Pressure-derived fractional collateral blood flow: a primary determinant of left ventricular recovery after reperfused acute myocardial infarction

Relationship between quality of coronary collateral and myocardial viability in chronic total occlusion: a magnetic resonance study

Revascularization of chronic total occlusion (CTO) is still debated regarding its indications and therapeutic benefits. Guidelines recommend patient selection based on ischemia detection and viability assessment. We aimed to investigate the relationship between the quality of coronary collaterals (CC), graded by Rentrop classification, and myocardial viability assessed by cardiovascular magnetic resonance (CMR). Unselected 100 consecutive patients with a single CTO were prospectively enrolled. CC of Rentrop grade two or three were considered as well-developed. Analyzing late gadolinium enhancement (LGE) images, CTO territories with mean segmental transmural scar extent < 50% were considered viable. Of the 100 patients (70 male, mean age 58.0 ± 6 years), 73 patients (73%) had angiographically visible CC. Based on LGE, patients were classified into viable (n = 50) and non-viable (n = 50) groups. Significant differences between both groups existed regarding frequency of diabetes mellitus (p = 0.044), frequency of congestive heart failure (p = 0.032), presence of pathological Q in CTO territory (p = 0.039); and presence of well-developed CC (p < 0.001). Binary logistic regression and receiver operating characteristic curve showed that presence of well-developed CC could independently (OR 9.4, 95% CI: 2.6-33.6, p < 0.001) predict myocardial viability with a sensitivity and a specificity of 72% and 74%, respectively (AUC: 0.796, 95% CI: 0.708-0.884, P < 0.001). The presence of well-developed CC could independently predict with high accuracy myocardial viability assessed by LGE in territories subtended by CTO vessels. Therefore, search for viable myocardium using different imaging modalities, e.g. CMR, may be recommended in CTO patients with well-developed CC.

In Acute ST-Segment Elevation Myocardial Infarction, Coronary Wedge Pressure Is Associated with Infarct Size and Reperfusion Injury as Evaluated by Cardiac Magnetic Resonance Imaging

Background. Coronary collateral flow influences patient prognosis in the setting of acute myocardial infarction. However, few data exist about the relation between coronary collaterals, infarct size, and reperfusion injury. The angiographic Rentrop score is prone to subjectivism and to the inherent limitations of angiographic images. Its prognostic value is controversial in the setting of acute myocardial infarction. The invasive measurement of coronary wedge pressure (CWP) represents an alternative to Rentrop score for the evaluation of coronary collateralization. Our study evaluates pre-revascularization CWP as a predictor of infarct size and reperfusion injury as evaluated by cardiac magnetic resonance imaging. Methods. Patients with acute ST-elevation myocardial infarction underwent preprocedural CWP measurement and primary percutaneous coronary intervention. Infarct size, microvascular obstruction, intramyocardial edema, and intramyocardial hemorrhage were evaluated by cardiac magnetic resonance imaging. Results. Mean CWP was inversely associated with infarct size p=0.01, microvascular obstruction p=0.02, intramyocardial edema p=0.05, and intramyocardial hemorrhage p=0.01. An excellent association was found between mean CWP and an infarct size ≥24% of left ventricular mass (AUC = 0.880, p=0.007), with an optimal cutoff value ≤24.5 mmHg. Both intramyocardial edema p=0.02 and hemorrhage p=0.03 had a larger extent in patients with coronary wedge pressure ≤24.5 mmHg. Rentrop grade <2 was associated with larger infarct size p=0.03, but not with the extent of edema, microvascular obstruction, or intramyocardial hemorrhage. Conclusions. Pre-revascularization CWP was a predictor of infarct size and was significantly associated with a larger extent of intramyocardial edema and intramyocardial hemorrhage. Rentrop grade <2 was associated with a larger infarct size, but had no influence on reperfusion injury. The clinical trial is registered with NCT03371784.

Measurement of microvascular function in patients presenting with thrombolysis for ST elevation myocardial infarction, and PCI for non-ST elevation myocardial infarction

BACKGROUND

In this prospective study, we compared the invasive measures of microvascular function in two subsets: patients with pharmacoinvasive thrombolysis for STEMI, and patients undergoing percutaneous coronary intervention (PCI) for NSTEMI.

METHODS

The study consisted of 17 patients with STEMI referred for cardiac catheterisation post thrombolysis, and 20 patients with NSTEMI. Coronary physiological indexes were measured in each patient before and after PCI.

RESULTS

The median pre-PCI index of microcirculatory function (IMR) at baseline was significantly higher in the STEMI group than the NSTEMI group (26 units vs. 15 units, p = 0.02). Following PCI, IMR decreased in both groups (STEMI 20 units vs. NSTEMI 14 units, p = 0.10). There was an inverse correlation between post PCI IMR and left ventricular ejection fraction (LVEF) (r = -0.52, p = 0.001). Furthermore, post PCI IMR was an independent predictor of index admission LVEF in the total population (β = -0.388, p = 0.02).

CONCLUSION

Invasive measures of microvascular function are inferior in a pharmacoinvasive STEMI group compared to a clinically stable NSTEMI group. In the STEMI population, the IMR following coronary intervention appears to predict LVEF.

Coronary Collaterals Function and Clinical Outcome Between Patients With Acute and Chronic Total Occlusion

OBJECTIVES

This study sought to demonstrate how changes in the collateral function and its clinical significance before and after percutaneous coronary interventions (PCIs) are compared between patients with acute coronary syndrome and total or nearly total occlusions (ATOs) and chronic total occlusions (CTOs).

BACKGROUND

The functional relevance of the collateral circulation in patients with ATOs and CTOs has not been fully investigated.

METHODS

The pressure-derived collateral pressure index (CPI), myocardial fractional flow reserve (FFRmyo), and coronary fractional flow reserve (FFRcor) at maximum hyperemia induced by intravenous adenosine were evaluated in occluded vessels at baseline, after the PCI, and at 1 year in 23 ATO and 74 CTO patients.

RESULTS

The FFRmyo and FFRcor were significantly lower, but the CPI was significantly higher in the CTO than ATO patients at baseline and after the PCI. There were significant increases in the FFRmyo (p < 0.001) and FFRcor (p < 0.001), whereas there was no significant change in the CPI immediately after the PCI in both ATO and CTO patients. In the CTO patients, a post-PCI FFRmyo <0.90 (p = 0.01) and post-PCI CPI <0.25 (p = 0.033) were independent predictors of the clinical outcome. Patients with a high post-PCI CPI had better clinical outcomes in CTO patients with a low post-PCI FFRmyo (log-rank p = 0.009), but not a high post-PCI FFRmyo (log-rank p = 0.492).

CONCLUSIONS

Recruitable coronary collateral flow did not regress completely immediately after the PCI both in patients with ATOs and CTOs. Despite good collaterals in CTO patients, aggressive efforts to reduce the ischemic burden might improve the clinical outcome.

Collateral Circulation in Chronic Total Occlusions – an interventional perspective

Human coronary collaterals are inter-coronary communications that are believed to be present from birth. In the presence of chronic total occlusions, recruitment of flow via these collateral anastomoses to the arterial segment distal to occlusion provide an alternative source of blood flow to the myocardial segment at risk. This mitigates the ischemic injury. Clinical outcome of coronary occlusion ie. severity of myocardial infarction/ischemia, impairment of cardiac function and possibly survival depends not only on the acuity of the occlusion, extent of jeopardized myocardium, duration of ischemia but also to the adequacy of collateral circulation. Adequacy of collateral circulation can be assessed by various methods. These coronary collateral channels have been used successfully as a retrograde access route for percutaneous recanalization of chronic total occlusions. Factors that promote angiogenesis and further collateral remodeling ie. arteriogenesis have been identified. Promotion of collateral growth as a therapeutic target in patients with no suitable revascularization option is an exciting proposal.

Sensitivity analysis and parameter estimation of a coronary circulation model for triple-vessel disease

Mathematical models of the coronary circulation have been shown to provide useful information for the analysis of intracoronary blood flow and pressure measurements acquired during coronary artery bypass graft (CABG) surgery. Although some efforts towards the patient-specific estimation of model parameters have been presented in this context, they are based on simplifying hypotheses about the collateral circulation and do not take advantage of the whole set of data acquired during CABG. In order to overcome these limitations, this paper presents an exhaustive parameter sensitivity analysis and a multiobjective patient-specific parameter estimation method, applied to a model of the coronary circulation of patients with triple vessel disease. The results of the sensitivity analysis highlighted the importance of capillary and collateral development. On the other hand, the estimation method was applied to intraoperative clinical data from ten patients obtained during CABG, which permitted to assess patient-specific collateral vessel situations. These approaches provide new insights regarding the heterogeneous configuration of the collateral circulation.

Relation of the systemic blood pressure to the collateral pressure distal to an infarct-related coronary artery occlusion during acute myocardial infarction

Collaterals to occluded coronary arteries have been observed early after the onset of acute myocardial infarction (AMI). The pressure distal to the occluded segment of the culprit coronary artery (P(d)) is generated by collateral flow from the feeding coronary artery supplied by the systemic circulation. The aim of the study was to assess the relation between systemic blood pressure (BP) and P(d). Systemic BP and P(d) were measured simultaneously during intervention of totally occluded coronary arteries in 152 patients admitted for AMI. Patients were divided into groups by time from symptom onset to P(d) measurement. There was a significant positive correlation between P(d) and the systolic, diastolic, and mean BPs measured during the first 3 hours from symptom onset (n = 60; p <0.05, p <0.006, and p <0.005, respectively), from 3 to 12 hours (n = 56; p <0.02 for all), and >12 hours after symptom onset (n = 36; p <0.003 for all). The collateral flow, represented by calculated collateral flow index (mean 0.37 ± 0.14, median 0.36), was correlated with mean BP (p = 0.05) but not with diastolic or systolic BP (p = NS) in the overall study population. A direct relation was established during AMI between systemic BP and P(d) at all time intervals from symptom onset. Collateral flow index correlated with mean BP and was strongly associated with P(d) at all time intervals. In conclusion, the relation between P(d) and systemic BP suggests caution when administering therapy that may lower systemic BP during AMI before restoring flow in the occluded culprit artery, as it may compromise collateral pressure and exacerbate myocardial ischemia.

Index of microcirculatory resistance as predictor for microvascular functional recovery in patients with anterior myocardial infarction

IMR is useful for assessing the microvascular dysfunction after primary percutaneous coronary intervention (PCI). It remains unknown whether index of microcirculatory resistance (IMR) reflects the functional outcome in patients with anterior myocardial infarction (AMI) with or without microvascular obstruction (MO).This study was performed to evaluate the clinical value of the IMR for assessing myocardial injury and predicting microvascular functional recovery in patients with AMI undergoing primary PCI. We enrolled 34 patients with first anterior AMI. After successful primary PCI, the mean distal coronary artery pressure (P(a)), coronary wedge pressure (P(cw)), mean aortic pressure (P(a)), mean transit time (T(mn)), and IMR (P(d)* hyperemic T(mn)) were measured. The presence and extent of MO were measured using cardiac magnetic resonance image (MRI). All patients underwent follow-up echocardiography after 6 months. We divided the patients into two groups according to the existence of MO (present; n = 16, absent; n = 18) on MRI. The extent of MO correlated with IMR (r = 0.754; P < 0.001), P(cw) (r = 0.404; P = 0.031), and P(cw)/P(d) of infarct-related arteries (r = 0.502; P = 0.016). The IMR was significantly correlated with the ΔRegional wall motion score index (r = -0.61, P < 0.01) and ΔLeft ventricular ejection fraction (r = -0.52, P < 0.01), implying a higher IMR is associated with worse functional improvement. Therefore, Intracoronary wedge pressures and IMR, as parameters for specific and quantitative assessment of coronary microvascular dysfunction, are reliable on-site predictors of short-term myocardial viability and Left ventricle functional recovery in patients undergoing primary PCI for AMI.

Coronary collateral circulation: Effects on outcomes of acute anterior myocardial infarction after primary percutaneous coronary intervention

Background

To investigate the effects of collateral coronary circulation on the outcome of the patients with anterior myocardial infarction (MI) with left anterior desending artery occlusion abruptly.

Methods

Data of 189 patients with acute anterior MI who had a primary percutaneous coronary intervention (PCI) in the first 12 h from the onset of symptoms between January 2004 and December 2008 were retrospective analyzed. Left anterior descending arteries (LAD) of all patients were occluded. LADs were reopened with primary PCI. According to the collateral circulation, all patients were classified to two groups: no collateral group (n = 111), patients without angiographic collateral filling of LAD or side branches (collateral index 0) and collateral group (n = 78), and patients with angiographic collateral filling of LAD or side branches (collateral index 1, 2 or 3). At one year's follow-up, the occurrence of death, reinfarction, stent thrombosis (ST), target vessel revascularization and readmission because of heart failure were observed.

Results

At one year, the mortality was lower in patients with collateral circulation compared with those without collateral circulation (1% vs. 8%, P = 0.049), whereas there were no differences in the occurrence of reinfarction, ST, target vessel revascularization and readmission because of heart failure. The occurrence of composite of endpoint was lower in patients with collateral circulation compared with those without collateral circulation (12% vs. 26%; P = 0.014).

Conclusions

Pre-exist collateral circulation may prefigure the satisfactory prognosis to the patients with acute anterior MI after primary PCI in the first 12 h of MI onset.

A more sensitive pressure-based index to estimate collateral blood supply in case of coronary three-vessel disease

With progressive occlusion of a coronary main artery, some anastomotic vessels are recruited in order to supply blood to the ischemic region. This collateral circulation is an important factor in the preservation of the myocardium until reperfusion of the area at risk. An accurate estimation of collateral flow is crucial in surgical bypass planning as it alters the blood flow distribution in the coronary network and can influence the outcome of a given treatment for a given patient. The evaluation of collateral flow is frequently achieved using an index based on pressure measurements. It is named Collateral Flow Index (CFI) and defined as: (P(w)-P(v))/(P(ao)-P(v)), where P(w) is the pressure distal to the thrombosis, P(ao) the aortic pressure and P(v) the central venous pressure. We propose here another index, that is more sensitive to the P(w) value and could thus describe the role of collateral flow with more precision. We illustrate this idea using some clinical pressure measurements in patients with severe coronary disease (stenoses on the left branches and total occlusion of the right coronary artery).

Theoretical study of the flow rate toward the right heart territory in case of total occlusion of the right coronary artery

In this work, patients with severe coronary disease and chronic occlusion of the right coronary artery (RCA) are studied. In this clinical situation, the collateral circulation is an important factor in the preservation of the myocardium until reperfusion of the area at risk. An accurate estimation of collateral flow is crucial in surgical bypass planning as it can influence the outcome of a given treatment for a given patient. The evaluation of collateral flow is frequently achieved using an index (CFI, Collateral Flow Index) based on pressure measurements. Using a model of the coronary circulation based on hydraulic/electric analogy, we demonstrate, through theoretical simulations, that a wide range of fractional collateral flow values can be obtained for any given distal pressure difference depending on the values of the capillary and collateral resistances.

Novel acute collateral flow index in patients with total coronary artery occlusion during ST-elevation myocardial infarction

BACKGROUND

The effect of collaterals to occluded coronary arteries during ST-elevation myocardial infarction (STEMI) is unclear. The conventional CVP-based formula to calculate collateral flow index during STEMI yields values higher than in elective patients, which prompted derivation of a modified formula, pertinent in STEMI when left ventricular mean diastolic pressure (LVMDP) is the extravascular pressure limiting collateral flow. We aimed to evaluate this new LVMDP-based acute collateral flow index (ACFI).

METHODS AND RESULTS

The pressure distal to coronary artery occlusion (P(d)) was measured during intervention in 111 consecutive STEMI patients, 67 (61%) of whom underwent primary intervention, followed for 58 months. ACFI (0.18 ± 0.17, median 0.15) correlated with both P(d) and collateral grade (P<0.0001). Higher creatine kinase levels and white cell counts were measured in the lowest ACFI tertile compared with the highest tertile group (P<0.012). ACFI correlated slightly with early regional but not with global left ventricular ejection fraction or with long-term coronary events and mortality.

CONCLUSIONS

The ACFI is appropriate for evaluating collateral function during STEMI. Collateral flow during STEMI may marginally limit myocardial damage but had no effect on left ventricular contraction or long-term mortality, most likely because of the low flow provided by emerging collaterals and the high proportion of patients undergoing intervention before the beneficial effect of collaterals could be realized.

The human coronary collateral circulation

BACKGROUND

Coronary collaterals are an alternative source of blood supply to myocardium jeopardized by ischaemia. Well-developed coronary collateral arteries in patients with coronary artery disease (CAD) mitigate myocardial infarcts and improve survival.

METHODS AND RESULTS

Collateral arteries preventing myocardial ischaemia during brief vascular occlusion are present in 1/3 of patients with CAD. Among individuals without relevant coronary stenoses, there are preformed collateral arteries preventing myocardial ischaemia in 20-25%. Collateral flow sufficient to prevent myocardial ischaemia during coronary occlusion amounts to double dagger25% of the normal flow through the open vessel. Myocardial infarct size, the most important prognostic determinant after such an event, is the product of coronary artery occlusion time, area at risk for infarction and the inverse of collateral supply. Coronary collateral flow can be assessed only during vascular occlusion of the collateral-receiving artery. The gold standard for coronary collateral assessment is the measurement of intracoronary occlusive pressure- or velocity-derived collateral flow index expressing collateral as a fraction of flow during vessel patency. Approximately one of five patients with CAD cannot be revascularized by percutaneous coronary intervention or coronary artery bypass grafting. Therapeutic promotion of collateral growth is a valuable treatment strategy in those patients.

CONCLUSIONS

Promotion of collateral growth should aim at inducing the development of large conductive collateral arteries (i.e. arteriogenesis) and not so much the sprouting of capillary like vessels (i.e. angiogenesis). Large conductive collateral arteries appear to be effectively promoted via the activation of monocytes/macrophages by means of granulocyte-colony stimulating factor or of augmenting coronary flow velocity.

Collateral pressure and flow in acute myocardial infarction with total coronary occlusion correlate with angiographic collateral grade and creatine kinase levels

BACKGROUND

The validity of angiographic collateral grade according to the Rentrop classification during acute myocardial infarction (AMI) and its relation to flow in occluded coronary arteries before angioplasty have never been evaluated.

METHODS

We assessed the validity of the angiographic collateral grade according to Rentrop classification in relation to collateral pressure and flow beyond occluded coronary arteries during AMI. Pressure distal to coronary artery occlusions before balloon dilatation was measured in 111 patients undergoing angioplasty for AMI. We calculated the collateral flow index (CFI) and compared it to observed Rentrop grade and measured creatine kinase sum.

RESULTS

The values of pressure distal to coronary artery occlusions with respect to collateral grades 0 to 3 were 33 +/- 12, 37 +/- 13, 42 +/- 10, and 60 +/- 14 mm Hg (P < .0001). Overall CFI was 0.35 +/- 0.13 (median 0.33), with CFI values of 0.3 +/- 0.13, 0.33 +/- 0.13, 0.39 +/- 0.1, and 0.57 +/- 0.2 for collateral grades 0 to 3, respectively (P < .0001). Larger creatine kinase elevation (P < .016) and higher white blood cell count (P < .022) were recorded in the lowest tertile CFI compared with highest tertile CFI group; but no difference in the global, regional, or infarct-related regional left ventricular contraction was found.

CONCLUSIONS

These observations demonstrate that the Rentrop classification is valid in AMI patients with occluded coronary arteries and that collaterals are recruited acutely. These collaterals, whose pressure-derived CFI during AMI was shown for the first time to be higher than its value reported in chronic conditions, may limit the immediate myocardial damage or the systemic inflammatory response. No impact on global or regional cardiac contraction was detected in a population where most patients were treated early.

Myocardial salvage for ST-elevation myocardial infarction with terminal QRS distortion and restoration of brisk epicardial coronary flow

Recently, it has been reported that large infarcts associated with terminal QRS distortion (QRSDIS) on the admission electrocardiograms of patients with ST-elevation myocardial infarctions (STEMIs) may be caused by a failure to achieve thrombolysis in myocardial infarction (TIMI) grade 3 flow after primary percutaneous coronary intervention (PCI). However, the relationship between QRSDIS and final infarct size when TIMI grade 3 flow could be achieved by primary PCI is still unclear. Sixty-two consecutive patients with first anterior STEMI and who achieved TIMI grade 3 flow by primary PCI were classified into two groups according to the presence (Group A, n = 18) or absence (Group B, n = 44) of QRSDIS. Two weeks after the onset of acute myocardial infarction, Group A had a larger left ventricular (LV) end-systolic volume index (LVESVI) and a lower LV ejection fraction (LVEF) than Group B (LVESVI: 38 +/- 13 vs 31 +/- 12 ml/m(2), P = 0.025: LVEF: 42% +/- 10% vs 51% +/- 10%, P = 0.004). Through multivariate analysis, independent predictors of poor LV systolic function (LVEF < 40%) were determined to be the presence of QRSDIS (odds ratio 21.04, P = 0.021) and proximal left anterior descending artery occlusion (odds ratio 16.15, P = 0.033). Myocardial damage could not be reduced in patients experiencing STEMI with QRSDIS, even when TIMI grade 3 flow could be achieved by primary PCI, as much as in patients experiencing STEMI without QRSDIS.

Diagnostic ultrasound combined with glycoprotein IIb/IIIa-targeted microbubbles improves microvascular recovery after acute coronary thrombotic occlusions

BACKGROUND

The high mechanical index (MI) impulses from a diagnostic ultrasound transducer may be a method of recanalizing acutely thrombosed vessels if the impulses are applied only when microbubbles are channeling through the thrombus.

METHODS AND RESULTS

In 45 pigs with acute left anterior descending thrombotic occlusions, a low-MI pulse sequence scheme (contrast pulse sequencing) was used to image the myocardium and guide the delivery of high-MI (1.9 MI) impulses during infusion of either intravenous platelet-targeted microbubbles or nontargeted microbubbles. A third group received no diagnostic ultrasound and microbubbles. All groups received half-dose recombinant prourokinase, heparin, and aspirin. Contrast pulse sequencing examined replenishment of contrast within the central portion of the risk area and guided the application of high-MI impulses. Angiographic recanalization rates, resolution of ST-segment elevation on ECG, and wall thickening were analyzed. Pigs receiving platelet-targeted microbubbles had more rapid replenishment of the central portion of the risk area (80% versus 40% for nontargeted microbubbles; P=0.03) and higher epicardial recanalization rates (53% versus 7% for prourokinase alone; P=0.01). Replenishment of contrast within the risk area (whether with platelet-targeted microbubbles or nontargeted microbubbles) was associated with both higher recanalization rates and even higher rates of ST-segment resolution (82% versus 21% for prourokinase alone; P=0.006). ST-segment resolution occurred in 6 pigs (40%) treated with microbubbles who did not have epicardial recanalization, of which 5 had recovery of wall thickening.

CONCLUSIONS

Intravenous platelet-targeted microbubbles combined with brief high-MI diagnostic ultrasound impulses guided by contrast pulse sequencing improve both epicardial recanalization rates and microvascular recovery.

Myocardial Perfusion in Patients With a Totally Occluded Left Anterior Descending Coronary Artery Reinjected by a Normal Right Coronary Artery: The Role of Collateral Circulation

In this article, myocardial perfusion in patients with a totally occluded left anterior descending artery reinjected by a normal right coronary artery is assessed using stress single photon emission computed tomography (SPECT). In all, 20 patients, with a totally occluded left anterior descending artery reinjected by normal right coronary artery, underwent myocardial single photon emission computed tomography imaging within 60 days of angiography. All patients had abnormal perfusion single photon emission computed tomography results and 70% had reversible defects. Perfusion defects at rest were present in 75% of patients, with perinecrotic residual ischemia in 45% of patients whereas for 30% of patients, no viable myocardium was detected in the collateral-dependent segments. In all, 25% of patients had no resting perfusion defects but all are presented with stress-induced ischemia. Collaterals are not protective against stress-induced ischemia, but they can preserve myocardial viability. This conclusion is highly supported by the presence of residual ischemia in the collateral-dependent segments.

Relationship between collateral circulation and successful myocardial reperfusion in acute myocardial infarction: a subanalysis of the PREMIAR trial

The aim of this study was to determine whether the presence of collateral circulation had a beneficial effect following primary angioplasty. In all, 114 patients who underwent primary angioplasty were included. Patients with collateral circulation had lower basal ST-segment deviation (P = .004), white cell count ( P = .001), peak creatine kinase (P = .001), and regional wall motion score values (P = .03) than patients without collateral circulation. After the procedure, the group with collaterals was associated with higher rates of normal myocardial blush, complete ST resolution, and shorter time to stable ST-recovery. Multivariable logistic analysis identified the presence of collateral circulation as independent predictor of normal myocardial blush (adjusted odds ratio = 3.98, 95% confidence interval, 1.12-14.09; P = .033) and rapid reperfusion (time to stable ST-segment recovery <7 minutes, adjusted odds ratio = 4.0, 95% confidence interval, 1.57-10.20; P = .004). The presence of collateral circulation has a protective effect on infarct size, resulting in faster reperfusion.

Good Collaterals Predict Viable Myocardium

The authors undertook this study to see whether highly developed coronary collaterals at an area shed by a totally occluded coronary artery predicts myocardial viability. Percutaneous coronary intervention (PCI) of a totally occluded coronary artery has been debated since its introduction. It is recommended to search for viable myocardium before opening a totally occluded coronary artery; however, there is no practical yet sensitive method of assessing myocardial viability in the catheterization laboratory. Forty-seven consecutive patients (12 women, 25.5%; 35 men, 74.5%), each with 1 totally occluded coronary artery, were prospectively enrolled to the study. After the diagnostic coronary angiography, all patients underwent dobutamine stress echocardiography to determine viable myocardium at the territory of the totally occluded coronary artery, and the status of angiographic coronary collaterals was assessed. Patients were then divided into 2 groups according to the presence (Group A) or absence (Group B) of viable myocardium by stress echocardiography. Eighteen patients (38.3%) had viable myocardium (Group A) in the area shed by the totally occluded coronary artery and 29 patients (61.7%) had nonviable myocardium (Group B). The incidences of significant coronary collateral circulation to the viable (Group A) and nonviable (Group B) areas were 66.7% (12 patients) and 20.7% (6 patients), respectively (p = 0.002). Logistic regression analysis was used to evaluate the independent factors for viable myocardium, and only significant coronary collateral circulation was found to be an independent factor for the detection of viable myocardium (p = 0.006, OR 16.7, 95% CI 2.25 to 124.4). The sensitivity and specificity of good collateral circulation for the detection of viable myocardium were 75% and 65.7%, respectively. The positive predictive and negative predictive values of the good coronary collateral circulation in detecting viable myocardium were 75% and 79%, respectively. The authors conclude that good coronary collaterals have a high sensitivity and positive predictive value for the prediction of viability as shown by dobutamine echocardiography, and only by assessing the coronary collateral circulation can one decide for percutaneous coronary revascularization, if not for coronary artery bypass surgery.

Detection of left ventricular dysfunction by Doppler tissue imaging in patients with complete recovery of visual wall motion abnormalities 6 months after a first ST-elevation myocardial infarction

AIMS

The aim of this study was to assess left ventricular (LV) systolic and diastolic function, using Doppler tissue imaging (DTI), in patients with complete recovery of visual wall motion abnormalities six months after a first ST-elevation myocardial infarction (STEMI).

METHODS

Out of 90 patients presenting with a STEMI, 68 patients without a history of heart disease were examined by echocardiography before discharge and after 6 months. The patients were compared to 41 age matched healthy subjects (HS). LV function was assessed by visual wall motion and mitral annular velocities using pulsed wave DTI.

RESULTS

Sixty-eight patients had visual wall motion abnormalities at baseline. Of these, 19 patients showed complete recovery of wall motion at 6-months follow-up. Patients with complete recovery of wall motion abnormalities had significantly reduced peak systolic and peak early diastolic mitral annular velocities compared to HS at 6 months (8.3 cm s(-1) versus 9.9 cm s(-1), P<0.001 for systolic velocity and 9.3 cm s(-1) versus 13.1 cm s(-1), P<0.001 for diastolic velocity, respectively).

CONCLUSION

In patients presenting with a first STEMI, mitral annular systolic and early diastolic velocities assessed by DTI at 6-months follow-up are significantly reduced compared to HS, despite normal standard echocardiographic parameters of LV function. This probably reflects a residual subendocardial damage not detected by conventional echocardiographic methods.

Persistent ST-segment elevation after primary stenting for acute myocardial infarction: its relation to left ventricular recovery

BACKGROUND

Early restoration of coronary artery patency in acute myocardial infarction (AMI) has been linked to improvement in survival. However, early recanalization of an occluded epicardial coronary artery by either thrombolytic agents or percutaneous transluminal coronary angioplasty (PTCA) does not necessarily lead to left ventricular (LV) function recovery.

HYPOTHESIS

The aim of this study was to evaluate the relation between persistent ST elevation shortly after primary stenting for acute myocardial infarction (AMI) and LV recovery.

METHODS

Thirty-one patients with primary stenting for AMI were prospectively enrolled. To evaluate the extent of microvascular injury, serial ST-segment analysis on a 12-lead electrocardiogram recording just before and at the end of the coronary intervention was performed. Persistent ST-segment elevation (Persistent Group, n = 11) was defined as > or = 50% of peak ST elevation and resolution (Resolution Group, n = 20) was defined as < 50% of peak ST elevation. Echocardiography was performed on Day 1 and 3 months after primary stenting.

RESULTS

At 3 months, infarct zone wall-motion score index (WMSI, 2.1 +/- 0.6 vs. 2.7 +/- 0.3, p < 0.05) was smaller in the Resolution Group than in the Persistent Group, whereas wall motion recovery index (RI, 0.4 +/- 0.3 vs. 0.1 +/- 0.2, p < 0.05) and ejection fraction (58 +/- 5 vs. 43 +/- 10%, p < 0.05) were larger in the Resolution Group than in the Persistent Group. The extent of persistent ST elevation (% ST) shortly after successful recanalization of the infarct-related artery was significantly related to RI at 3 months (r = -0.4, p < 0.05). However, time to reperfusion was not related to RI at 3 months. There was also significant correlation between corrected TIMI frame count and %ST (r = 0.4, p < 0.05).

CONCLUSIONS

Persistent ST-segment elevation shortly after successful recanalization (> or = 50% of the peak value), as a marker of impaired microvascular reperfusion, predicts poor LV recovery 3 months after primary stenting for AMI.

Pressure-derived collateral flow index: a strong predictor of late left ventricular remodeling after thrombolysis for acute myocardial infarction

OBJECTIVE

Despite proved efficacy of pressure-derived collateral flow index in determining microvascular dysfunction in patients with acute myocardial infarction, its role in prediction of left ventricular remodeling at long term has yet to be demonstrated. In this study, we investigated the relationship between quantitatively assessed microvascular dysfunction by using intracoronary pressure wire and late left ventricular remodeling.

PATIENTS AND METHODS

The study population consisted of 28 patients with first acute myocardial infarction. They were treated with fibrinolytic therapy. The inclusion criteria were thrombolysis in myocardial infarction grade II-III flow in infarct-related artery and all destined for stent implantation. Cardiac catheterization and stent implantation were performed in mean of 3.3 days after acute myocardial infarction. During the stent implantation procedure, the pressure-derived collateral flow index was measured by using intracoronary pressure wire. Control angiograms were performed at 6+/-2 months. Echocardiographic left ventricular volume indexes were measured at discharge, at 6 months and at 1 year. Changes in left ventricular volumes from baseline to 1 year were followed.

RESULTS

Left ventricular end-diastolic volume index at 1 year correlated significantly with the pressure-derived collateral flow index (r=0.69, P<0.01). A significant correlation was also observed between the change in left ventricular end-diastolic volume index from baseline to 1 year and the pressure-derived collateral flow index (r=0.65, P<0.01). The most important predictor of 1-year left ventricular remodeling was the pressure-derived collateral flow index (P<0.0001), and collateral circulation (P=0.03).

CONCLUSION

The pressure-derived collateral flow index is a powerful independent predictor of 1-year left ventricular dilatation. Given its simplicity of measurement, and correlation with microvascular obstruction and left ventricular outcome at long term, the pressure-derived collateral flow index may provide useful and valuable estimates of clinical outcomes after acute myocardial infarction.

Collaterals that regressed after angioplasty can be recruited to protect the left ventricle in case of an acute occlusion

A considerable fraction of collaterals has been shown to regress immediately after percutaneous transluminal coronary angioplasty (PTCA), but the fate of these well-developed collaterals is unknown. The authors aimed to show the protective role of these recruitable collaterals in case of an acute myocardial infarction (MI). They identified 22 patients who underwent PTCA and then were rehospitalized owing to acute myocardial infarction. These patients were compared with a group consisting of 48 patients hospitalized owing to acute MI without a history of previous PTCA. Then, the patients with collaterals were compared with the patients without collaterals to define the factors affecting the collateral formation. All the patients with collaterals before PTCA were shown to have collaterals also after AMI, and collateral grades were greater after MI (1.67 +/-0.98) when compared with those before PTCA (0.73 +/-0.7) (p = 0.001). Coronary collaterals were more commonly seen in patients with a history of previous PTCA (p = 0.005), and the grades of collaterals were also higher in these patients when compared with those without PTCA. Left ventricle score indices were lower and left ventricular ejection fractions (LVEF) were higher in patients with a history of PTCA (p = 0.001). Logistic regression analysis revealed that smoking increased the development of collaterals after AMI 3.8 fold, aspirin use 4.1 fold. On the contrary, diabetes mellitus (DM) decreased this 6.67 fold. As a result, well-developed coronary collaterals are preserved even if they have regressed after restoration of flow, and they may become functional and protect the myocardium against acute ischemia.

Relation between coronary pressure derived collateral flow, myocardial perfusion grade, and outcome in left ventricular function after rescue percutaneous coronary intervention

OBJECTIVE

To evaluate the relation between pressure derived coronary collateral flow (PDCF) index and angiographic TIMI (thrombolysis in myocardial infarction) myocardial perfusion (TMP) grade, angiographic collateral grade, and subsequent recovery of left ventricular function after rescue percutaneous coronary intervention (PCI) for failed reperfusion in acute myocardial infarction.

METHODS

The pressure wire was used as the guidewire in 38 consecutive patients who underwent rescue PCI between December 2000 and March 2002. Follow up angiography was performed at six months. Baseline and follow up single plane ventriculograms were analysed off line by an automated edge detection technique. A linear model was fitted to assess the relation between 0.1 unit increase in PDCF and change in left ventricular regional wall motion.

RESULTS

Patients with TMP 0 grade had significantly higher mean (SD) PDCF than patients with TMP 1-3 (0.30 (0.11) v 0.15 (0.07), p < 0.0001, r = -0.5). A similar relation was observed between TMP grade and coronary wedge pressure (mean (SD) 28 (16) mm Hg with TMP 0 v 9 (7) mm Hg with TMP 1-3, p = 0.001, r = -0.4). Higher PDCF was associated with increased left ventricular end diastolic pressures (0.28 (0.14) with end diastolic pressure > 20 mm Hg v 0.22 (0.09) with end diastolic pressure < 20 mm Hg, p = 0.08, r = 0.2). No correlation was observed between PDCF and Rentrops collateral grade (0.26 (0.13) with grade 0 v 0.25 (0.11) with grades 1-3, p = 0.4, r = -0.06). No linear relation existed between changes in PDCF and changes in left ventricular regional wall motion.

CONCLUSION

PDCF in the setting of rescue PCI for failed reperfusion after thrombolysis does not predict improvement in left ventricular function. Increased PDCF and coronary wedge pressure in acute myocardial infarction reflect a dysfunctional microcirculation rather than good collateral protection.

Reciprocal relationship between left ventricular filling pressure and the recruitable human coronary collateral circulation

AIMS

The aim of our study in patients with coronary artery disease (CAD) and present, or absent, myocardial ischaemia during coronary occlusion was to test whether (i) left ventricular (LV) filling pressure is influenced by the collateral circulation and, on the other hand, that (ii) its resistance to flow is directly associated with LV filling pressure.

METHODS AND RESULTS

In 50 patients with CAD, the following parameters were obtained before and during a 60 s balloon occlusion: LV, aortic (Pao) and coronary pressure (Poccl), flow velocity (Voccl), central venous pressure (CVP), and coronary flow velocity after coronary angioplasty (V(Ø-occl)). The following variables were determined and analysed at 10 s intervals during occlusion, and at 60 s of occlusion: LV end-diastolic pressure (LVEDP), velocity-derived (CFIv) and pressure-derived collateral flow index (CFIp), coronary collateral (Rcoll), and peripheral resistance index to flow (Rperiph). Patients with ECG signs of ischaemia during coronary occlusion (insufficient collaterals, n = 33) had higher values of LVEDP over the entire course of occlusion than those without ECG signs of ischaemia during occlusion (sufficient collaterals, n = 17). Despite no ischaemia in the latter, there was an increase in LVEDP from 20 to 60 s of occlusion. In patients with insufficient collaterals, CFIv decreased and CFIp increased during occlusion. Beyond an occlusive LVEDP > 27 mmHg, Rcoll and Rperiph increased as a function of LVEDP.

CONCLUSION

Recruitable collaterals are reciprocally tied to LV filling pressure during occlusion. If poorly developed, they affect it via myocardial ischaemia; if well grown, LV filling pressure still increases gradually during occlusion despite the absence of ischaemia indicating transmission of collateral perfusion pressure to the LV. With low, but not high, collateral flow, resistance to collateral as well as coronary peripheral flow is related to LV filling pressure in the high range.

Collateralization and the response to obstruction of epicardial coronary arteries

Occlusive coronary disease is an important cause of global morbidity and mortality. While mechanical revascularization is effective, some individuals are not amenable to such interventions, and have a poorer prognosis. However, collateral circulation can protect and preserve myocardium around the time of coronary occlusion, contribute to better residual myocardial contractility, and lessen symptoms. We describe the anatomy and physiology of coronary collateralization, its component parts (angiogenesis and arteriogenesis), the current methods for definition of the collateral response and how this might be manipulated. The manipulation of this process is a realistic possibility for future adjuvant treatment of coronary artery disease.

Evidence for association of coronary sinus levels of hepatocyte growth factor and collateralization in human coronary disease

The therapeutic use of angiogenic factors to protect ischemic myocardium is limited by our incomplete understanding of their endogenous production. We determined the association between angiogenic factors and collateral formation in patients with coronary artery disease (CAD). A total of 71 patients underwent catheterization with sampling of the pulmonary artery, aorta, and coronary sinus (CS) to determine the levels of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). VEGF and HGF levels were not different in the three vascular sites, suggesting that the heart is not a major source of these cytokines in the circulation. CS VEGF and HGF levels were similar in patients with and without CAD. Elevated CS HGF levels were associated with collateral formation, whereas VEGF levels were not. Additionally, CS HGF was significantly elevated in patients with left ventricular dysfunction. These data map for the first time the concentration of endogenous angiogenic factors in the coronary circulation and support further studies to determine whether HGF may be an endogenous cardioprotective angiogenic factor.

Physiologically assessed coronary collateral flow and adverse cardiac ischemic events: a follow-up study in 403 patients with coronary artery disease

OBJECTIVES

We sought to evaluate whether coronary collateral flow is clinically relevant for future cardiac ischemic events.

BACKGROUND

The link between good collateral supply related to less myocardial damage and fewer cardiac events has not been established prospectively beyond doubt.

METHODS

In 403 patients with stable angina pectoris undergoing percutaneous transluminal coronary angioplasty (PTCA) and quantitative collateral assessment, the occurrence of major adverse cardiac events ([MACE] cardiac death, myocardial infarction, unstable angina pectoris) and stable angina pectoris was monitored during follow-up. Collateral flow index (CFI) was determined using intracoronary pressure or Doppler guidewires. Mean aortic ([P(ao)] mm Hg) and distal coronary artery occlusive pressure ([P(occl)] mm Hg) during balloon angioplasty (PTCA), or distal coronary flow velocity time integral during ([V(occl)] cm) and after ([V(ø-occl)] cm) PTCA were measured continuously. Pressure-derived CFI was calculated as follows: (P(occl) - 5)/(P(ao) - 5). Doppler-derived CFI: V(occl)/V(ø-occl). Patients were subdivided into a group with well (CFI > or = 0.25) and poorly developed collaterals (CFI < 0.25).

RESULTS

Average follow-up was 94 +/- 56 (15 to 202) weeks. There were 134 patients with CFI >or =0.25 (61 +/- 11 years) and 269 with CFI <0.25 (61 +/- 10 years). The overall cardiac ischemic event rate (MACE and stable angina pectoris) during follow-up was 23% in patients with CFI > or =0.25 and 20% in patients with CFI <0.25 (p = NS). However, only 2.2% of patients with good collateral flow suffered a major cardiac ischemic event, compared with 9.0% among patients with poorly developed collaterals (p = 0.01). The incidence of stable angina pectoris was significantly higher in patients with well developed collaterals than in those with poorly developed collaterals (21% vs. 12%; p = 0.01).

CONCLUSIONS

In this relatively large population with chronic stable coronary artery disease undergoing quantitative collateral measurement, the beneficial impact of well developed collateral vessels on the occurrence of future major cardiac ischemic events is clearly demonstrated.

Coronary collateralization: determinants of adequate distal vessel filling after arterial occlusion

BACKGROUND

The protective effect of collateral vessels in coronary artery disease (CAD) is well established. Little is known, however, about factors that influence collateral formation.

METHODS

We studied the coronary angiograms of 200 consecutive patients with single-vessel coronary artery occlusion. Patients were excluded if obstructive stenoses were present in other vessels or if prior revascularization had been undertaken. Collateral circulation to the occluded artery was graded as 'poor' (no or incomplete filling) or 'rich' (complete filling). Patient characteristics, including mode of presentation, medications and CAD risk factors, were assessed.

RESULTS

Positive univariate correlates of rich collaterals included increasing age [odds ratio (OR) 1.03, P = 0.016], 'statin' use (OR 2.50, P = 0.005), nitrate use (OR 1.96, P = 0.034), calcium-channel blocker (CCB) use (OR 4.07, P < 0.001), presentation with stable angina (OR 2.34, P = 0.006), longer time since diagnosis of CAD (OR 1.12, P = 0.002) and history of hyperlipidemia (OR 3.55, P < 0.001). Significantly poorer collateralization was observed in the setting of acute myocardial infarction (MI) (OR 0.23, P < 0.001), diabetes mellitus (OR 0.33, P = 0.003), impaired left ventricular function (OR 0.64, P = 0.015) and occlusion of the left anterior descending coronary artery (LAD) (OR 0.28, P < 0.001). On multivariate analysis, rich collateralization was associated with hyperlipidemia (P = 0.003) and CCB use (P = 0.028). Independent predictors of poor collaterals were presence of diabetes (P < 0.001), LAD occlusion (P = 0.001) and presentation with acute MI (P = 0.017).

CONCLUSION

Diabetes mellitus, occlusion of the LAD and presentation with acute MI are independently associated with poor distal vessel collateralization, whereas hyperlipidemia and use of CCBs are associated with rich collateralization. Factors determining coronary collateral formation may in turn influence outcomes after coronary artery occlusion.

Frequency distribution of collateral flow and factors influencing collateral channel development. Functional collateral channel measurement in 450 patients with coronary artery disease

OBJECTIVES

We sought to determine the pathogenetic predictors of collateral channels in a large cohort of patients with coronary artery disease (CAD).

BACKGROUND

The frequency distribution of collateral flow in patients with CAD is unknown. Only small qualitative studies have investigated which factors influence the development of collateral channels.

METHODS

In 450 patients with one- to three-vessel CAD undergoing percutaneous transluminal coronary angioplasty (PTCA), collateral flow was measured. A collateral flow index (CFI; no unit) expressing collateral flow relative to normal anterograde flow was determined using coronary wedge pressure or Doppler measurements through sensor-tipped PTCA guide wires. Frequency distribution analysis of CFI and univariate and multivariate analyses of 32 factors, including gender, age, patient history, cardiovascular risk factors, medication and coronary angiographic data, were performed.

RESULTS

Two-thirds of the patients had a CFI < 0.25 and approximately 40% of patients had a CFI < 0.15, but only approximately 10% of the patients had a recruitable CFI > or =0.4. By univariate analysis, the following were predictors of CFI > or =0.25: high levels of high-density lipoprotein cholesterol, the absence of previous non-Q-wave myocardial infarction, angina pectoris during an exercise test, angiographic indicators of severe CAD and the left circumflex or right coronary artery as the collateral-receiving vessel. Percent diameter stenosis of the lesion undergoing PTCA was the only independent predictor of a high CFI.

CONCLUSIONS

This large clinical study of patients with CAD in whom collateral flow was quantitatively assessed reveals that two-thirds of the patients do not have enough collateral flow to prevent myocardial ischemia during coronary occlusion, and that coronary lesion severity is the only independent pathogenetic variable related to collateral flow.