European Journal of Echocardiography Advance Access originally published online on June 25, 2008
European Journal of Echocardiography 2009 10(1):127-132; doi:10.1093/ejechocard/jen190
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Prognostic value of transthoracic coronary flow reserve in medically treated patients with proximal left anterior descending artery stenosis of intermediate severity
1 Department of Cardiology and Intensive Care Unit, Centre Hospitalier de Compiègne, 8 rue Henri Adnot, 60200 Compiègne, France
2 INSERM, ERI 12, Department of Cardiology, Centre Hospitalier Universitaire d’ Amiens, France
Received 26 February 2008; accepted after revision 30 May 2008; online publish-ahead-of-print 25 June 2008.
* Corresponding author. Tel: +33 3 44 23 62 39; fax: +33 3 44 23 62 38. E-mail address: patrickmeimoun{at}free.fr; p.meimoun{at}ch-compiegne.fr
 |
Abstract |
|---|
 Top Abstract IntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
Aims: Prognostic value of transthoracic coronary flow reserve (T-CFR) is not established in patients with left anterior descending artery (LAD) stenosis of intermediate severity. Objective is to determine the prognosis value of T-CFR > 2 in medically treated patients with angiographically intermediate [50–70% QCA (quantitative coronary angiography)] proximal LAD stenosis.
Methods and results: Among 110 consecutive patients with intermediate LAD stenosis who underwent prospectively T-CFR in the distal part of the LAD after intravenous administration of adenosine to assess the functional significance of the stenosis, 80 patients had T-CFR > 2 and were treated medically without revascularization (Group 1). Among the 30 patients who had T-CFR < 2, an additional dobutamine stress echocardiography (DSE) was performed: 15 had a negative DSE; were treated medically and served as a comparative group (Group 2), and 15 had a positive DSE; underwent LAD revascularization, and were excluded from further analysis. All patients completed follow-up (16 ± 10 months). During the follow-up period (range 6–45 months), 76 patients (95%) remained free of death or LAD-related event in Group 1, vs. 12 patients (80%) in Group 2. By Kaplan–Meier method, at 30 months the per cent estimated survival free from death or target vessel-related events was 92 ± 4% in Group 1 and 44 ± 22% in Group 2 (P < 0.01). By multivariate analysis, T-CFR remained the only independent predictor of death or LAD-related events.
Conclusion: In patients with proximal LAD stenosis of intermediate severity and T-CFR > 2, deferral of revascularization is associated with low event rate.
Keywords: Coronary flow reserve; Transthoracic Doppler; Intermediate coronary stenosis; Left anterior descending artery
|
Introduction |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
Clinical decision making in patients with intermediate angiographic coronary stenosis (between 50 and 70%) is challenging.1,2 Discrepancy between anatomy and function is demonstrated in this setting by extensive data, which showed the unreliability of diameter stenosis as a measure of the physiological relevance to stenosis in terms of impairment of flow reserve.1–11 In this purpose, long-term follow-up of patients deferred for revascularization is now well established with invasive method such as fractional flow reserve (FFR)5–10 and to a lesser extent with invasive coronary flow reserve (CFR) using Doppler guide wires.11,12 CFR by transthoracic Doppler echocardiography (T-CFR) is a non-invasive and useful tool to assess the physiological significance of left anterior descending artery (LAD) stenosis of intermediate severity.13 However, its prognostic value is not established in this situation. No prospective data are available concerning the safety of deferring angioplasty in patients with intermediate stenosis, based on T-CFR measurements. Furthermore, based on stress echocardiography, significant proximal LAD stenosis seems to confer a poor prognosis.14 Therefore, we hypothesized that T-CFR is a valuable non-invasive tool in this setting. We prospectively followed-up patients with proximal LAD stenosis of intermediate severity deferred for revascularization on the basis of T-CFR > 2.
|
Methods |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
Study population
One hundred and ten consecutive patients who had proximal LAD stenosis of intermediate severity—50–70% luminal diameter stenosis by QCA (quantitative coronary angiography)—were prospectively evaluated. They underwent coronary angiography mainly for acute coronary syndrome (ACS) involving arteries other than LAD, or for suspected restenosis after angioplasty, or for chest pain with inconclusive exercise electrocardiography. Because in this subset of intermediate stenoses the decision of revascularization based solely on the angiogram is challenging and not recommended,15 the patients were submitted to functional evaluation of stenosis severity by T-CFR. Our hypothesis was that T-CFR > 2 confer a good prognosis given its high negative predictive value to detect ischaemia in this setting.13 Exclusion criteria were previous anterior myocardial infarction (MI), significant valvular disease, contraindication to adenosine, CCS (Canadian Cardiac Society) class IV, NYHA class IV, left ventricular ejection fraction (LVEF) < 45%, dilated or hypertrophic cardiomyopathy, and a poor life expectancy which would interfere follow-up (such as malignancy). Patients with multivessel disease could be included if beyond the LAD no other main epicardial vessel showed a lesion suitable for angioplasty or if any other vessel had been subject to prior interventions. Patients with ACS involving other arteries than the LAD were submitted to the functional evaluation of the LAD when they were in stable situation, at least 2 weeks after the acute event. All patients were in stable sinus rhythm and all presented stable coronary artery disease at the time of T-CFR. Eighty patients were treated medically and revascularization of the LAD was deferred on the basis of T-CFR > 2, though the vessel was suitable for angioplasty (Group 1, CFR > 2, n = 80). The cut-off value <2 of CFR was chosen because it detected significant coronary stenosis and predicted ischaemia in previous invasive and non-invasive studies.11–13,16–18 However, as CFR is a global evaluation of the coronary tree (from the epicardial artery to the microcirculation), when T-CFR was <2, an additional stress testing was performed in order to discriminate between truly significant epicardial coronary stenosis and microcirculatory impairment. Therefore, 30 patients had a T-CFR <2 and underwent an additional dobutamine stress echocardiography (DSE) performed as previously described,13,19 the same week as for the adenosine test. Beta-blockers were withheld 48 h before DSE in all cases. DSE was positive in LAD territory in 15 patients who subsequently underwent LAD revascularization, by angioplasty (n = 13) or by bypass graft (n = 2, 2 grafts), within 2 weeks after DSE (group revascularization, n = 15, excluded from subsequent analysis). DSE was negative in 15 patients who then were left to medical therapy (Group 2, CFR < 2, n = 15). (See Figure 1 for the summary of the study design). The choice of the medical treatment was left at the discretion of the treating physician for each case. Informed consent was obtained for all participants.
|
Coronary angiography
Selective coronary angiography was performed in all patients using standard techniques between 1 week and 1 month before adenosine and dobutamine tests. No cardiac event occurred during this interval. The severity of coronary stenosis was evaluated by multiple projections and was determined by experienced investigators, with commercially available quantitative cardiovascular angiographic software program (Philips, Integris, HM 3000).
Coronary flow reserve
T-CFR was performed with a commercially available machine (Acuson Sequoia 256, Mountain View Cal) as previously described.13,19 Briefly, first, the distal part of the LAD was studied using a low multifrequency transducer (3V2C probe). Visualization of the artery was performed with colour Doppler flow mapping guidance, either in the modified parasternal view or in the modified three-apical view. For colour Doppler echocardiography, the velocity range was set in the range of 12–16 cm/s. Blood flow velocity was measured by pulsed wave Doppler echocardiography using a sample volume of 3–4 mm, placed on the colour signal in the distal LAD. We tried to align the ultrasound beam direction as parallel as possible with the distal LAD flow. No angle correction was performed for CFR measurements given that CFR is the ratio between hyperaemic and baseline flow velocity, and is not affected by the actual flow velocity. However, the angle was kept as small as possible during the test.
CFR was measured during intravenous infusion of adenosine (0.14 mg/kg/min over 2 min). Spectral Doppler signals in the distal part of the LAD were recorded at baseline and during hyperaemia and the transducer position was not changed during administration of adenosine. Blood flow velocity measurements were performed offline by an experienced investigator who was blinded to the patient data by contouring the spectral Doppler signals using the integrated software package of the ultrasound system. CFR was calculated as the ratio of hyperaemic to basal mean diastolic flow velocities. Final values of flow velocity represented an average of three cardiac cycles. The intraobserver and interobserver variability of CFR as we previously described is 
5%.13,19 The electrocardiogram was monitored continuously throughout adenosine infusion. Blood pressure and heart rate were measured at baseline and at the time of peak action of adenosine.
Follow-up and clinical events
Follow-up clinical data were obtained in all patients by telephone contact with the patients, with the referring physician, or by an outpatient medical visit. Events were defined in the following order as death, non-fatal ACS, unstable angina, coronary angioplasty, coronary bypass surgery, and acute heart failure requiring hospitalization. Clinical events were sub-classified into LAD related or target vessel unrelated. LAD-related event was defined as ACS or unstable angina in the LAD territory, revascularization of the LAD, and acute heart failure, if electrocardiographic changes or echocardiographic wall motion abnormalities involving the LAD territory were demonstrated during the episode of heart failure. The primary outcome was defined as the occurrence of death or LAD-related event. Hospital records were used to corroborate outcomes. Two independent investigators blinded to the tests results collected outcome data.
Death was defined as all-cause mortality. In cases of deaths out of the hospital, sudden unexpected deaths were attributed to LAD-related event unless proven otherwise. ACS was defined as new-onset or worsening angina that required hospitalization and was associated with ischaemic ST-segment abnormalities, any elevation of cardiac troponin T (normal value < 0.01), or both. Unstable angina was defined by angina at rest or change in pattern of pre-existing angina requiring hospitalization but without ischaemic ST-segment abnormalities and cardiac troponin elevation. When at least one of these events occurred, the patient was censored at the time of the most severe event.
Statistics
Continuous variables are expressed as mean ± SD and categorical variables as percentages. Unpaired or paired t-test and the 
2 test (with the Yate's correction when appropriate) were performed to assess differences according to the variables tested. Patient survival curves for absence of adverse cardiac events were constructed according to the Kaplan–Meier method and compared by the log-rank test. A multivariate Cox proportional hazards model was used. Hazard ratio (HR) with 95% CI was estimated. A P < 0.05 was considered as significant.
|
Results |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
Acute results
No serious adverse events occurred during hospitalization in each group.
Among the 42 patients (53%) who had coronary angiography for ACS in Group 1, all but three had troponin elevation, and underwent revascularization. By comparison, nine patients (60%) had coronary angiography for ACS in Group 2, and all but one had troponin elevation and underwent revascularization (P = NS). The distribution of one/two/three vessel disease was similar in each group, before (0/36/6 in Group 1, vs. 0/7/2 in Group 2, respectively), and after revascularization of the culprit vessel(s) (36/6/0 in Group 1, vs. 7/2/0 in Group 2, respectively, P = NS). Patients who underwent angiography for suspected in-stent restenosis were as follows: nine (11%) in Group 1 (four BMS, five DES, mean time delay 7 ± 2 months), and two (13%) in Group 2 (one BMS, one DES, mean time delay 7 months) (P = NS). Twenty patients (25%) in Group 1, and four patients (27%) in Group 2 underwent angiography for chest pain with inconclusive exercise electrocardiography (P = NS). Three (3.75%) another patients underwent angiography for positive exercise electrocardiography and six for other reasons, in Group 1. The location of the lesion in the LAD was ostial in two cases (3%), proximal in 60 cases (75%), and mid-proximal in 18 cases (23%) in Group 1 vs. ostial in zero case, proximal in 10 cases (67%), and mid-proximal in five cases (23%) in Group 2 (P = NS).
Baseline characteristics
No complication occurred during the adenosine test in each group. The characteristics of the study population at the time of the adenosine test are shown in Table 1. Patients of Group 2 were significantly older than patients of Group 1 (P < 0.05). The mean CFR was 2.8 ± 0.5 in Group 1 and 1.75 ± 0.2 in Group 2 (P < 0.01). Compared with patients in Group 1, patients in Group 2 exhibited a higher resting coronary flow velocity and a lower hyperaemic coronary flow velocity (all, P < 0.05). No other significant differences were seen between groups 1 and 2 concerning baseline characteristics, including the left ventricular mass index and the rate pressure product at baseline (9125 ± 2753 in Group 1 vs. 9935 ± 2523 in Group 2, P = NS).
|
Follow-up
Mean follow-up was 16 ± 10 months with a range from 6 to 45 months. Clinical follow-up was completed in all patients. Globally, the proportion of cardiovascular protective drugs did not change over time in each group. The number of antianginal drugs did not increase over time neither in Group 1 nor in Group 2 as is it shown in Table 2.
|
In the group of patients with CFR > 2 and deferred revascularization, 76 patients (95%) remained free of death or target vessel-related events during follow-up. One patient died suddenly at 14 months. No MI was observed. Therefore, death or MI occurred in 1.25% of cases in this group (n = 1). LAD angioplasty was performed in two cases, in the setting of unstable angina at 6 months of follow-up. However, for these two patients the main lesion was a significant stenosis of the circumflex artery, which was responsible of the unstable angina and was treated by angioplasty before the LAD but during the same procedure. The angioplasty of the LAD was performed based on clinical and angiographic data only, by an angiographer not aware of the study. Due to disease progression, one patient underwent elective coronary artery bypass graft (CABG) at 18 months of follow-up (LAD and circumflex artery). Therefore, target vessel revascularization (LAD) was performed in 3.75% of cases in this group (n = 3). Non-target vessel unstable angina occurred in two cases. One was treated by circumflex angioplasty, at 6 months of follow-up, and one was left under medical therapy.
In the group of patients with a low CFR treated medically, 12 patients (80%) remained free of death or LAD-related events during follow-up. One patient died at 8 months (fatal ACS), one had resuscitated cardiac arrest and acute heart failure requiring mechanical ventilation at 15 months, and one had ACS and acute heart failure at 24 months. Therefore, death or target vessel-related event occurred in 20% of cases in this group (n = 3). Non-target vessel coronary angioplasty was performed at 10 months of follow-up in one patient, due to disease progression (circumflex artery). Table 3 summarizes the total events in each group during follow-up.
|
2 treated medicallyBy the Kaplan–Meier method, at 30 months the per cent estimated survival free from death or target vessel-related events was 92 ± 4% in Group 1 and 44 ± 22% in Group 2 (P < 0.01) (Figure 2). After adjustment by age, sex, hypertension, smoking, diabetes, dyslipidaemia, LVEF, % LAD stenosis, prior coronary revascularization, prior MI, multivessel disease, and medical treatment (aspirine, clopidrogel, beta-blockers, statins, angiotensin converting inhibitors/angiotensin receptor blockers, any antianginal drug, at the time of test), T-CFR > 2 remained the only independent predictor of total mortality or LAD events (HR = 0.12, 95% CI 0.01–0.77, P = 0.01).
|
Discussion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
The results of this study show that T-CFR is a useful non-invasive tool for evaluating patients with angiographically intermediate LAD stenosis. This tool is particularly useful in identifying low-risk patients for cardiac events who do not need additional tests and interventions. Deferral of angioplasty in patients with T-CFR > 2 appears a reasonable option, associated with a good clinical outcome in this setting.
FFR, which is determined from coronary pressure measurements during cardiac catheterization, is one of the most reliable tools to assess the functional significance of coronary stenosis of intermediate severity.4–10 However, it is expensive and not available in all catheterization laboratories. By contrast, T-CFR is totally non-invasive, easily available at bedside, at low cost. Despite T-CFR is a global evaluation of the coronary tree, limited by the coronary microcirculation impairment, FFR could also be affected by the confounding influence of microvascular disease in the setting of intermediate stenoses, with false-negative results [FFR > 0.75 and perfusion defects in single photon emission computed tomography (SPECT)] in cases of low maximal flow due to high coronary microvascular resistance.20,21 When T-CFR is >2, a high negative predictive value for detecting ischaemia was found in patients with angiographic LAD stenosis of intermediate severity.13 Until now, no data were available to determine the long-term usefulness of T-CFR in this setting, except in a recent multicentre study which demonstrated, in a group of 86 patients with single-vessel disease of intermediate severity, that decreased T-CFR (<2) was associated with a worse outcome.22 However, the methodology of this study slightly differed as ours because coronary angiography was performed after the stress echocardiography, and T-CFR was performed simultaneously with dipyridamole-stress to assess wall motion abnormalities in that study, whereas in our study T-CFR was used after coronary angiography for decision making as a single tool (when it was >2). The independent prognostic value of T-CFR has been demonstrated by recent studies, using simultaneous wall motion assessment and T-CFR during dipyridamole stress echo, in patients with known or suspected coronary artery disease, with or without diabetes.23,24
In patients with T-CFR > 2 deferred for LAD revascularization, the rate of death or MI at 30 months was 1.3% in this study, with a 92 ± 4% estimated survival free from death or LAD-related events during the same follow-up. These results are in agreement with previous studies, which demonstrated the usefulness of FFR and invasive CFR for risk stratification of patients with an intermediate coronary stenosis. In patients with intermediate coronary stenosis and FFR > 0.75 the combined risk for death or acute MI is 1% per year with medical treatment alone.8 In 22 patients with mean intermediate coronary stenosis of 66 ± 8.5% and invasive CFR > 2 (2.7 ± 0.75), the rate of major adverse cardiac events was 9% at 15 ± 6 months of follow-up, with no death or MI.11 In patients with multivessel disease and an intermediate non-significant coronary stenosis determined with an invasive CFR > 2, the rate of major adverse cardiac events was only 6% at the end of 1-year follow-up.12 Furthermore, invasive CFR was a more accurate predictor of events than was SPECT in this setting.12
Despite these coronary stenoses were non-significant, based on T-CFR > 2, they may progress over time and become significant, as it was the case in one of the patients who underwent CABG 16 months later. Continuous scrutiny is necessary with serial T-CFR for instance, and appropriate medical therapy is required, such as statin therapy, antiplatelet agents, and angiotensin-converting enzyme inhibitors, associated with life style modification, to slow the progression of atherosclerosis and reduce cardiac events in these patients. A recent study showed that in patients undergoing stent implantation, the event-rate beyond 1 year after stenting was 6%, related to disease progression in segments other than the stented lesion.25
The average number of antianginal drugs did not increase over time in Group 1 despite the LAD stenosis was left untreated. Maybe, this suggests that excluding the functional significance of the stenosis might have played a role in reassuring the patient.
Despite the small sample size, the follow-up of patients in Group 2 suggests that a low CFR in this setting confers a poor prognosis, particularly for patients not undergoing LAD angioplasty. However, these patients were older than those with T-CFR > 2, which could have influenced their prognosis. But in multivariate analysis, including other confounding variables, only CFR was an independent predictor of events.
In the era of drug-eluting stents, and according to the theory of ‘sealing the plaque’ a prophylactic strategy to reduce death and MI could have been discussed for these intermediate stenoses, given that the majority of plaque progression requiring PCI (percutaneous coronary intervention) are usually located in less severe stenoses26 and plaque rupture is unpredictable using clinical and angiographic findings alone. However, our study shows that except the patient who died suddenly, no patient suffered an ACS including transmural MI during follow-up in the group of patients with CFR > 2 and deferred revascularization. Furthermore a concern has recently risen concerning the safety of drug-eluting stents27 and no data are currently available to validate an aggressive approach.
|
Limitations |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
This is a single centre study with a high experience of non-invasive CFR and the number of patients is relatively small. Therefore our results need confirmation in a larger population before suggesting the systematic use of T-CFR for risk stratification of patients with intermediate LAD stenosis. Our methodology is only applicable with a high success rate in the LAD because the feasibility of non-invasive CFR is far from being equivalent for each coronary territory.28 Therefore our results cannot be extrapolated to other coronary territories. The sensitivity of stress echocardiography in patients with single vessel disease of intermediate severity is not optimal.29 Consequently some patients with low CFR and a negative DSE could have been misclassified as having a non-significant stenosis with only microcirculatory impairment. However, DSE was performed without anti-ischaemic therapy at the time of testing, with maximum achieved heart rate, and our main aim was to assess the safety of deferring angioplasty in patients with CFR > 2. Indeed, compared with patients with low CFR and positive DSE who underwent LAD revascularization (n = 15), patients in Group 2 with low CFR and negative DSE, had a less severe CFR reduction (1.75 ± 0.2 vs. 1.6 ± 0.2, P < 0.05), which could influence the appearance of wall motion abnormalities during DSE and induce a negative result due to a lack of transmural left ventricular ischaemia. Additional tests such as intravascular ultrasound or FFR should be useful in these patients.
|
|
Conclusion |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
In patients with proximal LAD stenosis of intermediate severity, non-invasive CFR is an interesting prognostic parameter. When T-CFR is >2 in this setting, deferral of revascularization is associated with low event rate.
Conflict of interest: none declared.
|
Funding |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
Remember that any funding used while completing this work should be highlighted in a separate Funding section. Please ensure that you use the full official name of the funding body.
|
References |
|---|
|
TopAbstractIntroductionMethodsResultsDiscussionLimitationsConclusionFundingReferences |
|---|
- White CW, Wright CB, Doty DB, Hiratza LF, Eastham CL, Harrison DG, et al. Does visual interpretation of the coronary arteriogram predict the physiologic importance of a coronary stenosis? N Eng J Med (1984) 310:819–24.[Abstract]
- Topol EJ, Nissen SE. Our preoccupation with coronary luminology: the dissociation between clinical and angiographic findings in ischemic heart disease. Circulation (1995) 92:2333–42.
[Abstract/Free Full Text] - Heller LI, Cates C, Popma J, Deckelbaum LI, Joye JD, Dahlberg ST, et al. Intracoronary Doppler assessment of moderate coronary artery disease. Comparison with 201TI imaging and coronary angiography. Circulation (1997) 96:484–90.
[Abstract/Free Full Text] - Fischer JJ, Samady H, Mc Pherson JA, Sarembock IJ, Powers ER, Gimple LW, et al. Comparison between visual assessment and quantitative angiography versus fractional flow reserve for native coronary narrowings of moderate severity. Am J Cardiol (2002) 90:210–5.[CrossRef][Web of Science][Medline]
- Bech GJW, De Bruyne B, Bonnier HJRM, Bartunek J, Wijns W, Peels K, et al. Long-term flollow-up after deferral of percutaneous transluminal coronary angioplasty of intermediate stenosis on the basis of coronary pressure measurement. J Am Coll Cardiol (1998) 31:841–7.
[Abstract/Free Full Text] - Bech GJW, De Bruyne B, Pijls NHJ, de Muinck ED, Hoorntje JCA, Escaned J, et al. Fractional flow reserve to determine the appropriateness of angioplasty in moderate coronary stenosis. A randomized trial. Circulation (2001) 103:2928–34.
[Abstract/Free Full Text] - Chamuleau SA, Meuwissen M, Koch KT, van Eck-Smit BL, Tio RA, Tijssen JG, et al. Usefulness of fractional flow reserve for risk stratification of patients with multivessel coronary artery disease and an intermediate stenosis. Am J Cardiol (2002) 89:377–80.[CrossRef][Web of Science][Medline]
- Rieber J, Schiele T, Koenig A, Erhard I, Segmiller T, Stempfle HU, et al. Long-term safety of therapy stratification in patients with intermediate coronary lesions based on intracoronary pressure measurements. Am J Cardiol (2002) 90:1160–4.[CrossRef][Web of Science][Medline]
- Berger A, Botman KJ, MacCarthy PA, Wijns W, Bartunek J, Heyndrickx GR, et al. Long-term clinical outcome after fractional flow reserve-guided percutaneous coronary intervention in patients with multivessel disease. J Am Coll Cardiol (2005) 46:438–42.
[Abstract/Free Full Text] - Legalery P, Schiele F, Seronde MF, Meneveau N, Wei H, Didier K, et al. One-year outcome of patients submitted to routine fractional flow reserve assessment to determine the need for angioplasty. Eur Heart J (2005) 26:2623–9.
[Abstract/Free Full Text] - Ferrari M, Shnell B, Werner GS, Figulla HS. Safety of deferring angioplasty in patients with normal coronary flow reserve. J Am Coll Cardiol (1999) 33:82–7.
[Abstract/Free Full Text] - Chalumeau SA, Tio RA, de Cooke CC, de Muinck ED, Pijls NHJ, Van Eck-Smith BLF, et al. Prognostic value of coronary blood flow velocity and myocardial perfusion in intermediate coronary narrowings and multivessel disease. J Am Coll Cardiol (2002) 39:852–8.
[Abstract/Free Full Text] - Meimoun P, Benali T, Sayah S, Luycx-Bore A, Boulanger J, Zemir H, et al. Evaluation of left anterior descending coronary artery stenosis of intermediate severity using transthoracic coronary flow reserve and dobutamine stress echocardiography. J Am Soc Echocardiogr (2005) 18:1233–40.[CrossRef][Web of Science][Medline]
- Baldini U, Dini FL, Raugi M, Genovesi-Ebert A. Incremental prognostic value of stress echo positivity in the left anterior descending coronary artery territory. Int J Cardiol (2006) 109:381–6.[CrossRef][Web of Science][Medline]
- Smith SC Jr, Feldman TE, Hirshfeld JW Jr, Jacobs AK, Kern MJ, King SB, et al. ACC/AHA/SCAI 2005 guideline update for percutaneous coronary intervention: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/SCAI Writing Committee to update 2001 guidelines for percutaneous coronary intervention). Circulation (2006) 113:e166–e286.
[Free Full Text] - Matsumara Y, Hozumi T, Watanabe H, Fujimoto K, Sugioka K, Takemoto Y, et al. Cut-off value of coronary flow velocity reserve by transthoracic Doppler echocardiography for diagnosis of significant left anterior descending artery stenosis in patients with coronary risk factors. Am J Cardiol (2003) 92:1389–93.[CrossRef][Web of Science][Medline]
- Kern MJ, Meier B. Evaluation of the culprit plaque and the physiological significance of coronary atherosclerotic narrowings. Circulation (2001) 103:3142–9.
[Free Full Text] - Miller DD, Donohue TJ, Younis LT, Bach RG, Aguirre FV, Wittry MD, et al. Correlation of pharmacological 99mTc-sestamibi myocardial perfusion imaging with poststenotic coronary flow reserve in patients with angiographically intermediate coronary artery stenoses. Circulation (1994) 89:2150–60.
[Abstract/Free Full Text] - Meimoun P, Sayah S, Tcheuffa JC, Benali T, Luycx-Bore A, Levy F, et al. Transthoracic coronary flow velocity reserve assessment: comparison between adenosine and dobutamine. J Am Soc Echocardiogr (2006) 19:1220–8.[CrossRef][Web of Science][Medline]
- Meuwissen M, Chamuleau SAJ, Siebes M, Schotborgh CE, Koch KT, de Winter RJ, et al. Role of variability in microvascular resistance on fractional flow reserve and coronary blood flow velocity reserve in intermediate coronary lesions. Circulation (2001) 103:184–7.
[Abstract/Free Full Text] - Meuwissen M, Siebes M, Chamuleau SAJ, van Eck-Smit BLF, Koch KT, de Winter RJ, et al. Hyperemic resistance stenosis index for evaluation of coronary lesion severity. Circulation (2002) 106:441–6.
[Abstract/Free Full Text] - Rigo F, Sicari R, Gherardi S, Djordjevic-Dikic A, Cortigiani L, Picano E. Prognostic value of coronary flow reserve in medically treated patients with left anterior descending coronary disease with stenosis 51% to 75% in diameter. Am J Cardiol (2007) 100:1527–31.[CrossRef][Web of Science][Medline]
- Rigo F, Cortigiani L, Pasanisi E, Richieri M, Cutaia V, Celestre M, et al. The additional prognostic value of coronary flow reserve on left anterior descending artery in patients with negative strss echo by wall motion criteria. A transthoracic vasodilator stress echocardiography study. Am Heart J (2006) 151:124–30.[CrossRef][Web of Science][Medline]
- Cortigiani L, Rigo F, Gherardi S, Sicari S, Galderisi M, Bovenzi F, et al. Additional prognostic value of coronary flow reserve in diabetics and nondiabetics patients with negative dipyridamole stress echocardiography by wall motion criteria. J Am Coll Cardiol (2007) 50:1354–61.
[Abstract/Free Full Text] - Cutlip DE, Chhabra AG, Baim DS, Chauan MS, Marulkar S, Massaro J, et al. Beyond restenosis. Five years clinical outcomes from second-generation coronary stent trials. Circulation (2004) 110:1226–30.
[Abstract/Free Full Text] - Glaser R, Selzer F, Faxon DP, Laskey WK, Cohen HA, Slater J, et al. Clinical progression of incidental, asymptomatic lesions discovered during culprit vessel coronary intervention. Circulation (2005) 111:143–9.
[Abstract/Free Full Text] - Stone GW, Moses JW, Ellis SG, Schofer J, Dawkins KD, Morice MC, et al. Safety and efficacy of sirolimus- and paclitaxel-eluting coronary stents. N Engl J Med (2007) 356:998–1008.
[Abstract/Free Full Text] - Meimoun P, Tribouilloy C. Non-invasive assessment of coronary flow and coronary flow reserve by transthoracic Doppler echocardiography: a magic tool for the real world. Eur J Echocardiogr (2008) Feb 19 [Epub ahead of print].
- Cortigiani P, Picano E, Landi P, Previtali M, Pirelli S, Bellotti P, et al. Value of pharmacologic stress echocardiography in risk stratification in patients with single-vessel disease: a report from the echo-Persantine and echo-dobutamine international cooperative studies. J Am Coll Cardiol (1998) 32:69–74.
[Abstract/Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||