Relationship between extent of residual myocardial viability and coronary flow reserve in patients with recent myocardial infarction

Quantitative flow ratio vs. angiography-only guided PCI in STEMI patients: one-year cardiovascular outcomes

BACKGROUND

Coronary physiology-guided PCIs are recommended worldwide. However, invasive coronary physiology methods prolong the procedure, create additional risks for the patients, and prolong the fluoroscopy time for an interventional cardiologist. Otherwise, there is a noninvasive coronary physiology evaluation method, QFR, that can be safely used even in STEMI patients.

METHODS

A total of 198 patients admitted with STEMI and at least one intermediate (35-75%) diameter stenosis other than the culprit artery between July 2020 and June 2021 were prospectively included in this single-center study. All patients were randomized into one of two groups (1 - QFR-guided PCI; 2 - visual-estimation-only guided PCI). A 12-month follow-up with echocardiography, exercise stress test, and quality of life evaluation was performed in all included patients. For the QOF evaluation, the Seattle Angina Score Questionnaire was chosen. Statistical analysis was performed using the Kolmogorov-Smirnov test, Student's t-test, Mann-Whitney U test, Pearson's chi-squared test and Kaplan-Meier estimator.

RESULTS

Ninety-eight (49.5%) patients were randomized to the first group, and 100 (50.5%) patients were included in the second group. Statistically, significantly more patients had a medical history of dyslipidemia (98 vs. 91, p = 0.002) and slightly better left ventricular ejection fraction (42.21 ± 7.88 vs. 39.45 ± 9.62, p = 0.045) in the QFR group. Six fewer patients required non-culprit artery revascularization within the 12-month FU in the QFR group (1.02% vs. 6%, p = 0.047). Survival analysis proved that patients in the Angio group had a more than 6-fold greater risk for death within a 12-month period after MI (OR 6.23, 95% CI 2.20-17.87, p = 0.006), with the highest mortality risk within the first two months after initial treatment.

CONCLUSION

Using QFR in non-culprit lesions in patients with ST-elevation myocardial infarction reduces mortality and revascularization at the 12-month follow-up and improves the quality of life of the patient.

TRIAL REGISTRATION

The study was approved by the Regional Bioethical Committee and conducted under the principles of the Helsinki Declaration and local laws and regulations.

Management of multivessel coronary artery disease in patients with non-ST-elevation myocardial infarction: a complex path to precision medicine

Recent analyses suggest the incidence of acute coronary syndrome is declining in high- and middle-income countries. Despite this, overall rates of non-ST-elevation myocardial infarction (NSTEMI) continue to rise. Furthermore, NSTEMI is a greater contributor to mortality after hospital discharge than ST-elevation myocardial infarction (STEMI). Patients with NSTEMI are often older, comorbid and have a high likelihood of multivessel coronary artery disease (MVD), which is associated with worse clinical outcomes. Currently, optimal treatment strategies for MVD in NSTEMI are less well established than for STEMI or stable coronary artery disease. Specifically, in relation to percutaneous coronary intervention (PCI) there is a paucity of randomized, prospective data comparing multivessel and culprit lesion-only PCI. Given the heterogeneous pathological basis for NSTEMI with MVD, an approach of complete revascularization may not be appropriate or necessary in all patients. Recognizing this, this review summarizes the limited evidence base for the interventional management of non-culprit disease in NSTEMI by comparing culprit-only and multivessel PCI strategies. We then explore how a personalized, precise approach to investigation, therapy and follow up may be achieved based on patient-, disease- and lesion-specific factors.

Changes of the coronary arteries and cardiac microvasculature with aging: Implications for translational research and clinical practice

Aging results in functional and structural changes in the cardiovascular system, translating into a progressive increase of mechanical vessel stiffness, due to a combination of changes in micro-RNA expression patterns, autophagy, arterial calcification, smooth muscle cell migration and proliferation. The two pivotal mechanisms of aging-related endothelial dysfunction are oxidative stress and inflammation, even in the absence of clinical disease. A comprehensive understanding of the aging process is emerging as a primary concern in literature, as vascular aging has recently become a target for prevention and treatment of cardiovascular disease. Change of life-style, diet, antioxidant regimens, anti-inflammatory treatments, senolytic drugs counteract the pro-aging pathways or target senescent cells modulating their detrimental effects. Such therapies aim to reduce the ineluctable burden of age and contrast aging-associated cardiovascular dysfunction. This narrative review intends to summarize the macrovascular and microvascular changes related with aging, as a better understanding of the pathways leading to arterial aging may contribute to design new mechanism-based therapeutic approaches to attenuate the features of vascular senescence and its clinical impact on the cardiovascular system.

Fractional Flow Reserve as a Standard of Reference for Ischemia Early After ST Elevation Myocardial Infarction

BACKGROUND

The purpose of the present study was to assess the value of the fractional flow reserve (FFR) of the infarct-related artery (IRA) early after ST elevation myocardial infarction (STEMI) in detecting reversible ischemia.

METHODS

Single photon emission computed tomography (SPECT) at rest and after dipyridamole stress, and within 24 hour FFR of the IRA was performed on 69 patients 3 to 7 days after STEMI. FFR was 0.80 or less in 61 (88.4%) of them. In these patients, percutaneous coronary intervention (PCI) was performed, and a second SPECT study was repeated within 14 days.

RESULTS

SPECT showed reversible ischemia in 36 (59%) of these 61 patients, and converted to negative in 29 of them. Thus, the SPECT results of these 29 patients were defined as true positive before angioplasty and true negative after angioplasty. Considering the true-positive and true-negative SPECT results as the gold standard, the sensitivity, specificity, and positive and negative predictive values of the FFR of 0.80 or less compared to this gold standard were 96.7%, 100%, 100%, and 96.6%, respectively (ĸ = 0.97, P < 0.001).

CONCLUSIONS

In the early phase after STEMI, the reliability of FFR to determine residual ischemia in the IRA is very high in those patients with true-positive SPECT before and true-negative SPECT after PCI.

Coronary flow reserve is related to the extension and transmurality of myocardial necrosis and predicts functional recovery after acute myocardial infarction

BACKGROUND

Few studies have examined the effect of transmurality of myocardial necrosis on coronary microcirculation. The aim of this study was to examine the influence of cardiac magnetic resonance-derived (GE-MRI) structural determinants of coronary flow reserve (CFR) after anterior myocardial infarction (STEMI), and their predictive value on regional functional recovery.

METHODS

Noninvasive CFR and GE-MRI were studied in 37 anterior STEMI patients after primary coronary angioplasty. The wall motion score index in the left descending anterior coronary artery territory (A-WMSI) was calculated at admission and follow-up (FU). Recovery of regional left ventricular (LV) function was defined as the difference in A-WMSI at admission and FU. The necrosis score index (NSI) and transmurality score index (TSI) by GE-MRI were calculated in the risk area. Baseline (BMR) and hyperemic (HMR) microvascular resistance, arteriolar resistance index (ARI), and coronary resistance reserve (CRR) were calculated at the Doppler echocardiography.

RESULTS

Bivariate analysis indicated that the CPK and troponin I peak, heart rate, NSI, TSI, BMR, the ARI, and CRR were related to CFR. Multivariable analysis revealed that TSI was the only independent determinant of CFR. The CFR value of >2.27, identified as optimal by ROC analysis, was 77% specific and 73% sensitive with accuracy of 76% in identifying patients with functional recovery.

CONCLUSIONS

Preservation of microvascular function after AMI is related to the extent of transmurality of myocardial necrosis, is an important factor influencing regional LV recovery, and can be monitored by noninvasive CFR.

Ischemia-based Coronary Revascularization: Beyond Anatomy and Fractional Flow Reserve

Treatment strategies for patients with coronary artery disease (CAD) should be based on objective evidence of inducible ischemia in the subtended myocardium to improve clinical outcomes, symptoms, and cost-effectiveness. Fractional flow reserve (FFR) is the most verified index to-date for invasively evaluating lesion-specific myocardial ischemia. Favorable results from large clinical trials that applied FFR-guided percutaneous coronary intervention (PCI) prompted changes in coronary revascularization guidelines to emphasize the importance of this ischemia-based strategy using invasive coronary physiology. However, the frequency of functional evaluations is lacking in daily practice, and visual assessment still dominates treatment decisions in CAD patients. Despite recent efforts to integrate functional and anatomical assessments for coronary stenosis, there is considerable discordance between the 2 modalities, and the diagnostic accuracy of simple parameters obtained from current imaging tools is not satisfactory to determine functional significance. Although evidence that supports or justifies anatomy-guided PCI is more limited, and FFR-guided PCI is currently recommended, it is important to be aware of conditions and factors that influence FFR for accurate interpretation and application. In this article, we review the limitations of the current anatomy-derived evaluation of the functional significance of coronary stenosis, detail considerations for the clinical utility of FFR, and discuss the importance of an integrated physiologic approach to determine treatment strategies for CAD patients.

A novel method for quantitative myocardial contrast echocardiography in mice

The small size of the mouse heart frequently imparts technical challenges when applying conventional in vivo imaging methods for assessing heart function. Here, we describe the use of high-frequency ultrasound imaging in conjunction with a size-tuned blood pool contrast agent for quantitatively assessing myocardial perfusion in living mice. A perflurocarbon microbubble formulation exhibiting a narrow size distribution was developed, and echogenicity was assessed at 18 MHz in vitro. Adult mice were subjected to permanent ligation of the left anterior descending artery. Ultrasound imaging was performed on day 7, and a cohort of intact mice was used as a control. Parasternal long-axis cine clips were acquired at 18 MHz before and after contrast administration. Reduced ejection fraction and increased end-systolic volume were observed in infarcted compared with control mice. In control animals, washin of the contrast agent was visible in all myocardial segments. Reduced contrast enhancement was observed in apical-posterolateral regions of all infarcted mice. A novel method for reslicing of the imaging data through the time domain provided a two-dimensional presentation of regional contrast agent washin, enabling convenient identification of locations exhibiting altered perfusion. Myocardial segments exhibiting diminished contractility were observed to have correspondingly low relative myocardial perfusion. The contrast agent formulation and methods demonstrated here provide the basis for simplifying routine in vivo estimation of infarct size in mice and may be particularly useful in longitudinal evaluation of revascularization interventions and assessment of peri-infarct ischemia. NEW & NOTEWORTHY Murine myocardial contrast echocardiography frequently suffers from poor sensitivity to contrast. Here, we formulated a novel size-tuned microbubble contrast agent and validated it for use with ultra-high-frequency ultrasound. A novel data method for evaluating myocardial perfusion based on reslicing the imaging data through the time domain is presented.

Clinical Relevance of Coronary Fractional Flow Reserve: Art-of-state

Objective:

The objective was to delineate the current knowledge of fractional flow reserve (FFR) in terms of definition, features, clinical applications, and pitfalls of measurement of FFR.

Data Sources:

We searched database for primary studies published in English. The database of National Library of Medicine (NLM), MEDLINE, and PubMed up to July 2014 was used to conduct a search using the keyword term “FFR”.

Study Selection:

The articles about the definition, features, clinical application, and pitfalls of measurement of FFR were identified, retrieved, and reviewed.

Results:

Coronary pressure-derived FFR rapidly assesses the hemodynamic significance of individual coronary artery lesions and can readily be performed in the catheterization laboratory. The use of FFR has been shown to effectively guide coronary revascularization procedures leading to improved patient outcomes.

Conclusions:

FFR is a valuable tool to determine the functional significance of coronary stenosis. It combines physiological and anatomical information, and can be followed immediately by percutaneous coronary intervention (PCI) if necessary. The technique of FFR measurement can be performed easily, rapidly, and safely in the catheterization laboratory. By systematic use of FFR in dubious stenosis and multi-vessel disease, PCI can be made an even more effective and better treatment than it is currently. The current clinical evidence for FFR should encourage cardiologists to use this tool in the catheterization laboratory.

Prognostic Value of Real Time Myocardial Contrast Echocardiography after Percutaneous Coronary Intervention

Real time myocardial contrast echocardiography (RTMCE) is a cost-effective and simple method to quantify coronary flow reserve (CFR). We aimed to determine the value of RTMCE to predict cardiac events after percutaneous coronary intervention (PCI). We have studied myocardial blood volume (A), velocity (β), flow indexes (MBF, A × β), and vasodilator reserve (stress-to-rest ratios) in 36 patients with acute coronary syndrome (ACS) who underwent PCI. CFR (MBF at stress/MBF at rest) was calculated for each patient. Perfusion scores were used for visual interpretation by MCE and correlation with TIMI flow grade. In qualitative RTMCE assessment, post-PCI visual perfusion scores were higher than pre-PCI (Z = -7.26, P < 0.01). Among 271 arteries with TIMI flow grade 3 post-PCI, 72 (36%) did not reach visual perfusion score 1. The β- and A × β-reserve of the abnormal segments supplied by obstructed arteries increased after PCI comparing to pre-PCI values (P < 0.01). Patients with adverse cardiac events had significantly lower β- and lower A × β-reserve than patients without adverse cardiac events. In the former group, the CFR was ≥ 1.5 both pre- and post-PCI. CFR estimation by RTMCE can quantify myocardial perfusion in patients with ACS who underwent PCI. The parameters β-reserve and CFR combined might predict cardiac events on the follow-up.

Fractional flow reserve vs. angiography in guiding management to optimize outcomes in non-ST-segment elevation myocardial infarction: the British Heart Foundation FAMOUS-NSTEMI randomized trial

AIM

We assessed the management and outcomes of non-ST segment elevation myocardial infarction (NSTEMI) patients randomly assigned to fractional flow reserve (FFR)-guided management or angiography-guided standard care.

METHODS AND RESULTS

We conducted a prospective, multicentre, parallel group, 1 : 1 randomized, controlled trial in 350 NSTEMI patients with ≥1 coronary stenosis ≥30% of the lumen diameter assessed visually (threshold for FFR measurement) (NCT01764334). Enrolment took place in six UK hospitals from October 2011 to May 2013. Fractional flow reserve was disclosed to the operator in the FFR-guided group (n = 176). Fractional flow reserve was measured but not disclosed in the angiography-guided group (n = 174). Fractional flow reserve ≤0.80 was an indication for revascularization by percutaneous coronary intervention (PCI) or coronary artery bypass surgery (CABG). The median (IQR) time from the index episode of myocardial ischaemia to angiography was 3 (2, 5) days. For the primary outcome, the proportion of patients treated initially by medical therapy was higher in the FFR-guided group than in the angiography-guided group [40 (22.7%) vs. 23 (13.2%), difference 95% (95% CI: 1.4%, 17.7%), P = 0.022]. Fractional flow reserve disclosure resulted in a change in treatment between medical therapy, PCI or CABG in 38 (21.6%) patients. At 12 months, revascularization remained lower in the FFR-guided group [79.0 vs. 86.8%, difference 7.8% (-0.2%, 15.8%), P = 0.054]. There were no statistically significant differences in health outcomes and quality of life between the groups.

CONCLUSION

In NSTEMI patients, angiography-guided management was associated with higher rates of coronary revascularization compared with FFR-guided management. A larger trial is necessary to assess health outcomes and cost-effectiveness.

Fractional flow reserve: an updated review

Revascularization of ischemia-producing coronary lesions is widely used in the management of coronary artery disease. However, some coronary lesions appear significant on the conventional angiogram when they are truly non-flow limiting. For this reason, it is becoming increasingly important to determine the coronary physiology. Fractional flow reserve (FFR) has emerged as a useful tool to determine the lesions that require revascularization. Measurement of FFR during invasive coronary angiography now has a class IA indication from the European Society of Cardiology for identifying hemodynamically significant coronary lesions when noninvasive evidence of myocardial ischemia is unavailable. Current data on FFR can be broadly classified into studies that compare the diagnostic accuracy of FFR measurement compared with other noninvasive modalities and studies that test treatment strategies of patients with intermediate coronary stenoses using a threshold value for FFR and that have clinical outcomes as endpoints. In this review, we will discuss the concept of FFR, current evidence supporting its usage, and future perspectives.

Adipose-derived cell construct stabilizes heart function and increases microvascular perfusion in an established infarct

We have previously shown that myocardial infarction (MI) immediately treated with an epicardial construct containing stromal vascular fraction (SVF) from adipose tissue preserved microvascular function and left ventricle contractile mechanisms. In order to evaluate a more clinically relevant condition, we investigated the cardiac recovery potential of an SVF construct implanted onto an established infarct. SVF cells were isolated from rat adipose tissue, plated on Vicryl, and cultured for 14 days. Fischer-344 rats were separated into MI groups: (a) 6-week MI (MI), (b) 6-week MI treated with an SVF construct at 2 weeks (MI SVF), (c) 6-week MI with Vicryl construct at 2 weeks (MI Vicryl), and (d) MI 2wk (time point of intervention). Emax, an indicator of systolic performance and contractile function, was lower in the MI and MI Vicryl versus MI SVF. Positron emission tomography imaging ((18)F-fluorodeoxyglucose) revealed a decreased percentage of relative infarct volume in the MI SVF versus MI and MI Vicryl. Total vessel count and percentage of perfusion assessed via immunohistochemistry were both increased in the infarct region of MI SVF versus MI and MI Vicryl. Overall cardiac function, percentage of relative infarct, and percentage of perfusion were similar between MI SVF and MI 2wk; however, total vessel count increased after SVF treatment. These data suggest that SVF treatment of an established infarct stabilizes the heart at the time point of intervention by preventing a worsening of cardiac performance and infarcted volume, and is associated with increased microvessel perfusion in the area of established infarct.

Fractional flow reserve versus angiography in guiding management to optimize outcomes in non-ST-elevation myocardial infarction (FAMOUS-NSTEMI): rationale and design of a randomized controlled clinical trial

BACKGROUND

In patients with acute non-ST-elevation myocardial infarction (NSTEMI), coronary arteriography is usually recommended; but visual interpretation of the angiogram is subjective. We hypothesized that functional assessment of coronary stenosis severity with a pressure-sensitive guide wire (fractional flow reserve [FFR]) would have additive diagnostic, clinical, and health economic utility as compared with angiography-guided standard care.

METHODS AND DESIGN

A prospective multicenter parallel-group 1:1 randomized controlled superiority trial in 350 NSTEMI patients with ≥1 coronary stenosis ≥30% severity (threshold for FFR measurement) will be conducted. Patients will be randomized immediately after coronary angiography to the FFR-guided group or angiography-guided group. All patients will then undergo FFR measurement in all vessels with a coronary stenosis ≥30% severity including culprit and nonculprit lesions. Fractional flow reserve will be disclosed to guide treatment in the FFR-guided group but not disclosed in the "angiography-guided" group. In the FFR-guided group, an FFR ≤0.80 will be an indication for revascularization by percutaneous coronary intervention or coronary artery bypass surgery, as appropriate. The primary outcome is the between-group difference in the proportion of patients allocated to medical management only compared with revascularization. Secondary outcomes include the occurrence of cardiac death or hospitalization for myocardial infarction or heart failure, quality of life, and health care costs. The minimum and average follow-up periods for the primary analysis are 6 and 18 months, respectively.

CONCLUSIONS

Our developmental clinical trial will address the feasibility of FFR measurement in NSTEMI and the influence of FFR disclosure on treatment decisions and health and economic outcomes.

Prognostic value of coronary flow reserve assessed by transthoracic Doppler echocardiography on long-term outcome in asymptomatic patients with type 2 diabetes without overt coronary artery disease

BACKGROUND

Cardiovascular risk stratification of asymptomatic diabetic patients is important and remains a difficult clinical problem. Our aim was to test the hypothesis that coronary flow reserve (CFR) assessed by noninvasive transthoracic Doppler echocardiography predicts prognosis in those patients.

METHODS

From February 2002 to January 2005, we evaluated 135 consecutive asymptomatic patients (74 male; mean age, 63 ± 9 years) with type 2 diabetes without a history of coronary artery disease. Adenosine triphosphate (0.14 mg/kg/min) stress Doppler echocardiography was performed to evaluate CFR of the left anterior descending artery. Patients with a CFR < 2.0 were also excluded based on the suspicion of significant coronary artery stenosis in the left anterior descending artery.

RESULTS

There were 111 patients (60 male; mean age, 64 ± 9 years) enrolled. During a median follow-up of 79 months, 20 events (5 deaths, 7 acute coronary syndromes, 8 coronary revascularizations) occurred. The optimal cut-off value of CFR to predict events was 2.5 (area under the receiver-operating characteristic curve = 0.65). Multivariate analysis showed that the independent prognostic indicators were male gender (p < 0.05) and a CFR < 2.5 (p < 0.01). Kaplan-Mayer analysis revealed that the event rate was significantly higher (log-lank, p < 0.01) in patients with CFR < 2.5 than in those with CFR ≥ 2.5.

CONCLUSIONS

CFR obtained by transthoracic Doppler echocardiography provides independent prognostic information in asymptomatic patients with type 2 diabetes without overt coronary artery disease. Patients with CFR < 2.5 had a worse long-term outcome.

Usefulness of fractional flow reserve to improve diagnostic efficiency in patients with non-ST elevation myocardial infarction

Myocardial fractional flow reserve (FFR) has emerging clinical utility and prognostic value in medically stabilized patients with non-ST-segment elevation myocardial infarction (NSTEMI). The aim of this study was to investigate whether measurement of FFR compared to coronary angiography alone improves diagnostic efficiency in patients with NSTEMIs. One hundred consecutive patients with NSTEMIs who had previously undergone clinically indicated FFR measurements were included. In a simulated decision exercise, 5 interventional cardiologists retrospectively and independently reviewed the clinical history and coronary angiogram of each patient and then made a treatment decision. FFR results were then disclosed, and the same cardiologists were asked to review their initial treatment decisions. A p value <0.05 indicates a difference between cardiologists. The proportion of patients allocated to each treatment option initially differed among the 5 cardiologists (p = 0.0061). Forty-two percent of all FFR measurements were made in culprit lesions. After FFR disclosure, the number of patients in whom the treatment decisions made by each cardiologist independently conformed (and so represented the majority with ≥ 3 of the 5 cardiologists) increased from 65% to 91% (p = 0.0094). After FFR disclosure, the cardiologists changed their initial treatment plans in 46% of patients (p = 0.0016). Changes in favor of medical therapy occurred in 24% of patients (p = 0.0016), and this increase was associated with reductions in "deferred" management (p = 0.0067), single-vessel percutaneous coronary intervention (p = 0.0052), and multivessel percutaneous coronary intervention (p = 0.046). In conclusion, FFR measurement reduced diagnostic variability and changed cardiologists' treatment decisions for patients with NSTEMIs.

Estimation of infarct size using transthoracic Doppler echocardiographic measurement of coronary flow reserve in infarct related and reference coronary artery

BACKGROUND

Patients in chronic phase of myocardial infarction (MI) have decreased coronary flow reserve (CFR) in infarct related artery (IRA) that is proportional to the extent of microvascular/myocardial damage. We proposed a novel model for the assessment of microvascular damage and infarct size using Doppler echocardiography evaluation of CFRs of the IRA (LAD) and reference artery (RCA).

METHODS

Our study included 34 consecutive patients (28 men, mean age 50 ± 11 years) with first anterior STEMI and single vessel disease successfully treated with primary PCI. All patients underwent SPECT MPI for the assessment of infarct size (expressed as a percentage of myocardium with fixed perfusion abnormalities) and CFR evaluation of LAD and RCA. CFR derived percentage of microvascular damage (CFR PMD) was calculated as: CFR PMD=(CFR RCA-CFR LAD)/(CFR RCA-1)×100 (%).

RESULTS

CFR PMD correlated significantly with all parameters evaluating the severity of myocardial damage including: peak CK activity (r=0.632, p<0.001), WMSI (r=0.857, p<0.001), ejection fraction (r=-0.820, p<0.001), left ventricular end diastolic (r=0.757, p<0.001) and end systolic volume (r=0.794, p<0.001). Most importantly, CFR PMD (22 ± 17%) correlated significantly with infarct size by SPECT MPI (21 ± 17%) (r=0.874, p<0.001).

CONCLUSIONS

CFR PMD derived from the proposed model was significantly related to echocardiographic and enzymatic parameters of infarct size, as well as to myocardial damage assessed by SPECT MPI in patients with successfully reperfused first anterior STEMI.

Predictors of contractile recovery after revascularization in patients with anterior myocardial infarction who received thrombolysis

BACKGROUND

Identification of viable myocardium after myocardial infarction has gained paramount importance with the current progress in coronary revascularization.

OBJECTIVE

To explore the prognostic power of certain patient characteristics to predict myocardial contractile recovery after revascularization in patients presenting with acute anterior ST elevation myocardial infarction (STEMI) who received thrombolytic therapy.

METHODS

Seventy-three consecutive patients presenting with first acute anterior STEMI who had received thrombolytic therapy and had significant coronary stenosis or occlusion of the infarct-related artery amenable for revascularization were enrolled. All patients underwent echocardiographic assessment of regional wall motion and left ventricular ejection fraction. Patients underwent coronary revascularization by either percutaneous angioplasty or surgical bypass. Echocardiography was repeated two to three months following revascularization. Patients were classified into two groups: group 1 had evidence of contractile recovery after revascularization at follow-up echocardiography and group 2 had no such evidence of recovery.

RESULTS

Predictors of contractile recovery after revascularization included a shorter time from symptom onset to the institution of thrombolytic therapy, a lower baseline wall motion score index, the presence of grade 3 collaterals to the infarct-related artery and the use of beta-blockers. Instead, the presence of diabetes mellitus and a totally occluded infarct-related artery predicted poor contractile recovery.

CONCLUSIONS

Myocardial contractile recovery after revascularization in patients presenting with first acute anterior STEMI may be predicted by the absence of diabetes, a shorter time from symptom onset to thrombolytic therapy, the use of beta-blockers, a lower initial wall motion index score and the presence of collaterals to the infarct-related artery.

Adipose stromal vascular fraction cell construct sustains coronary microvascular function after acute myocardial infarction

A three-dimensional tissue construct was created using adipose-derived stromal vascular fraction (SVF) cells and evaluated as a microvascular protection treatment in a myocardial infarction (MI) model. This study evaluated coronary blood flow (BF) and global left ventricular function after MI with and without the SVF construct. Fischer-344 rats were separated into four groups: sham operation (sham), MI, MI Vicryl patch (no cells), and MI SVF construct (MI SVF). SVF cells were labeled with green fluorescent protein (GFP). Immediately postinfarct, constructs were implanted onto the epicardium at the site of ischemia. Four weeks postsurgery, the coronary BF reserve was significantly decreased by 67% in the MI group and 75% in the MI Vicryl group compared with the sham group. The coronary BF reserve of the sham and MI SVF groups in the area at risk was not significantly different (sham group: 83 ± 22% and MI SVF group: 57 ± 22%). Griffonia simplicifolia I and GFP-positive SVF immunostaining revealed engrafted SVF cells around microvessels in the infarct region 4 wk postimplant. Overall heart function, specifically ejection fraction, was significantly greater in MI SVF hearts compared with MI and MI Vicryl hearts (MI SVF: 66 ± 4%, MI: 37 ± 8%, and MI Vicryl: 29 ± 6%). In conclusion, adipose-derived SVF cells can be used to construct a novel therapeutic modality for treating microvascular instability and ischemia through implantation on the epicardial surface of the heart. The SVF construct implanted immediately after MI not only maintains heart function but also sustains microvascular perfusion and function in the infarct area by sustaining the coronary BF reserve.

Non-invasive evaluation of myocardial reperfusion by transthoracic Doppler echocardiography and single-photon emission computed tomography in patients with anterior acute myocardial infarction

BACKGROUND

The study was designed to evaluate whether the preserved coronary flow reserve (CFR) 72 hours after reperfused acute myocardial infarction (AMI) is associated with less microvascular dysfunction and is predictive of left ventricular (LV) functional recovery and the final infarct size at follow-up.

METHODS

In our study, CFR was assessed by transthoracic Doppler echocardiography (TDE) in 44 patients after the successful percutaneous coronary intervention during the acute AMI phase. CFR was correlated with contractile reserve assessed by low-dose dobutamine echocardiography and with the total perfusion defect measured by single-photon emission computed tomography 72 hours after reperfusion and at 5 months follow-up. The ROC analysis was performed to determine test sensitivity and specificity based on CFR. Categorical data were compared by an χ² analysis, continuous variables were analysed with the independent Student's t test. In order to analyse correlation between CFR and the parameters of LV function and perfusion, the Pearson correlation analysis was conducted. The linear regression analysis was used to assess the relationship between CFR and myocardial contractility as well as the final infarct size.

RESULTS

We estimated the CFR cut-off value of 1.75 as providing the maximal accuracy to distinguish between patients with preserved and impaired CFR during the acute AMI phase (sensitivity 91.7%, specificity 75%). Wall motion score index was better in the subgroup with preserved CFR as compared to the subgroup with reduced CFR: 1.74 (0.29) vs. 1.89 (0.17) (p < 0.001) during the acute phase and 1.47 (0.30) vs. 1.81 (0.20) (p < 0.001) at follow-up, respectively. LV ejection fraction was 47.78% (8.99) in preserved CFR group vs. 40.79% (7.25) in impaired CFR group (p = 0.007) 72 hours after reperfusion and 49.78% (8.70) vs. 40.36% (7.90) (p = 0.001) after 5 months at follow-up, respectively. The final infarct size was smaller in patients with preserved as compared to patients with reduced CFR: 5.26% (6.14) vs. 23.28% (12.19) (p < 0.001) at follow-up.

CONCLUSION

The early measurement of CFR by TDE can be of high value for the assessment of successful reperfusion in AMI and can be used to predict LV functional recovery, myocardial viability and the final infarct size.

Restoration of microvascular function in the infarct-related artery by intracoronary transplantation of bone marrow progenitor cells in patients with acute myocardial infarction: the Doppler Substudy of the Reinfusion of Enriched Progenitor Cells and Infarct Remodeling in Acute Myocardial Infarction (REPAIR-AMI) trial

BACKGROUND

The Doppler Substudy of the randomized, double-blind, placebo-controlled Reinfusion of Enriched Progenitor Cells and Infarct Remodeling in Acute Myocardial Infarction (REPAIR-AMI) trial aimed to investigate the effects of intracoronary infusion of bone marrow-derived progenitor cells (BMCs) on coronary blood flow regulation in patients with reperfused acute myocardial infarction.

METHODS AND RESULTS

In a total of 58 patients (BMC group, n=30; placebo group, n=28), coronary flow reserve (CFR) in the infarct artery and a reference vessel was assessed by intracoronary Doppler at the time of study therapy (4.2+/-0.1 days after acute myocardial infarction) and at the 4-month follow-up. Initial CFR was reduced in the infarct artery compared with the reference vessel in both groups (BMC: 2.0+/-0.1 versus 2.9+/-0.2, P<0.05; placebo: 1.9+/-0.1 versus 2.8+/-0.2; P<0.05). At the 4-month follow-up, CFR in the infarct artery had slightly improved in the placebo group (+0.88+/-0.18; P<0.001 versus initial) but was markedly increased by 90% (+1.80+/-0.25; P=0.005 versus placebo) in BMC-treated patients, resulting in a normalization of CFR (3.8+/-0.2; P<0.001 versus initial and placebo at 4 months). In the infarct vessel, adenosine-induced minimal vascular resistance index declined slightly in the placebo group (from 1.77+/-0.12 to 1.52+/-0.15 mm Hg x s/cm; P<0.05) but considerably decreased by -29+/-6% in the BMC group (from 1.86+/-0.19 to 1.20+/-0.12 mm Hg x s/cm; P<0.05 versus initial and placebo at 4 months).

CONCLUSIONS

Intracoronary BMC therapy after acute myocardial infarction restores microvascular function of the infarct-related artery, which is associated with a significant improvement in maximal vascular conductance capacity. These data provide clinical proof of concept that progenitor cell transplantation promotes vascular repair.

Normalization of coronary blood flow in the infarct-related artery after intracoronary progenitor cell therapy: intracoronary Doppler substudy of the TOPCARE-AMI trial

BACKGROUND

Coronary microvascular dysfunction contributes to infarct extension and poor prognosis after an acute myocardial infarction (AMI). Recently, progenitor cell application has been demonstrated to improve neovascularization and myocardial function after experimental myocardial infarction. Therefore, we investigate coronary blood flow regulation in patients after AMI treated with intracoronary progenitor cell therapy.

METHODS AND RESULTS

In the TOPCARE-AMI trial, patients received either bone marrow-derived or circulating progenitor cells into the infarct-related artery 3-7 days after AMI. The present substudy investigates in 40 patients coronary blood flow regulation at the time of progenitor cell therapy and at 4-month follow-up by i.c. Doppler in the infarct artery as well as a reference vessel. At the initial measurement, coronary flow reserve (CFR) was reduced in the infarct artery compared to the reference vessel (median 2.5 vs. 3.4, p<0.001). At 4-month follow-up, intracoronary progenitor cell therapy was associated with a normalization of CFR in the infarct artery (median 3.9 vs. reference vessel 3.8, p=0.15). CFR also improved in the reference vessel, but mechanisms were different: reference vessel increase in CFR was secondary to an increased basal vascular resistance, probably due to reduced need for hypercontractility. In contrast, in the infarct artery, adenosine-induced minimal vascular resistance profoundly decreased, indicating an increased maximal coronary vascular conductance capacity. In addition, in a non-randomized matched control group (n=8), minimal vascular resistance in the infarct artery was significantly elevated compared to progenitor cell treated patients 4 months after AMI (p=0.012).

CONCLUSIONS

Intracoronary progenitor cell therapy after AMI is associated with complete restoration of coronary flow reserve due to a substantial improvement of maximal coronary vascular conductance capacity. The clinical importance of improved microcirculation by progenitor cell therapy in patients after AMI has to be established in further randomized trials.

Fractional Flow Reserve of Infarct-Related Arteries Identifies Reversible Defects on Noninvasive Myocardial Perfusion Imaging Early After Myocardial Infarction

OBJECTIVES

We hypothesized that fractional flow reserve (FFR) of an infarct-related artery (IRA) early after myocardial infarction (MI) identifies inducible ischemia on noninvasive imaging.

BACKGROUND

Early after MI, IRAs frequently have angiographically indeterminant lesions. Whether FFR can detect reversible perfusion defects early after MI when dynamic microvascular abnormalities are present is not known.

METHODS

Rest and dipyridamole (DP)-stress 99mTc sestamibi single-photon emission computed tomography (SPECT) were performed in 48 patients 3.7 +/- 1.3 days after MI, with 23 patients undergoing concurrent myocardial contrast echocardiography (MCE). Angiography, FFR, and percutaneous coronary intervention (PCI) of the IRA (as necessary) were subsequently performed. Follow-up SPECT was performed 11 weeks after PCI to identify true reversibility on baseline SPECT.

RESULTS

The sensitivity, specificity, positive and negative predictive value, and concordance of FFR < or =0.75 for detecting reversibility on SPECT were 88%, 50%, 68%, 89%, and 71% (chi-square <0.001), respectively; which improved to 88%, 93%, 88%, 93%, and 91% (chi-square <0.001), respectively, for the detection of true reversibility. The corresponding values of FFR < or =0.75 for detecting reversibility on DP-MCE were 90%, 100%, 100%, 75%, and 93% (chi-square <0.001), respectively, and on either SPECT or MCE were 88%, 93%, 91%, 91%, and 91% (chi-square <0.001), respectively. The optimal FFR value for discriminating inducible ischemia on noninvasive imaging was 0.78.

CONCLUSIONS

Fractional flow reserve of the IRA accurately identifies reversibility on noninvasive imaging early after MI. These findings support the utility of FFR early after MI.

Effect of simvastatin on coronary flow reserve in patients with atherosclerosis and hypercholesterolemia: an intracoronary Doppler study

BACKGROUND

Early stages of coronary atherosclerosis are accompanied by a functional impairment of coronary vasodilator capacity and endothelial dysfunction. Reduced coronary flow reserve has been reported in patients with hypercholesterolemia, despite angiographically normal coronary arteries. The aim of the study was to evaluate the effect of simvastatin on coronary flow reserve.

METHODS

The study was an open non-placebo-controlled serial investigation in which every patient acted as his own control: 36 male patients with hypercholesterolemia and a non-significant coronary artery lesion in a not previously revascularized coronary artery. Intracoronary Doppler measurements were performed. Coronary flow reserve, relative coronary flow reserve and average peak velocity were performed at baseline, after 3 months on a lipid-lowering diet (control period), and after another 12 months of simvastatin 40 mg/day. In the same patient cohort, significant reduction in lesion plaque plus media has been demonstrated by intravascular ultrasound.

RESULTS

Changes in coronary flow reserve were not influenced by either diet or simvastatin (2.5+/-0.6 vs. 2.6+/-0.5 vs. 2.6+/-0.6, P=ns). Maximum hyperemic flow (34.8+/-12.2 vs. 36.7+/-12.5 vs. 42.5+/-13.1, P<0.001) as well as resting flow (14.3+/-5.3 vs. 14.5+/-4.4 vs. 16.6+/-4.6, P<0.001) increased significantly after 12 months simvastatin therapy.

CONCLUSION

Despite plaque plus media, regression simvastatin therapy for 12 months does not affect coronary flow reserve obtained using serial intracoronary Doppler studies. Simvastatin, however, increases the hyperemic flow velocity.

Non-invasive coronary flow reserve is correlated with microvascular integrity and myocardial viability after primary angioplasty in acute myocardial infarction

OBJECTIVE

To test whether preserved coronary flow reserve (CFR) two days after reperfused acute myocardial infarction (AMI) is associated with less microvascular dysfunction (" no-reflow" phenomenon) and is predictive of myocardial viability.

DESIGN

24 patients with anterior AMI underwent CFR assessment in the left anterior descending coronary artery (LAD) with transthoracic echocardiography and myocardial contrast echocardiography (MCE) 48 h after primary angioplasty in the LAD (mean 4 (SD 2) and 3 (1) days, respectively). Low-dose dobutamine echocardiography was performed 6 (3) days after AMI and follow-up echocardiography at three months.

RESULTS

No-reflow extent was greater in patients with impaired CFR (< 2.5) than in those with preserved CFR (> 2.5) (55 (35)% v 11 (25)%, p < 0.001). MCE reflow was more common in patients with preserved CFR (8/12) than in those with reduced CFR (1/12, p < 0.05). Wall motion score index in the LAD territory (A-WMSI) was similar at the first echocardiography (2.14 (0.39) v 2.32 (0.47), NS), although it was better in patients with preserved CFR at dobutamine (1.38 (0.45) v 1.97 (0.67), p < 0.05) and follow-up echocardiography (1.36 (0.40) v 1.97 (0.64), p < 0.05). An inverse correlation was found between CFR and A-WMSI at dobutamine and follow-up echocardiography (r = -0.49, p = 0.016 and r = -0.55, p = 0.005) and between MCE and A-WMSI at dobutamine and follow-up echocardiography (r = -0.75, p < 0.001 and r = -0.75, p < 0.001). By multivariate analysis MCE reflow remained the only predictor of recovery at both dobutamine and follow-up echocardiography (odds ratio 1.06, 95% CI 1 to 1.1, p = 0.009).

CONCLUSION

CFR is inversely correlated with the extent of microvascular dysfunction at MCE two days after reperfused AMI. CFR and MCE reflow early after AMI are correlated with myocardial viability at follow up.

Early assessment of coronary flow reserve by transthoracic Doppler echocardiography predicts late remodeling in reperfused anterior myocardial infarction

BACKGROUND

Microvascular integrity is an essential determinant of favorable late outcome in reperfused myocardial infarction. Coronary flow reserve (CFR) can be assessed by transthoracic Doppler echocardiography and provides a functional estimate of microvascular integrity downstream from the patent infarct-related vessel.

OBJECTIVE

We sought to assess the effects of CFR in predicting late left ventricular (LV) remodeling in patients with reperfused acute anterior myocardial infarction treated with primary angioplasty.

METHODS

In all, 31 patients admitted with acute anterior myocardial infarction underwent primary angioplasty of the infarct-related vessel. After angioplasty, angiographic thrombosis in myocardial infarction (TIMI) grade and myocardial blush were scored. On the first day, all underwent stress echocardiography and CFR evaluation of left anterior descending coronary artery by transthoracic Doppler. All patients had resting 2-dimensional echocardiography at 1, 3, and 6 months for assessment of LV function.

RESULTS

CFR could be successfully assessed in 31 patients. After 6 months 5 patients showed LV dilatation (group I), whereas 26 patients did not show significant variation (group II). On day 1, CFR was higher (group I = 1.43 +/- 0.11 vs group II = 1.67 +/- 0.26, P =.005) and the deceleration time of diastolic left anterior descending coronary artery flow velocity was longer (group I = 212 +/- 41.4 milliseconds vs group II = 286 +/- 106.7 milliseconds, P <.02) in patients without, compared with those with LV remodeling, whereas there was no difference in angiographic parameters.

CONCLUSION

Early assessment of CFR and the pattern of baseline diastolic coronary flow velocity by transthoracic Doppler echocardiography is feasible, safe, and more useful than angiographic indices in identifying patients at high risk of remodeling in spite of successful primary angioplasty.

Usefulness of coronary flow reserve immediately after primary coronary stenting in predicting wall motion recovery in patients with anterior wall acute myocardial infarction

This study examined whether coronary flow reserve (CFR) measured immediately after primary coronary stenting could predict wall motion recovery in patients who have acute myocardial infarction. CFR significantly correlated with the change of wall motion score (r = 0.68, p <0.0001), and the optimal cut-off value of CFR for predicting wall motion recovery was 1.4 (sensitivity 85%, specificity 94%).

Convalescent stage coronary flow reserve and late myocardial morphologic outcomes in patients with first anterior acute myocardial infarction

BACKGROUND

Microvascular damage immediately after reperfusion therapy is an independent predictor of left ventricular function in patients with acute myocardial infarction (AMI). However, its recovery may vary among individuals and the relationship between convalescent stage microvasculature and late myocardial morphologic change is unclear.

METHODS AND RESULTS

Patients treated with coronary angioplasty within 12 h of their first anterior AMI were enrolled in this study. Coronary flow reserve (CFR) was measured 3 weeks post AMI, in both branches of the left coronary artery: culprit (left anterior descending artery: LAD) and non-culprit (left circumflex artery: LCX). Left ventriculography was performed at 3 weeks and 6 months post AMI and compared. Seventeen patients showed abnormal CFR in the LAD (Group 1: CFR<2), whereas 20 patients showed normal CFR (Group 2: CFR >/=2). Percent changes of end-diastolic volume tended to be higher in Group 1 than in Group 2 (11.8+/-21.6% vs -1.3+/-14.4%, p=0.056), and %changes of end-systolic volume was significantly smaller in Group 2 (11.8+/-22.1% vs -8.7+/-25.1%, p<0.05). A statistically significant correlation was found between absolute and relative CFR in the LAD and %change of end-systolic volume (r=-0.58: p<0.001, and r=0.40: p<0.05, respectively).

CONCLUSIONS

Microvascular function in the convalescent stage may be related to these favorable changes.

The predictive value of 201Tl rest-redistribution and 18F-fluorodeoxyglucose SPECT for wall motion recovery after recent reperfused myocardial infarction

201Tl and 18F-FDG are useful for acute myocardial infarction (MI) assessment. The goal of this study was to compare their predictive value for wall motion recovery in the culprit area after a recent reperfused MI using SPECT technique.

METHODS

Forty-one patients (mean age: 56 +/- 12 years) were included, 81% of them male; all were studied within 1-24 days post MI. They underwent angioplasty in 27 cases (12 primary); bypass grafting in 10 cases and successful thrombolysis in 4. SPECT 201Tl injected at rest and redistribution (R-R) and also 18F-FDG, were performed on different days. Processed tomograms were interpreted blinded to clinical or angiographic data. Segmental wall motion assessed with echocardiography at baseline was compared with the 3 month follow up.

RESULTS

Sensitivity [Confidence Interval] for 201Tl R-R was 74.6% [60.5-84.5], for FDG it was 82.1% [70.8-90.4]; specificities were 73% [64.3-80.5] and 54.8% [45.6-63.7], respectively. 18F-FDG tended to be more sensitive than 201Tl R-R, but the latter was more specific (p < 0.0004). Both 201Tl RR and 18F-FDG presented high negative predictive value (p: ns).

CONCLUSION

In recent MI, SPECT 201Tl R-R is a valuable and widely available technique for viability detection, with similar sensitivity and significant better specificity than SPECT 18F-FDG.

Coronary Flow Reserve after Coronary Intervention is Similar in Patients with Preserved Viability in Previous Myocardial Infarction and in Those with Angina Pectoris

The relationship between coronary flow reserve (CFR) and viability in the infarcted myocardium has not been fully clarified. We measured coronary blood flow velocity immediately after coronary intervention (with percutaneous transluminal coronary angioplasty [PTCA] or stenting) in 38 patients with previous myocardial infarction and preserved viability and 48 with angina pectoris. CFR was calculated and was similar between the two patient groups. No differences in the incidence of post-intervention CFR > 2.0 were detected; there were no differences in postintervention CFR between patients with preserved myocardial viability and those with angina pectoris who underwent PTCA. Coronary stenting reduced the percentage diameter stenosis in both groups compared with PTCA and slightly increased the post-intervention CFR. No differences were, however, detected in postintervention CFR between patients with preserved myocardial viability and those with angina pectoris who underwent additional stenting. These results reveal that in patients with preserved myocardial viability, post-intervention CFR was restored to values similar to those in patients with angina pectoris.

Effect of acute myocardial infarction on the utility of fractional flow reserve for the physiologic assessment of the severity of coronary artery narrowing

Fractional flow reserve (FFR) has been shown to be a useful physiologic index of coronary lesion severity in myocardial beds of patients without prior infarction and in those with remote infarction. Acute myocardial infarction (AMI) causes myocardial necrosis and microvascular stunning, embolization, and damage. Whether FFR remains a useful index of epicardial flow in the setting of recent myocardial infarction is not established. Cardiac risk factors, serum troponin I, angiographic minimal lumen diameter (MLD), percent diameter stenosis (DS), lesion length, vessel reference diameter, hyperemic central aortic pressure, hyperemic pressure distal to stenosis, and FFR were compared in 43 vessels subtending recent AMI beds to 25 control vessels, matched by lesion length and MLD, in patients without AMI. There were no differences in DS, MLD, lesion length, or reference diameter between AMI and non-AMI groups. Patients with AMI had mean troponin I levels of 91.8 +/- 162 ng/ml. Left ventricular ejection fraction was significantly lower in patients with than without AMI (55 +/- 9% vs 62 +/- 8%, p <0.05). There were no significant differences in hyperemic central aortic pressure (92 +/- 13 vs 99 +/- 15 mm Hg, p = NS), hyperemic pressure distal to the stenosis (62 +/- 17 vs 66 +/- 19 mm Hg, p = NS), or FFR (0.67 +/- 17 vs 0.68 +/- 17, p = NS) between recent AMI and non-AMI control patients. There was a significant correlation between DS and FFR for both patients with (p <0.001) and without (p = 0.003) infarctions. Thus, FFR and the relation between FFR and DS of lesions subtending AMI was not significantly different from FFR of angiographically matched lesions in patients without AMI.

Chronic heart failure: global left ventricular perfusion and coronary flow reserve with velocity-encoded cine MR imaging: initial results

PURPOSE

To quantify and compare global left ventricular (LV) perfusion and coronary flow reserve (CFR) in patients with chronic heart failure and in healthy volunteers by measuring coronary sinus flow with velocity-encoded cine (VEC) magnetic resonance (MR) imaging.

MATERIALS AND METHODS

MR measurements were performed in 10 consecutive patients with chronic heart failure due to coronary artery disease and in 10 volunteers. Global LV perfusion was quantified by measuring coronary sinus flow in an oblique imaging plane perpendicular to the coronary sinus with non-breath-hold VEC MR imaging. LV mass was measured by means of cine imaging that encompassed the heart. LV perfusion was calculated from coronary sinus flow and mass. CFR was measured from LV perfusion at rest and that after infusion of dipyridamole. Analysis of covariance was used to determine differences between groups. Differences within groups were analyzed by means of the Student t test for paired data. Regression analysis was used to determine correlation between CFR and LV ejection fraction.

RESULTS

At rest, LV perfusion was not significantly different in patients with chronic heart failure (0.46 mL/min/g +/- 0.19) and volunteers (0.52 mL/min/g +/- 0.21, P =.54). After administration of dipyridamole, LV perfusion was less than half in patients with chronic heart failure compared with that in volunteers (1.07 mL/min/g +/- 0.64 vs 2.19 mL/min/g +/- 0.98) (P =.03). CFR was severely reduced in patients with chronic heart failure compared with that in volunteers (2.3 +/- 0.9 vs 4.2 +/- 1.5, P =.01). A moderate but significant correlation was found between CFR and LV ejection fraction (r = 0.54, P =.02)

CONCLUSION

Combined cine and VEC MR imaging revealed that patients with chronic heart failure have normal LV perfusion at rest but severely depressed LV perfusion after vasodilation. Impaired CFR may contribute to progressive decline in LV function in patients with chronic heart failure.