Comparison of coronary collateral circulation in diabetic and nondiabetic patients suffering from coronary artery disease

Microvascular Complications Are Associated With Coronary Collateralization in Type 2 Diabetes and Chronic Occlusion

CONTEXT

Coronary collateral (CC) vessel development appears to be protective with regard to adverse cardiovascular events and survival in patients with coronary chronic total occlusion (CTO). The influence of type 2 diabetes mellitus (T2DM) on CC growth has been controversial. In particular, the role of diabetic microvascular complications (DMC) in determining coronary collateralization has not been elucidated.

OBJECTIVE

To investigate whether patients with DMC presented differences in CC vessel presence and grading as compared with patients without DMC.

METHODS

We conducted a single-center observational study, including consecutive T2DM patients, without previous cardiovascular history, undergoing a clinically indicated coronary angiography for chronic coronary syndrome (CCS) and angiographic evidence of at least one CTO. Patients were subdivided into 2 study groups according to the presence/absence of at least one DMC (neuropathy, nephropathy, or retinopathy). The presence and grading of angiographically visible CC development from the patent vessels to the occluded artery were assessed using the Rentrop classification.

RESULTS

We enrolled 157 patients (mean age 68.6 ± 9.8 years; 120 [76.4%] men). Patients with DMC (75 [47.8%]) had a higher prevalence of CC (69 [92.0%] vs 62 [75.6%], P = .006) and high-grade CC (55 [73.3%] vs 39 [47.6%], P = .001) compared with those without, and we found a positive association between the number of DMC in each patient and the prevalence of high-grade CC.

CONCLUSION

Among T2DM patients with coronary CTO, the presence of DMC was associated with a high CC development.

Cardiac magnetic resonance shows increased adverse ventricular remodeling in younger patients after ST-segment elevation myocardial infarction

OBJECTIVES

Young patients account for about half of ST-segment elevation myocardial infarction (STEMI) patients and display a unique risk profile compared with old patients. Whether these differences are related to disparities in ventricular remodeling remains unknown. This study aimed to evaluate age-related differences in ventricular remodeling after primary percutaneous coronary intervention (PPCI) for STEMI.

METHODS

In this observational study, consecutive STEMI patients between October 2019 and March 2021 who underwent serial cardiovascular magnetic resonance at index admission (3 to 7 days) and 3 months after PPCI were enrolled. Adverse remodeling was defined as ≥ 10% enlargement in left ventricular end-diastolic volume index (LVEDVi), while reverse remodeling was defined as a decrease in left ventricular end-systolic volume index (LVESVi) of more than 10%.

RESULTS

A total of 123 patients were included and grouped into young (< 60 years, n = 71) and old (≥ 60 years, n = 52) patients. Despite generally similar baseline structural and infarct characteristics, LVESVi significantly decreased only in old patients during follow-up (p = 0.034). The incidence of adverse remodeling was higher (49.3% vs 30.8%, p = 0.039), while the incidence of reverse remodeling was lower (31.0% vs 53.8%, p = 0.011) in young compared with old patients. Younger age (< 60 years) was associated with a significantly higher risk of adverse remodeling (adjusted OR 3.51, 95% CI 1.41-8.74, p = 0.007) and lower incidence of reverse remodeling (adjusted OR 0.42, 95% CI 0.18-0.97, p = 0.046).

CONCLUSIONS

In STEMI patients undergoing PPCI, young patients are at a higher risk of adverse remodeling and less probably develop reverse remodeling than old patients. Equal or more attention should be paid to young patients with STEMI compared with their older counterparts.

KEY POINTS

• In STEMI patients undergoing PPCI, young patients displayed unfavorable remodeling compared with old patients. • Young patients are at a higher risk of adverse remodeling and less probably develop reverse remodeling than old patients. • Equal or more attention should be paid to young patients compared with their older counterparts.

Occurrence of Coronary Collaterals in Acute Myocardial Infarction and Sleep Apnea

Background In patients with acute myocardial infarction (MI), cardioprotective effects of obstructive sleep apnea are postulated on account of hypoxemic preconditioning. The aim of this single-center substudy was to investigate a potential association between obstructive sleep apnea and the presence of coronary collaterals in patients with first-time acute MI who have been enrolled in an ongoing, multicenter clinical trial. Methods and Results In TEAM-ASV I (Treatment of Sleep Apnea Early After Myocardial Infarction With Adaptive Servo-Ventilation Trial; NCT02093377) patients with first acute MI who received a coronary angiogram within 24 hours after onset of symptoms underwent polygraphy within the first 3 days. Coronary collaterals were classified visually by assigning a Cohen-Rentrop Score (CRS) ranging between 0 (no collaterals) and 3. Of 94 analyzed patients, 14% had significant coronary collaterals with a CRS ≥2. Apnea-Hypopnea Index (AHI) score was significantly higher in patients with CRS ≥2 compared with those with CRS <2 (31/hour [11-54] versus 13/hour [4-27]; P=0.032). A multivariable regression model revealed a significant association between obstructive AHI and CRS ≥2 that was independent of age, sex, body mass index, and culprit lesion left anterior descending artery (odds ratio [OR], 1.06; 95% CI, 1.01-1.12; P=0.023), but no significant association between coronary collaterals and central AHI (OR, 1.02; 95% CI, 0.97-1.08; P=0.443). Conclusions Patients with first-time acute MI had more extensive coronary collateralization with an increased AHI or rather an increased obstructive AHI. This finding supports the hypothesis that obstructive sleep apnea exerts potential cardioprotective effects, in addition to its known deleterious effects, in patients with acute MI. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02093377.

Spontaneous coronary collateral recruitment in patients with recurrent ST elevation myocardial infarction (STEMI)

The spontaneous recruitment of acute coronary collaterals in the setting of an ST elevation myocardial infarction (STEMI) is seen frequently in those patients undergoing primary percutaneous coronary intervention (pPCI) and is associated with improved clinical outcomes. However, it is unknown whether in patients who present with a recurrent STEMI, the degree of collateral recruitment remains the same as in the index procedure. We reviewed all patients presenting to our tertiary centre with a STEMI undergoing primary or rescue percutaneous coronary intervention (PCI) from July 2010 until December 2018. We identified patients who presented with a recurrent STEMI following their index procedure. We defined patients with poor collateral recruitment as Rentrop grade 0 or 1, whilst patients with robust collateral recruitment as Rentrop grade 2 or 3. Of the 1795 patients who were identified, there were 27 cases in 25 patients who presented with a repeat STEMI following their index procedure. The median time between cases was 12.8 days (IQR 2.3-589.5 days). Compared to the index case, there was no statistically significant difference in the degree of collateral recruitment in recurrent presentations (Z = - 0.378, p = 0.70). In those patients presenting more than 6 months following the index procedure, the median time between cases was 654.5 days (IQR 479.5-1151.9). There was no difference in the degree of collateral recruitment in recurrent presentations (Z = 0.000, p = 1.0). Cases which had poorer collateral recruitment in recurrent presentations were less likely to be current smokers (0% vs 50%, p < 0.001) and less likely to have diabetes (0% vs 27.3%, p < 0.05) The recruitment of spontaneous coronary collaterals remains constant in recurrent STEMI presentations suggesting an innate biological process rather than merely a manifestation of alteration of haemodynamic blood flow. Further investigations to identify these processes is required.

Potassium Disturbances and Risk of Ventricular Fibrillation Among Patients With ST-Segment-Elevation Myocardial Infarction

Background Potassium disturbances per se increase the risk of ventricular fibrillation (VF). Whether potassium disturbances in the acute phase of ST-segment-elevation myocardial infarction (STEMI) are associated with VF before primary percutaneous coronary intervention (PPCI) is uncertain. Methods and Results All consecutive STEMI patients were identified in the Eastern Danish Heart Registry from 1999 to 2016. Comorbidities and medication use were assessed from Danish nationwide registries. Potassium levels were collected immediately before PPCI start. Multivariate logistic models were performed to determine the association between potassium and VF. The main analysis included 8624 STEMI patients of whom 822 (9.5%) had VF before PPCI. Compared with 6693 (77.6%) patients with normokalemia (3.5-5.0 mmol/L), 1797 (20.8%) patients with hypokalemia (<3.5 mmol/L) were often women with fewer comorbidities, whereas 134 (1.6%) patients with hyperkalemia (>5.0 mmol/L) were older with more comorbidities. After adjustment, patients with hypokalemia and hyperkalemia had a higher risk of VF before PPCI (odds ratio 1.90, 95% CI 1.57-2.30, P<0.001) and (odds ratio 3.36, 95% CI 1.95-5.77, P<0.001) compared with normokalemia, respectively. Since the association may reflect a post-resuscitation phenomenon, a sensitivity analysis was performed including 7929 STEMI patients without VF before PPCI of whom 127 (1.6%) had VF during PPCI. Compared with normokalemia, patients with hypokalemia had a significant association with VF during PPCI (odds ratio 1.68, 95% CI 1.01-2.77, P=0.045) after adjustment. Conclusions Hypokalemia and hyperkalemia are associated with increased risk of VF before PPCI during STEMI. For hypokalemia, the association may be independent of the measurement of potassium before or after VF.

Decreased National Rate of below the Knee Amputation in Patients with Popliteal Artery Injury

BACKGROUND

Popliteal arterial injury (PAI) is the second most common infrainguinal arterial injury after femoral artery injury with an incidence < 0.2%. A 2003 analysis of the National Trauma Data Bank (NTDB) reported a below the knee amputation (BKA) rate of 7.1% in patients with PAI as well as higher risk in those with an associated fracture or nerve injury. Given advances in vascular surgical techniques, improved multidisciplinary care, and expeditious diagnosis with computed tomography angiography, we hypothesized that the national rate of BKA in patients with PAI has decreased and sought to identify risk factors for BKA in patients with PAI.

METHODS

A retrospective analysis of the NTDB was performed from 2007 to 2015. Patients ≥15 years of age with PAI were included and grouped by mechanism of injury (blunt versus penetrating). Interfacility transfers were excluded. The primary outcome of interest was BKA. Univariable and multivariable analyses were performed to identify predictors of BKA in patients with PAI.

RESULTS

From 4,385,698 patients, 5,143 were identified with PAI (<0.2%) with most involved in a blunt mechanism (56.8%). The overall limb loss rate was 5.1% (decreased from 7.1% in 2003, P = 0.0037). After adjusting for covariates, a blunt mechanism (odds ratio [OR] = 3.53, confidence intervals [CI] = 2.49-5.01, P < 0.001) and open proximal tibia/fibula fracture or dislocation (OR = 2.71, CI = 2.08-3.54, P < 0.001) were independent risk factors for BKA in patients with PAI. A combined popliteal vein injury (PVI) did not increase the risk for BKA (P = 0.64).

CONCLUSIONS

The national rate of limb loss in trauma patients with PAI has decreased from 7.1 to 5.1%. A blunt mechanism of injury as well as proximal open tibia/fibula fracture or dislocation continue to be the independent risk factors for BKA. Confirming a previous report, we found a combined PVI not to be associated with higher risk for BKA. Future prospective research to determine other possible contributing factors such as intraoperative hemodynamics and utilization of vascular shunt and fasciotomy appears warranted.

Severity of coronary artery disease in type 2 diabetes mellitus: Does the timing matter?

AIM

The aim of our study was to compare the angiographic changes in 53 nondiabetic patients, 54 type 2 diabetic patients of less than 5 years of duration, 41 patients with 5-10 years of diabetes, and 27 with more than 10 years of diabetic duration.

METHODS

In this cross-sectional study, 175 patients, who underwent coronary angiogram for the evaluation of the coronary artery disease (CAD), were recruited. Based on the angiographic findings, syntax score, vessel score, and coronary collaterals grading were analyzed. The biochemical analysis was done by using the auto analyzer.

RESULTS

A significant increase in the mean syntax score (p=0.019), vessel score (p=0.007), and coronary collateral grade (p=0.008) was observed in the patients with 5-10 years of diabetes when compared to those with less than 5 years of diabetic duration. There was no significant difference in the mean syntax score (p=0.979), vessel score (p=0.299), and collateral grade (p=0.842) between the patients with 5-10 years and more than 10 years of diabetes. The difference in the mean syntax score (p=0.791), vessel score (p=0.098), and collateral grade (p=0.661) between the nondiabetic and the patients with less than 5 years of diabetes was not significant.

CONCLUSION

A significant structural change in the coronary arteries was found among the patients with 5-10 years of diabetes.

The association of plasma vitamin A and E levels with coronary collateral circulation

OBJECTIVE

To investigate if plasma levels of vitamin A and E have an association with coronary collateral development.

METHODS

A total of 189 patients who underwent coronary angiography and had total occlusion in at least one major epicardial coronary artery were enrolled in the study. To classify coronary collateral circulation (CCC), the Rentrop scoring system was used. Patients were classified as having poor CCC (Rentrop grades 0-1) or good CCC (Rentrop grades 2-3), and all patients were also screened for hypertension, hypercholesterolemia, diabetes, and smoking history.

RESULTS

There were no differences in plasma vitamin A and E levels between the two groups (vitamin A: 2.37 ± 0.65 vs. 2.35 ± 0.78, p = 0.253; vitamin E: 47.1 ± 12.8 vs. 44.6 ± 15.1, p = 0.082), and plasma vitamin A and E levels were not associated with CCC. Serum high-sensitivity C-reactive protein (hs-CRP) levels were significantly higher in patients with poor CCC (4.68 ± 2.52 vs. 3.89 ± 1.78, p = 0.001). The higher frequency of diabetes and higher serum hs-CRP levels were found to be an independent predictor for poor CCC (odds ratio = 2.44, p = 0.006; odds ratio = 1.24, p = 0.007, respectively). And a higher frequency of total occluded RCA was found to be a positive predictor for good CCC (odds ratio = 2.36, p = 0.06) in a multivariate logistic regression analysis.

CONCLUSIONS

We found that serum hs-CRP levels, presence of diabetes, and total occlusion of RCA have an effect on coronary collateral development. We found no correlation between plasma vitamin A and E levels and CCC.

Coronary Collateral Circulation and Cardiovascular Risk Factors: Is There a Paradox?

We sought to determine the association of major cardiovascular risk factors and other comorbidities with the presence or absence of coronary collateral (CC) circulation. All electronic medical records from 2010 to 2011 were retrospectively reviewed. A total of 563 patients were divided into 2 groups: CC present (180) and CC absent (383). Smoking (P = .012, odds ratio [OR] 1.58), hypercholesterolemia (P = .001, OR 2.21), and hypertension (P = .034, OR 1.75) were associated with the presence of CC. Increasing body mass index (BMI, P = .001) and decreasing estimated glomerular filtration rate (eGFR, P = .042) were associated with the absence of CC. On multivariable linear regression analysis, hypercholesterolemia (P = .001, OR 2.28), BMI (P = .012, OR 0.77), and eGFR (P = .001, OR 0.70) were found to be independently associated with CC. Our findings will help predict patient populations more likely to have presence or absence of CC circulation.

The relationship between diastolic pressure and coronary collateral circulation in patients with stable angina pectoris and chronic total occlusion

BACKGROUND

The most important biomechanical source of activation of the coronary collateral circulation (CCC) is increased tangential fluid shear stress at the arterial endothelial surface. The coronary circulation is unique in that most coronary blood flow occurs in diastole. Consequently, the diastolic blood pressure (DBP) may influence the tangential fluid shear stress on the arterial endothelial surface in diastole, therebyaffecting development of the CCC.

METHODS

To investigate this, we conducted a study of 222 patients with stable angina pectoris and chronic total occlusion of coronary arteries. All of the patients had no history of coronary artery interventional therapy, coronary artery bypass surgery, cardiomyopathy, or congenital heart disease. The extent of the collateral vasculature of the area perfused by the artery affected by chronic total occlusion was graded as poor or well-developed according to Rentrop's classification.

RESULTS

Univariate analysis showed a significant difference between the study subgroup with poorly developed collaterals and that with well-developed collaterals in terms of high diastolic blood pressure (DBP) and mean DBP. Multivariate analysis revealed high DBP as the only independent positive predictor of a well-developed collateral circulation.

CONCLUSIONS

High DBP is positively related to a well-developed CCC. Differences in development of the CCC may be one of the pathophysiologic mechanisms responsible for the J-curve phenomenon in the relationship between DBP and cardiovascular risk.

Aberrant angiogenesis: The gateway to diabetic complications

Diabetes Mellitus is a metabolic cum vascular syndrome with resultant abnormalities in both micro- and macrovasculature. The adverse long-term effects of diabetes mellitus have been described to involve many organ systems. Apart from hyperglycemia, abnormalities of angiogenesis may cause or contribute toward many of the clinical manifestations of diabetes. These are implicated in the pathogenesis of vascular abnormalities of the retina, kidneys, and fetus, impaired wound healing, increased risk of rejection of transplanted organs, and impaired formation of coronary collaterals. A perplexing feature of the aberrant angiogenesis is that excessive and insufficient angiogenesis can occur in different organs in the same individual. The current article hereby reviews the molecular mechanisms including abnormalities in growth factors, cytokines, and metabolic derangements, clinical implications, and therapeutic options of dealing with abnormal angiogenesis in diabetes.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.

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.

Cardiovascular risk factors and collateral artery formation

Arterial lumen narrowing and vascular occlusion is the actual cause of morbidity and mortality in atherosclerotic disease. Collateral artery formation (arteriogenesis) refers to an active remodelling of non-functional vascular anastomoses to functional collateral arteries, capable to bypass the site of obstruction and preserve the tissue that is jeopardized by ischaemia. Hemodynamic forces such as shear stress and wall stress play a pivotal role in collateral artery formation, accompanied by the expression of various cytokines and invasion of circulating leucocytes. Arteriogenesis hence represents an important compensatory mechanism for atherosclerotic vessel occlusion. As arteriogenesis mostly occurs when lumen narrowing by atherosclerotic plaques takes place, presence of cardiovascular risk factors (e.g. hypertension, hypercholesterolaemia and diabetes) is highly likely. Risk factors for atherosclerotic disease affect collateral artery growth directly and indirectly by altering hemodynamic forces or influencing cellular function and proliferation. Adequate collateralization varies significantly among atherosclerotic patients, some profit from the presence of extensive collateral networks, whereas others do not. Cardiovascular risk factors could increase the risk of adverse cardiovascular events in certain patients because of the reduced protection through an alternative vascular network. Likewise, drugs primarily thought to control cardiovascular risk factors might contribute or counteract collateral artery growth. This review summarizes current knowledge on the influence of cardiovascular risk factors and the effects of cardiovascular medication on the development of collateral vessels in experimental and clinical studies.

Metabolic syndrome and collateral vessel formation in patients with documented occluded coronary arteries: association with hyperglycaemia, insulin-resistance, adiponectin and plasminogen activator inhibitor-1

Aims

The metabolic syndrome (MS) is associated with an increased cardiovascular risk. Patients with the MS have endothelial dysfunction, decreased circulating adiponectin, and a high expression of angiogenic inhibitors such as plasminogen activator inhibitor-1 (PAI-1). We hypothesized that such patients, in the event of a coronary occlusion, might exhibit a less developed collateral circulation.

Methods and results

Three hundred and eighty-seven consecutive patients with at least one coronary occlusion of a major coronary vessel at diagnostic angiography were prospectively enrolled. Collateral development was graded with validated angiographic methods. The MS was defined according to the ATP-III definition. Fasting glucose, adiponectin, insulin concentrations, and PAI-1 were measured at the time of angiography. MS was associated with less developed collateral vessels (P = 0.005). In multivariable analysis adjusting for potential confounding factors including the duration of coronary occlusion (P = 0.0001), fasting glycaemia (P = 0.0007), low adiponectin concentration (P = 0.01), insulin-resistance (HOMA-IR; P = 0.01), high circulating PAI-1 concentration (P = 0.01), and hypertension (P = 0.008) were independently associated with poor coronary collateral vessel development.

Conclusion

This study shows that in patients with coronary occlusion, collateral circulation is impaired in patients with the MS. This association is partly related to fasting glycaemia and to key parameters linked to insulin resistance.

Hypoxic regulation of VEGF, HIF-1(alpha) in coronary collaterals development

BACKGROUND

The interindividual variability for the development of collaterals in coronary artery disease is dependent on the hypoxic induction level of VEGF. To determine whether the hypoxic induction of VEGF is controlled by the transcription of HIF-1 (alpha), the VEGF and HIF-1 (alpha) m-RNA levels were correlated to hypoxia in monocytes harvested from patients with coronary artery disease.

METHODS

The collateral scoring system used was modified from the TIMI system. The mononuclear cell layer of the patients' blood was cultured in hypoxia (1% O2, 5% CO2, 94%N2) and normoxia (5% CO2, 95% room air) for 17 hours. The VEGF and HIF-1 (alpha) mRNA levels were measured using a RT-PCR technique. We calculated the fold inductionsof VEGF, HIF-1 (alpha) mRNA with hypoxia by dividing the hypoxic and the normoxic values.

RESULTS

We found significantly higher hypoxic inductions of VEGF m-RNA in patients with collaterals compared to patients with no collaterals. However, there was no differencein the hypoxic inductions of HIF-1 (alpha) between the two groups (VEGF m-RNA mean fold inductions 3.71 +/- 3.30 versus 1.65 +/- 0.62, p=0.012, HIF-1(alpha) mRNA 1.42 +/- 0.58 versus 1.20 +/- 0.39, p=0.165).

CONCLUSIONS

We concluded that the interindividual variability in the hypoxic inductions of VEGF m-RNA in monocytes in patients is not controlled by the transcriptional levels of HIF-1 (alpha) with hypoxia. These findings suggest that a mechanism such as the post-transcriptional modification of HIF-1(alpha) is involved in the hypoxic inductions of VEGF.

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.

Influence of diabetes mellitus on coronary collateral flow: an answer to an old controversy

OBJECTIVES

To determine the influence of diabetes mellitus on coronary collateral flow by accurate means of collateral flow measurement in a large population with variable degrees of coronary artery disease.

METHODS

200 patients (mean (SD) age 64 (9) years; 100 diabetic and 100 non-diabetic) were enrolled in the study. Coronary collateral flow was assessed in 174 stenotic and in 26 angiographically normal vessels with a pressure guidewire (n = 131), Doppler guidewire (n = 36), or both (n = 33) to calculate pressure or flow velocity derived collateral flow index (CFI). Diabetic patients were perfectly matched with a non-diabetic control group for clinical, haemodynamic, and angiographic parameters.

RESULTS

CFI did not differ between the diabetic and the non-diabetic patients (0.21 (0.12) v 0.19 (0.13), not significant). Likewise, CFI did not differ when only angiographically normal vessels (0.20 (0.09) v 0.15 (0.08), not significant) or chronic total coronary occlusions (0.30 (0.14) v 0.30 (0.17), not significant) were compared. Fewer patients in the diabetic group tended to have angina pectoris during the one minute vessel occlusion (60 diabetic v 69 non-diabetic patients, p = 0.15).

CONCLUSION

Quantitatively measured coronary CFI did not differ between diabetic and non-diabetic patients with stable coronary artery disease.

Presence of the metabolic syndrome does not impair coronary collateral vessel formation in patients with documented coronary artery disease

OBJECTIVE

The metabolic syndrome confers an increased risk for cardiovascular morbidity and mortality. The presence of coronary collaterals may have beneficial effects during myocardial ischemia and may improve cardiovascular outcome in patients with coronary artery disease. Impaired collateral formation could be one of the reasons for the increased cardiovascular risk in patients with the metabolic syndrome. The aim of the present study was to determine the influence of the metabolic syndrome and insulin resistance on the presence of coronary collaterals.

RESEARCH DESIGNS AND METHODS

We conducted a cross-sectional study in 227 patients referred for elective percutaneous transluminal coronary angioplasty to the University Medical Centre Utrecht. The metabolic syndrome was diagnosed according to Adult Treatment Panel III, and homeostasis model assessment of insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) were used to quantify insulin resistance. Coronary collaterals were graded with Rentrop's classification. Rentrop grade >/=1 indicated the presence of collaterals. Results were adjusted for age, sex, and severity of coronary artery disease.

RESULTS

A total of 103 patients (45%) were diagnosed with the metabolic syndrome. There was no association between the metabolic syndrome and the presence of coronary collateral formation (odds ratio [OR] 1.2 [95% CI 0.7-2.0]). Also, the degree of insulin resistance was not related to the presence of coronary collaterals. The OR for HOMA-IR (highest versus lowest tertile) was 0.7 (0.3-1.5) and for QUICKI (lowest versus highest tertile) 0.8 (0.4-1.6).

CONCLUSIONS

The metabolic syndrome and insulin resistance are not related to the presence of coronary collaterals in patients with documented coronary artery disease.

Recent insights into human coronary collateral development

Enhancement of coronary collateral function is an intriguing approach to the preservation of ischaemic myocardium. Coronary collateral development consists of collateral recruitment and collateral growth. Collateral growth encompasses proliferation of capillaries in the ischaemic area (angiogenesis) and maturation of pre-existing collateral vessels (arteriogenesis), with the latter being more relevant in humans. Therefore, treatment intended directly for arteriogenesis of collateral vessels appears to be more effective. Promotion of coronary collateral growth has many attractive features, particularly in patients with angina who are not indicated for percutaneous coronary intervention or coronary artery bypass grafting surgery. A complete elucidation of the remaining practical and mechanistic questions of arteriogenesis may lead to a new remedy capable of developing collateral vessels more effectively.

Impaired Angiogenesis in the Aged

The process of angiogenesis, during which new blood vessels are formed, is impaired during aging. This Perspective describes many of the myriad components of the angiogenic response that are altered with age. In addition, the impact of impaired angiogenesis on wound healing, vascular disease, and cancer in the aged is discussed.

Abnormal angiogenesis in diabetes mellitus

The adverse long-term effects of diabetes mellitus have been well described and involve many organ systems. While diabetes management has largely focused on control of hyperglycemia, the presence of abnormalities of angiogenesis may cause or contribute to many of the clinical manifestations of diabetes. When compared with non-diabetic subjects, diabetics demonstrate vascular abnormalities of the retina, kidneys, and fetus. Diabetics have impaired wound healing, increased risk of rejection of transplanted organs, and impaired formation of coronary collaterals. In each of these conditions, and possibly in diabetic neuropathy as well, abnormalities of angiogenesis can be implicated in the pathogenesis. A perplexing feature of the aberrant angiogenesis is that excessive and insufficient angiogenesis can occur in different organs in the same individual. In this review, the clinical features, molecular mechanisms, and potential therapeutic options of abnormal angiogenesis in diabetes will be reviewed.

Haptoglobin phenotype and coronary artery collaterals in diabetic patients

Cross-cultural epidemiological studies of incident cardiovascular disease in the diabetic patient have demonstrated marked differences in susceptibility that may be due to a genetic factor. The coronary artery collateral circulation is the chief determinant of the size of a myocardial infarction and is highly variable between patients. We recently demonstrated that a functional allelic polymorphism in the haptoglobin gene is correlated with a number of diabetic vascular complications. We thus set out to test the hypothesis that haptoglobin phenotype is associated with collateral formation in the setting of diabetes. We correlated the Hp phenotype (1-1, 2-1 or 2-2) as determined by polyacrylamide electrophoresis with the presence or absence of coronary collaterals by angiography in 82 consecutive diabetic patients and 138 consecutive non-diabetic patients undergoing catheterization. We found that diabetic patients with the Hp phenotype 2-1 were more likely to have collaterals than diabetic patients with the Hp phenotype 2-2 (P=0.007). There was no correlation between Hp phenotypes and the presence of collaterals in non-diabetic patients. Hp phenotype thus appears to be associated with the development of the coronary collateral circulation in diabetic patients with coronary artery disease. Haptoglobin 2-2 may predispose to less compensation for coronary artery stenosis in diabetic patients, and thereby portend a worse prognosis.

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.

Aging-associated changes in vascular activity: a potential link to geriatric cardiovascular disease

Ischemic cardiovascular disease is a common cause of morbidity and mortality in the United States population over the age of 65. Prior clinical studies have demonstrated that the severity of cardiovascular pathophysiology is increased in older individuals. Both in vitro and in vivo experimental studies have shown that age-associated clinical events parallel changes in vascular function. Aging is associated with systemic as well as cardiac alterations in three basic vascular regulatory functions: vascular tone, hemostasis, and vascular repair/angiogenesis. This article reviews the molecular and cellular events that may contribute to senescent cardiac pathology. Indeed, a better understanding of the biology of aging-associated vascular dysfunction is fundamental for the development of therapeutics targeted for the treatment of cardiovascular disease in older individuals.