Assessment of myocardial viability using coronary zero flow pressure after successful angioplasty in patients with acute anterior myocardial infarction

Coronary Microcirculation: The Next Frontier in the Management of STEMI

Although the widespread adoption of timely invasive reperfusion strategies over the last two decades has significantly improved the prognosis of patients with ST-segment elevation myocardial infarction (STEMI), up to half of patients after angiographically successful primary percutaneous coronary intervention (PCI) still have signs of inadequate reperfusion at the level of coronary microcirculation. This phenomenon, termed coronary microvascular dysfunction (CMD), has been associated with impaired prognosis. The aim of the present review is to describe the collected evidence on the occurrence of CMD following primary PCI, means of assessment and its association with the infarct size and clinical outcomes. Therefore, the practical role of invasive assessment of CMD in the catheterization laboratory, at the end of primary PCI, is emphasized, with an overview of available technologies including thermodilution- and Doppler-based methods, as well as recently developing functional coronary angiography. In this regard, we review the conceptual background and the prognostic value of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), hyperemic microvascular resistance (HMR), pressure at zero flow (PzF) and angiography-derived IMR. Finally, the so-far investigated therapeutic strategies targeting coronary microcirculation after STEMI are revisited.

Predictors of Microvascular Reperfusion After Myocardial Infarction

Purpose of Review

In acute ST-segment elevation myocardial infarction (STEMI), successful restoration of blood flow in the infarct-related coronary artery may not secure effective myocardial reperfusion. The mortality and morbidity associated with acute MI remain significant. Microvascular obstruction (MVO) represents failed microvascular reperfusion. MVO is under-recognized, independently associated with adverse cardiac prognosis and represents an unmet therapeutic need.

Recent Findings

Multiple factors including clinical presentation, patient characteristics, biochemical markers, and imaging parameters are associated with MVO after MI.

Summary

Impaired microvascular reperfusion is common following percutaneous coronary intervention (PCI). New knowledge about disease mechanisms underpins precision medicine with individualized risk assessment, investigation, and stratified therapy. To date, there are no evidence-based therapies to prevent or treat MVO post-MI. Identifying novel therapy for MVO is the next frontier.

Intracoronary pressure gradient measurement in acute myocardial infarction patients with the no-reflow phenomenon during primary percutaneous coronary intervention

Background

Various experimental and clinical studies have reported on coronary microcirculatory dysfunction (“no-reflow” phenomenon). Nevertheless, pathogenesis and effective treatment are yet to be fully elucidated. This study aimed to measure the intracoronary pressure gradient in the no-reflow artery during emergent percutaneous coronary intervention and explore the potential mechanism of no-reflow.

Methods

From September 1st, 2018 to June 30th, 2019, intracoronary pressure in acute myocardial infarction patient was continuously measured by aspiration catheter from distal to proximal segment in the Department of Coronary Care Unit, Tianjin Chest Hospital, respectively in no-reflow arteries (no-reflow group) and arteries with thrombolysis in myocardial infarction-3 flow (control group). At least 12 cardiac cycles were consecutively recorded when the catheter was pulled back. The forward systolic pressure gradient was calculated as proximal systolic pressure minus distal systolic pressure. Comparison between groups was made using the Student t test, Mann-Whitney U-test or Chi-square test, as appropriate.

Results

Intracoronary pressure in 33 no-reflow group and 26 in control group were measured. The intracoronary forward systolic pressure gradient was −1.3 (−4.8, 0.7) and 3.8 (0.8, 8.8) mmHg in no-reflow group and control group (Z = −3.989, P < 0.001), respectively, while the forward diastolic pressure gradient was −1.0 (−3.2, 0) and 4.6 (0, 16.5) mmHg in respective groups (Z = −3.851, P < 0.001). Moreover, the intracoronary forward pressure gradient showed significant difference between that before and after nicorandil medication (Z = −3.668, P < 0.001 in systolic pressure gradient and Z = −3.530, P < 0.001 in diastolic pressure gradient).

Conclusions

No reflow during emergent coronary revascularization is significantly associated with local hemodynamic abnormalities in the coronary arteries. Intracoronary nicorandil administration at the distal segment of a coronary artery with an aspiration catheter could improve the microcirculatory dysfunction and resume normal coronary pressure gradient.

Clinical trial registration

www.ClinicalTrials.gov (No. NCT 03600259).

Pathophysiology and diagnosis of coronary microvascular dysfunction in ST-elevation myocardial infarction

Early mechanical reperfusion of the epicardial coronary artery by primary percutaneous coronary intervention (PCI) is the guideline-recommended treatment for ST-elevation myocardial infarction (STEMI). Successful restoration of epicardial coronary blood flow can be achieved in over 95% of PCI procedures. However, despite angiographically complete epicardial coronary artery patency, in about half of the patients perfusion to the distal coronary microvasculature is not fully restored, which is associated with increased morbidity and mortality. The exact pathophysiological mechanism of post-ischaemic coronary microvascular dysfunction (CMD) is still debated. Therefore, the current review discusses invasive and non-invasive techniques for the diagnosis and quantification of CMD in STEMI in the clinical setting as well as results from experimental in vitro and in vivo models focusing on ischaemic-, reperfusion-, and inflammatory damage to the coronary microvascular endothelial cells. Finally, we discuss future opportunities to prevent or treat CMD in STEMI patients.

Invasive Assessment of the Coronary Microcirculation in Reperfused ST-Segment-Elevation Myocardial Infarction Patients: Where Do We Stand?

For patients presenting with an acute ST-segment-elevation myocardial infarction, the most effective therapy for reducing myocardial infarct size and preserving left ventricular systolic function is primary percutaneous coronary intervention (PPCI). However, mortality and morbidity remain significant. This is partly attributed to the development of microvascular obstruction, which occurs in around 50% of ST-segment-elevation myocardial infarction patients post-PPCI, and it is associated with adverse left ventricular remodeling and worse clinical outcomes. Although microvascular obstruction can be detected by cardiac imaging techniques several hours post-PPCI, it may be too late to intervene at that time. Therefore, being able to predict the development of microvascular obstruction at the time of PPCI may identify high-risk patients who might benefit from further adjuvant intracoronary therapies, such as thrombolysis, vasodilators, glycoprotein IIb/IIIa inhibitors, and anti-inflammatory agents that may reduce microvascular obstruction. Recent studies have shown that invasive coronary physiology measurements performed during PPCI can be used to assess the coronary microcirculation. In this article, we provide an overview of the various invasive methods currently available to assess the coronary microcirculation in the setting of ST-segment-elevation myocardial infarction, and how they could potentially be used in the future for tailoring therapies to those most at risk.

Targeting the dominant mechanism of coronary microvascular dysfunction with intracoronary physiology tests

The coronary microcirculation plays a key role in modulating blood supply to the myocardium. Several factors like myocardial oxygen demands, endothelial and neurogenic conditions determine its function. Although there is available evidence supporting microvascular dysfunction as an important cause of myocardial ischaemia, with both prognostic and symptomatic implications, its diagnosis and management in clinical practice is still relegated to a second plane. Both diagnostic and therapeutic approaches are hampered by the broadness of the concept of microvascular dysfunction, which fails addressing the plurality of mechanisms leading to dysfunction. Normal microcirculatory function requires both structural integrity of the microcirculatory vascular network and preserved signalling pathways ensuring adequate and brisk arteriolar resistance shifts in response to myocardial oxygen demands. Pathological mechanisms affecting these requirements include structural remodelling of microvessels, intraluminal plugging, extravascular compression or vasomotor dysregulation. Importantly, not every diagnostic technique provides evidence on which of these pathophysiological mechanisms is present or predominates in the microcirculation. In this paper we discuss the mechanisms of coronary microvascular dysfunction and the intracoronary tools currently available to detect it, as well as the potential role of each one to unmask the main underlying mechanism.

Wave intensity analysis and its application to the coronary circulation

Wave intensity analysis (WIA) is a technique developed from the field of gas dynamics that is now being applied to assess cardiovascular physiology. It allows quantification of the forces acting to alter flow and pressure within a fluid system, and as such it is highly insightful in ascribing cause to dynamic blood pressure or velocity changes. When co-incident waves arrive at the same spatial location they exert either counteracting or summative effects on flow and pressure. WIA however allows waves of different origins to be measured uninfluenced by other simultaneously arriving waves. It therefore has found particular applicability within the coronary circulation where both proximal (aortic) and distal (myocardial) ends of the coronary artery can markedly influence blood flow. Using these concepts, a repeating pattern of 6 waves has been consistently identified within the coronary arteries, 3 originating proximally and 3 distally. Each has been associated with a particular part of the cardiac cycle. The most clinically relevant wave to date is the backward decompression wave, which causes the marked increase in coronary flow velocity observed at the start of the diastole. It has been proposed that this wave is generated by the elastic re-expansion of the intra-myocardial blood vessels that are compressed during systolic contraction. Particularly by quantifying this wave, WIA has been used to provide mechanistic and prognostic insight into a number of conditions including aortic stenosis, left ventricular hypertrophy, coronary artery disease and heart failure. It has proven itself to be highly sensitive and as such a number of novel research directions are encouraged where further insights would be beneficial.

Zero-Flow Pressure Measured Immediately After Primary Percutaneous Coronary Intervention for ST-Segment Elevation Myocardial Infarction Provides the Best Invasive Index for Predicting the Extent of Myocardial Infarction at 6 Months: An OxAMI Study (Oxford Acute Myocardial Infarction)

OBJECTIVES

The aim of this study was to define which measure of microvascular best predicts the extent of left ventricular (LV) infarction.

BACKGROUND

Microvascular injury after ST-segment elevation myocardial infarction (STEMI) is an important determinant of outcome. Several invasive measures of the microcirculation at primary percutaneous coronary intervention (PPCI) have been described. One such measure is zero-flow pressure (Pzf), the calculated pressure at which coronary flow would cease.

METHODS

In 34 STEMI patients, Pzf, hyperemic microvascular resistance (hMR), and index of microcirculatory resistance (IMR) were derived using thermodilution flow/pressure and Doppler flow/pressure wire assessment of the infarct-related artery following PPCI. The extent of infarction was determined by blinded late gadolinium enhancement on cardiac magnetic resonance at 6 months post-PPCI. Infarction of ≥24% total LV mass was used as a categorical cutoff in receiver-operating characteristic curve analysis.

RESULTS

Pzf was superior to both hMR and IMR for predicting ≥24% infarction area under the curve: 0.94 for Pzf versus 0.74 for hMR (p = 0.04) and 0.54 for IMR (p = 0.003). Pzf ≥42 mm Hg was the optimal cutoff value, offering 100% sensitivity and 73% specificity. Patients with Pzf ≥42 mm Hg also had a lower salvage index (61.3 ± 8.1 vs. 44.4 ± 16.8, p = 0.006) and 6-month ejection fraction (62.4 ± 3.6 vs. 49.9 ± 9.6, p = 0.002). In addition, there were significant direct relationships between Pzf and troponin area under the curve (rho = 0.55, p = 0.002), final infarct mass (rho = 0.75, p < 0.0001), percentage of LV infarction and percent transmurality of infarction (rho = 0.77 and 0.74, respectively, p < 0.0001), and inverse relationships with myocardial salvage index (rho = -0.53, p = 0.01) and 6-month ejection fraction (rho = -0.73, p = 0.0001).

CONCLUSIONS

Pzf measured at the time of PPCI is a better predictor of the extent of myocardial infarction than hMR or IMR. Pzf may provide important prognostic information at the time of PPCI and merits further investigation in clinical studies with relevant outcome measures.

Influence of isoflurane on the diastolic pressure-flow relationship and critical occlusion pressure during arterial CABG surgery: a randomized controlled trial

The effects of isoflurane on the determinants of blood flow during Coronary Artery Bypass Graft (CABG) surgery are not completely understood. This study characterized the influence of isoflurane on the diastolic Pressure-Flow (P-F) relationship and Critical Occlusion Pressure (COP) during CABG surgery. Twenty patients undergoing CABG surgery were studied. Patients were assigned to an isoflurane or control group. Hemodynamic and flow measurements during CABG surgery were performed twice (15 minutes after the discontinuation of extracorporeal circulation (T15) and again 15 minutes later (T30)). The zero flow pressure intercept (a measure of COP) was extrapolated from a linear regression analysis of the instantaneous diastolic P-F relationship. In the isoflurane group, the application of isoflurane significantly increased the slope of the diastolic P-F relationship by 215% indicating a mean reduction of Coronary Vascular Resistance (CVR) by 46%. Simultaneously, the Mean Diastolic Aortic Pressure (MDAP) decreased by 19% mainly due to a decrease in the systemic vascular resistance index by 21%. The COP, cardiac index, heart rate, Left Ventricular End-Diastolic Pressure (LVEDP) and Coronary Sinus Pressure (CSP) did not change significantly. In the control group, the parameters remained unchanged. In both groups, COP significantly exceeded the CSP and LVEDP at both time points. We conclude that short-term application of isoflurane at a sedative concentration markedly increases the slope of the instantaneous diastolic P-F relationship during CABG surgery implying a distinct decrease with CVR in patients undergoing CABG surgery.

Doppler-derived intracoronary physiology indices predict the occurrence of microvascular injury and microvascular perfusion deficits after angiographically successful primary percutaneous coronary intervention

BACKGROUND

A total of 40% to 50% of patients with ST-segment-elevation myocardial infarction develop microvascular injury (MVI) despite angiographically successful primary percutaneous coronary intervention (PCI). We investigated whether hyperemic microvascular resistance (HMR) immediately after angiographically successful PCI predicts MVI at cardiovascular magnetic resonance and reduced myocardial blood flow at positron emission tomography (PET).

METHODS AND RESULTS

Sixty patients with ST-segment-elevation myocardial infarction were included in this prospective study. Immediately after successful PCI, intracoronary pressure-flow measurements were performed and analyzed off-line to calculate HMR and indices derived from the pressure-velocity loops, including pressure at zero flow. Cardiovascular magnetic resonance and H2 (15)O PET imaging were performed 4 to 6 days after PCI. Using cardiovascular magnetic resonance, MVI was defined as a subendocardial recess of myocardium with low signal intensity within a gadolinium-enhanced area. Myocardial perfusion was quantified using H2 (15)O PET. Reference HMR values were obtained in 16 stable patients undergoing coronary angiography. Complete data sets were available in 48 patients of which 24 developed MVI. Adequate pressure-velocity loops were obtained in 29 patients. HMR in the culprit artery in patients with MVI was significantly higher than in patients without MVI (MVI, 3.33±1.50 mm Hg/cm per second versus no MVI, 2.41±1.26 mm Hg/cm per second; P=0.03). MVI was associated with higher pressure at zero flow (45.68±13.16 versus 32.01±14.98 mm Hg; P=0.015). Multivariable analysis showed HMR to independently predict MVI (P=0.04). The optimal cutoff value for HMR was 2.5 mm Hg/cm per second. High HMR was associated with decreased myocardial blood flow on PET (myocardial perfusion reserve <2.0, 3.18±1.42 mm Hg/cm per second versus myocardial perfusion reserve ≥2.0, 2.24±1.19 mm Hg/cm per second; P=0.04).

CONCLUSIONS

Doppler-flow-derived physiological indices of coronary resistance (HMR) and extravascular compression (pressure at zero flow) obtained immediately after successful primary PCI predict MVI and decreased PET myocardial blood flow.

CLINICAL TRIAL REGISTRATION URL

http://www.trialregister.nl. Unique identifier: NTR3164.

Evaluation of Microvascular Disease and Clinical Outcomes

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

Assessment of coronary microcirculation in a swine animal model

Coronary microvascular dysfunction has important prognostic implications. Several hemodynamic indexes, such as coronary flow reserve (CFR), microvascular resistance, and zero-flow pressure (P(zf)), were used to establish the most reliable index to assess coronary microcirculation. Fifteen swine were instrumented with a flow probe, and a pressure wire was advanced into the distal left anterior descending artery. Adenosine was used to produce maximum hyperemia. Microspheres were used to create microvascular dysfunction. An occluder was used to produce stenosis. Blood flow from the probe (Q(p)), aortic pressure, distal coronary pressure, and right atrium pressure were recorded. Angiographic flow (Q(a)) was calculated using a time-density curve. Flow probe-based CFR and angiographic CFR were calculated using Q(p) and Q(a), respectively. Flow probe-based (NMR(qh)) and angiographic normalized microvascular resistance (NMR(ah)) were determined using Q(p) and Q(a), respectively, during hyperemia. P(zf) was calculated using Q(p) and distal coronary pressure. Two series of receiver operating characteristic curves were generated: normal epicardial artery model (N model) and stenosis model (S model). The areas under the receiver operating characteristic curves for flow probe-based CFR, angiographic CFR, NMR(qh), NMR(ah), and P(zf) were 0.855, 0.836, 0.976, 0.956, and 0.855 in N model and 0.737, 0.700, 0.935, 0.889, and 0.698 in S model. Both NMR(qh) and NMR(ah) were significantly more reliable than CFR and P(zf) in detecting the microvascular deterioration. Compared with CFR and P(zf), NMR provided a more accurate assessment of microcirculation. This improved accuracy was more prevalent when stenosis existed. Moreover, NMR(ah) is potentially a less invasive method for assessing coronary microcirculation.

Diastolic dysfunction in diabetic patients assessed with Doppler echocardiography: relationship with coronary atherosclerotic burden and microcirculatory impairment

INTRODUCTION AND OBJECTIVES

Diabetes mellitus (DM) is associated with the development of both impaired left ventricular diastolic function (LVDF) and pathological changes in the coronary macro- and microcirculation. The aim of this study was to investigate the relationship between these manifestations of diabetic heart disease.

METHODS

The severity of atherosclerosis in the left anterior descending coronary artery (LAD) was quantified using intravascular ultrasound (IVUS) in 13 patients with DM and ischemic heart disease. The coronary flow velocity reserve (CFVR), instantaneous hyperemic diastolic velocity pressure slope index (IHDVPS) and zero-flow pressure were derived from digital intracoronary pressure and flow velocity measurements. The relationships between indices of LVDF (i.e. E/A and E/e' ratios) and intracoronary measurements were assessed.

RESULTS

The left ventricular ejection fraction was 66+/-7%, and the LVDF indices were: E/A=0.92+/-0.38 and E/e'=9.90+/-2.80. There was a direct proportional relationship (r=0.62; P=.02) between E/e' and coronary resistance (1.93+/-0.74 mmHg/s) and an inverse proportional relationship (r=-0.64; P=.02) between E/e' and IHDVPS (1.56+/-0.50 cm/s/mmHg). However, no significant relationship was found between either LVDF index and CFVR (2.43+/-0.56) or coronary zero-flow pressure (40.41+/-10.66 mmHg). The volume of atheroma in the proximal 20 mm of the LAD (179.34+/-57.48 .l, with an average plaque area of 8.39+/-2.20 mm2) was not related to either LVDF index.

CONCLUSIONS

In patients with DM and coronary atherosclerosis, there appeared to be a relationship between LVDF impairment (assessed by the E/e' ratio) and structural changes in the microcirculation.

Coronary microvascular dysfunction after myocardial infarction: increased coronary zero flow pressure both in the infarcted and in the remote myocardium is mainly related to left ventricular filling pressure

OBJECTIVE

To investigate the underlying mechanisms of a decreased coronary flow reserve after myocardial infarction (MI) by analysing the characteristics of the diastolic hyperaemic coronary pressure-flow relationship.

DESIGN

Prospective study.

SETTING

Tertiary care hospital.

PATIENTS

68 patients with a recent MI and 27 patients with stable angina pectoris (AP; control group).

MAIN OUTCOME MEASURES

The intercept with the pressure axis (the zero flow pressure or Pzf) and slope index of the pressure-flow relationship (SIPF) were calculated from the simultaneously recorded hyperaemic intracoronary blood flow velocity and aortic pressure after successful coronary stenting.

RESULTS

A stepwise increase in Pzf from AP (14.6 (8.0) mm Hg), over non-Q-wave MI (22.5 (9.1) mm Hg), to Q-wave MI (37.1 (12.9) mm Hg; p<0.001) was observed. Similar changes in Pzf were found in a reference artery perfusing the non-infarcted myocardium. Multivariate analysis showed that in both regions the left ventricular end-diastolic pressure (LVEDP) was the most important determinant of the Pzf. The SIPF was not statistically different in the treated vessel between patients with MI and AP, but was increased in MI patients with a markedly increased LVEDP.

CONCLUSIONS

After an MI, the coronary pressure-flow relationship is shifted to the right both in the infarcted and in the non-infarcted remote myocardium, as shown by the increased Pzf. The correlation with Pzf suggests that elevated left ventricular filling pressures contribute to the impediment of myocardial perfusion in patients with infarction.

Instantaneous diastolic pressure–flow relationship in arterial coronary bypass grafts

OBJECTIVE

The objective of this study was to describe the diastolic pressure-flow relationship and to assess critical occlusion pressure in arterial coronary bypass grafts in human beings.

METHODS AND RESULTS

Fifteen patients were studied following elective surgical coronary artery bypass grafting. Flow in the left internal mammary artery bypass to the left anterior descending artery was measured and simultaneously, aortic pressure, coronary sinus pressure and left ventricular end-diastolic pressure were recorded. The zero-flow pressure intercept as a measure of critical occlusion pressure was extrapolated from the linear regression analysis of the instantaneous diastolic pressure-flow relationship. Mean diastolic flow was 46 +/- 17 mL min(-1), mean diastolic aortic pressure was 60.5 +/- 10.0 mmHg. Diastolic blood flow was linearly related to the respective aortic pressure in all patients (R-values 0.7-0.99). The regression lines had a mean slope of 2.1 +/- 1.2 mL min(-1) mmHg(-1). Mean critical occlusion pressure was 32.3 +/- 9.9 mmHg and exceeded mean coronary sinus pressure and mean left ventricular end-diastolic pressure by factors of 3.1 and 2.6, respectively.

CONCLUSIONS

Our data demonstrate the presence of a vascular waterfall phenomenon in the coronary circulation after internal mammary artery bypass grafting. Critical occlusion pressure in arterial grafts considerably exceeds coronary sinus pressure as well as left ventricular end-diastolic pressure and should thus be used as the effective downstream pressure when calculating coronary perfusion pressure. Our data further suggest that the slope of diastolic pressure-flow relationships provides a more rational approach to assess regional coronary vascular resistance than conventional calculations of coronary vascular resistance.

Coronary pressure measurements in post-myocardial infarction patients

The development of pressure monitoring guide-wires has facilitated the measurements of coronary pressures distal to a stenosis. The ratio of the distal coronary and aortic pressures (P(d)/P(a)) measured during maximal hyperaemia is a useful index for diagnosis and monitoring the treatment of patients with coronary artery disease and for guiding percutaneous coronary intervention. However, the role of coronary pressure measurements in post- myocardial infarction (MI) patients is not well established. Coronary pressure measurements should be used with caution during the acute phase of MI due to serious micro-vascular impairment. The hyperaemic pressure P(d)/P(a) ratio can identify ischaemic myocardial territories in patients with recent MI. Theoretically, coronary pressure measurements may be of value in predicting myocardial recovery after revascularization in post-MI patients with a moderate stenosis of the infarct-related artery and without angiographically evident collaterals.

Relation between aortic stiffness and coronary flow reserve in patients with coronary artery disease

OBJECTIVES

To investigate the relation between aortic stiffness and coronary flow reserve (CFR) in patients with coronary artery disease (CAD).

DESIGN

Observational study.

SETTING

Coronary care unit of a primary care hospital.

PATIENTS

192 consecutive patients who underwent coronary angiography.

MAIN OUTCOME MEASURE

Brachial-ankle pulse wave velocity (ba-PWV), CFR, and severity of CAD.

RESULTS

According to the angiographic findings, patients were divided into four subgroups: patients without significant stenosis (normal coronary artery (NCA) group, n = 28) and those with one vessel disease (1VD group, n = 92), two vessel disease (2VD group, n = 50), or three vessel disease (3VD group, n = 22). ba-PWV increased with the number of diseased vessels and was significantly correlated with the number of diseased vessels (NCA group v 1VD group v 2VD group v 3VD group: 1481 (252) v 1505 (278) v 1577 (266) v 1727 (347) cm/s, p < 0.001). CFR had a significant negative correlation with ba-PWV (r = -0.45, p < 0.0001). The diastolic to systolic velocity ratio obtained in 45 patients also was significantly correlated with ba-PWV (r = -0.35, p < 0.05). Multiple regression analysis showed that ba-PWV was an independent determinant of CFR (p < 0.01).

CONCLUSIONS

Coronary flow is altered with aortic stiffening in patients with CAD. These results suggest one possible mechanism for recent reports that aortic stiffness is a key cardiovascular risk factor.