Clinical significance of pressure measurement in the infarct-related coronary artery in acute myocardial infarction: evaluation of variables predicting recovery of left ventricular function in the convalescent stage

Early reperfusion and good antegrade flow are essential in restoring better regional left ventricular function in acute myocardial infarction, but they do not always correlate with the extent of recovery. This study evaluated coronary circulation using the new "pressure wire" technique to measure the direct pressure of the coronary circulation including antegrade and collateral flow before and after reperfusion in patients with acute myocardial infarction, and to clarify the influence of these variables on recovery of left ventricular function in the convalescent stage. Fifty six consecutive patients with first acute myocardial infarction underwent percutaneous transluminal coronary angioplasty(PTCA) for totally occluded or severely narrowed infarct-related lesion and evaluation of coronary circulation using pressure wire. Left ventriculography was analyzed at 1 month after the onset in 41 patients. Treatment variables including reperfusion time, reperfusion modality, Thrombolysis in Myocardial Infarction(TIMI) grade after PTCA, and pressure wire variables were compared with parameters of left ventricular function. Reperfusion time was not related to regional wall motion evaluated by the SD chord of left ventriculography in the infarcted zone. Pressure wire measurements showed a correlation between fractional flow reserve measured after PTCA and infarcted regional wall motion(r = 0.558, p < 0.01). Patients with infarct-related lesion in the right coronary artery showed the magnitude of left ventricular regional wall motion was related to fractional collateral flow reserve(maxQc/Qn) during PTCA(r = 0.768, p < 0.05), but no such relationship was observed in patients with infarct-related lesion in the left anterior descending artery. Fractional flow reserve measured after PTCA varied widely in patients with the same TIMI flow grade, so did not vary with it. The pressure wire technique enables assessment of the collateral circulation distal to infarct-related lesion quantitatively before reperfusion in patients with acute myocardial infarction. The fractional flow reserve derived by coronary pressure after reperfusion was significantly related to the recovery of regional wall motion in the infarcted area in the convalescent stage. The fractional flow reserve after reperfusion with PTCA is a better parameter than TIMI flow grade for predicting recovery of regional left ventricular function after myocardial infarction.     

Time course of microvascular resistance of the infarct and noninfarct coronary artery following an anterior wall acute myocardial infarction

Previous studies have suggested that coronary flow velocity reserve (CFVR) in the early phase of acute myocardial infarction (AMI) is abnormal in infarcted and remote regions. This study determined the coronary microvascular resistance of infarct-related arteries (IRAs) and non-IRAs during AMI and at follow-up in patients who were treated with primary percutaneous intervention. In 73 patients with a first anterior wall AMI, baseline and minimal microvascular resistance in IRAs and non-IRAs immediately after reperfusion and at 1-week and 6-month follow-up were calculated as the ratio of mean transvascular pressure gradient to mean baseline and to adenosine-induced hyperemic blood flow velocity, respectively. CFVR in IRAs increased from 1.6 +/- 0.4 after reperfusion to 1.9 +/- 0.5 at 1 week and to 3.0 +/- 0.8 at 6 months (p <0.0001) and in non-IRAs from 2.4 +/- 0.5 to 2.7 +/- 0.6 at 1 week to 3.3 +/- 0.6 at 6 months (p <0.0001). Minimal microvascular resistance in IRAs and non-IRAs (3.2 +/- 1.7 and 2.2 +/- 0.6 mm Hg/second/cm, respectively) decreased significantly at follow-up (2.0 +/- 0.6 and 1.7 +/- 0.6 mm Hg/second/cm at 1 week and 1.8 +/- 0.6 and 1.8 +/- 0.7 mm Hg/second/cm at 6 months, respectively). After correction for rate-pressure product, baseline microvascular resistance after reperfusion and at 6 months did not significantly differ between IRAs and non-IRAs. In conclusion, minimal microvascular resistance is higher in infarcted and noninfarcted regions during AMI than at follow-up. The low CFVR in remote regions during AMI is probably due more to disturbed autoregulation than to increased myocardial workload.     

心肌呈色分级评价急性心肌梗死溶栓疗法的疗效

目的以心肌呈色分级(MBG)评估急性心肌梗死溶栓后的心肌灌注状况.方法89例急性心肌梗死患者给予重组组织型纤溶酶原激活剂治疗.各例于给药后90分钟行冠状动脉造影,观察梗死相关动脉前向血流,评估心肌灌注情况,并记录6个月心脏事件发生率.结果溶栓后符合临床再通标准的为87.6%,未再通的为12.4%.冠状动脉造影结果显示,全组梗死相关动脉的再通率(TIMI 2或3级)为82%;心肌再灌注率(MBG 2或3级)为88.8%,完全再通(TIMI 3级)且完全心肌再灌注(MBG 3级)者为40.4%.6个月死亡率为10.1%.多因素分析结果表明,入院时Killip分级和MBG分级是急性心肌梗死死亡的主要独立预测因子(P=0.0001).结论成功的再灌注治疗应该是梗死相关动脉前向血流TIMI 3级且伴良好心肌灌注.     

Secretome of apoptotic peripheral blood cells (APOSEC) attenuates microvascular obstruction in a porcine closed chest reperfused acute myocardial infarction model: role of platelet aggregation and vasodilation

Although epicardial blood flow can be restored by an early intervention in most cases, a lack of adequate reperfusion at the microvascular level is often a limiting prognostic factor of acute myocardial infarction (AMI). Our group has recently found that paracrine factors secreted from apoptotic peripheral blood mononuclear cells (APOSEC) attenuate the extent of myocardial injury. The aim of this study was to determine the influence of APOSEC on microvascular obstruction (MVO) in a porcine AMI model. A single dose of APOSEC was intravenously injected in a closed chest reperfused infarction model. MVO was determined by magnetic resonance imaging and cardiac catheterization. Role of platelet function and vasodilation were monitored by means of ELISA, flow cytometry, aggregometry, western blot and myographic experiments in vitro and in vivo. Treatment of AMI with APOSEC resulted in a significant reduction of MVO. Platelet activation markers were reduced in plasma samples obtained during AMI, suggesting an anti-aggregatory capacity of APOSEC. This finding was confirmed by in vitro tests showing that activation and aggregation of both porcine and human platelets were significantly impaired by co-incubation with APOSEC, paralleled by vasodilator-stimulated phosphoprotein (VASP)-mediated inhibition of platelets. In addition, APOSEC evidenced a significant vasodilatory capacity on coronary arteries via p-eNOS and iNOS activation. Our data give first evidence that APOSEC reduces the extent of MVO during AMI, and suggest that modulation of platelet activation and vasodilation in the initial phase after myocardial infarction contributes to the improved long-term outcome in APOSEC treated animals.     

Impact of spontaneous anterograde flow of the infarct artery on left ventricular function in patients with a first anterior wall acute myocardial infarction

To assess the impact of spontaneous anterograde flow of the infarct artery on outcomes in patients with acute myocardial infarction (AMI), we studied 478 patients with a first anterior wall AMI who underwent coronary angiography within 12 hours after the onset of chest pain; Thrombolysis In Myocardial Infarction (TIMI) 3 flow was obtained after reperfusion therapy. Patients were divided into 3 groups: 119 patients with spontaneous anterograde flow (initial TIMI 2 or 3 flow) of the infarct artery, 118 patients with an initially occluded artery (TIMI 0 or 1 flow) and time to angiography or=55% (odds ratio 7.13, 95% confidence interval 3.10 to 16.4, p <0.001). In conclusion, although very early reperfusion improved LV function more than late reperfusion, spontaneous anterograde flow was associated with better acute and predischarge LV function after AMI compared with very early reperfusion of an initially occluded artery.     

The use of myocardial contrast echocardiography in clinical evaluation after myocardial infarction

Because disruption of the microvasculature is a hallmark of myocyte necrosis, MCE may be able to distinguish between viable and infarcted tissue. In order to interpret images appropriately following myocardial infarction, however, one should be versed in the pathophysiology of post-ischemic reflow, and understand that reperfusion to infarcted tissue is a heterogeneous combination of hyperemia, low-reflow, no-reflow, and impaired microvascular flow reserve. Furthermore, the relative mix of these perfusion patterns changes both temporally and spatially, which has implications for the timing of MCE following reperfusion. The identification of no- and low-reflow by MCE predicts regions unlikely to demonstrate segmental functional recovery, and is associated with adverse clinical events. To date, studies documenting the utility of MCE in the AMI setting have been performed using intracoronary injections in the cardiac catheterization laboratory. With the advent of intravenous contrast agents and innovations in ultrasound imaging systems, it may be possible to make these determinations without the need for coronary instrumentation, thus expanding the role of MCE in acute infarction and reperfusion to settings such as the emergency room and intensive care unit.     

Selective thrombolytic patency of the coronary arteries in patients with acute myocardial infarction

Urgent selective coronarography followed by intracoronary infusion of nitroglycerin and streptokinase (2000-4000 U/min) was performed in 24 patients with acute myocardial infarction. Mechanical recanalization of an occluded coronary artery was also performed in two patients. The coronary artery supplying the infarcted area was occluded in 22 patients while 2 patients had third-degree stenosis. Following intracoronary drug infusion, antegrade flow was recovered completely in 16 of 22 occluded coronary arteries (72.7%). All patients, however, retained acute coronary arterial stenosis around former occlusions. Aortal-coronary shunting was performed within 1 to 20 days in 6 patients.     

Reperfusion arrhythmias during coronary angioplasty for acute myocardial infarction predict ST-segment resolution

BACKGROUND: Despite early recanalization of an occluded infarct-related artery, myocardial reperfusion may remain impaired due to microvascular injury. Reperfusion arrhythmias may indicate successful microvascular reperfusion. METHODS: Microvascular reperfusion was assessed prospectively in 42 consecutive patients with ST-segment elevation acute myocardial infarction (AMI) by evaluation of the resolution of ST-segment elevation (<50% of initial level) immediately after successful coronary angioplasty. Patients were divided into two groups: those with ST resolution (n=24) and those without ST resolution (n=18). The presence of reperfusion arrhythmias immediately after recanalization was recorded. RESULTS: Patients with ST resolution were younger (54+/-12 years compared with 64+/-17 years, P=0.04), their pain-to-recanalization time was shorter (195+/-87 min compared with 294+/-179 min, P=0.05), they were less often diabetic (13% compared with 24%, P=0.05) and were more often given IIb/IIIa inhibitors (58% compared with 22%, P=0.02). Reperfusion arrhythmias were observed in 15 out of 24 patients with ST resolution (62%) but in only one out of 18 without ST resolution (5%) (P<0.01). Reperfusion arrhythmias included accelerated idioventricular rhythm, 13 (81%); multifocal ventricular premature beats, two (13%); and ventricular tachycardia, one (6%). The sensitivity and specificity of reperfusion arrhythmias for ST resolution were 62 and 95%, respectively. In a logistic regression model including age, time to treatment, diabetes, use of IIb/IIIa inhibitors and reperfusion arrhythmias, only the latter was found to be an independent predictor of ST resolution (P<0.01). CONCLUSION: Reperfusion arrhythmias following coronary angioplasty for AMI are a highly specific marker for ST resolution and may indicate successful microvascular reperfusion.     

急性心肌梗死的治疗进展--从再通到再灌注

对于急性心肌梗死患者冠状动脉的再灌注治疗已得到广泛开展。然而,由于微循环无复流现象的存在,使得梗死相关血管的再通并不完全意味着心肌水平再灌注的实现。几项研究发现,超过 25%的急性心肌梗死患者经成功的溶栓或经皮冠脉介入术后都存在无复流现象,即未达到充分的心肌再灌注。所以,我们应把更多的注意力和研究重点转移到对心肌微循环再灌注的实现,而非冠状动脉的再通。     

Patency of the infarct-related coronary artery and ventricular geometry.

The pathogenesis of acute myocardial infarction (AMI) involves a sudden thrombotic occlusion of a coronary artery. Spontaneous or pharmacologic thrombolysis may lead to myocardial salvage if patency is achieved within a narrow time window. However, patients in whom thrombolysis occurs late seem to demonstrate improved left ventricular (LV) function and prognosis, which may be independent of myocardial salvage. Preservation of normal LV geometry by reducing expansion of the infarcted segment is a likely mechanism for this benefit. Infarct expansion is most pronounced in patients with anterior wall AMI who have a persistently occluded infarct-related vessel. This process of expansion leads to early increases in LV volume and distortions of LV contour (abnormal LV geometry). Patients whose infarct segment is largest, patients who have manifested infarct expansion, and patients with a persistently occluded infarct-related artery are at highest risk for progressive LV dilation. Experimental data support the concept that reperfusion of occluded vessels that occurs too late for myocardial salvage will preserve LV geometry by limiting infarct expansion. Prospective clinical trials should address whether there is a late, "second time window" during which infarct expansion and distortions of LV geometry may be reduced by (1) therapy with thrombolytic agents applied late after infarction, (2) late mechanical reperfusion with percutaneous transluminal coronary angioplasty (PTCA) or related methods, and (3) load-reducing agents to decrease remodeling, such as angiotensin-converting enzyme inhibitors or nitroglycerin.     

通心络持续干预对猪急性心肌梗死再灌注晚期微血管再生的影响

目的研究通心络持续干预对猪急性心肌梗死(AMI)再灌注后7天心肌微血管再生的影响。方法中华小型猪40只,随机分为假手术组、对照组、小剂量(0.1g/kg)、中剂量(0.2g/kg)和大剂量(0.4g/kg)通心络组,每组8只。冠状动脉前降支阻断90 min,再灌注120 min建立缺血再灌注动物模型,各通心络组于冠脉阻断前按双倍常规剂量灌胃给药1次,之后按各常规剂量每日喂食给药至第7天。通过原位杂交检测各组心肌梗死区、边缘区和正常区内皮型一氧化氮合酶(eNOS)和胎肝激酶-1(FLK-1)mRNA水平;Western Blot检测eNOS、FLK-1蛋白表达;免疫组化α-肌动蛋白和血小板内皮黏附分子-1双染色法测定心肌微血管密度。结果与对照组相比,各通心络组显著增加梗死区微血管内皮eNOS和FLK-1 mRNA及蛋白水平表达,同时在梗死区显著增加新生微血管密度,且大剂量通心络疗效更显著。结论持续应用通心络能够促进AMI再灌注后晚期心肌微血管再生,且对梗死区心肌效果更加显著。     

Coronary flow velocity immediately after reperfusion reflects myocardial microcirculation in canine models of acute myocardial infarction

Recent reports indicate that the coronary microcirculation is sometimes injured, despite successful reperfusion in acute myocardial infarction (AMI). However, it is difficult to evaluate the coronary microcirculation immediately after reperfusion by using only angiography. The purpose of this study was to examine the relationship between the pattern of coronary blood flow velocity and myocardial microcirculatory injury immediately after reperfusion in AMI. The authors recorded the left circumflex coronary flow velocity by using the Doppler guide wire method 10 minutes after reperfusion in a canine model of AMI. In addition, myocardial contrast echocardiography was performed with the injection of contrast medium into the left circumflex coronary artery before clamping of the coronary artery and 15 minutes after release of the clamp. From these images, the ratio of the normalized gray-level postreperfusion to preclamping in the contrast-enhanced area was determined. It was compared with coronary flow velocity variables. In the 10 dogs with a diastolic-to-systolic velocity ratio (DSVR) < 4.0, this velocity ratio 10 minutes after reperfusion correlated positively (r = 0.75, p < 0.01) with the normalized gray-level ratio. However, the remaining three dogs with a DSVR > or = 4.0 markedly deviated from this pattern. Coronary flow velocities in the three dogs were characterized by a greater decrease in systolic flow velocity and occurrence of early systolic retrograde flow. Myocardial contrast echocardiographic images in these three dogs demonstrated a lower normalized gray-level ratio. In conclusion, the coronary flow velocity pattern immediately after reperfusion may reflect myocardial microcirculatory injury.     

Intracoronary injection of granulocyte colony-stimulating factor ameliorates the progression of left ventricular remodeling after myocardial ischemia/reperfusion in rabbits.

BACKGROUND: Although granulocyte colony-stimulating factor (G-CSF) is known to prevent left ventricular (LV) remodeling after acute myocardial infarction (AMI), the best method of administration is unknown. METHODS AND RESULTS: A rabbit ischemia/reperfusion model was created and G-CSF was administered into the coronary artery immediately after reperfusion. The LV size and contraction were determined by echocardiography, and the extent of infarcted myocardium was measured by Masson-Trichrome staining. The benefits of intracoronary injection of G-CSF on LV remodeling were similar to subcutaneous injection. CONCLUSIONS: Direct intracoronary G-CSF injection may become a new therapy for AMI with lower adverse effects.     

Increase of myocardial salvage and left ventricular function recovery with intracoronary abciximab downstream of the coronary occlusion in patients with acute myocardial infarction treated with primary coronary intervention.

In this prospective randomized trial on patients with acute myocardial infarction (AMI) treated with primary percutaneous coronary intervention (PCI), we hypothesized that abciximab administered intracoronarily, downstream of the coronary occlusion, leads to a greater degree of myocardial salvage and better left ventricular function recovery compared with the usual abciximab administration. Forty-five consecutive patients with first AMI and infarct-related artery TIMI flow 0-1 undergoing primary PCI were enrolled. Twenty-two patients were randomly assigned to the intracoronary treatment and 23 to the usual treatment. The initial perfusion defect, final infarct size, myocardial salvage, salvage index, and left ventricular function recovery were assessed by serial scintigraphic scans performed at admission and 7 days and 1 month after PCI. Angiographic myocardial blush grade, corrected TIMI frame count, and electrocardiographic ST segment elevation reduction were also assessed as markers of myocardial reperfusion. Final infarct size was significantly smaller (P = 0.043) and salvage index significantly higher (P = 0.003) in the intracoronary treatment group as a result of a greater degree of myocardial salvage (P = 0.0001). The increase of left ventricular ejection fraction at 1 month was significantly higher in the intracoronary treatment patients (P = 0.013). The markers of myocardial reperfusion were also significantly better in the intracoronary treatment group. In patients with AMI and occluded infarct-related artery treated with primary PCI, intracoronary abciximab given just before PCI downstream of the occlusion is associated to a greater degree of myocardial salvage than the usual abciximab protocol. This benefit is mainly related to a substantial reduction in final infarct size, which leads to an improvement in left ventricular ejection fraction.     

Multimodality reperfusion therapy for acute myocardial infarction

With the strong and direct relation between early reperfusion in acute myocardial infarction (AMI) and improved clinical outcomes, attention has focused on new means of improving rates of reperfusion and accelerating every stage of AMI evaluation and management, from the onset of symptoms of myocardial infarction to the achievement of reperfusion. Critical pathways to streamline the evaluation and management of AMI have cut minutes and even hours off in-hospital treatment times for patients with AMI; public health initiatives focus on educational efforts to shorten time to hospital arrival. The latest advance in fibrinolytic therapy is the availability of bolus fibrinolytic agents with safety and efficacy in large phase III trials comparable to accelerated intravenous infusion regimens. Faster and simpler fibrinolytic regimens may shorten door-to-needle time, reduce medication errors, and facilitate prehospital thrombolysis. Bolus fibrinolytic agents are being evaluated for use in combination with other interventions to open occluded coronary arteries, including acute percutaneous coronary intervention, the glycoprotein IIb/IIIa platelet inhibitors, or both. The goal of this "multimodality" approach to AMI management is to minimize time to reperfusion and maximize the percentage of patients who achieve complete arterial patency and myocardial perfusion without bleeding complications.     

Novel Therapeutic Strategies to Reduce Reperfusion Injury After Acute Myocardial Infarction

For almost 30 years, urgent revascularization termed primary percutaneous coronary intervention has been a cornerstone of modern care for acute myocardial infarction (AMI). It lowers mortality and improved cardiovascular outcome compared to conservative therapy including thrombolysis. Reperfusion injury, which occurs after successful re-opening of the formerly occluded coronary artery, had been exploited as a potential therapeutic target. When revascularization became faster and primary percutaneous coronary intervention was successfully performed within 60-90 minutes of symptom onset, the interest in a potential additive effect of targeting reperfusion injury vanished. More recently, several meta-analyses indicated that limiting reperfusion injury prevents microvascular obstruction and reduces final infarct size, thereby lowering the probability of heart failure events and improving quality of life in AMI survivors. Here, we describe the current strategies to limit reperfusion injury and to improve post-AMI outcomes such as systemic or intracoronary hypothermia, left-ventricular unloading, intracoronary infusion of super-saturated oxygen, intermittent coronary sinus occlusion, and C-reactive protein apheresis.     

Relationship between collateral blood flow and microvascular perfusion after reperfused acute myocardial infarction

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

The distinction between coronary and myocardial reperfusion after thrombolytic therapy by clinical markers of reperfusion

Objectives. We sought to examine the hypothesis that rapid resolution of ST-segment elevation in acute myocardial infarction (AMI) patients with early peak creatine kinase (CK) after thrombolytic therapy differentiates among patients with early recanalization between those with and those without adequate tissue (myocardial) reperfusion.Background. Early recanalization of the epicardial infarct-related artery (IRA) during AMI does not ensure adequate reperfusion on the myocardial level. While early peak CK after thrombolysis results from early and abrupt restoration of the coronary flow to the infarcted area, rapid ST-segment resolution, which is another clinical marker of successful reperfusion, reflects changes of the myocardial tissue itself.Methods. We compared the clinical and the angiographic results of 162 AMI patients with early peak CK (≤12 h) after thrombolytic therapy with (group A) and without (group B) concomitant rapid resolution of ST-segment elevation.Results. Patients in groups A and B had similar patency rates of the IRA on angiography (anterior infarction: 93% vs. 93%; inferior infarction: 89% vs. 77%). Nevertheless, group A versus B patients had lower peak CK (anterior infarction: 1,083 ± 585 IU/ml vs. 1,950 ± 1,216, p < 0.01; and inferior infarction: 940 ± 750 IU/ml vs. 1,350 ± 820, p = 0.18) and better left ventricular ejection fraction (anterior infarction: 49 ± 8, vs. 44 ± 8, p < 0.01; inferior infarction: 56 ± 12 vs. 51 ± 10, p = 0.1). In a 2-year follow-up, group A as compared with group B patients had a lower rate of congestive heart failure (1% vs. 13%, p < 0.01) and mortality (2% vs. 13%, p < 0.01).Conclusions. Among patients in whom reperfusion appears to have taken place using an early peak CK as a marker, the coexistence of rapid resolution of ST-segment elevation further differentiates among patients with an opened culprit artery between the ones with and without adequate myocardial reperfusion.     

Contrast echocardiography accurately predicts myocardial perfusion before angiography during acute myocardial infarction

OBJECTIVES: To determine whether myocardial contrast echocardiography (MCE) can quickly and accurately assess myocardial perfusion and infarct-related artery (IRA) patency before emergency angiography during acute myocardial infarction (AMI). BACKGROUND: Despite encouraging experimental and clinical studies, the reliability and practicality of MCE in predicting IRA patency during AMI before angiography has not been proven. METHODS: Two-dimensional echocardiography and MCE were performed in 51 patients with AMI just before emergency angiography. With knowledge of the electrocardiogram findings and regional wall motion, myocardial perfusion was assessed to predict IRA patency. RESULTS: Myocardial perfusion studies were adequate for interpretation in 40 patients. An occluded IRA was predicted in 28 patients; the artery was occluded in 22 patients, and six patients had Thrombolysis In Myocardial Infarction (TIMI) grade 2 flow or less. A patent IRA was predicted in 12 patients; eight patients had TIMI grade 3 flow, one patient had TIMI grade 2 flow and the IRA was occluded in three patients. In one of the three patients, the appropriate view was not obtained. In another patient, collateral flow was adequate for near-normal regional wall motion, and in the last, the findings suggested reperfusion of the proximal artery with distal embolic occlusion. Taken together, MCE accurately predicted either TIMI grade 2 flow or less, or TIMI grade 3 flow in 36 of 40 patients. Sensitivity was 87.5%, specificity and positive predictive value were 100% and negative predictive power was 66.7% (P<0.001). CONCLUSIONS: MCE, together with the electrocardiogram and regional wall motion, can be used to quickly and reliably predict IRA patency early during AMI and may be useful to facilitate a management strategy.     

Persistent ST-segment elevation after primary stenting for acute myocardial infarction: its relation to left ventricular recovery

BACKGROUND: Early restoration of coronary artery patency in acute myocardial infarction (AMI) has been linked to improvement in survival. However, early recanalization of an occluded epicardial coronary artery by either thrombolytic agents or percutaneous transluminal coronary angioplasty (PTCA) does not necessarily lead to left ventricular (LV) function recovery. HYPOTHESIS: The aim of this study was to evaluate the relation between persistent ST elevation shortly after primary stenting for acute myocardial infarction (AMI) and LV recovery. METHODS: Thirty-one patients with primary stenting for AMI were prospectively enrolled. To evaluate the extent of microvascular injury, serial ST-segment analysis on a 12-lead electrocardiogram recording just before and at the end of the coronary intervention was performed. Persistent ST-segment elevation (Persistent Group, n = 11) was defined as > or = 50% of peak ST elevation and resolution (Resolution Group, n = 20) was defined as < 50% of peak ST elevation. Echocardiography was performed on Day 1 and 3 months after primary stenting. RESULTS: At 3 months, infarct zone wall-motion score index (WMSI, 2.1 +/- 0.6 vs. 2.7 +/- 0.3, p < 0.05) was smaller in the Resolution Group than in the Persistent Group, whereas wall motion recovery index (RI, 0.4 +/- 0.3 vs. 0.1 +/- 0.2, p < 0.05) and ejection fraction (58 +/- 5 vs. 43 +/- 10%, p < 0.05) were larger in the Resolution Group than in the Persistent Group. The extent of persistent ST elevation (% ST) shortly after successful recanalization of the infarct-related artery was significantly related to RI at 3 months (r = -0.4, p < 0.05). However, time to reperfusion was not related to RI at 3 months. There was also significant correlation between corrected TIMI frame count and %ST (r = 0.4, p < 0.05). CONCLUSIONS: Persistent ST-segment elevation shortly after successful recanalization (> or = 50% of the peak value), as a marker of impaired microvascular reperfusion, predicts poor LV recovery 3 months after primary stenting for AMI.