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

Diagnostic comparison of automatic and manual TIMI frame-counting-generated quantitative flow ratio (QFR) values

Quantitative flow ratio (QFR) is a computational measurement of FFR (fractional flow reserve), calculated from coronary angiography. Latest QFR software automates TIMI frame counting (TFC), which occurs during the flow step of QFR analyses, making the analysis faster and more reproducible. The objective is to determine the diagnostic performance of QFR values obtained from analyses using automatic TFC compared to those obtained from analyses using manual TFC. This was a single-arm clinical trial that used the prospective analysis of the coronary angiographic image series of 97 patients who underwent evaluation of stable coronary artery disease with FFR/iFR at MedStar Washington Hospital Center in Washington, DC, USA. Automatic and manual TFC QFR values were obtained from the analyses of each of the 97 patients' image series, with manual TFC QFR values as the current gold standard for comparison. The diagnostic performance of automatic TFC QFR values was measured as follows: sensitivity was 0.87 (95% CI 0.66-0.97) and specificity was 1.00 (95% CI 0.9514-1.00), positive predictive value (PPV) was 1.00 (95%CI 1.00-1.00), while the NPV was 0.96 (95% CI 0.96-0.99). Overall accuracy was 96.91% (95% CI 91.23%-99.36%). The agreement as illustrated by the Bland-Altman plot shows a bias of 0.0023 (SD 0.0208) and narrow limits of agreement (LOA): Upper LOA 0.0573 and Lower LOA - 0.0528. The area under curve (AUC) was 0.996. QFR values generated from automatic TFC are comparable to those generated from manual TFC in diagnostic capability. The most recent software update produces values equivalent to those of the previous manual option, and can therefore be used interchangeably.

Pathophysiology and diagnosis of coronary microvascular dysfunction in ST-elevation myocardial infarction

Early mechanical reperfusion of the epicardial coronary artery by primary percutaneous coronary intervention (PCI) is the guideline-recommended treatment for ST-elevation myocardial infarction (STEMI). Successful restoration of epicardial coronary blood flow can be achieved in over 95% of PCI procedures. However, despite angiographically complete epicardial coronary artery patency, in about half of the patients perfusion to the distal coronary microvasculature is not fully restored, which is associated with increased morbidity and mortality. The exact pathophysiological mechanism of post-ischaemic coronary microvascular dysfunction (CMD) is still debated. Therefore, the current review discusses invasive and non-invasive techniques for the diagnosis and quantification of CMD in STEMI in the clinical setting as well as results from experimental in vitro and in vivo models focusing on ischaemic-, reperfusion-, and inflammatory damage to the coronary microvascular endothelial cells. Finally, we discuss future opportunities to prevent or treat CMD in STEMI patients.

Re-infarction after primary percutaneous coronary intervention

PURPOSE OF REVIEW

Thrombus formation, usually on a ruptured atherosclerotic plaque, is pivotal in the pathogenesis of ST segment elevation myocardial infarction (STEMI). This thrombus formation provides the milieu for re-occlusion of the infarct-related artery, the main location of re-infarction post-STEMI. Although rates of re-infarction are lower after reperfusion by primary percutaneous coronary intervention (PCI) than after fibrinolytic therapy, re-infarction remains a major cause of morbidity and mortality.

RECENT FINDINGS

The predominant cause of re-infarction after primary PCI is stent thrombosis. Two recent trials [A Prospective, Randomized Trial of Ambulance Initiation of Bivalirudin vs. Heparin ± Glycoprotein IIb/IIIa Inhibitors in Patients with STEMI Undergoing Primary PCI (EUROMAX) and Unfractionated heparin versus bivalirudin in primary percutaneous coronary intervention (HEAT-PPCI)] have each reported higher rates of stent thrombosis in the first 24 h after primary PCI in patients assigned to receive bivalirudin, which affects the balance of risks and benefit of bivalirudin post-STEMI. Also, in a subanalysis of the Platelet Inhibition And Patient Outcomes trial, ticagrelor reduces re-infarction compared with clopidogrel in patients with STEMI after primary PCI. Other nonpharmacological or mechanical interventions during primary PCI, with the exception of newer-generation drug-eluting stents in the Swedish Coronary Angiography and Angioplasty Registry, have not affected rates of re-infarction.

SUMMARY

Re-infarction remains a major cause of morbidity and mortality. Re-infarction rates are altered by pharmacological strategy and stent selection in primary PCI. The design of future trials to detect possible treatment differences in relatively low event rates will provide challenges, and may require more novel strategies such as administrative data collection for patient characteristics and key outcomes.

Fluoroscopy Assisted Scoring of Myocardial Hypoperfusion (FLASH) ratio as a novel predictor of mortality after primary PCI in STEMI patients

BACKGROUND

The aim of this study was to investigate whether Fluoroscopy Assisted Scoring of Myocardial Hypoperfusion (FLASH) enabled a more accurate assessment of coronary blood flow and prediction of cardiac mortality after primary PCI (pPCI), than the presently used angiographic scores of reperfusion.

METHODS

We included 453 STEMI patients who received pPCI at our hospital. Using the novel FLASH algorithm, based on contrast passage time and quantitative coronary analysis, FLASH flow was measured after pPCI and was used to calculate FLASH ratio of culprit and reference artery. In 28 of the 453 patients, FLASH flow was compared to Doppler-derived-flow.

RESULTS

FLASH flow had a good correlation with Doppler derived flow (Pearson's R=0.65, p<0.001) and had a high inter-observer agreement (ICC=0.83). FLASH flow was significantly lower in patients that died of cardiac death within six months (25.9±17.7 ml/min vs. 38.2±18.8 ml/min, p=0.004). FLASH ratio had a high accuracy of predicting cardiac mortality with a significant higher area under the curve as compared with CTFC and QuBe (p=0.041 and p=0.008). FLASH ratio was an independent predictor of mortality at 6 months (HR=0.98 per 1% increase, p=0.014).

CONCLUSION

FLASH is a simple non-invasive method to estimate coronary blood flow and predict mortality directly following pPCI in STEMI patients, with a higher accuracy compared to the presently used angiographic scores.

Clinical importance of hyperemic coronary blood flow (thrombolysis in myocardial infarction-intravenous flow) after primary percutaneous coronary intervention

We aimed to investigate clinical, demographic and angiographic factors associated with hyperemic coronary blood flow (HCBF) and the relation of HCBF with mortality at 30 days. Our study included 809 consecutive patients with acute ST-segment elevation myocardial infarction who underwent primary percutaneous coronary intervention (PCI). We divided corrected thrombolysis in myocardial infarction (TIMI) frame count (TFC) values into three tertiles: less than 14, 14-28 and more than 28. Corrected TFC less than 14 was defined as HCBF or TIMI intravenous flow. The primary end-point of the present study was all-cause mortality within 30 days. Among the HCBF group (n = 58), the patients with poor myocardial perfusion demonstrated the highest mortality rate within the 30-day follow-up period (33%). Low TIMI myocardial perfusion grade, history of no smoking, left ventricular ejection fraction (LVEF), and high Killip status and low LVEF were found to be independently associated with 1-month all-cause mortality. The present study showed that HCBF after primary PCI has a high 30-day mortality when associated with impaired reperfusion.

Coronary flow, VO2 peak and anaerobic threshold in patients with dilated cardiomyopathy

BACKGROUND

Coronary flow is influenced by several determinants and may change according to external stimuli. In patients with dilated cardiomyopathy (DC), adaptive mechanisms could induce alterations in coronary flow, possibly related to oxygen consumption.

METHODS

In 67 consecutive patients with DC (mean age 52.06+/-13.84, 52 male gender, left ventricle ejection fraction (LVEF) 29.49%+/-8.68) and normal coronary angiography findings, coronary flow in left anterior descending (LAD), right coronary artery (RC) and left circumflex (LCx) was reported as TIMI frame count (TFC). All patients underwent a cardiopulmonary test with VO2 peak and anaerobic threshold (AT) measurement, New York Heart Association (NYHA) class stratification, two-dimensional echocardiographic evaluation including LVEF and left ventricle end-diastolic diameter (LVEDD) assessment. All patients were receiving optimal medical treatment.

RESULTS

In a multivariate analysis, a statistically significant correlation was found between VO2 peak and TFC (B 7.61, p<0.001, R2 0.61 for LAD; B 3.42, p<0.001, R2 0.33 for RC); an inverse correlation was found between AT and TFC (B -9.77, p<0.001, R2 0.61 for LAD; B -4.26, p<0.001, R2 0.33 for RC).

CONCLUSIONS

Coronary flow is related to VO2 peak and AT in patients with DC, suggesting a "compensatory" mechanism.

Antiplatelet therapy and progression of coronary artery disease: a placebo-controlled trial with angiographic and clinical follow-up after myocardial infarction

INTRODUCTION

In patients after ST-elevation myocardial infarction (STEMI), antiplatelet therapy reduces subsequent cardiac events, which are often attributed to recurrent thrombosis with (sub)total occlusion in the infarct-related artery. Whether antiplatelet therapy influences the often subclinical process of coronary disease progression in noninfarct arteries has not been reported.

METHODS

Quantitative coronary angiography of noninfarct arteries was performed on paired cine-angiograms of 149 patients from fibrinolytic trials who had a patent infarct-related artery 3 to 4 weeks following STEMI and who were randomized to either continue the daily combination of 50-mg aspirin and 400-mg dipyridamole or to matching placebo. Follow-up angiography was scheduled at 1 year.

RESULTS

On a per-patient basis, the change in minimal luminal diameter (MLD) was 0.00 mm in the aspirin/dipyridamole group (n = 76) and was 0.01 mm in the placebo group (n = 73). There was no difference between these groups in the changes in MLD (-0.02 mm; 95% CI -0.09 to 0.05), neither were there significant differences in mean luminal diameter and diameter stenosis. Progression (1 segment/patient with > or = 0.40 mm decrease in MLD) was seen in two thirds of patients and did not independently predict long-term death and/or reinfarction.

CONCLUSION

In this placebo-controlled trial after STEMI, the combination of aspirin and dipyridamole did not affect noninfarct artery disease progression. Progression did not predict long-term clinical outcome.

Association of a history of systemic hypertension with mortality, thrombotic, and bleeding complications following non-ST-segment elevation acute coronary syndrome

Chronic hypertension is a well established risk factor for the development of cardiovascular disease; however, its prognostic significance after a non-ST-segment elevation acute coronary syndrome remains to be established. Data from 15,414 patients included in six randomized Thrombolysis in Myocardial Infarction (TIMI) trials (TIMI 3B, TIMI 11A, TIMI 11B, TIMI 12, the Orbofiban in Patients With Unstable Coronary Syndromes [OPUS]-TIMI 16, and the Treat Angina With Aggrastat and Determine Cost of Therapy With an Invasive or Conservative Strategy [TACTICS]-TIMI 18) were analyzed. A history of hypertension was present in 10,998 (71.35%) patients; comorbidities and higher TIMI risk scores were more likely in these patients. However, positive troponin and ST-segment deviations were less frequent among hypertensive patients. After multivariate analysis, the history of hypertension was associated with more adverse outcomes, specifically the composite end point of death/myocardial infarction at 30 days and 1 year (odds ratio [OR] 1.54, 95% confidence interval [CI] 1.31-1.81; p<0.001 at 1 year) than in patients without this history. An independent relationship was also observed with mortality (OR 1.70, 95% CI 1.34-2.16; p<0.001 at 1 year), myocardial infarction (OR 1.50, 95% CI 1.23-1.82; p<0.001 at 1 year), recurrent ischemia (OR 1.24, 95% CI 1.11-1.38; p<0.001 at 1 year), and major bleeding (OR 1.45, 95% CI 1.03-2.06; p=0.036 at 30 days). It was concluded that chronic hypertension remains an independent marker for major short- and long-term cardiac adverse outcomes after non-ST-segment elevation acute coronary syndrome.

Early management of ST-segment elevation myocardial infarction

Improvements in the management of ST-segment elevation myocardial infarction(STEMI) have led to a reduction in the acute and long-term mortality rates. The first important decision in the care of patients who have STEMI is the method of reperfusion. Whether percutaneous intervention (PCI) or fibrinolytic therapy is chosen depends on a number of factors. This article reviews the data on PCI and fibrinolytics in the context of consensus guidelines, outlines adjunctive medical therapies important in the first 24 hours, and discusses a strategy for making the decisions and a hypothetical construct for evaluating new drugs and procedures in the future.

Relation between the TIMI frame count and the degree of microvascular injury after primary coronary angioplasty in patients with acute anterior myocardial infarction

OBJECTIVE

To investigate the relation between thrombolysis in myocardial infarction (TIMI) frame count (TFC) and coronary blood flow velocity (CBFV) parameters reflecting the degree of microvascular injury in patients with acute myocardial infarction.

RESULTS

TFC and CBFV were measured after primary coronary angioplasty in 103 consecutive patients with their first anterior wall acute myocardial infarction. TFC correlated inversely with the averaged peak velocity (r = -0.43, p < 0.0001). However, TFC did not correlate significantly with diastolic deceleration time and with the averaged systolic peak velocity (r = -0.16, p = 0.22, and r = -0.23, p = 0.16, respectively). The patients were divided into two groups according to presence (35 patients) or absence (68 patients) of systolic flow reversal. There was no significant difference in TFC between the two groups (29 (16) v 25 (13), p = 0.20).

CONCLUSIONS

These findings suggest that the TFC reflects epicardial CBFV. However, it is not accurate enough to assess the degree of microvascular injury after primary coronary angioplasty.

High-grade infarct-related stenosis after successful thrombolysis: strong predictor of reocclusion, but not of clinical reinfarction

BACKGROUND

After successful thrombolysis, a high-grade stenosis at 24-hour angiography is strongly predictive of reocclusion and is often believed to result in high reinfarction rates. However, routine angioplasty did not reduce death or reinfarction in past trials. Systematic angiographic follow-up shows that reocclusion often occurs without clinical reinfarction. This study investigates whether the increased risk for reocclusion associated with a high-grade lesion translates into impaired clinical outcome.

METHODS

In the ischemia-guided Antithrombotics in the Prevention of Reocclusion in COronary Thrombolysis (APRICOT-1) trial, 240 patients with ST-elevation MI who had an open infarct artery 24 hours after thrombolysis had 3-month repeat angiography to assess reocclusion, with clinical follow-up at 3 months and 3 years.

RESULTS

On the basis of the optimal discriminative stenosis severity, the reocclusion rate was 40% (47/118) in patients with a high-grade residual stenosis and 16% (20/122) in patients with a low-medium-grade lesion (risk ratio [RR], 2.43; 95% CI, 1.54-3.84; P <.01). Three-month death and reinfarction rates did not differ: 6% (7/118) versus 9% (11/122; RR, 0.66; 95% CI, 0.26-1.64; P = not significant). Systematic angiographic follow-up revealed that reocclusion of a high-grade lesion occurred in the absence of clinical reinfarction in 85% (40/47) of patients, as compared with 45% (9/20) in patients with a low-medium-grade stenosis (RR, 1.89; 95% CI, 1.15-3.12; P <.01). Despite an independent association with reocclusion, a high-grade stenosis was not predictive of either short- or long-term death and reinfarction.

CONCLUSIONS

After successful thrombolysis and adopting an ischemia-guided revascularization strategy, patients with a high-grade stenosis experience death/reinfarction rates similar to that of patients with a low-medium-grade lesion. This is true despite a 2- to 3-fold higher risk for reocclusion. The finding that reocclusion of a high-grade lesion often occurs without clinical reinfarction explains the absence of a relationship between a severe stenosis and death/reinfarction. Appreciation of these observations may contribute to an optimal design of a future randomized trial to re-evaluate the impact of a routine invasive strategy.

Sequential risk stratification using TIMI risk score and TIMI flow grade among patients treated with fibrinolytic therapy for ST-segment elevation acute myocardial infarction

In the setting of ST-segment elevation myocardial infarction (STEMI), the Thrombolysis In Myocardial Infarction (TIMI) risk score (TRS) and indexes of epicardial and myocardial perfusion are associated with mortality. The association between TRS at presentation and angiographic indexes of epicardial and myocardial perfusion after reperfusion therapy has not been investigated. We hypothesized that TRS, TIMI flow grade (TFG), and TIMI myocardial perfusion grade (TMPG) would provide independent prognostic information and that angiographic indexes of poor flow and perfusion would be associated with a higher TRS. TRS and angiographic data were evaluated in 3,801 patients from the TIMI 4, 10A, 10B, 14, 20, 23, and 24 trials. Within each TRS stratum (TRS 0 to 2, 3 to 4, >/=5), 30-day mortality increased stepwise among patients with impaired TFG at 60 minutes after fibrinolytic administration. In a multivariate model adjusting for the TRS strata, impaired TMPG (0/1) was independently associated with higher mortality (odds ratio 2.28, p = 0.018). In a multivariate model adjusting for the TFG and infarct location, the likelihood of impaired TMPG (0/1) was greater among intermediate-risk (TRS 3 to 4) and high-risk (TRS >/=5) patients than among low-risk (TRS 0 to 2) patients (odds ratio 1.43, p = 0.019 and 1.50, p = 0.055, respectively). Thus, impaired epicardial flow and myocardial perfusion are independently associated with increased 30-day mortality among patients identified by TRS as high risk, although there is no synergism between either TFG or TMPG and TRS. High TRS at presentation is associated with abnormal myocardial perfusion, even after adjusting for possible confounders.

Effect of rescue or adjunctive percutaneous coronary intervention of the culprit artery after fibrinolytic administration on epicardial flow in nonculprit arteries

We hypothesized that blood flow in noninfarct arteries would improve after percutaneous coronary intervention of the culprit artery in the setting of ST-elevation myocardial infarction (STEMI). The corrected Thrombolysis In Myocardial Infarction (TIMI) frame count was measured in 94 patients (102 arteries) enrolled in the INTEGRITI, ENTIRE, and FASTER trials of reduced dose fibrinolytic and glycoprotein IIb/IIIa inhibition. The corrected TIMI frame count in nonculprit arteries improved by 3.4 +/- 13.4 frames after percutaneous coronary intervention but remained significantly slower than flow in normal arteries.

Association of peripheral neutrophilia with adverse angiographic outcomes in ST-elevation myocardial infarction

We hypothesized that absolute and relative neutrophilia would be associated with adverse angiographic outcomes in the 394 patient Limitation of Myocardial Infarction Following Thrombolysis in Acute Myocardial Infarction (LIMIT) Acute Myocardial Infarction (AMI) trial of fibrinolysis in ST-elevation myocardial infarction. The mean neutrophil count was 7.9 x 10(9)/L, with a mean neutrophil percentage of 72%. Patients with time from symptom onset to fibrinolytic treatment more than the median (2.7 hours) had a higher neutrophil count and percentage of neutrophils than patients with shorter time to treatment. Patients with a closed infarct-related artery at 90 minutes (Thrombolysis In Myocardial Infarction [TIMI] grade 0/1 flow) had higher neutrophil counts (8.8 +/- 3.8 vs 7.6 +/- 3.0, p = 0.02) but no difference in the percentage of neutrophils than patients with an open artery. Higher neutrophil counts were also mildly correlated with longer corrected TIMI frame counts (CTFC) in the infarct-related artery (r = 0.14, p = 0.02). Patients with impaired myocardial perfusion by TIMI myocardial perfusion grade (TMPG) had a greater percentage of neutrophils (73.2 +/- 10.7% for TMPG 0/1 vs 69.9 +/- 12.6% for TMPG 2/3, p = 0.047) but no detectable difference in neutrophil counts (8.2 +/- 3.3 vs 7.7 +/- 2.9, p = 0.24). There were no significant associations between other indexes in the cell differential and angiographic or clinical outcomes. Higher neutrophil counts remained independently associated with both closed arteries and CTFC in multivariable models controlling for age, left anterior descending artery infarct location, time to treatment, and pulse and blood pressure on admission. A greater percentage of neutrophils remained independently associated with impaired microvascular perfusion in a similar multivariable model. In patients with ST-elevation myocardial infarction, absolute and relative neutrophilia were associated with impaired epicardial and microvascular perfusion.

Association of creatinine and creatinine clearance on presentation in acute myocardial infarction with subsequent mortality

OBJECTIVES

We hypothesized that impaired renal function would also be associated with poorer clinical outcomes among patients with ST-segment elevation myocardial infarction (STEMI) treated with fibrinolysis.

BACKGROUND

Previous studies have demonstrated that impaired renal function is associated with poorer clinical outcomes in the setting of unstable angina and non-STEMI and after percutaneous coronary intervention.

METHODS

Data were drawn from the Thrombolysis In Myocardial Infarction (TIMI)-10, TIMI-14, and Intravenous nPA for the Treatment of Infarcting Myocardium Early (InTIME-II) trials.

RESULTS

Within each TIMI risk score (TRS) for STEMI category (0 to 2, 3 to 4, >/=5), 30-day mortality increased stepwise among patients with normal (creatinine [Cr] </=1.2 mg/dl), mildly (Cr >1.2 to 2 mg/dl), and severely (Cr >2.0 mg/dl) impaired renal function (p < 0.001) and in patients with normal (creatinine clearance [CrCl] >/=90 ml/min), mildly (60 to <90 ml/min), moderately (30 to <60 ml/min), and severely (<30 ml/min) impaired CrCl (p < 0.001). Impaired renal function was associated with increased mortality after adjusting for previously identified correlates of mortality (using Cr: odds ratio [OR] for mild impairment 1.52, 95% confidence interval [CI] 1.30 to 1.77, p < 0.001; OR for severe impairment 3.73, 95% CI 2.55 to 5.45, p < 0.001; using CrCl: OR for mild impairment 1.38, 95% CI 1.10 to 1.73, p = 0.006; OR for moderate impairment 2.06, 95% CI 1.59 to 2.66, p < 0.001; OR for severe impairment 3.81, 95% CI 2.57 to 5.65, p < 0.001).

CONCLUSIONS

In the setting of STEMI, elevated Cr and/or impaired CrCl on presentation is associated with increased mortality, independent of other conventional risk factors and TRS. This association does not appear to be mediated by reduced fibrinolytic efficacy among patients with impaired renal function or by the presence of congestive heart failure on presentation.

Myocardial Reperfusion: Its Assessment and Its Relation to Clinical Outcomes

It has become increasingly apparent that epicardial blood flow restoration is necessary, but not sufficient, to achieve optimal clinical outcomes in the setting of acute coronary syndromes. Indeed, clinical outcomes are strongly associated with myocardial perfusion. The diagnostic tools available to assess myocardial perfusion following acute myocardial infarction and their association with clinical outcomes are reviewed here. Many simple angiographic markers--the Thrombolysis in Myocardial Infarction (TIMI) count frame, TIMI myocardial perfusion grade, pulsatile flow--are all readily available measures and are strongly related to clinical outcomes. Other tools, while accurate, remain limited by their high cost, low availability, and complexity for routine use.

Keeping the coronary arteries open: current opportunities

Thrombolysis has reduced mortality from myocardial infarction, but effective opening of the artery with normal flow continues to be an important goal. Thrombolysis is not always as successful as it should be; alternatives include adjunctive therapy and mechanical opening of the arteries. In patients with acute coronary occlusion opening the artery should continue to be the primary aim.

Assessing coronary blood flow dynamics with the TIMI frame count method: comparison with simultaneous intracoronary Doppler and ultrasound

This study compared the TIMI frame count (TFC), which has been proposed as a method for quantifying coronary blood flow, with coronary flow and microvascular function measured with intracoronary Doppler and intracoronary ultrasound. Coronary blood flow volume was calculated from coronary blood velocity (by intracoronary Doppler) and lumen area (by intracoronary ultrasound) in the LAD in 46 post-heart transplant patients at baseline and after intracoronary adenosine. TFC correlated significantly with average peak coronary blood velocity (r = -0.42; P = 0.004) and coronary lumen area (r = 0.39; P = 0.008), but not with coronary blood flow volume (r = -0.01; P = 0.96) or the coronary flow reserve response to adenosine (r = 0.09; P = 0.58). In conclusion, TFC is a simple method of assessing coronary blood velocity but not volumetric flow. While TFC does not predict coronary flow reserve, as a measure of velocity it does provide an assessment of basal microvascular tone, information that is complementary to that afforded by flow reserve measurements.

Impact of contrast agent type (ionic versus nonionic) used for coronary angiography on angiographic, electrocardiographic, and clinical outcomes following thrombolytic administration in acute myocardial infarction

The goal of this study was to examine the relationship between contrast agent type (ionic vs. nonionic) and angiographic, electrocardiographic, and clinical outcomes after thrombolytic administration. Ionic or nonionic contrast agents were selected in a nonrandomized fashion for 90-min angiography and percutaneous coronary intervention (PCI) following thrombolytic administration in the TIMI 14 trial [tissue plasminogen activator (tPA) or reteplase (rPA) vs. low-dose lytic + abciximab]. There was no relationship between contrast agent type and overall patency, rate of TIMI grade 3 flow, or corrected TIMI frame counts (CTFCs) in open culprit arteries and in post-PCI patency rates or post-PCI CTFCs. In patients treated with ionic contrast, ejection fractions at 90 min were slightly but significantly lower (56.2 +/- 16.5, n = 122, vs. 59.8 +/- 14.4, n = 322; P = 0.02), chest pain duration was longer (2.8 +/- 4.1 hr, n = 255, vs. 1.7 +/- 3.6, n = 550; P = 0.0003), and complete ST segment resolution was less frequent (41.5% vs. 50.8%; P = 0.04). While there was no difference in epicardial blood flow, ionic contrast agent use was associated with poorer ST segment resolution, longer chest pain duration, and poorer ejection fractions, perhaps as a result of microvascular dysfunction.

Comparative efficacy of primary angioplasty with stent implantation and thrombolysis in restoring basal coronary artery flow in acute ST segment elevation myocardial infarction: quantitative assessment using the corrected TIMI frame count

Following thrombolysis and primary percutaneous transluminal coronary angioplasty (PTCA) for acute ST segment elevation myocardial infarction, basal flow in the culprit artery is known to influence prognosis. The purpose of this study was to determine if differences exist in basal flow in culprit and nonculprit coronary arteries in patients with acute ST segment elevation myocardial infarction who were treated with thrombolysis or primary PTCA with stent implantation. Twenty patients were randomized to thrombolysis (with recombinant tissue plasminogen activator) and 24 to primary PTCA with stent implantation within 3 hours of onset of acute ST segment elevation myocardial infarction. Coronary angiography was performed 90-120 minutes after thrombolysis or immediately after PTCA with stent implantation and again at 18-36 hours after intervention in both groups. Patients who failed to achieve thrombolysis in myocardial infarction (TIMI) grade 2 or 3 flow were excluded. The corrected TIMI frame count was used as the index of basal coronary artery flow. Early after intervention the mean corrected TIMI frame count in the culprit coronary artery was significantly lower in the primary PTCA with stent group (27.4 +/- 7.7 frames) than in the thrombolysis group (39.8 +/- 10 frames, p < 0.001). Eight thrombolysis patients (40%) and 20 primary PTCA patients (83%, p < 0.01) achieved TIMI grade 3 flow early after intervention. By 18-36 hours after intervention there were no significant differences in the mean correct TIMI frame count between the thrombolysis and primary PTCA with stent groups. There were no significant differences in the mean corrected TIMI frame count between these two groups in the nonculprit coronary artery, either early after intervention or at 18-36 hours. In successfully reperfused coronary arteries following acute ST segment elevation myocardial infarction, primary angioplasty with stent implantation reestablished TIMI grade 2 or 3 flow faster and more effectively than thrombolysis did.

Impact of injections during diagnostic coronary arteriography on coronary patency in the setting of acute myocardial infarction from the TIMI trials. Thrombolysis In Myocardial Infarction

The mechanical force of injection at 90 minutes opens 13.4% of occluded arteries, but overall, only 2.4% of all culprit arteries (already open and occluded combined) are opened. Thus, although some arteries are opened by the force of hand injection, the frequency of mechanical opening among all arteries is low, and hand injections appear to alter current 80% patency rates by approximately 2.5%.

Association between white blood cell count, epicardial blood flow, myocardial perfusion, and clinical outcomes in the setting of acute myocardial infarction: a thrombolysis in myocardial infarction 10 substudy

BACKGROUND

Elevation of the white blood cell (WBC) count during acute myocardial infarction (AMI) is associated with adverse outcomes. We examined the relationship between the WBC count and angiographic findings to gain insight into this relationship. Results and Methods-We evaluated data from 975 patients in the Thrombolysis In Myocardial Infarction (TIMI) 10A and 10B trials. Patients with a closed artery at 60 and 90 minutes had higher a WBC count than patients with an open artery (P:=0.02). Likewise, the presence of angiographically apparent thrombus was associated with a higher WBC count (11.5+/-5.2x10(9)/L, n=290, versus 10.7+/-3. 5x10(9)/L, n=648; P=0.008). In addition, a higher WBC count was associated with poorer TIMI myocardial perfusion grades (4-way P=0.04). Mortality rates were higher in patients with a higher WBC count (0% for WBC count 0 to 5x10(9)/L, 4.9% for WBC count 5 to 10x10(9)/L, 3.8% for WBC count 10 to 15x10(9)/L, 10.4% for WBC count >15x10(9)/L; P=0.03). The development of new congestive heart failure or shock was also associated with a higher WBC count (0% for WBC count 0 to 5x10(9)/L, 5.2% for WBC count 5 to 10x10(9)/L, 6.1% for WBC count 10 to 15x10(9)/L, 17.1% for WBC count >15x10(9)/L; P<0.001), an observation that remained significant in a multivariable model that adjusted for potential confounding variables (odds ratio 1.21, P=0.002).

CONCLUSIONS

Elevation in WBC count was associated with reduced epicardial blood flow and myocardial perfusion, thromboresistance (arteries open later and have a greater thrombus burden), and a higher incidence of new congestive heart failure and death. These observations provide a potential explanation for the higher mortality rate observed among AMI patients with elevated WBC counts and helps explain the growing body of literature that links inflammation and cardiovascular disease.

Medical treatment for acute coronary syndromes

The medical treatment of acute coronary syndromes with thrombolytic, antithrombin, and antiplatelet agents is a major area of research and a vast topic for clinical review. This review summarizes important recent findings on the background of existing pathological and clinical knowledge to provide an understanding of the basis of current therapy and the new therapies that are likely to be introduced in the near future. Current controversies regarding the management of these conditions and the choice between medical, interventional, and combined strategies in different situations are also discussed.

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.

Improved coronary artery flow after coronary angioplasty in patients with unstable angina

BACKGROUND

Coronary artery flow is impaired after myocardial infarction but there is limited information regarding coronary flow in unstable angina.

AIM

To assess baseline coronary artery flow and the effects of coronary angioplasty on coronary flow in patients with unstable angina.

METHODS

Twenty-one patients with unstable angina with a culprit lesion suitable for coronary angioplasty were enrolled in the study. Coronary flow was assessed with the Thrombolysis In Myocardial Infarction (TIMI) grade and the Corrected TIMI Frame Count (CTFC) pre and post angioplasty.

RESULTS

Baseline flow was impaired in the culprit artery compared to the non culprit artery (42.0+/-28.1 vs 25.3+/-7.0 frames, p<0.02). Pre angioplasty coronary flow was TIMI grade 2 in 52% and TIMI grade 3 in 48% of patients. Post angioplasty flow improved with TIMI grade 2 flow in 5% and TIMI grade 3 in 95%. After angioplasty coronary flow improved from 42.0+/-28.1 frames to 21.6+/-16.3 (p=0.0001). The culprit coronary stenosis decreased from 74+/-9% pre angioplasty to 28+/-12% after intervention (p=0.0001).

CONCLUSIONS

Angioplasty and stenting of the culprit vessel restores normal coronary flow in most patients with unstable angina. This suggests that impaired flow in unstable angina is predominantly related to the culprit lesion residual stenosis.

Importance of the TIMI frame count: implications for future trials

Although the TIMI (Thrombolysis In Myocardial Infarction) flow grade classification scheme is widely used to assess angiographic outcomes, it is limited by poor reproducibility and its categoric nature. The corrected TIMI frame count (CTFC) is a simple, more objective continuous variable index of coronary blood flow that can be broadly and inexpensively applied. This measure of the time for dye to traverse a coronary artery is both accurate (highly correlated with Doppler velocity measurements) and precise (reproducible). The method has been prospectively validated as providing independent risk stratification above and beyond the conventional TIMI flow grades. It has been shown to be a predictor of restenosis, and has been of value in elucidating the underlying pathophysiology of acute myocardial infarction. In view of the above and its ease of use, we anticipate that CTFC will become a widely used method to evaluate coronary blood flow.

Effect of potential confounding factors on the thrombolysis in myocardial infarction (TIMI) trial frame count and its reproducibility

BACKGROUND

The potential factors that introduce variability into TIMI frame count (TFC) have not been systematically investigated. The goal of this study was to determine if nitrate use, dye injection rate, catheter size, the phase of the cardiac cycle in which dye is injected, or heart rate affect the TFC and to investigate the reproducibility of the TFC.

METHODS AND RESULTS

The dye injection rate was increased 1 mL/s, and angiography was repeated. A coronary angiogram was taken first with an 8F catheter and then with a 6F catheter. After taking angiograms, intracoronary nitrate was given to the patient, and the second angiography was performed. Basal heart rate was increased 20 beats/min, and angiography was repeated. Dye injection was performed at the beginning of systole and diastole. The TFC was not significantly changed by increasing the dye injection rate (P=0.467) or by changing catheter size (P=0.693). Nitrate administration significantly increased the TFC from 26.4+/-11.9 to 32.8+/-13.3 frames (P<0.001). Dye injection at the beginning of diastole significantly decreased the TFC from 30.1+/-8.8 to 24.4+/-7.9 frames (P<0.001) for the left coronary artery and from 24.16+/-4.49 to 21. 24+/-4.45 frames (P<0.001) for the right coronary artery. Increasing heart rate significantly decreased the TFC from 30.4+/-6.1 to 25. 3+/-7.2 frames (P<0.001). Intraobserver and interobserver reproducibility of the TFC was good (mean difference, 1.33+/-1.24 and 2.57+/-1.72 frames, respectively).

CONCLUSIONS

Nitrate use, heart rate, and the phase of the cardiac cycle in which dye is injected had significant effects on the TFC. Therefore, studies comparing TFC need to consider these factors, and the use of nitrates should be either standardized or randomized.

Weight-adjusted dosing of TNK-tissue plasminogen activator and its relation to angiographic outcomes in the thrombolysis in myocardial infarction 10B trial. TIMI 10B Investigators

Fixed doses of thrombolytic agents are generally administered to patients of varying body weights, and the dose-response relation may be confounded by the variability in patient weight. We hypothesized that higher doses of TNK-tissue plasminogen activator (tPA) per unit body weight would be related to improved flow at 90 minutes after thrombolytic administration. A total of 886 patients with acute myocardial infarction were randomized to receive either a single bolus of 30, 40, or 50 mg of TNK-tPA or front-loaded tPA in the Thrombolysis In Myocardial Infarction (TIMI) 10B trial. The dose of TNK-tPA administered was divided by the patient's weight to arrive at the TNK-tPA dose (mg) per unit body weight (kg), and patients were stratified into tertiles based on mg/kg of TNK-tPA: low dose, 0.2 to 0.39 mg/kg; mid-dose, 0.40 to 0.51 mg/kg; high dose, 0.52 to 1.24 mg/kg. Flow in the culprit and nonculprit arteries was analyzed using the TIMI flow grades and the corrected TIMI frame count (CTFC). The median CTFC in culprit arteries differed between the tertiles (3-way p = 0.007), with the CTFC being 7.2 frames faster in high-dose than in low-dose patients (43.1 +/- 30.1, median 31.2, n = 171 vs 54.6 +/- 34.8, median 38.4, n = 166, 2-way p = 0.002). Patients in the mid- and high-dose tertiles achieved patency more frequently (TIMI grade 2 or 3 flow) by 60 minutes (p = 0.02), and the 90-minute percent diameter stenosis was less severe in patients in the high- versus low-dose tertile (p = 0.03). In nonculprit arteries, the CTFC was faster in high- than in low-dose tertiles (29.6 +/- 13.4, median 26.9, n = 130 vs 34.7 +/- 16.3, median 32.8, n = 108, 3-way p = 0.03, 2-way p = 0.008). In patients who underwent percutaneous transluminal coronary angioplasty (PTCA), the CTFC in culprit arteries after PTCA was fastest in the high- and mid-dose tertiles than in those receiving low doses (2-way p = 0.05). Thus, higher doses per unit body weight of TNK-tPA result in not only faster culprit artery flow, but also faster nonculprit, global, and post-PTCA flow, which may reflect earlier opening, reduced stunning, or improved microvascular function. The greater effectiveness of thrombolysis must be weighed against any increase in risk.

Determinants of coronary blood flow after thrombolytic administration. TIMI Study Group. Thrombolysis in Myocardial Infarction

OBJECTIVES

This study evaluated the determinants of coronary blood flow following thrombolytic administration in a large cohort of patients.

BACKGROUND

Tighter residual stenoses following thrombolysis have been associated with slower coronary blood flow, but the independent contribution of other variables to delayed flow has not been fully explored.

METHODS

The univariate and multivariate correlates of coronary blood flow at 90 min after thrombolytic administration were examined in a total of 2,195 patients from the Thrombolysis in Myocardial Infarction (TIMI) 4, 10A, 10B and 14 trials. The cineframes needed for dye to first reach distal landmarks (corrected TIMI frame count, CTFC) were counted as an index of coronary blood flow.

RESULTS

The following were validated as univariate predictors of delayed 90-min flow in two cohorts of patients: a greater percent diameter stenosis (p < 0.0001 for both cohorts), a decreased minimum lumen diameter (p = 0.0003, p = 0.0008), a greater percent of the culprit artery distal to the stenosis (p = 0.03, p = 0.02) and the presence of any of the following: delayed achievement of patency (i.e., between 60 and 90 min) (p < 0.0001 for both cohorts), a culprit location in the left coronary circulation (left anterior descending or circumflex) (p = 0.02, p < 0.0001), pulsatile flow (i.e., reversal of flow in systole, a marker of heightened microvascular resistance, p = 0.0003, p < 0.0001) and thrombus (p = 0.002, p = 0.03). Despite a minimal 16.4% residual stenosis following stent placement, the mean post-stent CTFC (25.8 +/- 17.2, n = 181) remained significantly slower than normal (21.0 +/- 3.1, n = 78, p = 0.02), and likewise 34% of patients did not achieve a CTFC within normal limits (i.e., <28 frames, the upper limit of the 95th percent confidence interval previously reported for normal flow). Those patients who failed to achieve normal CTFCs following stent placement had a higher mortality than did those patients who achieved normal flow (6/62 or 9.7% vs. 1/118 or 0.8%, p = 0.003).

CONCLUSIONS

Lumen geometry is not the sole determinant of coronary blood flow at 90 min following thrombolytic administration. Other variables such as the location of the culprit artery, the duration of patency, a pulsatile flow pattern and thrombus are also related to slower flow. Despite a minimal 16% residual stenosis, one-third of the patients treated with adjunctive stenting still have a persistent flow delay following thrombolysis, which carries a poor prognosis.

Impaired coronary blood flow in nonculprit arteries in the setting of acute myocardial infarction. The TIMI Study Group. Thrombolysis in myocardial infarction

OBJECTIVES AND BACKGROUND

While attention has focused on coronary blood flow in the culprit artery in acute myocardia infarction (MI), flow in the nonculprit artery has not been studied widely, in part because it has been assumed to be normal. We hypothesized that slower flow in culprit arteries, larger territories infarcted and hemodynamic perturbations may be associated with slow flow in nonculprit arteries.

METHODS

The number of frames for dye to first reach distal landmarks (corrected TIMI [Thrombolysis in Acute Myocardial Infarction] frame count [CTFC]) were counted in 1,817 nonculprit arteries from the TIMI 4, 10A, 10B and 14 thrombolytic trials.

RESULTS

Nonculprit artery flow was slowed to 30.9 +/- 15.0 frames at 90 min after thrombolytic administration, which is 45% slower than normal flow in the absence of acute MI (21 +/- 3.1, p < 0.0001). Patients with TIMI grade 3 flow in the culprit artery had faster nonculprit artery CTFCs than those patients with TIMI grades 0, 1 or 2 flow (29.1 +/- 13.7, n = 1,050 vs. 33.3 +/- 16.1, n = 752, p < 0.0001). The nonculprit artery CTFC improved between 60 and 90 min (3.3 +/- 17.9 frames, n = 432, p = 0.0001), and improvements were related to improved culprit artery flow (p = 0.0005). Correlates of slower nonculprit artery flow included a pulsatile flow pattern (i.e., systolic flow reversal) in the nonculprit artery (p < 0.0001) and in the culprit artery (p = 0.01), a left anterior descending artery culprit artery location (p < 0.0001), a decreased systolic blood pressure (p = 0.01), a decreased ventriculographic cardiac output (p = 0.02), a decreased double product (p = 0.0002), a greater percent diameter stenosis of the nonculprit artery (p = 0.01) and a greater percent of the culprit artery bed lying distal to the stenosis (p = 0.04). Adjunctive percutaneous transluminal coronary angioplasty (PTCA) of the culprit artery restored a culprit artery CTFC (30.4 +/- 22.2) that was similar to that in the nonculprit artery at 90 min (30.2 +/- 13.5), but both were slower than normal CTFCs (21 +/- 3.1, p < 0.0005 for both). If flow in the nonculprit artery was abnormal (CTFC > or = 28 frames) then the CTFC after PTCA in the culprit artery was 17% slower (p = 0.01). Patients who died had slower global CTFCs (mean CTFC for the three arteries) than patients who survived (46.8 +/- 21.3, n = 47 vs. 39.4 +/- 16.7, n = 1,055, p = 0.02).

CONCLUSIONS

Acute MI slows flow globally, and slower global flow is associated with adverse outcomes. Relief of the culprit artery stenosis by PTCA restored culprit artery flow to that in the nonculprit artery, but both were 45% slower than normal flow.

Estimation of coronary flow reserve using the Thrombolysis In Myocardial Infarction (TIMI) frame count method

A simple and readily available method of estimating coronary flow velocity reserve may have significant clinical value. With use of intracoronary adenosine we documented a very good correlation between coronary flow reserve values obtained with the Thrombolysis In Myocardial Infarction trial frame count method and the invasive Doppler wire (Flowire) technique.

Coronary artery flow ten weeks after myocardial infarction or unstable angina: effects of combined warfarin and aspirin therapy

Forty-three patients presenting with unstable angina or myocardial infarction were randomised double blind to warfarin [target international normalised ratio (INR), 2.0 to 2.5] and aspirin (150 mg) daily or placebo plus aspirin (150 mg) daily. Coronary flow was assessed with the thrombolysis in myocardial infarction (TIMI) flow grade and corrected TIMI frame count (CTFC). Coronary artery flow was reduced (higher CTFC) at baseline in culprit arteries (mean +/-SD, 37.1+/-15.4 frames) compared to nonculprit arteries (22.5+/-6.7 frames, P<0.0001). In patients with a patent artery at follow-up, coronary flow was unchanged after ten weeks of warfarin and aspirin (-2.0+/-19.9 frames) or aspirin alone (3.8+/-10.4 frames, P = 0.20). Patients randomised to aspirin alone were more likely to progress to total occlusion [aspirin, 7 of 19 (37%) vs. warfarin and aspirin, 1 of 24 (4%); P = 0.01). Higher baseline culprit artery CTFC was also associated with an increased risk of late occlusion [+10 frames; odds ratio (OR), 1.65; 95% CI, 1.01 to 2.33]. Coronary flow remained impaired ten weeks after presentation with myocardial infarction or unstable angina. Combination warfarin and aspirin therapy did not improve flow in vessels that remained patent but did reduce the risk of progression to occlusion.

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.