These patients were randomized to receive either ongoing daily therapy of 50 mg aspirin and 400 mg dipyridamole, or placebo. All angiograms were interpreted blind in our core angiographic laboratory. Infarct-artery flow, assessed by corrected TIMI frame counts, was normal (< or = 27) in 46% and 45% of patients at 4 weeks and 1 year, respectively. At 4 weeks, patients with corrected TIMI frame counts < or = 27 had higher ejection fractions (60+/-11% vs 56+/-12%; p = 0.04) than those with corrected TIMI frame counts >27. On multivariate analysis, corrected TIMI frame count and stenosis severity were predictive of late abnormal infarct-artery flow (TIMI 0 to 2 flow, both p <0.01). Only stenosis severity at 4 weeks predicted reocclusion at 1 year (p <0.0001). Aspirin and dipyridamole had no effect on flow or reocclusion. Thus, corrected TIMI frame count and stenosis severity at 4 weeks was highly correlated with infarct-artery flow at 1 year.

Fibrinolysis for Acute Myocardial Infarction in the Elderly Patient: Is it Effective or Too Dangerous?

The incidence of myocardial infarction, and the subsequent mortality and morbidity increases markedly with age. Randomized placebo-contolled trials of fibrinolytic therapy have lacked adequate statistical power due to the relatively small numbers of older patients enrolled, but nevertheless have strongly suggested a mortality benefit in the older age group. Despite this, fibrinolytic therapy remains under-utilized in older patients, largely due to a perception that the risk, particularly of intracranial hemorrhage, outweighs any potential benefit of treatment. While the risk of intracranial hemorrhage following fibrinolysis does increase with age, the net clinical benefit, or the combined endpoints of death or disabling stroke, is still lower with treatment than without. Therapy with t-PA confers the greatest net clinical benefit in all but the very elderly. Age alone should not be a contraindication to fibrinolytic therapy for acute myocardial infarction.

Randomized, double-blind comparison of hirulog versus heparin in patients receiving streptokinase and aspirin for acute myocardial infarction (HERO). Hirulog Early Reperfusion/Occlusion (HERO) Trial Investigators

BACKGROUND

Thrombolytic therapy improves survival after myocardial infarction through reperfusion of the infarct-related artery. Thrombin generated during thrombolytic administration may reduce the efficacy of thrombolysis. A direct thrombin inhibitor may improve early patency rates.

METHODS AND RESULTS

Four hundred twelve patients presenting within 12 hours with ST-segment elevation were given aspirin and streptokinase and randomized in a double-blind manner to receive up to 60 hours of either heparin (5000 U bolus followed by 1000 to 1200 U/h), low-dose hirulog (0.125 mg/kg bolus followed by 0.25 mg x kg(-1) x h(-1) for 12 hours then 0.125 mg x kg(-1) x h(-1)), or high-dose hirulog (0.25 mg/kg bolus followed by 0.5 mg x kg(-1) x h(-1) for 12 hours then 0.25 mg x kg(-1) x h(-1)). The primary outcome was Thrombolysis In Myocardial Infarction trial (TIMI) grade 3 flow of the infarct-related artery at 90 to 120 minutes. TIMI 3 flow was 35% (95% CI, 28% to 44%) with heparin, 46% (95% CI, 38% to 55%) with low-dose hirulog, and 48% (95% CI, 40% to 57%) with high-dose hirulog (heparin versus hirulog, P=.023; heparin versus high-dose hirulog, P=.03). At 48 hours, reocclusion had occurred in 7% of heparin, 5% of low-dose hirulog, and 1% of high-dose hirulog patients (P=NS). By 35 days, death, cardiogenic shock, or reinfarction had occurred in 25 heparin (17.9%), 19 low-dose hirulog (14%), and 17 high-dose hirulog patients (12.5%) (P=NS). Two strokes occurred with heparin, none with low-dose hirulog, and two with high-dose hirulog. Major bleeding (40% from the groin site) occurred in 28% of heparin, 14% of low-dose hirulog, and 19% of high-dose hirulog patients (heparin versus low-dose hirulog, P<.01).

CONCLUSIONS

Hirulog was more effective than heparin in producing early patency in patients treated with aspirin and streptokinase without increasing the risk of major bleeding. Direct thrombin inhibition may improve clinical outcome.

Defective antigen-induced lymphocyte proliferation in the X-linked hyper-IgM syndrome

We examined T-cell proliferation in five patients with X-linked hyper-IgM syndrome (XHIM), using a panel of antigens and lectins. All patients had impaired antigen-induced proliferation, whereas their lectin responses were normal. Thus, in addition to severely depressed antibody responses, patients with XHIM have a defect in antigen-specific T-cell proliferation, which may explain their susceptibility to pathogens such as Pneumocystis carinii.

Coronary revascularisation in young adults

OBJECTIVE

To evaluate the long-term outcome of coronary artery bypass surgery (CABG) in patients < 40 years old and to determine factors predictive of adverse outcomes.

METHODS

Retrospective review of data on 220 patients who underwent isolated CABG at Green Lane Hospital, New Zealand from 1970 to 1992.

RESULTS

The actuarial survival after surgery was 91, 74 and 50% at 5, 10 and 15 years, respectively. Recurrence of ischaemic symptoms occurred at a median time of 72 months, and only 20% of patients remained asymptomatic 10 years after CABG. Univariate analysis of potentially adverse surgical factors showed that patients who had prolonged bypass time (> or = 100 min, P < 0.007) had increased late mortality. There were two distinct operative eras with respect to the use of IMA conduits (4% pre 1985, 87% post 1984) The relationship between IMA conduits use and survival was significant on time independent analysis (P < 0.02), but was not using the log-rank test. Preoperative clinical characteristics associated with increased late mortality were impaired left ventricular function (end-systolic volume (ESV) > or = 80 ml, P = 0.008; ejection fraction < 40%, P = 0.0005), and lack of aspirin use either pre- or post-operatively (P < 0.0001). Multivariate analysis indicated that reduced ejection fraction (P = 0.04) and prolonged bypass time (P = 0.05) was associated with an increased risk of late death. Aspirin therapy (P = 0.001) was associated with decreased late mortality. Cumulative events rate of reintervention and mortality was reduced in female patients (P = 0.0009). At review, 45% of patients had total cholesterol > 6.5 mmol/l.

CONCLUSION

To avoid the early recurrence of symptoms, the need for reintervention and late mortality, young patients should receive IMA conduits, cardioplegia as myocardial protection, aspirin and therapy to modify/ameliorate their risk factors including dyslipidaemia, diabetes and left ventricular dysfunction.

Prospective evaluation of eligibility for thrombolytic therapy in acute myocardial infarction

OBJECTIVES

To determine the proportion of patients presenting with acute myocardial infarction who are eligible for thrombolytic therapy.

DESIGN

Cohort follow up study.

SETTING

The four coronary care units in Auckland, New Zealand.

SUBJECTS

All 3014 patients presenting to the units with suspected myocardial infarction in 1993.

MAIN OUTCOME MEASURES

Eligibility for reperfusion with thrombolytic therapy (presentation within 12 hours of the onset of ischaemic chest pain with ST elevation > or = 2 mm in leads V1-V3, ST elevation > or = 1 mm in any other two contiguous leads, or new left bundle branch block); proportions of (a) patients eligible for reperfusion and (b) patients with contraindications to thrombolysis; death (including causes); definite myocardial infarction.

RESULTS

948 patients had definite myocardial infarction, 124 probable myocardial infarction, and nine ST elevation but no infarction; 1274 patients had unstable angina and 659 chest pain of other causes. Of patients with definite or probable myocardial infarction, 576 (53.3%) were eligible for reperfusion, 39 had definite contraindications to thrombolysis (risk of bleeding). Hence 49.7% of patients (537/1081) were eligible for thrombolysis and 43.5% (470) received this treatment. Hospital mortality among patients eligible for reperfusion was 11.7% (55/470 cases) among those who received thrombolysis and 17.0% (18/106) among those who did not.

CONCLUSIONS

On current criteria about half of patients admitted to coronary care units with definite or probable myocardial infarction are eligible for thrombolytic therapy. Few eligible patients have definite contraindications to thrombolytic therapy. Mortality for all community admissions for myocardial infarction remains high.

Late outcome after coronary artery bypass graft surgery in patients < 40 years old

BACKGROUND

Randomized trials confirm the long-term efficacy of coronary artery bypass graft surgery (CABG), although there are no randomized data in patients < 40 years old. Because these patients have been reported to have an early recurrence of symptoms, the long-term postoperative outcome was examined.

METHODS AND RESULTS

The long-term outcome of patients (n = 221) < 40 years old undergoing CABG at Green Lane Hospital, New Zealand, from 1970 to 1992 was determined. The 30-day mortality rate was 1.8% for initial and 9.5% for redo CABG. The median times to angina or myocardial infarction (recurrent ischemic event), further intervention, and death were 6.0, 9.6, and 14.2 years, respectively. Factors associated with increased late mortality on univariate analysis included end-systolic volume (ESV) > or = 80 mL (P = .004; 10-year mortality 19% versus 39% ESV > or = 80 mL), no internal mammary conduit (P = .01), no lipid-modifying therapy (P = .005), and no postoperative aspirin use (P = .0002); the latter was also associated with increased recurrent ischemic events (P = .04) or increased reintervention (P = .02). On stepwise logistic regression analysis, factors associated with increased late mortality were increasing ESV (P = .004), no internal mammary artery conduit (P = .009), diabetes (P = .04), and no postoperative aspirin (P = .02); the latter was also associated with increased recurrent ischemic events (P = .02). Hypercholesterolemia (> or = 6.5 mmol/L) was present in 65% of patients at presentation and 45% at follow-up.

CONCLUSIONS

To attempt to prevent recurrent ischemia or late death, patients < 40 years old who require CABG should receive internal mammary conduits, aspirin, lipid-modifying therapy, therapy to inhibit ventricular dilatation, and strict diabetes management.

Effects of streptokinase in patients presenting within 6 hours of prolonged chest pain with ST segment depression

BACKGROUND

The effects of streptokinase on the occurrence of a combined clinical outcome in patients presenting with recent chest pain and ST depression were investigated in view of the role of thrombus in the pathogenesis of acute ischaemic syndromes.

METHODS

112 patients aged < or = 75 years presenting within 6 h of the last episode of ischaemic chest pain of least 20 min duration with > or = 1 mm ST depression were randomised in a double blind manner to receive either streptokinase 1.5 million units over 30 min (n = 57) or placebo (n = 55). The primary end point was the combination of death, frequency of myocardial infarction (defined as peak creatine kinase > 600 U/ml), need for angiography because of uncontrollable ischaemia, and an exercise test within 35 days showing > or = 1 mm ST depression at < or = 6 min. The secondary end points were safety, frequency of chest pain, readmission with myocardial infarction or unstable angina, or need for revascularisation between 35 days and 1 year. The severity of ST depression on presentation was analysed with respect to clinical outcome.

RESULTS

The frequency of the combined hierarchical end point of death, myocardial infarction, early angiography, and a positive exercise test was 82% (47 of 57 patients) with streptokinase and 75% (41 of 55 patients) with placebo. There were four deaths, two in each group. 27 patients (47%) receiving streptokinase and 22 (40%) receiving placebo developed myocardial infarction. 11 patients (eight streptokinase and three placebo) required coronary arteriography and subsequent revascularisation because of angina uncontrolled by medical treatment. 44 patients (22 in each group) had a positive exercise test. There were three further cardiac deaths (one streptokinase, two placebo), and three noncardiac deaths within 1 year. A conservative approach to intervention was adopted and over a period of 1 year 29 patients (26%) (13 streptokinase and 16 placebo) underwent revascularisation procedures. Three patients (two streptokinase and one placebo) required transfusion. ST depression > or = 3 mm had 90% specificity but only 60% positive predictive value for myocardial infarction at presentation (P = 0.008, stepwise logistic regression). ST depression > or = 2 mm was predictive of death, late development of myocardial infarction, or a need for angiography (P = 0.02).

CONCLUSION

Patients presenting with ischaemic chest pain and ST depression frequently develop myocardial infarction. Severe ST depression is predictive of an adverse outcome. The 35 day (3.6% cardiac and total) and 1 year mortality (8.9% total, 6.3% cardiac) are low with conservative management and expeditious revascularisation. Streptokinase treatment within 6 h of the last episode of pain does not seem to be beneficial.

Left ventricular function following thrombolytic therapy for myocardial infarction

1. The aim of this study was to evaluate the utility of measurement of left ventricular function in assessing the efficacy of thrombolytic agents. 2. All published studies were reviewed. 3. The major effect of the introduction of thrombolytic therapy on mortality after myocardial infarction has been a dramatic decrease in the number of patients dying from cardiac failure. In the thrombolytic era, left ventricular function has remained the most important prognostic factor after recovery from acute myocardial infarction. There are three trials with the statistical power to evaluate left ventricular function, where both left ventricular function and survival were improved compared to placebo or control treatment. The recent Global Utility of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) Trial supports these findings, with left ventricular function being strongly correlated with mortality reduction. Left ventricular function, measured at 90 min either as ejection fraction, end-systolic volume or infarct zone contractility, closely correlated with 30 day mortality, P < 0.01. 4. Left ventricular function remains an important factor in the evaluation of the efficacy of different thrombolytic and adjuvant regimens.

Frequent reocclusion of patent infarct-related arteries between 4 weeks and 1 year: effects of antiplatelet therapy

OBJECTIVES

This study assessed the effect of the combination of aspirin and dipyridamole on patency of the infarct-related artery between 4 weeks and 1 year after myocardial infarction.

BACKGROUND

Patency of the infarct-related artery is an important determinant of prognosis after myocardial infarction. The incidence of late reocclusion and the effects of antiplatelet therapy are unknown.

METHODS

To investigate the importance of antiplatelet therapy for the prevention of late reocclusion, 215 patients who had a patent infarct-related artery 4 weeks after myocardial infarction were randomized in a double-blind manner to receive either a combination of 25 mg of aspirin and 200 mg of dipyridamole twice daily or placebo. One hundred fifty-four patients underwent further coronary arteriography 1 year later.

RESULTS

At 1 year, 38 (25%) of 154 patients had reocclusion of the infarct-related artery; 18 (23%) of 79 patients receiving aspirin and dipyridamole had late reocclusion versus 20 (27%) of 75 who received placebo (p = NS). The rate of reocclusion was related to the severity of the residual coronary artery stenosis at 4 weeks (< 50% stenosis 9.2%; 50% to 69% stenosis 11.6%; 70% to 89% stenosis 30.4%; > or = 90% stenosis 70%, p < 0.01). The majority of reocclusions were silent, and only 17 (45%) of 38 were clinically associated with further infarction. There were no differences for a hierarchic end point of cardiac death, myocardial infarction or revascularization (14.8% aspirin and dipyridamole vs. 17.8% placebo).

CONCLUSIONS

Late reocclusion of the patent infarct-related artery is a frequent event, occurring in 25% of patients. Antiplatelet therapy with the combination of aspirin and dipyridamole does not alter the overall rate of late reocclusion. Other strategies are required to reduce late reocclusion.

Association of angiographically detected coronary artery disease with low levels of high-density lipoprotein cholesterol and systemic hypertension

The prevalence of risk factors for atherosclerosis in 488 consecutive patients undergoing cardiac catheterization for the investigation of chest pain was compared with that in 868 subjects from a population sample. The presence and severity of angiographic coronary artery disease (CAD) (defined as mean diameter stenosis > 50%), total and high-density lipoprotein (HDL) cholesterol, triglycerides, history of systemic hypertension, smoking, diabetes mellitus, family history and drug therapy were assessed. Low HDL cholesterol (< 0.9 mmol/liter [35 mg/dl]) was more prevalent in patients with CAD than in the population sample in both men (44% [95% confidence interval 38 to 48] vs 21% [12 to 28]; p < 0.01) and women (12% [9 to 15] vs 1% [0 to 3]; p < 0.01). There were no differences in total cholesterol levels between these 2 groups. Total:HDL cholesterol ratios were significantly greater in patients with CAD. History of systemic hypertension was more prevalent in both men and women with CAD than in the population sample (47% [37 to 57] vs 20% [16 to 25] for men, and 31% [26 to 36] vs 21% [17 to 26] for women; p < 0.01). The prevalence of other risk factors was not significantly different between the 2 groups. In patients with CAD, the severity of disease was inversely correlated with levels of HDL cholesterol in both men and women (p < 0.01), and positively correlated with total cholesterol in men aged < 55 years (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)