Incremental diagnostic value of ultrasonographic assessment of coronary flow reserve with high-dose dipyridamole in patients with acute coronary syndrome

Dual imaging stress echocardiography versus computed tomography coronary angiography for risk stratification of patients with chest pain of unknown origin

Background

Dual imaging stress echocardiography, combining the evaluation of wall motion and coronary flow reserve (CFR) on the left anterior descending artery (LAD), and computed tomography coronary angiography (CTCA) are established techniques for assessing prognosis in chest pain patients. In this study we compared the prognostic value of the two methods in a cohort of patients with chest pain having suspected coronary artery disease (CAD).

Methods

A total of 131 patients (76 men; age 68 ± 9 years) with chest pain of unknown origin underwent dipyridamole (up to 0.84 mg/kg over 6 min) stress echo with CFR assessment of LAD by Doppler and CTCA. A CFR ≤ 1.9 was considered abnormal, while > 50% lumen diameter reduction was the criterion for significant CAD at CTCA.

Results

Of 131 patients, 34 (26%) had ischemia at stress echo (new wall motion abnormalities), and 56 (43%) had reduced CFR on LAD. Significant coronary stenosis at CTCA was found in 69 (53%) patients. Forty-six patients (84%) with abnormal CFR on LAD showed significant CAD at CTCA (p < 0.001). Calcium score was higher in patients with reduced than in those with normal CFR (265 ± 404 vs 131 ± 336, p = 0.04). During a median follow-up of 7 months (1st to 3rd quartile: 5–13 months), there were 45 major cardiac events (4 deaths, 11 nonfatal myocardial infarctions, and 30 late [≥6 months] coronary revascularizations). At Cox analysis, independent prognostic indicators were calcium score > 100 (HR 2.84, 95% CI 1.33-6.07, p = 0.007), significant CAD at CTCA (HR 2.68, 95% CI 1.23-5.82, p = 0.013), and inducible ischemia or CFR <1.9R on LAD on dual imaging stress echo (HR 2.25, 95% CI 1.05-4.84, p = 0.038).

Conclusions

Functional and anatomical evaluation using, respectively, dual imaging stress echocardiography and CTCA are both effective modalities to risk stratify patients with chest pain of unknown origin, yielding independent and comparable prognostic value. Compared to CTCA, however, stress echocardiography has the advantage of lower cost and of being free of radiations.

The relationship between early left ventricular myocardial alterations and reduced coronary flow reserve in non-insulin-dependent diabetic patients with microvascular angina

AIMS

To evaluate left ventricular (LV) systolic and diastolic myocardial function, and their relation to coronary flow reserve in patients with non-insulin-dependent diabetes mellitus (DM) and microvascular angina.

METHODS AND RESULTS

We selected a population of 45 normotensive patients with DM (56.3 ± 8.2 years; 25 males) with LV ejection fraction >50% and microvascular angina (anginal pain, positive imaging stress test and normal coronary angiography). Thirty-five age- and sex-matched healthy controls were also enrolled. All the patients underwent standard echocardiography, Tissue Doppler (TDI), two-dimensional strain (2DSE) imaging, and coronary flow reserve (CFR) measurement. LV myocardial early diastolic peak velocities (E(m)) and peak systolic 2DSE were reduced in both interventricular septum (IVS) and LV lateral wall (p<0.01) in DM, as well as CFR (1.89 ± 0.7 vs 2.55 ± 0.56, p<0.0001) compared with controls. By multivariate analysis, the independent determinants of E(m) were glycated haemoglobin (β coefficient=-0.36; p<0.01) and age (β=-0.46, p<0.001), while global longitudinal strain was predicted by glycated haemoglobin (β=0.48, P<0.001) and by the duration of the disease (β=0.38, P<0.005). An independent association between LV global longitudinal strain and CFR (β coefficient=-0.47, p<0.001) in DM patients was also evidenced.

CONCLUSIONS

TDI, 2DSE and CFR are valuable non-invasive and easy-repeatable tools for detecting LV myocardial and coronary function in DM patients with microvascular angina.

Implication of the continuous prognostic spectrum of Doppler echocardiographic derived coronary flow reserve on left anterior descending artery

The additive prognostic value of coronary flow reserve (CFR) over regional wall motion has been established, but there is more than a binary (normal-abnormal) response in CFR, which can be continuously titrated. We assessed the prognostic value of quartiles of CFR, evaluated by transthoracic Doppler of the left anterior descending coronary artery (LAD), in patients with known or suspected coronary artery disease (CAD). One thousand six hundred twenty patients (1,006 men, 64 +/- 11 years of age) underwent dipyridamole (up to 0.84 mg/kg over 6 minutes) stress echocardiography with CFR evaluation of LAD by Doppler and coronary angiography. Patients were followed up for a median of 19 months. Mean CFR in the entire population was 2.25 +/- 0.65. Stress echocardiogram was positive for ischemia in 480 patients (30%). Obstructive (>or=70% vessel stenosis) CAD at angiography was present in 650 patients (40%). During follow-up, there were 298 events (42 deaths, 73 ST-elevation myocardial infarctions, and 183 non-ST-elevation myocardial infarctions). Patients (n = 399) undergoing revascularization were censored. With the Kaplan-Meier method, the first quartile of CFR (<or=1.80) was associated with a worse (p <0.0001) event rate than other quartiles in the entire population and in patients with no ischemia at stress echocardiography. Furthermore, the second quartile of CFR (1.81 to 2.16) was predictive of increased (p <0.0001) risk compared to the higher quartiles. In conclusion, Doppler echocardiographically derived CFR in LAD is a strong and independent prognostic predictor in patients with known or suspected CAD, but the spectrum of prognostic stratifications is expanded if the response is titrated according to a continuous scale rather than artificially dichotomized.

Prognostic value of coronary flow reserve in medically treated patients with left anterior descending coronary disease with stenosis 51% to 75% in diameter

According to American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions 2005 guidelines on percutaneous intervention, intracoronary physiologic measurement in the assessment of effects of intermediate coronary stenoses in patients with anginal symptoms is a class IIa indication. This study assessed the additional prognostic value of Doppler echocardiographically derived coronary flow reserve (CFR) in patients with single-vessel disease and intermediate stenosis severity. We enrolled 86 patients (44 men; 66 +/- 10 years of age) with angiographically assessed single-vessel coronary artery disease of the left anterior descending coronary artery (LAD) with quantitatively assessed diameter stenosis severity 50% to 75%. All patients underwent dipyridamole (up to 0.84 mg/kg over 6 minutes) stress echocardiography with wall motion analysis by 2-dimensional echocardiography and CFR evaluation of the affected artery by Doppler. All patients were followed up for a median of 14 months (first quartile 10, third quartile 18) after diagnostic coronary angiography (without percutaneous intervention for a clinically driven decision). Mean diameter stenosis of the LAD was 58 +/- 10%. Mean CFR of the LAD was 2.09 +/- 0.5. Regional wall motion abnormality at peak stress was present in 17 patients. During follow-up, 24 events occurred: 6 nonfatal ST-elevation myocardial infarctions and 18 non-ST-elevation myocardial infarctions. Thirty-month spontaneous event-free survival was higher in patients with normal CFR and lower in patients with decreased CFR (86% vs 30%, p = 0.0001). At Cox analysis, a CFR <2 (hazard ratio 24.2, 95% confidence interval 3.2 to 179.7, p = 0.002) was the only independent prognostic predictor of outcome. In conclusion, in medically treated patients with single-vessel disease of intermediate severity, decreased CFR is associated with a worse outcome.

Associations between left ventricular myocardial involvement and endothelial dysfunction in systemic sclerosis: noninvasive assessment in asymptomatic patients

OBJECTIVES

Systemic sclerosis (SSc) is a multisystem disorder characterized by widespread vascular lesions and fibrosis of skin and distinct internal organs. Cardiac involvement is a common finding in SSc, but often clinically occult.

AIM OF THE STUDY

To analyze possible associations of left ventricular (LV) myocardial function with coronary flow reserve (CFR) and endothelial function in asymptomatic patients with SSc.

METHODS

30 healthy patients and 33 age- and sex-comparable asymptomatic patients classified as having either diffuse (18 patients) or limited form (15 patients) of SSc underwent standard Doppler Echo, Doppler myocardial imaging, Strain rate imaging of interventricular septum and LV lateral wall, transthoracic CFR of left anterior descending coronary vessel (after dipyridamole infusion), and brachial artery vasodilatation measurement (Vivid 7, GE Medical Systems Inc).

RESULTS

LV diameters and ejection fraction were comparable between the two groups, while systolic pulmonary pressure (P < 0.001) was increased in SSc. By chest-CT, 15 SSc patients showed interstitial pulmonary fibrosis. Serological antibodies analysis detected anti-centromere pattern in 14 SSc patients, and anti Scl-70 in 19 patients. In SSc, LV myocardial early diastolic peak velocity, peak systolic strain rate and strain were both reduced in basal and middle interventricular septum, and in basal and middle LV lateral wall. Both CFR (P < 0.0001) and endothelial flow-mediated dilatation (P < 0.001) were significantly lower in SSc patients. By stepwise forward multivariate analyses, CFR (P < 0.001) and endothelial function (P < 0.001) were powerful independent determinants of middle LV strain.

CONCLUSIONS

Strain rate imaging, transthoracic CFR, and brachial artery flow-mediated dilatation are valuable noninvasive and easily repeatable tools for detecting LV myocardial and vascular involvement caused by SSc. Their combined use may be therefore useful for early identifying patients with more diffused and severe form of SSc, ideally in asymptomatic cases prior to the development of severe vasculopathy, when it may be most feasible to modify the disease process by new potential therapies.

Myocardial and vascular dysfunction in systemic sclerosis: The potential role of noninvasive assessment in asymptomatic patients

Systemic sclerosis (SSc) is a multi-system disorder characterized by widespread vascular lesions and fibrosis of skin and distinct internal organs. The aim of the present study was to analyze possible associations of left ventricular (LV) myocardial function with coronary flow reserve (CFR) and endothelial function in asymptomatic patients with SSc. Thirty healthy subjects and 33 age- and sex-comparable asymptomatic SSc patients underwent standard Doppler Myocardial Imaging, Strain Rate (SR) Imaging of interventricular septum (IVS) and LV lateral wall, transthoracic CFR of left anterior descending coronary vessel, and brachial artery vasodilatation measurement. In SSc patients, LV myocardial early diastolic peak velocity, peak systolic SR and strain were both reduced in basal and middle IVS, and in basal and middle LV lateral wall (p<0.001). In addition, both CFR (p<0.0001) and endothelial flow-mediated dilatation (p<0.001) were significantly lower in SSc patients. By stepwise forward multivariate analyses, CFR (p<0.001) and endothelial function (p<0.001) were powerful independent determinants of middle LV strain of SSc patients. In conclusion, SR Imaging, transthoracic CFR and brachial artery flow-mediated dilatation are valuable non-invasive and easy-repeatable tools for detecting early LV myocardial and vascular involvement caused by SSc.

Additional prognostic value of coronary flow reserve in diabetic and nondiabetic patients with negative dipyridamole stress echocardiography by wall motion criteria

OBJECTIVES

The aim of this prospective, multicenter, observational study was to compare the prognostic value of Doppler echocardiographic-derived coronary flow reserve (CFR) in diabetic and nondiabetic patients with known or suspected coronary artery disease and negative dipyridamole stress echocardiography.

BACKGROUND

The prognostic value of CFR in diabetic patients with negative stress echocardiography remains unknown.

METHODS

The study group consisted of 1,130 patients (207 diabetics) with known (n = 418) or suspected (n = 712) coronary artery disease and negative stress echocardiography by wall motion criteria. All underwent dipyridamole (up to 0.84 mg/kg over 6 min) echocardiography with CFR evaluation of left anterior descending artery by Doppler. A value of CFR < or =2.0 was considered abnormal.

RESULTS

Coronary flow reserve was abnormal in 309 (27%) patients. During a median follow-up of 16 months, 98 events (8 deaths, 24 ST-segment elevation myocardial infarctions, and 66 non-ST-segment elevation myocardial infarctions) occurred. In addition, 101 patients underwent revascularization and were censored. Multivariable prognostic indicators were abnormal CFR (p < 0.0001), anti-ischemic therapy at the time of testing (p = 0.002), age (p = 0.02), and resting wall motion abnormality (p = 0.05). The event rate was markedly higher (p < 0.0001) for both diabetic and nondiabetic patients with abnormal CFR as compared with diabetic and nondiabetic patients with normal CFR. Of note, a preserved CFR off therapy identified diabetic and nondiabetic patients with better survival and comparable yearly event rates (2.2% vs. 2.0%, p = 0.80).

CONCLUSIONS

Coronary flow reserve provides independent prognostic information in diabetic and nondiabetic patients with known or suspected coronary artery disease and negative dipyridamole stress echocardiography. In particular, a normal CFR off therapy is associated with better and similar survival in the 2 populations.

Coronary flow reserve evaluation in stress-echocardiography laboratory

The assessment of coronary flow reserve by transthoracic echocardiography has recently been introduced into clinical practice with good results for the diagnosis of left anterior descending artery disease and fairly promising results for posterior descending coronary artery disease. By looking at what is behind wall motion, we may realize a sonographer's dream and, in particular, the addition of coronary flow reserve to regional wall motion analysis allows us to have - in the same sitting - high specificity (regional wall motion) and a highly sensitive (coronary flow reserve) diagnostic marker, with an improvement in overall diagnostic accuracy. Coronary flow reserve evaluation may shift the balance of stress choice in favor of vasodilators, which are easier to perform with dual imaging than dobutamine or exercise coronary flow reserve evaluation and may shift the choice in favor of dipyridamole or adenosine stress tests, which are also easier to perform with dual imaging than those using dobutamine or exercise. Lastly, it adds quantitative support to the exquisitely qualitative assessment of wall motion analysis, thereby facilitating the communication of stress echo results to the cardiological world outside the echo laboratory.

Coronary flow reserve in stress-echo lab. From pathophysiologic toy to diagnostic tool

The assessment of coronary flow reserve by transthoracic echocardiography has recently been introduced into clinical practice with gratifying results for the diagnosis of left anterior descending artery disease simultaneously reported by several independent laboratories. This technological novelty is changing the practice of stress echo for 3 main reasons. First, adding coronary flow reserve to regional wall motion allows us to have - in the same sitting - high specificity (regional wall motion) and a high sensitivity (coronary flow reserve) diagnostic marker, with an obvious improvement in overall diagnostic accuracy. Second, the technicalities of coronary flow reserve shift the balance of stress choice in favour of vasodilators, which are a more robust hyperemic stress and are substantially easier to perform with dual imaging than dobutamine or exercise. Third, the coronary flow reserve adds a quantitative support to the exquisitely qualitative assessment of wall motion analysis, thereby facilitating the communication of stress echo results to the cardiological world outside the echo lab. The next challenges involve the need to expand the exploration of coronary flow reserve to the right and circumflex coronary artery and to prove the additional prognostic value - if any - of coronary flow reserve over regional wall motion analysis, which remains the cornerstone of clinically-driven diagnosis in the stress echo lab.