Collateral circulation as a marker of the presence of viable myocardium in patients with recent myocardial infarction

Comparison of the effect of uric acid/albumin ratio on coronary colleteral circulation with other inflammation-based markers in stable coronary artery disease patients

BACKGROUND

The Uric acid/Albumin ratio (UAR) has recently been identified as a prominent marker in cardiovascular diseases. In this study, we aimed to reveal the effect of UAR on coronary collateral circulation (CCC) in patients with stable coronary artery disease (CAD) patients by comparing it with conventional inflammation-based markers.

METHODS

In this study, 415 consecutive patients who underwent coronary angiography for stable angina pectoris and were found to have chronic total occlusion in at least one coronary artery were retrospectively included. The study population was divided into two groups as good CCC (Rentrop 2-3) and poor CCC (Rentrop 0-1) according to the Rentrop classification, and the groups were compared in terms of UAR and other traditional inflammation-based markers.

RESULTS

In the poor CCC group, C-reactive protein/albumin ratio (CAR), monocyte/high-density lipoprotein cholesterol ratio (MHR), neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), systemic immune-inflammation index (SII) and UAR were found to be significantly high (p < .05, for all). UAR negatively correlated with rentrop classification (r = -0.383, p < .001). In multivariate regression analysis, MHR, NLR, SII and UAR were determined as independent predictors for poor CCC (p < .05, for all). The ability of UAR to predict poor CCC was superior to uric acid and albumin alone (p < .0001, for both). In addition, UAR was found to be superior to other inflammation-based markers in predicting poor CCC (p < .005, for all).

CONCLUSION

UAR was identified as a strong and independent predictor of CCC. In this context, UAR may be a useful biomarker in the risk prediction of patients with stable CAD.

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.

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.

Exercise-induced negative U waves in precordial leads as a marker of viable myocardium in patients with recent anterior myocardial infarction

Patients with recent anterior myocardial infarction and a significant stenosis in the left anterior descending coronary artery were divided into two groups according to the presence (Group A, n=24) or absence (Group B, n=77) of negative U waves in the precordial leads during exercise stress test to compare the coronary arteriographic findings. Both total occlusion of the left anterior descending coronary artery (79% vs. 31%, P<0.01)) and good (index=2, 3) collateral circulation to the territory of this artery (92% vs. 36%, P<0.01) were observed more often in group A than in group B. In order to determine whether detection of exercise-induced negative U waves in precordial leads can predict the presence of viable myocardium, the 56 patients (20 of group A and 36 of group B) with total or subtotal occlusion of the left anterior descending coronary artery were studied further. The coronary arteriographic and exercise 201Tl scintigraphic findings were compared between the groups. Good collateral circulation to the territory of this artery was observed significantly (P<0.05) more often in group A (100%) than in group B (61%). Patients with multivessel disease were significantly (P<0.05) more prevalent in group A (70%) than in group B (33%). The incidence of a significant partial redistribution in the anteroseptal area in the 20Tl images 4 h after exercise was significantly (P<0.01) higher in group A (85%) than in group B (39%). In 29 patients with anterior Q-wave myocardial infarction and exercise-induced ST elevation in precordial leads, a significant 201Tl redistribution in the anteroseptal area was observed in 8 (80%) of 10 patients of group A in contrast to only 4 (21%, P<0.05) of 19 in group B. In the diagnosis of the viability associated with 201Tl redistribution in the anteroseptal area by the finding of exercise-induced negative U waves, the sensitivity was 67% and the specificity was 88% in these patients. We conclude that exercise-induced negative U waves in precordial leads are a convenient and specific marker for the presence of viable myocardium in patients with recent anterior myocardial infarction.

Angiogenesis and hypertension

BACKGROUND

The formation of new blood vessels is an important process in embryonic development and in physiological repair processes. Abnormalities in blood vessel growth have been associated with various pathologies.

HYPERTENSION AND IMPAIRED VASCULAR GROWTH

The basic observation underlying the hypothesis that essential hypertension is based on an impaired capacity for vascular growth is the nature of the structural alterations of microvascular beds in essential hypertension. Recent advances in understanding the molecular and cellular mechanisms of vascular growth suggest that the remodeling of individual vessels and vascular networks in hypertension may be a pathological variant of the formation of mature networks.

PATHOGENESIS OF IMPAIRED VASCULAR GROWTH

Genetic and fetal influences appear to have significant effects in determining impaired vascular development as an early cause of essential hypertension.

Assessment of myocardial viability: Dobutamine echocardiography and thallium-201 single-photon emission computed tomographic imaging predict the postoperative improvement of left ventricular function after bypass surgery

The aim of this study was to evaluate the usefulness of dobutamine echocardiography and quantitative thallium-201 single photon emission computed tomography myocardial scintigraphy with reinjection in the detection of viable myocardium in patients with coronary artery disease and reduced left ventricular function, which will improve after aortocoronary bypass surgery. Forty-eight patients (47 men, aged 61 +/- 6 years) with angiographically documented reduced left ventricular function (ejection fraction 35 +/- 14, 63% with chronic transmural myocardial infarction) were examined by dobutamine two-dimensional echocardiography (before and during low dosage), 201Tl, and gated radionuclide ventriculography before and 3 +/- 2 months after aortocoronary bypass surgery. Four of 55 areas classified viable before operation were revascularized inadequately and discarded. Global left ventricular ejection fraction at rest rose from 35% +/- 14% before operation to 40% +/- 13% (p < 0.05) after operation. Stress-induced perfusion defects involved 40% +/- 19% of the left ventricle circumference after stress and showed a significant reduction of size to 23% +/- 14% (p < 0.01) at rest, 4 hours later, and after reinjection. This value fell to 16% +/- 12% (p < 0.05) 3 months after aortocoronary bypass surgery. We conclude that both dobutamine echocardiography (sensitivity 95%, specificity 80%, positive predictive value 87%, negative predictive value 88%) and 201Tl studies (sensitivity 87%, specificity 98%, positive predictive value 97%, negative predictive value 93%) are suitable and comparable accurate methods for predicting improvement in systolic function 3 months after revascularization in a selected population with a high prevalence of viable but hypokinetic or akinetic myocardium.

Dipyridamole-induced angina pectoris during sestamibi stress test in patients with significant coronary artery disease: clinical, angiographic, and nuclear determinants

Intravenous dipyridamole induces angina pectoris (AP) in some patients with significant coronary artery disease (CAD). The aim of this prospective study was to identify the angiographic, nuclear, and clinical determinants. The authors examined 50 patients consecutively with significant CAD on coronary angiography. All antiischemic medications were stopped twenty-four hours (nitrates only 6 hours) before injection of dipyridamole (0.84 mg/kg). ECGs were taken before, during, and after this injection. The regional myocardial activity of Tc-99m-Sestamibi at rest and after dipyridamole injection was measured with single-photon emission computed tomography (SPECT). During dipyridamole injection 20 patients had AP, of whom 15 had ST segment depression on ECG (P < 0.001). The only significant difference on coronary angiography between patients with dipyridamole-induced AP and those without AP was the presence of collaterals (P < 0.05). In patients with AP and collaterals, ECG and SPECT changes were always noted in the collateralized territory. Subgroup analysis showed that patients without previous myocardial infarction (MI, n = 17, P < 0.05) or nontransmural MI (n = 17, P < 0.05) had a good correlation between collaterals and AP, whereas patients with a history of transmural MI (n = 16) did not. No further significant variables could be found as a predictor of AP after dipyridamole injection. These findings suggest that AP during dipyridamole stress test is due to ischemia, which is not related to the severity of CAD. Ischemia is probably due to coronary steal to the collateralized territory in patients without transmural MI. Dipyridamole-induced angina pectoris is predictive for collaterals and may indicate viability in patients with MI.

Myocardial revascularization with laser. Preliminary findings

BACKGROUND

We assessed the transmyocardial laser revascularization (TMLR) as sole therapy in patients with symptomatic coronary artery disease refractory to interventional or medical treatment.

METHODS AND RESULTS

Thirty-one patients were evaluated with positron emission tomography (PET), dobutamine echocardiography, 201Tl single-photon emission computed tomography (201Tl-SPECT), and multigated acquisition radionuclide ventriculography (MUGA). TMLR was performed in 21 patients who had demonstrable ischemia in viable myocardium. The mean Canadian Cardiovascular Society (CCS) angina class was 3.70 +/- 0.7 (4 patients with unstable angina). Untreated septal segments were used as controls. At 3 months, (n = 15 patients), the mean CCS angina class was to 2.43 +/- 0.9 (P < .05). On dobutamine echocardiography, the mean resting wall motion score index was improved by 16% in lased segments (P < .03 vs control), and mean LVEF at peak stress increased by 19% (P = NS vs baseline). On 201Tl-SPECT, perfusion of lased and nonlased segments did not change. On PET, the mean ratio of subendocardial to subepicardial perfusion (SEn/SEp) increased 14% over baseline (P < .001 vs control). At 6 months (n = 15 patients), the mean CCS angina class was 1.7 +/- 0.8 (P < .05). The mean resting wall motion score index was up by 13% in lased segments (P < .05 vs control). Resting LVEF was unchanged. Stress LVEF increased 21% (P = NS vs baseline). Myocardial perfusion remained unchanged by 201Tl-SPECT. On PET, 36% of the lased segments were better, and 25% were worse compared with baseline. The resting SEn/SEp by PET was up 21% (P < .001 vs control). All deaths (two perioperative and three late) occurred in patients with preoperative congestive heart failure. Two patients required repeat revascularization of new coronary lesions.

CONCLUSIONS

These results suggest that TMLR improves anginal status, relative endocardial perfusion, and cardiac function in patients who do not have preoperative congestive heart failure.

Myocardial viability: nuclear medicine versus stress echocardiography

The failure of nonimaging techniques in the identification of myocardial viability has promoted the clinical application of radioisotopic and echocardiographic methods. Unfortunately, none of these techniques provides, per se, a 100% predictive accuracy and only few studies have been based on the postoperative improvement in regional wall motion, the absolute "gold standard" for myocardial viability. The recent thallium-201 protocols (reinjection, late redistribution, rest studies) have provided nuclear cardiology with a cell membrane integrity image able to unmask viable myocardium in more than 85% of viable segments. Sestamibi has been introduced as a nonrecirculating flow tracer able to detect transient ischemia as well as thallium-201. Its main limit, a high sensitivity to intermediate reductions in coronary blood flow, determines a high incidence of false positive studies. Positron emission tomography allows the evaluation of regional myocardial blood flow and metabolism. The marker of viable myocardium is the mismatch between reduced blood flow and normal or increased uptake of 18-F fluorodeoxyglucose. This technique allows the detection of viable tissue in most segments showing improved postoperative function. In our experience, applying a multiparametric approach, rest thallium-201 scan, rest sestamibi, dobutamine, and dipyridamole echocardiography showed a sensitivity and a specificity of 86%, 75%, 82%, 75% and 92%, 84%, 92%, and 89%, respectively, in the detection of residual viability. The main advantages of thallium-201 are reproducibility and standardization; those of stress echo are low cost and availability. In patients with severely depressed ventricular function, positron emission tomography retains a primary role when compared to thallium-201 and stress echocardiography.

Myocardial viability in asynergic regions subtended by occluded coronary arteries: relation to the status of collateral flow in patients with chronic coronary artery disease

OBJECTIVES

This study aimed to determine whether angiographically visualized collateral vessels in patients with chronic coronary artery disease imply the presence of viable myocardium in asynergic regions subtended by completely occluded coronary arteries.

BACKGROUND

Patients with chronic coronary artery disease who are being considered for revascularization frequently exhibit angiographically visualized collateral vessels to completely occluded coronary arteries supplying severely asynergic myocardial regions. However, little is known about the relation between angiographic collateral flow and myocardial viability in these patients.

METHODS

We studied 42 patients with 78 completely occluded coronary arteries supplying asynergic territories. Angiographic collateral vessels were interpreted as absent (grade 1) in 14 patients, minimal (grade 2) in 27 and well developed (grade 3) in 37. Myocardial viability was determined with positron emission tomography using nitrogen-13 (N-13) ammonia and fluorine-18 (F-18) deoxyglucose for assessment of regional perfusion and glucose uptake, respectively. Positron emission tomographic patterns were interpreted as mismatch (perfusion defect with enhanced F-18 deoxyglucose uptake); transmural match (severe concordant reduction or absence of both perfusion and F-18 deoxyglucose uptake) or nontransmural match (mild to moderate concordant reduction of both perfusion and F-18 deoxyglucose uptake).

RESULTS

There was no significant correlation (p = 0.14) between the severity of perfusion deficit assessed by positron emission tomography and the collateral grade. The extent of mismatch was unrelated to either the presence or the magnitude of collateral vessels. Conversely, with increasing collateral vessels from grade 1 to 3, the total extent of positron emission tomographic match remained similar, whereas the ratio of transmural to nontransmural match decreased. Myocardial viability was usually present in severely hypokinetic regions (82%). It was lower in akinetic-dyskinetic regions (49%). Of the 64 regions with angiographic collateral vessels, 37 (58%) (95% confidence interval [CI] 46% to 70%) showed positron emission tomographic mismatch. In contrast, 7 (50%) of 14 (95% CI 24% to 76%) regions without collateral vessels on angiography exhibited positron emission tomographic mismatch. The presence of angiographically visualized collateral vessels was a sensitive (84%) but not specific (21%) marker of viability.

CONCLUSIONS

In patients with chronic coronary artery disease, angiographically visualized collateral vessels to asynergic myocardial regions subtended by occluded coronary arteries do not always imply the presence of viable myocardium, suggesting that revascularization may not always provide a functional benefit.

Relation between collateral channel filling and flow grade in recipient coronary arteries in patients with stable effort angina

OBJECTIVES

The purpose of the present study was to elucidate the relation between the extent of perfusion of the ischemia-related coronary artery and the degree of visualization of the collateral circulation to the ischemic area.

BACKGROUND

Because it is difficult to accurately assess coronary stenosis severity with standard angiographic techniques, the inclusion of flow grade in recipient coronary arteries would provide an additional perspective concerning the effect of the progression of atherosclerotic obstructive disease on the development of collateral circulation.

METHODS

The coronary arteriograms of 54 consecutive patients with chronic effort angina without prior myocardial infarction were examined. Patients were classified into four groups according to the extent of perfusion of the ischemia-related coronary artery (Thrombolysis in Myocardial Infarction [TIMI] grade 0 to 3). The degree of angiographically demonstrable collateral circulation was also classified into four grades (collateral index 0 to 3).

RESULTS

Eighteen patients had TIMI grade 0, 6 had grade 1, 13 had grade 2 and 17 had grade 3 perfusion. The collateral indexes of TIMI 0, 1, 2 and 3 groups were 2.7 +/- 0.7 (mean +/- SEM), 2.2 +/- 0.6, 1.2 +/- 1.1 and 0.4 +/- 0.9, respectively (p < 0.01 vs. TIMI 0, p < 0.05 vs. TIMI 1).

CONCLUSIONS

These findings indicate that all patients with chronic effort angina have the potential for collateral development as a result of coronary artery narrowing, and the functional state of well developed collateral vessels may be primarily determined by the pressure gradient across the collateral network.

Value of rest thallium-201/technetium-99m sestamibi scans and dobutamine echocardiography for detecting myocardial viability

The relation between radioisotopic and echocardiographic markers of myocardial viability and postrevascularization recovery of function is still to be defined. To this purpose, 14 patients (11 men, 3 women, aged 35 to 64 years, mean 54 +/- 7) with ventricular dysfunction were studied by a multiparametric approach. Each patient underwent, on separate days, rest thallium-201 and technetium-99m sestamibi scintigraphy, dobutamine echocardiography and coronary angiography. Coronary angiography was analyzed by a quantitative approach. Thallium uptake at rest was quantified from planar early (10-minute) and delayed (16-hour) thallium-201 images and expressed as a percentage of maximal activity in each projection using a 13-segment model. Sestamibi uptake was expressed in the same way. Dobutamine (up to 10 micrograms/kg/min) echocardiography was analyzed using a score index ranging from 1 (normokinesia) to 4 (dyskinesia) and a similar segmental model. Before revascularization 50 segments were grouped as normal (coronary stenosis < 50% and normal function, group 1); of the remaining 132 segments with > 50% coronary stenosis, 57 had normal wall motion (group 2) and 75 showed regional dyssynergies (group 3). Early and delayed thallium-201 regional percent activities did not differ in group 1 and in group 2 but were significantly less in group 3 segments. Sestamibi percent activity was more in group 1 and significantly reduced both in group 2 and 3 segments. Segments with improved wall motion after dobutamine had more early, delayed thallium-201 and sestamibi percent activities than unresponsive segments. Postrevascularization echocardiography was performed in all patients. Delayed thallium-201 scans and dobutamine echocardiography showed good sensitivity and specificity in detecting viable myocardium. (ABSTRACT TRUNCATED AT 250 WORDS)

Salvage of infarcted myocardium by angiogenic action of basic fibroblast growth factor

Coronary collateral vessels reduce damage to ischemic myocardium after coronary obstruction. Factors that stimulate collateral formation are expected to have ameliorating effects on myocardial infarction. In a canine experimental myocardial infarct model, intracoronary injection of basic fibroblast growth factor (bFGF) improved cardiac systolic function and reduced infarct size. Treatment with bFGF increased the number of arterioles and capillaries in the infarct. Thus, the angiogenic action of bFGF might lead to a reduction in infarct size. The application of bFGF might bring about a therapeutic modality for the salvage of infarcted myocardium.