Epicardial Coronary Flow Research Articles

Pharmacological Management of No Reflow During Percutaneous Coronary Intervention

Angiographic no reflow is a recognized phenomenon during percutaneous coronary intervention (PCI). It usually follows successful lesion dilation and, by definition, it represents a reduction in epicardial coronary blood flow in the absence of identifiable dissection, obstruction or distal vessel cut off (indicative of distal embolisation). No reflow appears to be more commonly associated with PCI for acute myocardial infarction and PCI for saphenous vein graft occlusions. While the exact mechanism of no reflow is unknown, theoretical causes include local humoral and microembolic effects leading to microcirculatory dysfunction. As the process is multifactorial, various therapeutic strategies are required in different situations. The present day pharmacological management involves the use of vasodilators including nitrates, verapamil, papaverine, adenosine, nicardipine and sodium nitroprusside, but interestingly a vasoconstrictor like epinephrine may also have a role. Glycoprotein IIb/IIIa platelet receptors antagonist have shown a powerful de-thrombotic effect, and the intracoronary administration appears to be particularly promising. We review the pathogenesis of a reduced epicardial flow during PCI and focus on those drugs that have been studied for the treatment of no reflow. Although no double blind, randomized trial has been conducted to assess any of these agents, or to determine the appropriate dosage, we try to identify some useful conclusions from the published evidence.

Effect of Reactive Hyperemia After Coronary Recanalization on Myocardial Tissue Reperfusion by Thrombolysis In Myocardial Infarction Flow Grade in Acute Myocardial Infarction

Thrombolysis In Myocardial Infarction (TIMI) flow grade is widely used to evaluate myocardial tissue reperfusion in acute myocardial infarction (AMI), but the current grading system is incomplete. Therefore, we clarified the regulation of epicardial coronary flow velocity with the progression of microvascular dysfunction in AMI. We studied 36 patients with first anterior AMI. After intervention, we assessed TIMI flow grade and measured average peak velocity (APV) at baseline and after infusion of adenosine triphosphate (48 microg; baseline and hyperemic APVs, respectively) with a Doppler guidewire. We performed myocardial contrast echocardiography after 2 weeks to assess microvascular integrity (good reflow vs no reflow) and left ventriculography at admission and discharge (24 +/- 2 days) to measure regional wall motion (SD/chord). Patients were classified into 3 groups based on TIMI flow grade and microvascular integrity: TIMI grade 3 flow/good reflow (n = 16), TIMI grade 3 flow/no reflow (n = 12), and TIMI grade 2 flow (n = 8). Baseline APV was comparable in the patients with TIMI grade 3 flow but hyperemic APV was higher in patients with TIMI grade 3 flow/good reflow than in those with TIMI grade 3 flow/no reflow (hyperemic APV 59.3 +/- 25.8 vs 32.8 +/- 8.9 cm/s, p <0.01). All patients with TIMI grade 2 flow showed no reflow and the lowest values of baseline and hyperemic APVs. Regional wall motion at discharge was higher in patients with TIMI grade 3 flow/good reflow than in those with TIMI grade 3 flow/no reflow and TIMI grade 2 flow (-1.44 +/- 0.70, -2.69 +/- 0.31, and -2.88 +/- 0.48 SD/chord, respectively, p <0.01). In conclusion, compensatory reactive hyperemia preserves epicardial coronary flow velocity even in patients with microvascular damage, and with the progression of damage, this compensatory hyperemia can no longer preserve epicardial coronary flow velocity, and baseline APV is decreased in TIMI grade 2 flow.

Behavior of both epicardial and intramural coronary artery flow velocities in various models of myocardial hypertrophy: Role for left ventricular outflow tract obstruction

The assessment of coronary flow velocity is becoming crucial in the diagnosis and management of several cardiac dysfunctions and conventional Doppler echocardiography is currently the technique most widely used for detecting their abnormalities noninvasively. We sought to evaluate the differences in coronary flow velocity using conventional transthoracic Doppler echocardiography, measuring both the left anterior descending and such intramural (IM) coronary arteries' flow, among the following 4 categories of patients with myocardial hypertrophy: group A, obstructive hypertrophic cardiomyopathy (n = 12); group B, nonobstructive hypertrophic cardiomyopathy (n = 10); group C, left ventricular hypertrophy (LVH) due to hypertension (n = 10); and group D, LVH due to aortic valve stenosis (n = 10). No significant difference between the 4 groups was found with respect to the left anterior descending velocity. Diastolic peak (P < .01) and mean (P < .05) velocities in the IM arterioles were significantly higher in patients from groups A and D than in groups B and C. At multivariate analysis, both dynamic (group A) and fixed (group D) systolic peak gradients, measured by continuous wave Doppler sampling through the left ventricular (LV) outflow tract or the aortic valve, respectively, were found to be major determinants of the IM diastolic velocity, independently on the LV mass. About 75% of patients with obstructive hypertrophic cardiomyopathy showed IM peak and mean velocity >100 cm/s and >70 cm/s, respectively (P = .005). These findings likely suggest [corrected] a role for the LV systolic obstruction within the intricate adaptive mechanisms of coronary blood flow to LVH.

Infarct angioplasty: beyond stents and glycoprotein IIb/IIIa inhibitors

The primary goal of treatment in acute myocardial infarction is to salvage jeopardised myocardium, preserve ventricular function, and improve long term survival.1 Since de Wood’s landmark observations ushered in the...

How should we evaluate an open artery in STEMI patients?

This editorial refers to ‘Ageing, impaired myocardial perfusion, and mortality in patients with ST-segment elevation myocardial infarction treated by primary angioplasty’† by G. De Luca et al. , on page 662, and ‘Combined prognostic utility of ST-segment recovery and myocardial blush after primary percutaneous coronary intervention in acute myocardial infarction’‡ by P. Sorajja et al. , on page 667 Acute ST-elevation myocardial infarction (STEMI) is a major cause of mortality and morbidity. After plaque rupture and intracoronary thrombus formation, ischaemia causes damage to myocytes and coronary microcirculation soon after occlusion. In the 1980s, mortality reduction with thrombolytic therapy generated a new standard of care for medical treatment of patients with STEMI. However, fibrinolytic therapy is limited by inadequate epicardial patency, and subsequently it has been shown that mechanical revascularization of the infarct-related coronary artery offers an even greater clinical benefit to patients with STEMI. Thus, the goal of reperfusion treatment in patients with STEMI is to re-establish a patent infarct-related epicardial artery as soon as possible. The Thrombolysis In Myocardial Infarction (TIMI) group has categorized epicardial coronary flow into four grades (0–3) to standardize the angiographic characterization of reperfusion. The restoration of TIMI flow grade 3 (normal epicardial flow) in patients with STEMI is associated with improved survival and enhanced recovery of left ventricular function. This observation has led to the ‘Open artery theory’ explanation that restoration of TIMI flow grade 3 has been used as the gold standard for reperfusion success. However, the angiographic picture only gives an acute image of the flow in the epicardial artery and, therefore, a normal TIMI flow … *Corresponding author. Tel: +46 8 585 817 33; fax: +46 8 585 867 10. E-mail address : stefan.agewall{at}karolinska.se

Reperfusion of myocardium does not necessarily equate with epicardial coronary artery blood flow

Reperfusion of myocardium does not necessarily equate with epicardial coronary artery blood flow

Prognostic implication of ST-segment resolution following primary percutaneous transluminal coronary angioplasty for ST-elevation acute myocardial infarction.

ST-segment changes have been shown to correlate with myocardial tissue perfusion. Complete ST-segment resolution after thrombolysis in acute myocardial infarction is associated with lower mortality and better left ventricular function. Primary percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction restores better epicardial coronary flow to the infarct-related artery than thrombolysis. However, ST changes may persist and flow can remain poor despite a patent vessel. To examine the prognostic implication of ST-segment resolution immediately following primary and rescue PTCA for ST-elevation acute myocardial infarction (STEMI). Records of 201 consecutive primary and rescue PTCA performed at Westmead Hospital for STEMI from January 2000 to December 2001 were reviewed. ST-segment elevation (taken 20 ms after the end of the QRS complex) was measured immediately before and after the procedure. ST-segment resolution of greater than 70% after the procedure was considered as -'complete' ST-segment resolution, whereas ST-segment resolution of less than 70% was considered as 'incomplete' ST-segment resolution. Of the 201 patients, 117 (58%) had complete ST-elevation resolution and 84 (42%) did not. There was a significant difference in survival free of major adverse cardiovascular events; 60% of those with complete ST-segment resolution were event-free at 2 years compared with 35% of those patients without complete ST-segment resolution. ST-segment resolution after primary and rescue PTCA for STEMI is associated with significantly higher event-free survival. The goal of primary angio-plasty should be the restoration of normal epicardial flow with normalization of ST-segments.

Coronary and myocardial angiography: angiographic assessment of both epicardial and myocardial perfusion.

Angiographic assessment of epicardial coronary artery blood flow has played a pivotal role in our understanding of the “time-dependent open artery hypothesis” and in the evaluation of reperfusion strategies over the past 2 decades.1–8 It has become increasingly apparent, however, that clinical outcomes are not only associated with angiographic flow in the epicardial artery, but also with angiographic flow in the myocardium.9–13 To this end, the goal of reperfusion therapies has shifted to include reperfusion downstream at the level of capillary bed, and it might be more appropriate that the hypothesis now be termed “the time dependent open artery and open microvascular hypothesis.” The goal of this article is to review angiographic methods used to evaluate myocardial ischemia and infarction and to discuss the insights into the pathophysiology of acute coronary syndromes provided by these angiographic indexes of coronary artery blood flow and myocardial perfusion. For nearly 2 decades now, the Thrombolysis In Myocardial Infarction (TIMI) flow grade classification scheme has been successfully used to assess coronary blood flow in acute coronary syndromes1 (Table). It has been a valuable tool to compare angiographic outcomes following reperfusion, and the association of the TFGs with clinical outcomes (including mortality) has been well documented.2–8 The relationship between TFG and mortality does satisfy what some consider to be 3 criteria required to validate a surrogate end point for mortality, as follows: (1) There is an association between TIMI grade 3 flow and mortality, (2) an agent such as recombinant tissue plasminogen activator improves TIMI grade 3 flow by 22% over another agent such as streptokinase, and (3) the agent tissue plasminogen activator improves mortality 1.1% over streptokinase. View this table: Definitions of the TFG and the TMPG Systems On the basis of this relationship between TIMI flow and mortality observed in the GUSTO …

Echocardiographic Predictors of Remote Outcome in Patients With Angiographically Successful Reflow After Acute Myocardial Infarction

The angiographically no-reflow phenomenon after percutaneous coronary intervention (PCI) predicts poor left ventricular (LV) functional recovery and a high risk of cardiac events in patients with their first acute myocardial infarction (AMI). However, risk factors of long-term adverse outcome for patients with angiographically successful reflow (TIMI (Thrombolysis in Myocardial Infarction) flow grade 3) for the AMI remain unknown. Of 168 echocardiograms were performed before PCI and at discharge, 113 were suitable for analysis. Clinical, angiographic, and echocardiographic variables were submitted to statistical analysis to detect the risk factors of cardiac events. During the follow-up period of 46+/-20 months, 31 patients had cardiac events, though there were no cardiac deaths. The 2 most important risk factors for congestive heart failure (CHF) or total cardiac events were LV dilation (chi-square: 7.5 and 9.4; both p<0.01) and pseudonormal transmitral flow pattern (PN, chi-square: 4.9, p<0.05 and 6.7, p<0.01, respectively). However, only multivessel disease (chi-square: 9.4, p=0.05) became the predictor for revascularization after PCI. The incidence of CHF or total cardiac events in patients with PN and LV dilation at discharge determined by the Kaplan-Meier method were significantly higher than those with normal or abnormal relaxation transmitral flow pattern (log-rank: 41 and 27, both p<0.001) and no LV dilation (log-rank: 20 and 20, both p<0.001). Poor LV diastolic function and LV dilation at discharge are predictors of the cardiac events in patients in whom epicardial coronary flow was well-restored after PCI for the first AMI.

The Diagnostic Usefulness of Cardiovscular Magnetic Resonance Imaging for Non-Ischemic Myocardial Injury : The Value of the Endocardial Sparing Pattern on Delayed Enhancement

Background and Objectives:Cardiovascuar MR using contrast enhancement has recently been reported to be useful for diagnosing myocarditis. It is also well known that irreversible myocardial injury by epicardial coronary artery flow obstruction spreads from the endocardium to the epicardium in a wave-front pattern with a time-dependent manner. We investigated characteristics of the patterns of contrast-enhanced MR imaging according to the underlying myocardial injury mechanism. Subjects and Methods:Of all 275 patients who underwent coronary angiogram at our hospital due to cheat pain and elevated cardiac enzymes between October, 2002 and August, 2003, 48 patients who underwent cardiac MR were enrolled in this study. We retrospectively analyzed the pattern of delayed hyperenhancement according to presence or absence of a documented infarct related artery. Endomyocardial biopsies were done in selected patients. Results:Contrast MR images of all patients showed delayed hyperenhancement. The study group was divided into 2 groups according to whether the areas of hyper-enhancement were involved in the sub-endocardial portion (endocardial sparing pattern, ESP) or not. In 8 patients (Group A, 17%) who showed the endocardial sparing pattern on contrast MR, the findings of coronary angiogram were all normal. In 40 patients (Group B, 83%), who did not show the endocardial sparing pattern on contrast MR, 39 patients (97.5 %) had an infarct related artery on coronary angiogram (p=0.001). Endomyocardial biopsies were performed in 3 patients of group A. The findings of the 3 biopsies were 2 cases of definite myocarditis and 1 case of myocardial degeneration. Conclusion:The endocardial sparing pattern of myocardial injury demonstrated by delayed enhancement MR imaging was very useful to predict the presence of an infarct related artery in patients with myocardial necrosis that has been determined by elevated cardiac enzymes. This result can be a useful clue to determine the nature of the underlying injury mechanism such as ischemic or non-ischemic. (Korean Circulation J 2004;34(12):1174-1181)

Emerging, noninvasive surrogate markers of atherosclerosis.

Noninvasive surrogate markers of atherosclerosis allow the physician to identify subclinical disease before the occurrence of adverse cardiovascular events, thereby limiting the need to perform invasive diagnostic procedures. Imaging modalities, such as carotid artery ultrasound, two-dimensional echocardiography, coronary artery calcium imaging, cardiac magnetic resonance imaging, ankle-brachial indices, brachial artery reactivity testing, and epicardial coronary flow reserve measurements, provide information that may improve the predictive value of a person's risk of developing clinically significant atherosclerotic disease. Newer imaging modalities have also emerged to bring insight into the pathophysiology and treatment of atherosclerosis.

Effects of a distal protection device during primary stenting in patients with acute anterior myocardial infarction.

The angiographic no-reflow phenomenon is an adverse prognostic factor in patients with acute myocardial infarction (AMI). The aim of the present study was to evaluate the effects of an occlusive balloon type distal protection device (PercuSurge GuardWire: GW) during primary stenting in patients with anterior AMI. The GW group included 42 patients treated by primary stenting with GW protection and the control group included 30 patients treated by primary stenting after thrombectomy without distal protection. Left ventricular (LV) function was measured and compared by left ventriculography obtained soon after percutaneous coronary intervention (PCI) and 3 weeks after onset. The corrected TIMI frame count values were lower in the GW group than in the control group (27.5+/-2.3 vs 35.1 +/-2.5, p=0.030). The number of patients with myocardial blush grade 3 after PCI was higher in the GW group than in the control group (45.7 vs 20.0%, p=0.029). Peak concentration of creatine kinase myocardial fraction was lower in the GW group than in the control group (326.6+/-41.5 vs 454.9+/-46.2 mg/dl, p=0.043). GW patients showed greater improvement at 3 weeks after PCI in terms of LV ejection fraction (+4.6+/-1.2 vs -1.1+/-1.5, p=0.004), LV end-systolic volume index (+0.5+/-2.4 vs +9.0+/-2.7, p=0.023), and regional wall motion abnormalities (-2.03+/-0.14 vs -2.51+/-0.14, p=0.018). Primary stenting with GW protection can restore epicardial coronary flow and myocardial perfusion, and also preserve LV function in anterior AMI.

Myocardial contrast echocardiography in the assessment of pharmacologic intervention of the reperfusion injury

See doi:10.1053/S1095-668X(02)00318-4for the article to which this editorial refers. Treatment of patients with an acute myocardial infarction (AMI) aims at timely restoration of adequate flow in the infarct related coronary artery. Percutaneous coronary intervention (PCI) has been shown to be superior compared to thrombolysis in terms of achieving immediate and long term patency of the epicardial artery. The adequacy of myocardial perfusion in acute infarction, however, also depends on the integrity of the distal circulation. In recent years, it has become clear that in a substantial percentage of patients, even in the presence of adequate epicardial coronary flow, lack of microvascular reperfusion may be observed.1 This event has been described as theno-reflow phenomenon. In this situation distalembolization of platelet aggregates, release ofvasoconstrictive platelet mediators and/or microvascular reperfusion injury due to cardiac inflammatory responses, compromise the perfusion at the microcirculatory level.2,3 In this issue, Petronio et al.4 describe the effect of abciximab on microvascular perfusion and recovery of left ventricular function …

Reduced atrial blood flow in patients with coronary artery disease

The thrombolysis in myocardial infarction (TIMI) frame count and TIMI perfusion grade are measures of epicardial and microvascular ventricular coronary artery blood flow, respectively. Similar angiographic methods for measuring atrial coronary artery blood flow have not been developed. To utilize two new angiographic measures of atrial blood flow (ABF), the atrial frame count (AFC) and the atrial perfusion score (APS), to determine whether ABF differs between patients with and without coronary artery disease (CAD). The AFC was defined as the number of frames for dye to reach standardized, distal atrial arterial landmarks during coronary angiography. The APS was utilized as a measure of microvascular atrial perfusion. AFCs were measured in 36 patients prior to isolated coronary artery bypass grafting (CABG), isolated valve surgery or in control patients (with neither CAD nor valvular disease). Sinus node artery and left atrial branch AFCs were higher (that is, ABF was reduced) in patients with CAD undergoing CABG than in those undergoing valve surgery (P < 0.05) or in control patients (P < 0.05). The APS was reduced in 63% of CAD patients but in only 5% of those without CAD (P < 0.001). The severity of CAD was a significant predictor of decreased ABF independent of the degree of proximal epicardial stenosis (P < 0.03). ABF is measurable with the AFC and APS. A significant reduction in ABF is present in patients with CAD undergoing CABG compared to patients without CAD. This reduction appears to be related to the overall severity of CAD independent of the degree of proximal stenosis.

Relation of initial platelet counts to Thrombolysis In Myocardial Infarction-3 flow rates at 90 minutes after commencing fibrinolytic therapy in patients with acute myocardial infarction

In our previous study of patients with a first acute myocardial infarction (AMI) recruited into the Hirulog Early Reperfusion/Occlusion (HERO-1) trial, the independent predictors of Thrombolysis In Myocardial Infarction (TIMI)-3 flow at 90 minutes after the commencement of streptokinase were younger age, shorter time duration from symptom onset to treatment, and absence of initial Q waves. 1 Wong C.K. French J.K. Alyward P.E. Frey M.J. Adgey A.A.J. White H.D. Usefulness of the presenting electrocardiogram in predicting successful reperfusion with streptokinase in acute myocardial infarction. Am J Cardiol. 1999; 83: 164-168 Abstract Full Text Full Text PDF PubMed Scopus (39) Google Scholar In this study, we investigated whether the initial platelet count was independently related to early epicardial coronary flow after controlling for these known predictors and other hematologic parameters, including white blood cell counts.

Endogenous nitric oxide prevents myocardial ischemia in patients with hypertension and left ventricular hypertrophy

Background Left ventricular hypertrophy (LVH) caused by chronic pressure overload is associated with increased risk of myocardial ischemia without epicardial coronary artery disease. We aimed to test the hypothesis that endogenous nitric oxide (NO) prevents myocardial ischemia in patients with LVH. Methods Epicardial coronary blood flow (Doppler wire and quantitative coronary arteriography) and myocardial lactate metabolism (paired arterial and coronary sinus blood sampling) were measured in 12 patients with hypertension, LVH, and angiographically normal epicardial coronary arteries and in 7 control subjects. Measurements were done under 3 pacing protocols: with no treatment (control), with intracoronary N G-monomethyl-L-arginine (L-NMMA; NO synthesis inhibitor), and with intracoronary L-arginine (NO substrate). Results In control subjects the myocardial lactate extraction ratio was normal and stable during the 3 pacing protocols. In contrast, lactate uptake was significantly decreased from 0.21 ± 0.05 to 0.10 ± 0.06 ( P <.05) during L-NMMA pacing in patients with LVH; in 6 of them, lactate production was demonstrated. After L-arginine administration, the lactate extraction ratio during pacing was normalized (0.18 ± 0.04) and lactate production was not observed in any patient. The level of myocardial lactate uptake at peak pacing after L-NMMA was correlated with that under untreated condition ( P <.0001). Conclusions In patients with hypertension, LVH, and angiographically normal coronary arteries, inhibition of endogenous NO synthesis in the coronary circulation unmasked myocardial ischemia during tachycardia, and L-arginine reversed the adverse effects of L-NMMA. Although the precise mechanism remains to be determined, our results suggest that constitutive NO in the coronary circulation plays an anti-ischemic role in this population. (Am Heart J 2002;143:684-9.)

Impact of normalized myocardial perfusion after successful angioplasty in acute myocardial infarction

ObjectivesWe sought to evaluate and validate the ability of the angiographic myocardial blush grade to risk stratify patients after successful angioplasty in acute myocardial infarction (AMI). BackgroundAlthough epicardial Thrombolysis In Myocardial Infarction (TIMI)-3 flow is restored in >90% of patients undergoing primary percutaneous coronary intervention (PCI), normal myocardial perfusion may be present less frequently and may detrimentally impact survival. MethodsA cohort of 173 consecutive patients undergoing intervention within 24 h of AMI onset were studied. High-risk features of this population included failed thrombolysis in 39%, cardiogenic shock in 17% and saphenous vein graft culprit in 11% of patients. ResultsDespite the restoration of TIMI-3 flow in 163 (94.2%) patients, myocardial perfusion, as evidenced by normal contrast opacification of the myocardial bed subtended by the infarct artery (myocardial blush), was normal in only 29.4% of patients with TIMI-3 flow following PCI, and in no patient with TIMI 0 to 2 flow. In patients in whom TIMI-3 flow was restored, survival was strongly dependent on the myocardial perfusion grade; one-year cumulative mortality was 6.8% with normal myocardial blush, 13.2% with reduced myocardial blush and 18.3% in patients with absent myocardial blush (p = 0.004). ConclusionsAbnormal myocardial perfusion is present in most patients following primary or rescue PCI in AMI, despite restoration of brisk epicardial coronary flow. In high risk patients achieving TIMI-3 flow after intervention, the myocardial blush score may be used to stratify prognosis into excellent, intermediate and poor survival. Further study is warranted to examine whether adjunctive mechanical or pharmacologic strategies can further improve myocardial perfusion and survival of patients with acute myocardial infarction undergoing intervention.

Relationship of creatine kinase-myocardial band release to Thrombolysis in Myocardial Infarction perfusion grade after intracoronary stent placement: An ESPRIT substudy

Background The etiology of creatine kinase-myocardial band (CK-MB) release after percutaneous coronary intervention (PCI) remains unclear. The goal of this study was to evaluate the relationship of both epicardial and tissue level perfusion at the completion of stent placement to CK-MB release after the procedure. Given the high rates of Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow after PCI, we hypothesized that abnormalities in tissue level perfusion would instead explain CK-MB release. Methods Data were drawn from the angiographic substudy of the Enhanced Suppression of the Platelet IIb/IIIa Receptor With Integrilin Therapy (ESPRIT) trial of eptifibatide versus placebo in patients undergoing planned coronary stent implantation. In the substudy, cinefilms of 65 patients were analyzed by an angiographic core laboratory blinded to enzymatic and clinical outcomes. Results The release of CK-MB was not associated with TIMI grade 3 flow or the corrected TIMI frame count; 100% of patients had TIMI grade 3 flow at the completion of PCI. In contrast, tissue level perfusion using the TIMI myocardial perfusion grade (TMPG) was related to postintervention CK-MB release: patients with a closed myocardium (TMPG 0/1) or delayed myocardial perfusion (TMPG 2) had an average CK-MB release 2.2 ± 2.7 times the upper limit of normal (n = 34), whereas those patients with normal myocardial perfusion (TMPG 3, n = 24) had CK-MB 0.8 ± 0.6 times the upper limit of normal (P =.01). Although no patients with TMPG 3 sustained death/myocardial infarction/urgent target vessel revascularization or thrombotic bailout, 17.7% of patients with TMPG 0/1/2 did by 48 hours (P =.037). Conclusions Impaired tissue level perfusion as assessed by the TMPG and not epicardial coronary blood flow is associated with CK-MB elevation after PCI. These data provide a pathophysiologic link between impaired tissue level perfusion, post-PCI infarction, and adverse clinical outcomes. (Am Heart J 2002;143:106-10.)

Predictors and prognosis of suboptimal coronary blood flow after primary coronary angioplasty in patients with acute myocardial infarction

We hypothesized that certain clinical and angiographic characteristics on presentation predict suboptimal infarct artery flow after percutaneous intervention during acute myocardial infarction (AMI). The goal of angioplasty (percutaneous transluminal coronary angioplasty [PTCA]) during AMI is the prompt restoration of normal flow to achieve myocardial reperfusion. However, inadequate epicardial coronary flow is observed in 10% to 20% of patients. From 2 large randomized trials—Global Use of Strategies To open Occluded arteries in Acute Coronary Syndromes-IIb, and Randomized Placebo-Controlled Trial of Platelet glycoprotein IIb/IIIa Blockade With Primary Angioplasty for Acute Myocardial Infarction—patients undergoing primary PTCA during AMI were included in the analysis. A multivariate logistic model was used to identify factors associated with final Thrombolysis In Myocardial Infarction (TIMI) flow grade ≤2. The 891 patients were aged (mean ± SD) 61 ± 12 years, 75% were men, and 39% had an anterior wall AMI. Patients underwent PTCA within 4.8 ± 3.2 hours from the onset of chest pain. The incidence of final TIMI 3 flow was 81%. TIMI flow grade ≤2 was independently associated with increasing age (odds ratio [OR] 1.39 for every 10 years, 95% confidence interval [CI] 1.19 to 1.62), increasing heart rate (OR 1.16 for every 10 beats, 95% CI 1.05 to 1.28), and presence of visible thrombus on baseline angiogram (OR 1.89, 95% CI 1.18 to 3.05). Conversely, baseline TIMI 2 or 3 flow grade (OR 0.46, 95% CI 0.28 to 0.75) and left circumflex intervention (OR 0.42, 95% CI 0.23 to 0.79) correlated with normal postprocedural coronary flow. Mortality was significantly higher in patients with TIMI ≤2 than TIMI 3 flow grade (10.2% vs 1.5%, p <0.001, respectively). Thus, angiographic evidence of thrombus and 2 pivotal clinical characteristics, advanced age and elevated heart rate, predict lack of adequate coronary reperfusion. Conversely, the presence of normal or near-normal coronary flow before intervention correlates with a good angiographic result. Mortality risk is increased in patients with postprocedural suboptimal angiographic coronary flow.

Pharmacological preconditioning with the adenosine triphosphate–sensitive potassium channel opener pinacidil

Background. Ischemic preconditioning (IPC) decreases infarct size after global or regional ischemia. Potassium channel openers also precondition but are subject to dose-limiting vasodilation. We compared the mechanical and electrophysiological effects of ischemic and pharmacological preconditioning in an isolated rabbit heart model. Methods. Rabbit hearts were preconditioned with either 10 μmol/L pinacidil alone (P−), 10 μmol/L pinacidil with 10 μmol/L phenylephrine (P+), or two cycles of global ischemia and reperfusion (IPC) before 1 hour of LAD occlusion. Left ventricular pressure, epicardial monophasic action potential duration (APD) and coronary flow were monitored throughout. Infarct size was determined at the end of reperfusion. Results. Regional ischemia uniformly decreased APD ( p < 0.05). During reperfusion, APDs were prolonged beyond preischemic values in all preconditioned groups ( p < 0.05). P− and P+ reduced the incidence of fibrillation. P− significantly increased coronary flow (+15%, p = 0.001), whereas IPC and P+ did not. However, IPC and P− significantly decreased systolic function ( p < 0.05) but P+ did not. In addition, IPC depressed diastolic function ( p < 0.05) but P− and P+ did not. Infarct size was reduced by all methods ( p < 0.05). Conclusions. Pinacidil presents a safe and effective alternative to IPC for preserving the heart during regional ischemia. Its coronary vasodilatory effects are safely and effectively reversed by the addition of phenylephrine.