Functional significance of recruitable collaterals during temporary coronary occlusion evaluated by 99mTc-sestamibi single-photon emission computerized tomography

The Never-ending Story: Assessing coronary collateral circulation with myocardial perfusion imaging

The role of coronary collateral circulation has been thoroughly studied, and myocardial perfusion imaging has been a frequently employed method. Even angiographic invisible collaterals can support some degree of tracer uptake, but the clinical role of this evaluation is still uncertain, and this remains the main issue that should be clarified.

Relationship of mean platelet volume to lymphocyte ratio and coronary collateral circulation in patients with stable angina pectoris

BACKGROUND

In patients with coronary artery disease, coronary collateral circulation (CCC) develops as an adaptation to ischemia and contributes toward reduction of cardiovascular events. Recently, the mean platelet volume-to-lymphocyte ratio (MPVLR) has emerged as a novel and readily available marker of inflammation and thrombosis. This study aimed to investigate the relationship between MPVLR and development of CCC.

PATIENTS AND METHODS

A total of 332 patients with stable angina pectoris undergoing coronary arteriography were enrolled and divided on the basis of the development of CCC into two groups: group with adequate CCC (n=243) and group with impaired CCC (n=89). Routine complete blood count parameters and high-sensitivity C-reactive protein (hsCRP) were measured before coronary arteriography.

RESULTS

Both MPVLR and hsCRP levels were higher in the impaired CCC group (P<0.001 and P=0.007, respectively). Multivariate logistic regression analysis indicated that MPVLR was associated independently with impaired CCC [odds ratio (OR): 1.706, 95% confidence interval (CI): 1.328-2.192, P<0.001]. In addition to MPVLR, hsCRP (OR: 1.144, P=0.030) and fasting blood glucose (OR: 1.007, P=0.049) were also associated independently with impaired CCC. In receiver operating characteristics curve analysis, an optimal cut-off point for MPVLR (4.47) was found to predict the presence of good CCC with a sensitivity of 75.3% and a specificity of 71.2% (P<0001).

CONCLUSION

Our findings suggest that measurement of MPVLR may predict the development of CCC in patients with stable coronary artery disease. An increased MPVLR is associated independently with impaired CCC in these patients.

Endocan Levels and Coronary Collateral Circulation in Stable Angina Pectoris: A Pilot Study

We investigated the relationship between endocan (a marker of systemic inflammation) and the development of coronary collateral circulation (CCC) as evaluated by coronary angiography in patients with chronic stable angina pectoris. A total of 90 patients (32 poor CCC and 58 good CCC) were included in this study. Endocan levels were determined using a commercially available sandwich enzyme-linked immunosorbent assay kit with high sensitivity and specificity for detection of human endocan. In multivariate logistic regression analysis, low endocan levels were independently associated with good CCC ( P < .001). Moreover, low high-sensitivity C-reactive protein levels were also independently associated with good CCC ( P = .020). We found an optimal cutoff point for endocan of 1.7 ng/mL; it predicted the presence of good CCC with a sensitivity of 72.4% and specificity of 65.6% ( P < .001). The results of the present study suggest that measurement of endocan level may help clinicians to predict the development of CCC in patients with stable coronary artery disease.

The relation of platelet-lymphocyte ratio and coronary collateral circulation in patients with stable angina pectoris and chronic total occlusion

OBJECTIVES

We aimed to investigate the relationship between the platelet-lymphocyte ratio (PLR) and coronary collateral circulation (CCC) in patients with stable angina pectoris (SAP) and chronic total occlusion (CTO).

METHODS

A total of 294 patients with both SAP and CTO were classified according to their Rentrop collateral grades as either poor (Rentrop grades/0-1) or good (Rentrop grades/2-3).

RESULTS

The PLR values were significantly higher in patients with poor CCC than in those with good CCC (156.8 + 30.7 vs 132.1 + 24.4, P < 0.001). In regression analysis, PLR (unit = 10) [odds ratio 1.48, 95% confidence interval (CI) 1.33 -1.65; P < 0.001] and high-sensitivity C-reactive protein were found to be the independent predictors of poor CCC. In receiver operator characteristic curve analysis, optimal cut-off value of PLR to predict poor CCC was found as 138.1, with 76% sensitivity and 65% specificity.

CONCLUSION

PLR may be an important, simple, and cost effective tool predicting the degree of collateralization in patients with SAP and CTO.

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.

High incidence of TIMI flow 0 to I in patients with ST-elevation myocardial infarction without electrocardiographic lytic criteria

BACKGROUND

Most patients with ST-elevation myocardial infarction fulfilling ST-segment elevation (STE) lytic criteria present an occluded culprit artery but the occlusion rate in those with minimal STE (minSTE) not fulfilling lytic criteria is unknown.

METHODS

In 63 patients with minSTE (mean STE:1.2 +/- 0.6 mm) and 149 with lytic STE criteria (lyticSTE, 4.8 +/- 3.1 mm), an emergency coronary angiography was performed, serial creatine kinase-MB was determined, and ejection fraction was measured by 2-dimensional echocardiography.

RESULTS

The 2 groups showed similar time from pain onset to electrocardiogram (minSTE 196 +/- 199 vs lyticSTE, 176 +/- 172 min, P = .444), and although time to catheterization was longer in patients with minSTE (426 +/- 314 vs 253 +/- 239 min, P < .001), the rate of TIMI flow 0 to I (88% vs 81%, P = .21) was similar and percutaneous coronary intervention was performed in >80% of patients from the 2 groups. Moreover, patients with minSTE had higher rate of collateral circulation (27% vs 13%, P = .013), lower rate of Q waves (44% vs 60%, P = .041), lower creatine kinase-MB (202 +/- 150 vs 335 +/- 280, microg/L, P < .001), higher ejection fraction (54% +/- 9% vs 49% +/- 12%, P = .004), and lower mortality (0% vs 7.4%, P = .036).

CONCLUSIONS

ST-elevation myocardial infarction patients with minSTE present a high prevalence of TIMI flow 0 to I similar to those meeting lyticSTE suggesting an identical underlying mechanism and the potential to benefit from primary angioplasty.

Collateral function in patients with coronary occlusion evaluated by 201 thallium scintigraphy

The present study evaluated the impact of the angiographically documented collaterals on regional myocardial perfusion measured by 201thallium scintigraphy in patients with a chronic total occlusion. The study included 60 patients with chronic total occlusion who underwent rest-stress myocardial perfusion scintigraphy and coronary angiography. All patients had angiographic evidence of coronary collaterals. Patients were divided into two groups: group one had well-developed coronary collateral vessels (n=35) and group II had poor coronary collateral development (n=25). Patients with chronic total occlusion had severe and extensive stress-induced myocardial perfusion defects regardless of the grade of angiographic coronary collaterals. The perfusion defects in the group with good collaterals were predominantly reversible, suggesting that coronary collaterals preserved myocardial viability in the regions subtended by a total coronary occlusion. A significant correlation between good collaterals with complete protection and poor collaterals with no protection was noted. Our results demonstrate a protective effect of collaterals on myocardial perfusion during coronary occlusion. The effective angiographic collaterals may prevent resting regional wall motion abnormalities but do not appear to protect against stress-induced perfusion defect.

The impact of placing multiple grafts to each myocardial territory on long-term survival after coronary artery bypass grafting

OBJECTIVE

Incomplete myocardial revascularization decreases survival for patients undergoing coronary artery bypass grafting. The effects of constructing multiple grafts to each major diseased artery territory are unknown. We aimed to determine the impact on long-term survival after coronary artery bypass grafting of placing multiple grafts to each myocardial territory.

METHODS

We reviewed data from 1129 consecutive patients who underwent coronary artery bypass grafting at our institution between 1997 and 2007 and compared outcomes between patients who received multiple grafts to each major diseased artery territory (n = 549) with those of patients who received single grafts to each territory (n = 580). We assessed long-term survival with Kaplan-Meier curves generated by log-rank tests, adjusting for confounding factors with Cox proportional hazards regression analysis.

RESULTS

Patients who received multiple grafts to each major diseased artery territory had longer cardiopulmonary bypass and aortic crossclamp times than patients who received single grafts per territory. Patient groups had similar early outcomes, including 30-day mortalities (1.3% vs 1.4%, P > .999) and incidences of major adverse cardiac events (2.9% vs 2.2%, P = .57). Cox regression 10-year survival curves were also similar between groups (adjusted hazard ratio 0.94, 95% confidence interval 0.67-1.34, P = .74).

CONCLUSION

Patients who received multiple grafts to each major diseased artery territory had early outcomes similar to those who received single grafts per territory. Constructing multiple grafts to each major diseased artery territory increases operative time and does not improve long-term survival.

Extent of myocardial ischemia during coronary occlusion in single vessel disease. A comparison between patients with exercise-induced angina and patients with recurrent angina at rest

Patients with exercise angina >2 months (n:13) showed significantly lower SigmaST elevation during 120 s balloon coronary occlusion than those with =<2 months (n:7), or those with angina at rest <=2 days (n:8) but similar to patients with angina at rest >2 days (n:7). These results underscore the importance of the kind and duration of angina in limiting the extent of ischemia during coronary occlusion.

The effect of electrical neurostimulation on collateral perfusion during acute coronary occlusion

Background

Electrical neurostimulation can be used to treat patients with refractory angina, it reduces angina and ischemia. Previous data have suggested that electrical neurostimulation may alleviate myocardial ischaemia through increased collateral perfusion. We investigated the effect of electrical neurostimulation on functional collateral perfusion, assessed by distal coronary pressure measurement during acute coronary occlusion. We sought to study the effect of electrical neurostimulation on collateral perfusion.

Methods

Sixty patients with stable angina and significant coronary artery disease planned for elective percutaneous coronary intervention were split in two groups. In all patients two balloon inflations of 60 seconds were performed, the first for balloon dilatation of the lesion (first episode), the second for stent delivery (second episode). The Pw/Pa ratio (wedge pressure/aortic pressure) was measured during both ischaemic episodes. Group 1 received 5 minutes of active neurostimulation before plus 1 minute during the first episode, group 2 received 5 minutes of active neurostimulation before plus 1 minute during the second episode.

Results

In group 1 the Pw/Pa ratio decreased by 10 ± 22% from 0.20 ± 0.09 to 0.19 ± 0.09 (p = 0.004) when electrical neurostimulation was deactivated. In group 2 the Pw/Pa ratio increased by 9 ± 15% from 0.22 ± 0.09 to 0.24 ± 0.10 (p = 0.001) when electrical neurostimulation was activated.

Conclusion

Electrical neurostimulation induces a significant improvement in the Pw/Pa ratio during acute coronary occlusion.

Effect of clinical variables on the correlation between amount of ST elevation and myocardial scintigraphic perfusion defect during coronary occlusion

PURPOSE

We investigated if the correlation between the amount of ST elevation (STE) and myocardial ischemia could be altered by variables such as hypertension or body mass index (BMI).

METHODS

A 12-lead electrocardiogram and a technetium-99m tetrofosmin injection were performed during balloon coronary occlusion in 34 patients with single-vessel disease.

RESULTS

The sum of STE correlated with scintigraphic extent of ischemia (r = 0.441; P = .009), but this correlation improved significantly in men and patients with BMI of 28 kg/m2 or less and was highest in nonhypertensive patients (r = 0.763; P < .001). In contrast, it was poor in women and patients with BMI greater than 28 kg/m2 or arterial hypertension, being lowest in the latter subset (r = 0.110; P = .664). Moreover, 8 (80%) of 10 patients with extensive hypoperfusion but with low SigmaSTE (< or =20 mm) were hypertensive.

CONCLUSIONS

If confirmed by larger studies, electrocardiographic underestimation of transmural ischemia during coronary occlusion in patients with hypertension or increased BMI may lead to adjustments in STE criteria for reperfusion therapy.

Comparison of ST-segment deviation to scintigraphically quantified myocardial ischemia during acute coronary occlusion induced by percutaneous transluminal coronary angioplasty

This study compared ST-segment changes during acute coronary artery occlusion with measurements of ischemia by myocardial scintigraphy. Forty patients who were referred for elective prolonged percutaneous transluminal coronary angioplasty underwent 12-lead electrocardiographic recording before the procedure (baseline) and continuously during the entire balloon inflation (occlusion). For each patient, the summed ST-segment deviation was calculated as the maximal absolute difference, elevation or depression, between baseline and occlusion recordings in all 12 leads. Each patient underwent 2 myocardial scintigraphies, 1 with technetium-99m sestamibi injected during the balloon inflation and 1 on the following day as a control study. Ischemia that was induced by balloon occlusion was quantified in terms of extent and severity. Results for the entire study group showed that summed ST deviation correlated with extent (r = 0.59, p < 0.0001) and severity (r = 0.61, p < 0.0001) of ischemia. The location of maximal ST deviation differed for the 3 arteries. For occlusion of the left anterior descending artery, maximal ST deviation was elevated in lead V3. For occlusion of the left circumflex artery, maximal ST deviation was depressed in lead V2. Occlusion of the right coronary artery caused ST elevation in lead III and ST depression in lead V2. In conclusion, this study demonstrated a significant correlation between summed ST deviation and myocardial ischemia during coronary occlusion that is induced by percutaneous transluminal coronary angioplasty.

Arterial concentration of 99mTc-sestamibi at rest, during peak exercise and after dipyridamole infusion

Tracers for myocardial perfusion imaging during stress should not only have high cardiac uptake but they should also have a fast blood clearance to prevent myocardial tracer uptake after the ischaemic stimulus. The present study characterize the early phase of the arterial (99m)Tc-sestamibi (MIBI) time-activity curve after venous bolus injection at rest, during peak exercise and after dipyridamole infusion. We included 11 patients undergoing angioplasty for one-vessel disease (rest study) and 20 patients evaluated for the detection of haemodynamic significant coronary stenoses by (99m)Tc-sestamibi single photon emission computed tomography (SPECT) using either bicycle exercise testing (10 patients) or standard dipyridamole testing (10 patients). Arterial blood samples of 1 ml were taken from the left femoral artery (rest study) or the right radial artery (exercise and dipyridamole studies) every 5 s during the first 5 min postinjection. In the exercise and the dipyridamole studies blood sampling were extended to include blood samples every 5 min 5-30 min postinjection. Peak MIBI concentration was lower and decrease in concentration slower after tracer injection during exercise than during dipyridamole stress testing. This may cause an underestimation of perfusion defects during exercise because of MIBI uptake after the ischaemic stimulus. The implications of the study not only refer to the choice of stress modality when using MIBI. This study also underlines the importance of considering early blood clearance in addition to regional myocardial tracerkinetic aspects such as myocardial extraction fraction when new tracers are introduced.

Pharmacological modulation of the ATP sensitive potassium channels during repeated coronary occlusions: no effect on myocardial ischaemia or function

BACKGROUND

Repeated episodes of myocardial ischaemia may lead to ischaemic preconditioning. This is believed to be mediated by the ATP sensitive potassium channels.

OBJECTIVE

To examine the effect of pharmacological modulation of the ATP sensitive potassium channels during repeated coronary occlusions.

DESIGN

Double blind, double dummy study.

METHODS

38 patients with a proximal stenosis of the left anterior descending coronary artery and no visible coronary collateral vessels underwent three identical 90 second balloon occlusions, each followed by five minutes of reperfusion. The patients were randomised to pinacidil 25 mg, glibenclamide 10.5 mg, or matching placebo 90 minutes before the start of the procedure. Myocardial ischaemia was measured by continuous monitoring of ECG ST segment changes. Changes in left ventricular function were recorded with a miniature radionuclide detector, and angina was scored on the Borg scale.

RESULTS

In all patients the first balloon occlusion led to significant ST segment elevation, a clear decrease in left ventricular ejection fraction, and angina pectoris. This response was not attenuated at the second or third balloon occlusion, either in the placebo group or in the patients pretreated with pinacidil or glibenclamide.

CONCLUSIONS

Under the given experimental conditions, this randomised and double blind study did not support the view that the human myocardium has an intrinsic protective mechanism that is activated by short lasting episodes of ischaemia.

Assessment of myocardium at risk with computerized vectorcardiography and technetium-99m-sestamibi-single photon emission computed tomography during coronary angioplasty

OBJECTIVE

To compare the myocardium at risk (MAR) as estimated by computerized vectorcardiography (cVCG) with MAR determined by Tc-99m-sestamibi-SPECT using coronary angioplasty as the model for transient transmural ischemia in humans.

METHODS AND RESULTS

In 37 patients with stable angina pectoris, cVCG was recorded continuously during coronary angioplasty. The scintigraphic defect was quantified using an automated software program (CEqual). The ST vector magnitude (ST-VM) and the ST change vector magnitude (STC-VM) correlated well with MAR estimated by scintigraphy, ST-VM (r = 0.71, p < 0.001) and STC-VM (r = 0.84, p < 0.001). All patients with STC-VM <50 microV during occlusion had defects of less than 10% of the left ventricle.

CONCLUSION

1) ST-VM and STC-VM give a reasonable useful estimate of MAR size during transient coronary occlusion. 2) STC-VM <50 microV is a reliable limit to identify patients with MAR size less than 10%. 3) ST-VM does not add information to STC-VM with respect to detection of ischemia. 4) The existence of collateral vessels has great impact on both ST-vector changes and scintigraphic imaging of myocardial ischemia.

Determinants and prognostic implications of terminal QRS complex distortion in patients treated with primary angioplasty for acute myocardial infarction

Terminal QRS complex distortion on admission has an impact on a patient's prognosis after primary angioplasty for acute myocardial infarction (AMI). We evaluated the determinants and prognostic significance of terminal QRS complex distortion in 153 consecutive patients with AMI after primary angioplasty. The study population was divided into 2 groups according to the presence (group I, n = 41) or absence (group II, n = 112) of terminal QRS complex distortion. The primary end points were the occurrence, within 6 weeks after AMI, of death, nonfatal reinfarction, or congestive heart failure. Baseline characteristics were similar between the 2 groups. However, patients in group I had higher peak levels of serum creatine kinase than those in group II (5,100 +/- 3,100 vs 3,000 +/- 1,800 U/L, respectively, p <0.01). The rate of angiographic no-reflow (Thrombolysis In Myocardial Infarction flow grade < or =2) was 31.7% in group I and 10.7% in group II (p <0.01). The predischarge left ventricular ejection fraction was 45.0 +/- 12.0% in group I and 54.0 +/- 8.0% in group II (p <0.01). Multivariate analysis identified the pressure-derived fractional collateral flow index and the culprit lesion in the left anterior descending coronary artery as independent determinants of the terminal QRS complex distortion. No patients died during 6 weeks of follow-up. The 2 groups were similar for life-threatening arrhythmia or reinfarction. However, there were more patients in group I than in group II with congestive heart failure (26.8% vs 5.4%, respectively, p <0.01) or who reached the primary end points (29.3% vs 5.4%, respectively, p <0.01). In conclusion, terminal QRS complex distortion on admission is associated with poor clinical outcome after primary angioplasty for AMI, and collateral flow may have a major influence on terminal QRS complex distortion during AMI.

Determinants of coronary blood flow following primary angioplasty for acute myocardial infarction

The aim of this study was to evaluate determinants of coronary blood flow following primary angioplasty (PA) in acute myocardial infarction (AMI). The corrected TIMI (thrombolysis in myocardial infarction) frame count and the TIMI flow grade were used as indexes of coronary blood flow, and its determinants were examined in 115 consecutive AMI patients who underwent PA (pain onset </= 12 hr). The following were validated as univariate predictors of slower corrected TIMI frame count: a lower pressure-derived farctional collateral flow (PDCF) index (P < 0.01), poor angiographic collaterals (P < 0.01), TIMI flow 0, 1 before PA (P < 0.05), and the presence of heavy thrombi (P < 0.01). The PDCF index and the presence of heavy thrombi were independent predictors of the corrected TIMI frame count. Likewise, the PDCF index (chi(2) = 12.9; P < 0.01) and the presence of heavy thombi (chi(2) = 11.4; P < 0.01) were independent predictors of TIMI 3 flow. In conclusion, collateral flow and the presence of thrombi are major determinants of coronary blood flow after PA in AMI.

Clinical evidence for myocardial derecruitment downstream from severe stenosis: pressure-flow control interaction

To verify the interaction between coronary pressure (CP) and blood flow (CBF) control, we studied nine candidates for angioplasty of an isolated lesion of the left anterior descending coronary artery [i.e. , percutaneous transluminal coronary angioplasty (PTCA)]. CBF (i.e., flow velocity x coronary cross-sectional area at the Doppler tip) and CP were monitored during washout of 2-5 mCi of (133)Xe after bolus injection into the left main artery before and after PTCA. Xe mean transit time (MTT) was calculated as the area under the time-activity curve, acquired by a gamma camera, divided by the dose obtained from a model fit of the Xe curve in the anterior wall. CBF response to intracoronary adenosine (2 mg) was also assessed. PTCA increased baseline CBF (from 14.5 +/- 9.4 to 20 +/- 8 ml/min, P < 0.01), coronary flow reserve (from 1.52 +/- 0.24 to 2.33 +/- 0.8, P < 0.01), and CP (from 64 +/- 9 to 100 +/- 10 mmHg, P < 0.05). MTT decreased from 89 +/- 32 to 70 +/- 19 s (P < 0.05) after PTCA; however, MTT and CBF changes were not correlated (r = -0.09, not significant). Inasmuch as MTT is the ratio of distribution volume to CBF, MTT x CBF was used as an index of perfused myocardial volume. Volume increased after PTCA from 23 +/- 18 to 56 +/- 30 ml. A direct correlation was observed between the percent increase in distal CP and percent increase in perfused volume (r = 0.91, P < 0.01). Thus low CP was not associated with exhaustion of flow reserve but, rather, with reduction of perfused myocardial volume. These data suggest that, in the presence of a severe coronary stenosis, derecruitment of vascular units occurs that is proportional to the decrease in driving pressure. Residual perfused units maintain a vasomotor tone, thus explaining the paradoxical persistence of coronary reserve.