Determination of angiographic (TIMI grade) blood flow by intracoronary Doppler flow velocity during acute myocardial infarction

Prognostic role of coronary artery ectasia in patients with nonobstructive coronary artery disease

AIMS

Coronary artery ectasia (CAE) has been linked to the occurrence of adverse events in patients with ischemia/angina and no obstructive coronary arteries (INOCA/ANOCA), while the relationship between CAE and myocardial infarction with nonobstructive coronary arteries (MINOCA) has been poorly investigated. In our study we aimed at assessing differences in clinical, angiographic and prognostic features among patients with CAE and MINOCA vs. INOCA/ANOCA presentation.

METHODS

Patients with angiographic evidence of CAE were enrolled at the University Hospital of Parma and divided into MINOCA vs. INOCA/ANOCA presentation. Clinical and quantitative angiographic information was recorded and the incidence of major adverse cardiovascular events (MACE) was assessed at follow-up.

RESULTS

We enrolled a total of 97 patients: 49 (50.5%) with MINOCA and 48 (49.5%) with INOCA/ANOCA presentation. The presentation with MINOCA was associated with a higher frequency of inflammatory diseases ( P  = 0.041), multivessel CAE ( P  = 0.030) and thrombolysis in myocardial infarction (TIMI) flow < 3 ( P  = 0.013). At a median follow-up of 38 months, patients with MINOCA had a significantly higher incidence of MACE compared with those with INOCA/ANOCA [8 (16.3%) vs. 2 (4.2%), P  = 0.045], mainly driven by a higher rate of nonfatal MI [5 (10.2%) vs. 0 (0.0%), P  = 0.023]. At multivariate Cox regression analysis, the presentation with MINOCA ( P  = 0.039) and the presence of TIMI flow <3 ( P  = 0.037) were independent predictors of MACE at follow-up.

CONCLUSION

Among a cohort of patients with CAE and nonobstructive coronary artery disease, the presentation with MINOCA predicted a worse outcome.

Machine learning-based prediction of infarct size in patients with ST-segment elevation myocardial infarction: A multi-center study

BACKGROUND

Cardiac magnetic resonance imaging (CMR) is the gold standard for measuring infarct size (IS). However, this method is expensive and requires a specially trained technologist to administer. We therefore sought to quantify the IS using machine learning (ML) based analysis on clinical features, which is a convenient and cost-effective alternative to CMR.

METHODS AND RESULTS

We included 315 STEMI patients with CMR examined one week after morbidity in final analysis. After feature selection by XGBoost on fifty-six clinical features, we used five ML algorithms (random forest (RF), light gradient boosting decision machine, deep forest, deep neural network, and stacking) to predict IS with 26 (selected by XGBoost with information gain greater than average level of 56 features) and the top 10 features, during which 5-fold cross-validation were used to train and optimize models. We then evaluated the value of actual and ML-IS for the prediction of adverse remodeling. Our finding indicates that MLs outperform the linear regression in predicting IS. Specifically, the RF with five predictors identified by the exhaustive method performed better than linear regression (LR) with 10 indicators (R² of RF: 0.8; LR: 0). The finding also shows that both actual and ML-IS were independently associated with adverse remodeling. ML-IS ≥ 21% was associated with a twofold increase in the risk of LV remodeling (P < 0.01) compared with patients with reference IS (1st tertile).

CONCLUSION

ML-based methods can predict IS with widely available clinical features, which provide a proof-of-concept tool to quantitatively assess acute phase IS.

Coronary Flow Disturbance Phenomenon After Percutaneous Coronary Intervention Is Associated with New-Onset Atrial Fibrillation in Patients with Acute Myocardial Infarction

Atrial fibrillation (AF) is a common complication of acute myocardial infarction (AMI). Although previous studies have investigated mortality rates and the incidences of adverse events associated with new-onset AF (NOAF) in patients with AMI, the effects of emergency percutaneous coronary intervention (PCI) on the incidence of NOAF in patients with AMI remain unclear. The purpose of this study was to investigate the relationship of clinical characteristics, medical history, and the coronary flow disturbance phenomenon (TIMI < 3) following emergency PCI with NOAF in patients with AMI. Between 2012 and 2016, 731 patients with AMI underwent PCI at our facility. Among these, 52 had a history of chronic/paroxysmal AF before admission and were excluded. The remaining 679 patients (mean age 66.4 years, 532 males) were analyzed in this retrospective observational study.New-onset AF was observed in 45 patients (6.6%). In univariate analysis, the hazard ratios (HRs) for patient age (HR 1.04, 95%CI 1.02-1.07), Killip II-IV (HR 2.34, 95%CI 1.29-4.23), elevated D-dimer level (> 1.0 μg/mL; HR 3.32; 95%CI 1.77-6.23), and coronary flow disturbance phenomenon (HR 5.61; 95%CI 2.88-10.9) were significantly higher in the NOAF group. In multivariate analysis, an elevated D-dimer level (> 1.0 μg/mL; HR 2.44; 95%CI 1.17-5.11) and coronary flow disturbance phenomenon (HR 4.61; 95%CI 2.29-9.27) were found to be independent risk factors for NOAF. An elevated D-dimer level at admission and the presence of coronary flow disturbance phenomenon after PCI were risk factors for NOAF following emergency PCI in patients with AMI.

Multivessel Coronary Artery Disease and Subsequent Thrombolysis in Myocardial Infarction Flow Grade After Primary Percutaneous Coronary Intervention

Background

In underdeveloped countries, coronary artery disease (CAD) has developed into a serious health issue due to the high rates of risk factors such as obesity and smoking amongst the population. This study has been performed to find the rate of multivessel CAD (MVD) and subsequent thrombolysis in myocardial infarction (TIMI) flow grade III in patients undergoing primary percutaneous coronary intervention (PCI).

Methods

This transverse study was carried out involving 110 patients from the emergency department of the National Institute of Cardiovascular Diseases, Karachi, Pakistan, from August 2015 to March 2016. All patients were diagnosed as ST-segment elevation myocardial infarction (STEMI) and had gone through primary PCI. Pre-procedure angiographic findings regarding the number of vessels involved and post-procedure TIMI flow grade were assessed and analysed.

Results

The average age of the study sample was 56.3 ± 11.4 years. The proportion of male patients was 81.8% (n=90), and hypertension was the most prevalent risk factor followed by type II diabetes with a frequency of 67.3% (n=74) and 40.0% (n=44), respectively. Coronary angiography showed MVD in 50.0% (n=55) of the patients, of whom 34 patients had two-vessel disease, and the remaining 21 had three-vessel disease. Ninety percent (n=99) of the patients exhibited TIMI flow grade III after the procedure with no significant difference between patients with MVD and those with single-vessel disease with a rate of 87.3% (n=48/55) versus 92.7% (n=51/55, P=0.527), respectively.

Conclusion

Post-procedure TIMI flow grade III was accomplished in almost 90% of the subjects with or without MVD. It can be concluded that primary PCI has a significant role in the early restoration of myocardial blood flow following STEMI regardless of the vessels involved.

Periprocedural and clinical outcomes of percutaneous coronary intervention of chronic total occlusions in patients with low- and mid-range ejection fractions

Background

The benefit and safety of percutaneous coronary intervention (PCI) to chronic total occlusions (CTO) in patients with low and mid-range left ventricular ejection fraction (LVEF) continue to be evidence limited. The aim of our study was to investigate the impact of LVEF in patients undergoing CTO PCI and to evaluate the mid-term clinical outcome of those with low and mid-range LVEF. We assessed the periprocedural and mid-term outcomes of 75 patients undergoing CTO PCIs according to pre-procedural LVEF: group (N), ≥ 50% (normal, nom.= 25); group (M), 40-49% (mid-range, nom.= 25); and group (L), < 40% (low, nom.= 25); within 6 months of follow-up.

Results

The prevalence of DM and chronic kidney disease (CKD) was significantly higher in low LVEF group (60%, p = 0.04 and 48%, p = 0.01 respectively). Apart from significantly lower contrast volume in patients with low LVEF (p = 0.04), there was no significant difference between the three groups regarding the procedural time, SYNTAX score and J-CTO score. We noticed similar procedural success in the three groups (88% vs. 84% vs. 76%, p = 0.521). LVEF category failed to predict procedural success (OR = 0.652, p = 0.268). There was a highly significant improvement in angina 6 months following intervention in normal LVEF group (p value < 0.001). Grade of dyspnea significantly improved 6 months following intervention in mid-range LVEF and low LVEF groups (p value = 0.04 and 0.031 respectively). There was no significant difference between the three groups regarding the reported MACCEs (12% vs. 16% vs. 28%, p = 0.268).

Conclusion

CTO PCI represents an efficient and safe strategy in patients with low and mid-range LVEFs. Mid-term outcomes in these patients were significantly improved following successful CTO PCI, without higher risk of MACCE at 6 months follow-up.

Echocardiographic assessment of left ventricular function recovery post percutaneous coronary intervention of chronic total occlusions in patients with low and mid-range left ventricular ejection fractions

OBJECTIVES

Coronary chronic total occlusion (CTO) is a frequent condition encountered in cardiac catheterization laboratory with a prevalence of about 20%. Through literature, data are scarcely reported regarding the left ventricular (LV) function recovery post CTO percutaneous coronary intervention (PCI) in patients with low (<40%) and mid-range (40%-49%) LV ejection fraction (LVEF). The aim of this study was to assess the echocardiographic outcomes of CTO patients with low and mid-range LVEF successfully revascularized at 6-month follow-up.

METHODS

This prospective study included 75 patients with at least one CTO of an epicardial coronary artery proved by previous diagnostic coronary angiography with PCI attempt indication, and successfully revascularized. They were equally divided according to LVEF into three groups, and echocardiographic remodeling indices were assessed at baseline and 6 months post PCI.

RESULTS

Our study showed significant improvement of LVEF, S-wave velocity by tissue doppler imaging (TDI), LV wall-motion score (LVWMS), and LV systolic sphericity index (LVSIS) 6 months post CTO PCI in low LVEF group, and a significant improvement in LVEF, S-wave velocity, and LVWMS in mid-range LVEF group (P < .05). The delta change in LVEF was significantly more in low LVEF group, compared to the other two groups (F = 4.739, P < .05).

CONCLUSION

Successful CTO PCI in patients with low and mid-range LVEF is associated with significant improvement of LVEF and other indices of myocardial remodeling after 6 months of follow-up.

Health Status Benefits of Successful Chronic Total Occlusion Revascularization Across the Spectrum of Left Ventricular Function: Insights From the OPEN-CTO Registry

OBJECTIVES

This study sought to describe the association between chronic total occlusion (CTO) revascularization (CTO percutaneous coronary intervention [PCI]) and health status in patients with and without cardiomyopathy.

BACKGROUND

Prior PCI trials for cardiomyopathy have excluded CTO patients. Whether patients with reduced left ventricular ejection fraction (LVEF) receive similar health status benefit from CTO-PCI compared with patients with normal LVEF is unclear.

METHODS

We assessed health status change, using the Seattle Angina Questionnaire (SAQ) Summary, SAQ Angina Frequency, and Rose Dyspnea Scale scores, among patients undergoing successful CTO PCI in the OPEN-CTO (Outcomes, Patient Health Status, and Efficiency in Chronic Total Occlusion) Registry. Participants were classified by LVEF (normal, ≥50%; mild-moderate, 30% to 49%; and severe, <30%), with higher SAQ and lower Rose Dyspnea Scale scores indicating better health status. Differences in 1-year outcomes were compared using hierarchical multivariable regression.

RESULTS

Of 762 patients, 506 (66.4%), 193 (25.3%), and 63 (8.3%) had normal, mild-moderate, and severely reduced LVEF. SAQ Summary score improvements were observed in each group (27.1 ± 20.4, 26.7 ± 21.2, and 20.3 ± 18.1, respectively). Compared with patients with LVEF ≥50%, those with LVEF <30% had less improvement in SAQ Summary Score (-5.2 points; 95% confidence interval: -9.0 to -1.5; p = 0.01) and Rose Dyspnea Scale (+0.5 points; 95% confidence interval: 0.1 to 0.8; p = 0.01), with no difference in odds of angina (odds ratio: 1.3; 95% confidence interval: 0.6 to 3.0; p = 0.48). Health status improvement was similar between patients with LVEF ≥50% and LVEF 30% to 49%.

CONCLUSIONS

Although health status improvement was less in patients with severely reduced LVEF compared with those with normal LVEF, each group experienced large health status improvements after CTO-PCI.

A comparison of rescue and primary percutaneous coronary interventions for acute ST elevation myocardial infarction

Objective

To perform a comparative analysis of in-hospital results obtained from patients with acute ST elevation myocardial infarction (STEMI), who underwent rescue or primary percutaneous coronary intervention (PCI). The aim is to determine rescue PCI as a practical option for patients with no immediate access to primary PCI.

Methods

From the Cardiology PCI Clinic of the National Hospital of Sri Lanka (NHSL), we selected all consecutive patients presenting with acute STEMI </ = 24 h door-to-balloon delay for primary PCI and </ = 72 h door-to-balloon delay, (90 min after failed thrombolysis) for rescue PCI, from March 2013 to April 2015 and their in-hospital results were analyzed, comparing rescue and primary PCI patients.

Results

We evaluated 159 patients; 78 underwent rescue PCI and 81 underwent primary PCI. The culprit left anterior descending (LAD) vessel (76.9% vs. 58.8%; P = 0.015) was more prevalent in rescue than in primary patients. Thrombus aspiration was less frequent in rescue group (19.2% vs. 40.7%; p = 0.004). The degree of moderate-to-severe left ventricular dysfunction reflected by the ejection fraction <40% (24.3% vs. 23.7%; P = 0.927) and prevalence of multivessel disease (41.0% vs. 43.8%; P = 0.729) revealed no significant difference. Coronary stents were implanted at similar rates in both strategies (96.2% vs. 92.6%; P = 0.331). Procedural success (97.4% vs. 97.5%; P = 0.980) and mortality rates (5.1% vs. 3.8%; P = 0.674), were similar in the rescue and primary groups.

Conclusion

In-hospital major adverse cardiac events (MACE) are similar in both rescue and primary intervention groups, supporting the former as a practical option for patients with no immediate access to PCI facilities.

Effect of Fixed-Bolus (5,000 Units) Unfractionated Heparin Before Primary Percutaneous Coronary Intervention on Activated Clotting Time, Time Flow, and All-Cause Mortality

The American College of Cardiology Foundation /American Heart Association guidelines recommend a weight-based dose of unfractionated heparin (UFH) for primary percutaneous coronary intervention (PCI). However, it is convention to administer a fixed-bolus dose of 5,000 units of UFH. It is unclear if 5,000 units are sufficient to achieve a therapeutic first activated clotting time (ACT). We conducted a retrospective cohort study to determine the proportion of therapeutic first ACT in patients who received 5,000 units of UFH before primary PCI. We examined the association of therapeutic first ACT with clinical outcomes, including post-PCI Thombolysis in Myocardial Infarction (TIMI) grade flow, myocardial infarction, bleeding, and mortality. Among the 269 included patients, 74.7% were men, and 61.4% were overweight or obese. The mean first ACT was 243.4 (SD = 61.5) seconds. Most patients (56.1%) had an infratherapeutic first ACT, 21.9% had a therapeutic first ACT, and 21.9% had a supratherapeutic first ACT. Furthermore, 44.6% of patients who achieved the American College of Cardiology Foundation/American Heart Association target weight-based dosing had an infratherapeutic ACT. The proportion of patients with post-PCI TIMI grade flow 0 to 2 was 14.6% among those with a first ACT that was infratherapeutic versus 6.8% among those with a first ACT that was not infratherapeutic (relative risk 2.15, 95% CI 0.99 to 4.65). In conclusion, over half of patients with ST-elevation myocardial infarction administered 5,000 units of UFH have an infratherapeutic first ACT and the high rate of poor TIMI grade flow in patients with an infratherapeutic ACT is concerning.

Intravascular hemodynamics and coronary artery disease: New insights and clinical implications

Intracoronary hemodynamics play a pivotal role in the initiation and progression of the atherosclerotic process. Low pro-inflammatory endothelial shear stress impacts vascular physiology and leads to the occurrence of coronary artery disease and its implications.

Effect of statins on coronary blood flow after percutaneous coronary intervention in patients with stable coronary artery disease

Aims

Statins have favourable effects on the vascular system. However, few data are available regarding the effect of these drugs on patients undergoing percutaneous coronary intervention (PCI). We sought to determine the impact of prior statin use on coronary blood flow after PCI in patients with stable coronary artery disease (CAD) by using the corrected thrombolysis in myocardial infarction (TIMI) frame count (CTFC).

Methods

A total of 80 consecutive eligible patients (mean age: 60 ± 7 years, 65 % male) with the diagnosis of stable CAD who were hospitalised for elective PCI were retrospectively enrolled in our study. The study population was divided into two groups according to statin use at least 6 months before PCI. Group 1 comprised of 51 patients (67 % male; mean age: 58 ± 4 years) taking statins and group 2 comprised of 29 patients (62 % male; mean age: 60 ± 3 years) not taking statins. PCI was applied to de novo type A lesions. CTFC was calculated for the treated vessels at baseline and after PCI.

Results

The two groups had similar characteristics in terms of age, sex, concomitant medications, lesion characteristics, pre-procedural CTFC, lipid parameters, and risk factors for CAD. Post-PCI CTFC (16 ± 3 vs. 22 ± 5, p = 0.01) and hs-CRP (2.1 ± 0.7 mg/l vs. 6.1 ± 2 mg/l, p = 0.01) in patients receiving statins before PCI were significantly lower than in patients without statin therapy. Multiple logistic regression analysis showed that statin pre-treatment (OR 2.5, 95 % CI 1.2 to 3.8, p < 0.001) and hs-CRP level (OR 1.8, 95 % CI 1.2 to 2.4, p = 0.001) were independent predictors of post-PCI CTFC.

Conclusions

In patients with stable CAD undergoing PCI, receipt of long-term statin therapy was associated with improvement in epicardial perfusion after PCI.

History and Development of Coronary Flow Reserve and Fractional Flow Reserve for Clinical Applications

We discuss the historical development of clinical coronary physiology, emphasizing coronary flow reserve (CFR) and fractional flow reserve (FFR). Our analysis focuses on the clinical motivations and technologic advances that prompted and enabled the application of physiology for patient diagnosis. CFR grew from the general concepts of physiologic and coronary reserve, linking the anatomic severity of a lesion to its impact on hyperemic flow. FFR developed from existing models relating pressure measurements to the potential for flow to increase after removing a stenosis. Because pressure measurements have proved easier and more robust than flow measurements, FFR has become the dominant metric.

Evaluation of Microvascular Disease and Clinical Outcomes

Although coronary microcirculatory dysfunction occurs in numerous cardiac conditions and influences prognosis, it has been largely ignored in clinical practice due to the lack of adequate methods for its assessment. Microcirculatory dysfuntion may result from a variety of causes, including structural remodelling (arterioles or capillaries), dysregulation (paradoxical arteriolar vasoconstriction), hypersensitivity to vasoactive factors or adrenergic drive, and extravascular compression of collapsable elements. Thus, the selection of a method to interrogate coronary microcirculation should be based on the suspected cause of dysfunction. This article reviews such assessment tools and their prognostic information.

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.

Relationship between QRS score and microvascular obstruction after acute anterior myocardial infarction

BACKGROUND

The QRS score on electrocardiogram (ECG) in patients with myocardial infarction (MI) reportedly reflects the severity of myocardial damage. The presence of microvascular obstruction (MO) assessed by cardiac magnetic resonance (CMR) imaging is associated with irreversible myocardial damage. MO assessed by CMR is known to be a predictor for adverse clinical outcome after ST-elevation MI. The aim of the present study was to examine the relationship between QRS score and MO in acute anterior MI patients.

METHODS

Sixty-two patients with first acute anterior MI who successfully underwent primary percutaneous coronary intervention (PCI) were enrolled. The QRS score after PCI on admission ECG was calculated by a Selvester-Wagner QRS scoring system. CMR imaging was performed at 11.4±3.9 days after MI. MO was defined as delayed enhancement with contrast-devoid core. Patients were divided into two groups as follows: 37 patients who showed MO (MO group) and 25 patients who did not show it (non-MO group).

RESULTS

The QRS score was significantly greater in the MO group than in the non-MO group. The QRS score significantly correlated with MO volume (r=0.418, p=0.010). Multivariate analysis showed that the QRS score (odds ratio 1.362, 95% CI: 1.038-1.951, p=0.024) and the peak creatine kinase levels (odds ratio 1.001, 95% CI: 1.000-1.002, p<0.001) were independent predictors for MO.

CONCLUSIONS

Our results indicate that the QRS score derived from simple and widely available ECG may be a useful parameter for assuring the presence of MO.

Impact of oral beta-blocker therapy on mortality after primary percutaneous coronary intervention for Killip class 1 myocardial infarction

The use of beta-blockers therapy has been recommended to reduce mortality in patients with left ventricular dysfunction after acute myocardial infarction (AMI). Primary percutaneous coronary intervention (PCI), which has become the mainstay of treatment for AMI, is associated with a lower mortality than fibrinolysis. The benefits of beta-blockers after primary PCI in AMI patients without pump failure are unclear. We hypothesized that oral beta-blocker therapy after primary PCI might reduce the mortality in AMI patients without pump failure. The assessment of lipophilic vs. hydrophilic statin therapy in acute myocardial infarction (ALPS-AMI) study was a multi-center study that enrolled 508 AMI patients to compare the efficacy of hydrophilic and lipophilic statins in secondary prevention after myocardial infarction. We prospectively tracked cardiovascular events for 3 years in 444 ALPS-AMI patients (median age 66 years; 18.2 % women) who had Killip class 1 on admission and were discharged alive. The primary endpoint was all-cause mortality. The 3-year follow-up was completed in 413 patients (93.0 %). During this follow-up, 21 patients (4.7 %) died. In Kaplan–Meier analysis, patients on beta-blockers had a significantly lower incidence of all-cause mortality (2.7 vs. 7.3 %, log-rank p = 0.025). After adjusting for the calculated propensity score for using beta-blockers, their use remained an independent predictor of all-cause mortality (hazard ratio 0.309; 95 % confidence interval 0.116–0.824; p = 0.019). In the statin era, the use of beta-blocker therapy after primary PCI is associated with lower mortality in AMI patients with Killip class 1 on admission.

Primary PCI: time to change focus from epicardial reperfusion towards protection of the microvasculature

Myocardial tissue perfusion remains compromised in 30-40% of patients with ST-segment elevation myocardial infarction (STEMI) despite restored epicardial patency after primary percutaneous coronary intervention (pPCI). This phenomenon is attributed to microvascular dysfunction secondary to numerous pathophysiological mechanisms, including distal embolisation of plaque and thrombus material. Its association with larger post-infarction myocardial necrosis, impaired left ventricular recovery, and worse clinical outcome illustrates the pertinence of a comprehensive armamentarium for the diagnosis, protection and treatment of microvascular dysfunction in STEMI patients. Current strategies to protect the microvasculature during pPCI are based on the assumption that distal embolisation of thrombotic and atheromatous debris is the main mechanism precipitating impaired myocardial tissue perfusion. However, recent findings suggest that this assumption is only true for the border zone of the ischaemic myocardium, whereas the infarct core consists of intramyocardial haemorrhage secondary to microvascular destruction, rather than obstruction. This observation has pertinent implications for contemporary and future adjuvant treatment strategies in STEMI patients. In this review, we provide an overview of the currently available armamentarium to assess the microvasculature, review contemporary strategies in pPCI to protect the myocardium, and discuss novel insights into microvascular pathophysiology that may help guide our focus from the coronary arteries to the microvasculature.

CORONARY ARTERY PATHOLOGY IN RIGHT VENTRICULAR MYOCARDIAL INFARCTION

Aim. To study anatomical and functional features of coronary blood flow in myocardial infarction (MI) of left ventricular (LV) inferior wall with the involvement of right ventriculum (RV).

Material and methods. The study included 120 patients who suffered MI of LV inferior wall with (Group 2 – LVMI; n=58) or without (Group 1 – RVMI; n=62) RV involvement.

Results. One coronary artery (CA) was affected in 65,0% of the participants. Right CA (RCA) pathology was registered in 97,4% (n=76), while circumflex CA (CxCA) pathology was observed only in 2,6% (n=2). Involvement of two and three or more CA was observed in 26,7% and 8,3% of the patients, respectively. Single CA pathology was at least 1,3 times more common in the RVMI group (p<0,05), while three or more CA were affected at least 8 times more often in the LVMI group (p<0,05). The right dominant, co-dominant, and left dominant types of coronary flow were registered in 76,7%, 15,0%, and 8,3% of the patients, respectively, all of whom were from the LVMI group. In 85% and 15% of the cases, the infarct-related artery (IRA) was RCA and CxCA, respectively. Among LVMI patients, RCA was the IRA almost three times more often than CxCA; among RVMI patients, this difference was 18-fold (p<0,001 for both comparisons). All LVMI patients (n=47) had distal occlusion of RCA, while all RVMI patients (n=55) had its proximal occlusion.

Conclusion. Over two-thirds of the cases оf ST elevation MI of LV inferior wall with RV involvement occur in patients with the right dominant type of coronary blood flow. RVMI typically occurs in patients with right dominant type of coronary blood flow and PCA pathology. MI of LV inferior wall with RV involvement is characterised by proximal RCA occlusion.

Coronary flow reserve varies depending upon the location within the artery it is assessed and the TIMI myocardial perfusion grade: a PROTECT TIMI-30 analysis

Coronary flow reserve (CFR) is a measure of the capacity of the epicardial coronary artery and the microvasculature to achieve maximal blood flow in response to hyperemic stimulation. It is not known whether the CFR varies along the length of the artery. Likewise, the interaction between CFR and the thrombolysis in myocardial infarction (TIMI) myocardial perfusion grade (TMPG) is unknown. CFR was measured using the number of cineframes required for the contrast to traverse the same length of the coronary artery before and following the administration of intracoronary adenosine. Following percutaneous coronary intervention (PCI), CFR was assessed both proximal and distal to the lesion in 192 consecutive patients with non-ST-segment elevation acute coronary syndrome (NSTEACS) from the PROTECT TIMI-30 trial. TMPG was also assessed. The difference between the distal and proximal CFR for patients with TMPG 0/1 (n = 76) was 0.11 (95% CI 0.01-0.20, P = 0.026), while among those with TMPG 2/3 (n = 114) it was -0.02 (95% CI -0.09-0.06, P = 0.65). The difference in the CFR between the distal and proximal segments among patients with TMPG 0/1 and TMPG 2/3 was significant (P interaction = 0.044). Following PCI among patients with impaired TMPG (0/1) in the setting of NSTEACS, CFR varies significantly between the proximal and distal segment of coronary arteries and is associated with higher (greater) distal CFR.

Intraoperative evaluation of revascularization effect on ischemic muscle hemodynamics using near-infrared diffuse optical spectroscopies

Arterial revascularization in patients with peripheral arterial disease (PAD) reestablishes large arterial blood supply to the ischemic muscles in lower extremities via bypass grafts or percutaneous transluminal angioplasty (PTA). Currently no gold standard is available for assessment of revascularization effects in lower extremity muscles. This study tests a novel near-infrared diffuse correlation spectroscopy flow-oximeter for monitoring of blood flow and oxygenation changes in medial gastrocnemius (calf) muscles during arterial revascularization. Twelve limbs with PAD undergoing revascularization were measured using a sterilized fiber-optic probe taped on top of the calf muscle. The optical measurement demonstrated sensitivity to dynamic physiological events, such as arterial clamping/releasing during bypass graft and balloon inflation/deflation during PTA. Significant elevations in calf muscle blood flow were observed after revascularization in patients with bypass graft (+48.1 ± 17.5%) and patients with PTA (+43.2 ± 11.0%), whereas acute post-revascularization effects in muscle oxygenation were not evident. The decoupling of flow and oxygenation after revascularization emphasizes the need for simultaneous measurement of both parameters. The acute elevations/improvements in calf muscle blood flow were associated with significant improvements in symptoms and functions. In total, the investigation corroborates potential of the optical methods for objectively assessing the success of arterial revascularization.

Shock wave-pretreated bone marrow cells further improve left ventricular function after myocardial infarction in rabbits

BACKGROUND

We tested whether shock wave (SW) offers additional benefits in improving left ventricular (LV) function after acute myocardial infarction (AMI) in rabbits receiving SW-treated autologous bone marrow-derived mononuclear cells (BMDMNCs) transplantation.

METHODS AND RESULTS

Saline (750 microL; group 2), BMDMNCs (1.0 x 10(7); group 3), or preimplant SW-treated BMDMNCs (group 4) were implanted into the infarct area of male rabbits 15 minutes after left coronary artery ligation, whereas eight rabbits without AMI served as controls (group 1; n = 8 per group). The results showed that in infarct area of LV, protein expressions of Cx43 and cytochrome C in mitochondria and endothelial nitric oxide synthase mRNA expression were lower in group 2 than in other groups, and decreased in group 3 as compared with groups 1 and 4 (all p values < 0.01). Conversely, mRNA expressions of endothelin-1 and matrix metalloproteinase-9, mitochondrial oxidative stress, and total fibrotic area were higher in group 2 than in other groups (all p values < 0.05). Furthermore, 6-month LV function by 2-D echo/angiogram showed significant impairment in group 2 than in other groups and in group 3 than in groups 1 and 4 (all p values < 0.005).

CONCLUSIONS

Application of SW-treated autologous BMDMNCs is superior to BMDMNCs alone for preserving LV function after AMI.

Coronary flow slows as renal function worsens

BACKGROUND

Slow coronary flow in patients without obstructive coronary artery disease is an angiographic finding that could easily be detected by thrombolysis in myocardial infarction (TIMI) frame counts. On the other hand, impaired renal function is a frequent problem. We searched the association between the 2 entities.

HYPOTHESIS

We evaluated the impact of impaired renal function on slow coronary flow.

METHODS

In this study, 105 patients with normal coronary arteries and impaired renal function in the form of a calculated glomerular filtration rate (GFR) < 90 mL/min/1.73 m(2) were enrolled and compared with 102 age- and sex-matched controls who had normal a GFR.

RESULTS

Calculated GFR was found to be negatively correlated with TIMI frame count in LAD (r = - 0.579, p < 0.001), in CX (r = - 0.499, p < 0.001), and in RCA (r = - 0.491, p < 0.001) in patients with impaired renal function. After adjusting for systolic and diastolic blood pressure and high-density lipoprotein (HDL) cholesterol, multiple regression analysis demonstrated a statistically significant and independent relationship between TIMI frame count for 3 vessels and calculated GFR.

CONCLUSIONS

Impaired renal function seems to denote slower coronary flow in patients with normal coronary arteries compared with those with normal renal function, and there seems to be an independent association between GFR and TIMI frame count in those with impaired renal function.

Prognostic factors and outcomes in young chinese patients with acute myocardial infarction undergoing primary coronary angioplasty

We investigated the prognostic risk and the clinical outcome of young-adult patients with ST-segment elevation (ST-se) acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI). Between May 1999 and September 2007, primary PCI was performed in 1680 consecutive patients with AMI of onset < 12 hours (cardiogenic shock within 18 hours) at Kaohsiung Chang Gung Memorial Hospital. Of these patients, 163 (9.7%) young-age patients (defined as male of < 45 years old and female of < 55 years old) were enrolled into this study. A comparable number (n = 175) of patients > or = 55 years old, who presented with AMI of < 12 hours duration having undergone primary PCI between November 2004 and May 2006, were retrospectively reviewed and enrolled as control subjects. The procedural success (defined as normal blood flow achieved in the infract-related artery) was similar between the young-age and old-age patients (P = 1.0). Additionally, the incidence of an advanced Killip score (defined as > or = score 3 upon presentation), 30-day and 6-month cumulative mortality did not differ between these two groups of patients (P > 0.1). However, the 30-day major adverse clinical outcome (MACO) (defined as New York Heart Association Functional Classification > or = 3 or 30-day mortality) was significantly lower in the young-age than in the old-age patients (P < 0.001). Further, multiple stepwise logistic regression analysis showed that an advanced Killip score along with the peak level of CK-MB was independently predictive of 30-day MACO (P < 0.05) in young-age patients. In conclusion, the prognostic outcome is favorable in young-adult ST-se AMI undergoing primary PCI. Traditional risk factors remain effective for stratification of young-adult AMI patients into high- or low-risk subgroups.

Concordant improvements in coronary flow reserve and ST-segment resolution during percutaneous coronary intervention for acute myocardial infarction: a benefit of postconditioning

OBJECTIVE

To assess the effect of ischemic postconditioning on indices of coronary microvascular function during percutaneous coronary intervention (PCI) for acute ST segment elevation myocardial infarction (STEMI).

BACKGROUND

Myocardial tissue level perfusion remains suboptimal in many patients with STEMI despite restoration of antegrade flow in the epicardial coronary artery.

METHODS

Twenty-four patients with an evolving anterior STEMI were randomized to undergo a previously-validated ischemic postconditioning protocol or usual care during PCI. The extent of resolution of ST segment elevation along with Doppler-tip catheter velocimetry was used as indices of myocardial reperfusion and microvascular function, respectively.

RESULTS

Postconditioned patients exhibited a greater, and therefore more rapid, extent of ST segment resolution (postconditioning, 70% +/- 15%; control, 48% +/- 16%; P = 0.0002) by the end of the procedure. Postconditioned patients also exhibited a greater hyperemic coronary vasodilator response at the completion of the procedure (coronary flow velocity reserve, CFVR: postconditioning, 2.2 +/- 0.1; control, 1.5 +/- 0.1; P < 0.0001). The end-procedure CFVR was directly related to the extent of the ST segment resolution (r = 0.85) but inversely related to the absolute magnitude of ST segment elevation at end procedure (r = -0.76). Peak serum creatine kinase was significantly lower in postconditioned patients (postconditioning, 1,524 +/- 435 IU/l; control, 1,862 +/- 561 IU/l; P = 0.03).

CONCLUSIONS

Ischemic postconditioning, as described, can be expeditiously performed during PCI for STEMI. Concordant changes in coronary flow reserve and ST segment resolution, measures of microcirculatory function, and myocardial perfusion, were greater in postconditioned patients.

Angiographic correlations of patients with small vessel disease diagnosed by adenosine-stress cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) with adenosine-stress myocardial perfusion is gaining importance for the detection and quantification of coronary artery disease (CAD). However, there is little knowledge about patients with CMR-detected ischemia, but having no relevant stenosis as seen on coronary angiography (CA). The aims of our study were to characterize these patients by CMR and CA and evaluate correlations and potential reasons for the ischemic findings. 73 patients with an indication for CA were first scanned on a 1.5T whole-body CMR-scanner including adenosine-stress first-pass perfusion. The images were analyzed by two independent investigators for myocardial perfusion which was classified as subendocardial ischemia (n = 22), no perfusion deficit (n = 27, control 1), or more than subendocardial ischemia (n = 24, control 2). All patients underwent CA, and a highly significant correlation between the classification of CMR perfusion deficit and the degree of coronary luminal narrowing was found. For quantification of coronary blood flow, corrected Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) was evaluated for the left anterior descending (LAD), circumflex (LCX) and right coronary artery (RCA). The main result was that corrected TFC in all coronaries was significantly increased in study patients compared to both control 1 and to control 2 patients. Study patients had hypertension or diabetes more often than control 1 patients. In conclusion, patients with CMR detected subendocardial ischemia have prolonged coronary blood flow. In connection with normal resting flow values in CAD, this supports the hypothesis of underlying coronary microvascular impairment. CMR stress perfusion differentiates non-invasively between this entity and relevant CAD.

Intracoronary boluses of adenosine and sodium nitroprusside in combination reverses slow/no-reflow during angioplasty: a clinical scenario of ischemic preconditioning

No or slow reflow following percutaneous coronary intervention (PCI), despite the presence of a patent epicardial vessel, is a serious complication resulting in increased morbidity and mortality. In the present study, we have evaluated the combination therapy of adenosine and sodium nitroprusside administered as sequential intracoronary (IC) boluses on no-reflow during PCI. Seventy-five high risk acute coronary syndrome patients who underwent PCI with evidence of initial less than TIMI (thrombolysis in myocardial infarction) III flow or developed deterioration in TIMI flow during the procedure were randomized to prophylactic administration of multiple boluses of IC saline solution, adenosine (12 microg/bolus) or the combination of adenosine (12 microg/bolus) and sodium nitroprusside (50 microg/bolus), sequentially. Assessment of TIMI and the TMP (tissue myocardial perfusion) grade was done and major adverse cardiac events (MACE) were assessed at the end of 6 months. Slow or no-reflow was persistent in 70% patients receiving saline solution, 31% patients receiving adenosine, and 4% patient receiving the combination. IC injection with saline solution did not produce improvement in TIMI flow or TMP grade. IC injection with combination resulted in greater improvement of TIMI flow and TMP grade. The crossover of patients with no-reflow in saline solution group or adenosine with combination treatment was associated with reestablishment of TIMI II in 4 and TIMI III in 20 patients. Our data suggest that combination therapy of adenosine and nitroprusside is safe and provides better improvement in coronary flow and MACE as compared with IC adenosine alone in cases of impaired flow during coronary interventions.

Predictors and prognosis for complex coronary lesions in patients with acute myocardial infarction: data from RICO survey

BACKGROUND

We aimed to investigate the determinants and outcomes of multiple complex lesions (MCLs) on coronary angiography in patients with an acute myocardial infarction.

METHODS

One thousand one hundred fifty-two consecutive nonselected myocardial infarction patients who underwent coronary angiography within 24 hours after admission were analyzed. A complex lesion was defined by the presence of thrombus, ulceration, irregular plaque, and flow impairment. Patients with < or = 1 complex lesion were considered with single complex lesion (SCL), and patients with > 1 complex lesions with MCLs.

RESULTS

Multiple complex lesions were identified in 360 patients (31%). Patients from the MCL group were older and had a higher rate of cardiovascular risk factors but were less likely to be smokers when compared with the SCL group. Patients with MCLs were more likely to have altered left ventricular ejection fraction and multivessel disease and showed a trend toward an increased median time delay to revascularization (360 vs 285 minutes; P = .070). Moreover, the C-reactive protein (CRP) plasma levels increased with the number of CLs. By multivariate analysis, multivessel disease and CRP level were associated with the presence of MCLs. When compared with the SCL group, patients with MCLs had a higher risk of inhospital cardiogenic shock (18% vs 11%; P = .005) and 30-day mortality (11% vs 6%; P = .002). At 1-year follow-up, the presence of MCLs was an independent predictive factor of death.

CONCLUSIONS

This study shows that the presence of MCLs is associated with worse outcomes and that risk factors such as CRP are able to identify patients at a high risk for MCLs.

Combination of electrocardiographic and angiographic markers of reperfusion in the prediction of infarct size in patients with ST-segment elevation myocardial infarction undergoing successful primary angioplasty

BACKGROUND

Optimal epicardial recanalization does not guarantee optimal myocardial perfusion. The aim of the current study was to evaluate angiographic and electrocardiographic markers of reperfusion in the prediction of infarct size in patients with STEMI undergoing successful primary angioplasty.

METHODS

Our population is represented by 270 STEMI patients with ST successful primary angioplasty (postprocedural TIMI 3 flow and residual stenosis <50%) with available corrected TIMI frame count (cTFC), myocardial blush grade (MBG), ST-segment resolution and enzymatic infarct size (peak CK-MB) analyses.

RESULTS

A significant linear relationship with enzymatic infarct size was observed for all markers of reperfusion, except for ST-segment resolution. These data were confirmed even when analyzed as continuous variables in case of cTFC (r=0.13, p=0.035), postprocedural residual cumulative ST-segment elevation (r=0.41, p<0.0001) and deviation (r=0.45, p<0.0001). At multivariate analysis applied to postprocedural angiographic and electrocardiographic markers of reperfusion, cumulative residual ST-segment deviation, myocardial blush grade, and corrected TIMI frame count were independent predictors of enzymatic infarct size.

CONCLUSIONS

This study showed that, among patients with STEMI treated by primary angioplasty, cTFC, MBG and cumulative residual ST-segment deviation are independent predictors of infarct size. Therefore, angiography and electrocardiography may provide complementary information in the evaluation of myocardial perfusion.

Coronary Flow Velocity Pattern Assessed Noninvasively by Transthoracic Color Doppler Echocardiography Serves as a Predictor of Adverse Cardiac Events and Left Ventricular Remodeling in Patients with Acute Myocardial Infarction

BACKGROUND

Quantitative assessment of microvascular injury is possible in patients with reperfused anterior myocardial infarction by invasive method. Coronary flow velocity patterns can also be assessed by transthoracic color Doppler echocardiography (TTCDE).

OBJECTIVES

The purpose of this study was to determine whether the coronary flow velocity pattern assessed by TTCDE serves as a predictor of adverse cardiac events and left ventricular remodeling.

METHODS

The study population consisted of 64 consecutive patients. We could analyze coronary flow velocity patterns by TTCDE in 59 of 64 patients (92%) after coronary intervention. The patients were followed up for the occurrence of complications and underwent serial measurement of left ventricular volumes.

RESULTS

In patients with a short deceleration time of diastolic flow velocity, the frequency of adverse cardiac events and left ventricular remodeling was higher.

CONCLUSION

It is possible to predict clinical outcome by assessing coronary flow velocity pattern by TTCDE.

Cigarette Smoking Induced Oxidative Stress may Impair Endothelial Function and Coronary Blood Flow in Angiographically Normal Coronary Arteries

BACKGROUND

Smoking contributes to the progression of atherosclerotic heart disease by causing endothelial dysfunction. In the present study the effect of smoking on endothelial functions and coronary flow was investigated, as well as the relationship of these factors with oxidative stress parameters, in subjects with normal coronary arteries.

MATERIALS AND RESULTS

The study group comprised 87 patients with angiographically normal coronary arteries (36 smokers, 51 nonsmokers). Coronary flow patterns were determined by the Thrombolysis In Myocardial Infarction (TIMI) frame count method. Endothelial function was evaluated by high-frequency ultrasound imaging of the brachial artery. Superoxide dismutase (SOD) and reduced glutathione (GSH) and reduction of oxidative material in the body and the endproduct of lipid peroxidation, malondialdehyde (MDA), were measured as oxidative stress markers. Mean TIMI frame count was significantly higher in smokers than nonsmokers (42.2 +/- 16 vs 29.5 +/- 9.5, p = 0.0001). Endothelium-dependent flow-mediated dilatation was 6.81+/-1.95% in nonsmokers and 5.7 +/- 2.2% in smokers (p = 0.0001). The smokers had dramatically higher levels of SOD and MDA and lower levels of GSH than the nonsmoker group.

CONCLUSION

Smoking induced oxidative stress deteriorates coronary blood flow by disturbing endothelial function.

Impact of PercuSurge Device Conjugative With Intracoronary Administration of Nitroprusside on No-Reflow Phenomenon Following Primary Percutaneous Coronary Intervention

BACKGROUND

The present study tested the hypothesis that when administered in conjunction with a PercuSurge device for treatment of acute myocardial infarction (AMI), intracoronary (IC) administration of nitroprusside (NTP) is safe and superior to IC administration of NTP alone or nitroglycerin (NTG) for reversing slow-flow or no-reflow, both of which occur frequently during primary percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Sixty-two patients with ST-segment elevation AMI of <12 h duration undergoing primary PCI were enrolled. When the final Thrombolysis In Myocardial Infarction (TIMI) flow was normal (TIMI-3), NTG 200 microg was administered first, followed by (5 min later) NTP 100 microg via an intra-guiding catheter. When final TIMI flow was <or=2, NTG 200 mug was given, followed by NTP 100 microg via an export suction catheter advanced into the infract-related artery (IRA). Primary endpoint was epicardial blood flow (TIMI-flow), corrected TIMI frame counts, or microvascular circulation [myocardial blush (MB) grade]. Analytical results indicated that the final TIMI-3 flow was significantly higher in patients receiving NTP than in those receiving NTG therapy (100% vs 88.7%, p=0.023). As compared with NTG, NTP therapy significantly improved final MB grade (p<0.0001) and corrected TIMI flame count time (p<0.0001). Subgroup analysis demonstrated that final MB grade (p<0.001) and corrected TIMI flame count time (p<0.01) were significantly higher in patients (n=33) with than in patients (n=29) without the PercuSurge. No significant NTP related adverse events occurred, apart from insignificant transient hypotension.

CONCLUSION

IC administration of NTP is safe and superior to NTG for improving final epicardial blood flow and microvascular circulation in patients with AMI undergoing primary PCI. Combination therapy of PercuSurge device and NTP provided an additional benefit to NTP alone for improving microvascular circulation.

Brief repetitive balloon occlusions enhance reperfusion during percutaneous coronary intervention for acute myocardial infarction: a pilot study

The objective of this study was to determine whether acutely ischemic myocardium may be conditioned during percutaneous coronary intervention for acute myocardial infarction. Ischemic preconditioning is a powerful cardioprotective mechanism that limits infarct size in animal investigations and ischemic sequelae during percutaneous coronary intervention in man. However, the conditioning stimulus in all these studies has been applied prior to the defining episode of ischemia. Seventeen patients undergoing percutaneous coronary intervention for acute myocardial infarction were randomly assigned to a standard ischemic preconditioning protocol (n = 10) or a usual-care control group (n =7). ST segment shift response and Doppler-derived distal coronary velocity data were compared. Despite similar degrees of baseline ST segment elevation, the magnitude of final ST segment elevation in the conditioning group was less than that in controls at the protocol conclusion (conditioning, 1.60 +/- 0.8 mV; control, 4.0 +/- 0.5 mV; P < 0.001). The rate of ST segment resolution was greater in the conditioning group (conditioning, 0.28 +/- 0.1 mV/min; control, 0.12 +/- 0.1 mV/min; P = 0.02). Distal coronary velocimetry indicated significant improvement in coronary flow velocity reserve in the conditioning group at the protocol conclusion (conditioning, 1.8 +/- 0.2; control, 1.4 +/- 0.1; P < 0.008). Brief periods of occlusion and reperfusion during percutaneous intervention for acute myocardial infarction mitigate the extent of ischemic injury and improve distal myocardial perfusion. Such ischemic conditioning represents a potentially useful adjunct to strategies for enhancing reperfusion during acute myocardial infarction.

The effects of prior use of atorvastatin on coronary blood flow after primary percutaneous coronary intervention in patients presenting with acute myocardial infarction

BACKGROUND

Statins exert a variety of favourable effects on the vascular system not directly related to their lipid lowering function known as pleiotropic effects. There are not enough data regarding the effects of prior statin use on coronary blood flow after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI). Accordingly, in the present study, we aimed to investigate the effects of prior statin use on coronary blood flow after primary PCI in patients with AMI using the Thrombolysis In Myocardial Infarction (TIMI) frame count method.

METHODS

The study population consisted of 200 patients (161 men; mean age=62+/-7 years) referred to cardiology clinics with AMI who subsequently underwent successful primary PCI. The study population was divided into two groups according to statin use before primary PCI. Group 1 consisted of 98 patients (75 men; mean age=63+/-7 years) not taking statin and group 2 consisted of 102 patients (86 men; mean age=61+/-7 years) taking daily dose of at least 40 mg atorvastatin for at least 6 months. Coronary blood flow was determined by TIMI frame count method using the angiographic images obtained just after PCI and stenting.

RESULTS

Only mean TIMI frame count was detected to be significantly lower in patients taking at least 40 mg atorvastatin for at least 6 months compared with that of the patients taking no statin (P<0.001). After confounding variables were controlled for, the mean TIMI frame count of patients in group 2 was significantly lower than that of the patients in group 1 (P=0.001). Pain to balloon time and vessel type were detected as important confounding variables of TIMI frame count after analysis of covariances.

CONCLUSIONS

Prior statin use may improve coronary blood flow after PCI in patients with AMI, possibly by its beneficial effects on microvascular function.