Should we screen for coronary artery disease in asymptomatic chronic dialysis patients?

The hemodialysis population is characterized by a high prevalence of 'asymptomatic' coronary artery disease (CAD), which should be interpreted differently from asymptomatic disease in the general population. A hemodynamically significant stenosis may not become clinically apparent owing to impaired exercise tolerance and autonomic neuropathy. The continuous presence of silent ischemia may cause heart failure, arrhythmias, and sudden death. Whether revascularization of an asymptomatic dialysis patient improves outcome remains a moot point, although several observational studies and one small RCT suggest a benefit. It can therefore be defended to screen asymptomatic dialysis patients for CAD. A number of noninvasive screening tests are available, but none has proved equally practical and reliable in the dialysis population as in the general population. Myocardial perfusion scintigraphy (MPS) before and after a pharmacological stress such as dipyridamole can reveal both ischemia and myocardial scarring. When compared with coronary angiography, low sensitivities were reported and attributed to impaired vasodilation to dipyridamole in dialysis patients. A more likely explanation is that not every anatomical stenosis will lead to impaired coronary blood flow on MPS. Numerous studies have shown an incremental prognostic value of dipyridamole-MPS over clinical data for prediction of adverse cardiac events, in some studies even over coronary angiography. Pending the availability of high-quality evidence, in our opinion asymptomatic dialysis patients could undergo dipyridamole-MPS, followed by coronary angiography in case of an abnormal scan. This combined physiological and anatomical evaluation of the coronary circulation allows us to determine which coronary stenosis is clinically relevant and therefore should be revascularized.     

Technetium myocardial perfusion scanning in prerenal transplant evaluation in the United kingdom

Because death with a functioning graft remains one of the most important causes of long-term renal transplant failure, cardiac risk stratification and screening for coronary artery disease are essential components of pretransplant assessment. Pretransplant screening for occult coronary artery disease in a subset of these patients may improve outcome. The UK follows the European Best practice guideline 1.5.5 E. Although echocardiography, thallium myocardial perfusion scanning (MPS), dobutamine stress echocardiography, and coronary angiography have been suggested as means of cardiovascular assessment, the best means of assessment remains undetermined. Therefore, we investigated the role of 99m technetium sestamibi myocardial perfusion scanning as an assessment tool for identifying those patients with end-stage renal failure at high risk of cardiovascular death after renal transplantation. Retrospectively, we studied 126 patients that had a MPS as part of their pretransplant assessment. Overall unadjusted survival was 65% at 3 years. Twelve deaths resulted from cardiovascular causes. A reversible defect on MPS was associated with a fatal cardiac event and all-cause mortality. The unadjusted hazard ratio of cardiac event with reversible defect on MPS was 3.1 (95% confidence interval, 1.1 to 18.2) and hazard ratio of death with reversible defect on MPS was 1.92 (95% confidence interval, 1.1 to 4.4). Thus, MPS may be a useful tool in cardiac risk stratification and in selecting patients with a favorable outcome after renal transplantation. Our patients with a reversible defect in particular have increased cardiac mortality. This group may benefit from coronary angiography.     

Coronary artery calcification is related to coronary atherosclerosis in chronic renal disease patients: a study comparing EBCT-generated coronary artery calcium scores and coronary angiography.

BACKGROUND: Coronary artery calcification (CAC) measured by electron beam computed tomography (EBCT) correlates with plaque burden, vessel stenosis and is predictive of future cardiac events in the general population. Extensive CAC has been described recently in dialysis cohorts. For the first time we studied the relationship between CAC and coronary angiographic findings in patients with chronic renal failure, on dialysis and after renal transplantation. METHODS: We studied 46 patients who all had an EBCT-derived Agatston coronary calcium score and a diagnostic coronary angiogram within a 12-month period. The mean age was 55.7+/-13.2 (SD) years (range 29-80). The mean duration of dialysis was 54.4 months (range 1-372). RESULTS: The mean CAC was 2370+/-352.8. The mean CAC in patients with an abnormal coronary angiogram (n = 35) was 2869.6+/-417.9, while that in patients with a normal coronary angiogram (n = 11) was 559.4+/-255.1 (P = 0.001 for the inter-mean comparison). Total CAC correlated with the number of diseased vessels (P = 0.0001) and with severity of atherosclerosis in all the vessels (P = 0.0001). The individual coronary artery calcification score correlated well with the severity of atherosclerotic coronary disease (P<0.0001 for all) in the left anterior descending, right coronary and circumflex arteries. Running a multivariate regression analysis for atherosclerosis burden, we found that the only predictor was CAC (r = 0.34, P = 0.0001). CONCLUSION: CAC is common and more severe in patients with chronic kidney disease. Although in chronic kidney disease patients CAC can occur in the absence of occlusive coronary atherosclerosis, our data suggest that, as in the general population, CAC in chronic kidney disease patients is associated with obstructive atherosclerosis and may therefore be associated with a worse outcome.     

Limits of arterial myocardial revascularization

A prospective study of myocardial blood perfusion after coronary artery bypass graft (CABG) was conducted in two groups of patients. In group 1, a two-year assessment by exercise thallium myocardial scintigraphy without medical treatment was performed in 122 patients who consecutively underwent CABG with exclusive use of both internal mammary arteries (IMA) and gastroepiploic artery (GEA). In group 2, myocardial function and perfusion were determined by radionuclide investigations performed before and one year after CABG in 100 patients with preoperative LV dysfunction (defined as LV ejection fraction (LVEF) less than 0.40), comparing results of myocardial revascularization performed with either exclusive arterial grafts (arterial group, 54 patients) or one arterial graft (IMA) associated with a sequential vein graft (vein group, 46 patients). In group 1, 21% of patients presented silent residual electric ischemia during exercise stress testing and 26% had reversible scintigraphic ischemic defect despite complete revascularization, 18% of those in the inferior wall bypassed with GEA and 8% in the anterior wall bypassed with the right IMA. In group 2, the significant preoperative ischemia significantly decreased in both the vein group and the arterial group. LV function was significantly improved in the vein group; in contrast there was no modification of LV function in the arterial group. A multivariate analysis showed that the surgical technique used and the preoperative LVEF were independent prognostic factors of the postoperative myocardial outcome, with a positive impact of the vein use on the postoperative myocardial function recovery. It is important to recognize that arterial grafts have some limitations in the ability to supply blood flow for coronary circulation that may induce postoperatively silent residual myocardial ischemia and a lack of LV function recovery.     

Late coronary artery lesions after neonatal arterial switch operation: results of surgical coronary revascularization.

OBJECTIVE: To evaluate the results of surgical revascularization in children with coronary artery lesions following neonatal arterial switch operation (ASO). METHODS: Among 755 neonates who underwent ASO, there were 713 late survivors (94%). Coronary lesions were detected in 34 patients (5%). Coronary revascularization was carried out in 19 children (mean age: 5.6+/-3.2 years) in whom myocardial ischemia was demonstrated by myocardial perfusion imaging studies. Coronary lesions involved the left main coronary artery in 14 cases, the left anterior descending artery in 3, and the right coronary artery in 2. Sixteen patients had coronary angioplasty (left main coronary artery in 11, left anterior descending artery in 3, right coronary artery in 2). Two patients underwent a mammary bypass and one had a saphenous vein proximal bypass. RESULTS: There was no mortality or coronary event. Mean follow-up was 6.3+/-2.8 years. Patency of coronary repair was demonstrated in all patients; however, in one child with angioplasty of the left main coronary artery, there was a residual stenosis of the left anterior descending artery, and reoperation with a mammary bypass was required. Myocardial perfusion imaging was performed in 18 patients; myocardial perfusion was normal in 16 and 2 had minimal residual perfusion defects. Treadmill exercise testing was performed in 11 patients and was normal in all. CONCLUSIONS: (1) Following ASO, coronary lesions are not uncommon and they are progressive. Routine and sequential coronary evaluation is necessary. (2) Coronary revascularization can be achieved using coronary angioplasty in most cases. Mammary bypass may be used in selected circumstances. Normal myocardial perfusion is restored in most patients.     

Active distal coronary perfusion to prevent regional myocardial ischemia in off-pump coronary artery bypass grafting.

Regional myocardial ischemia during anastomosis in off-pump coronary artery bypass (OPCAB) can occasionally cause hemodynamic instability. To prevent regional myocardial ischemia and stabilize the hemodynamics during the procedure, perfusion of the distal coronary artery to the anastomotic site is necessary as the only reliable method. We have applied an active coronary perfusion method using a servo-controlled pump in selected patients in place of conventional passive perfusion methods (intraluminal shunt and external shunt). We present a case in which the active perfusion method proved useful in avoiding regional myocardial ischemia. A 74-year-old male patient with triple-vessel coronary disease underwent OPCAB for unstable angina. During revascularization of the main right coronary artery, the hemodynamics collapsed due to regional myocardial ischemia. As soon as the distal coronary artery was perfused at a high flow rate around 80 ml/min, the hemodynamics stabilized and the operation was completed successfully. This active coronary perfusion method in OPCAB is particularly useful in cases in which regional myocardial ischemia cause hemodynamic instability.     

Scintigraphic demonstration of myocardial perfusion and ischaemia associated with coronary artery bypass grafting

OBJECTIVES: To assess if myocardial perfusion scintigraphy (MPS) at rest can be of value in elucidating myocardial perfusion, ischaemia and perioperative myocardial infarction (PMI) associated with coronary artery bypass graft (CABG) surgery. DESIGN: This was a prospective randomized study of patients undergoing elective CABG. Forty-eight patients in the control group underwent serial ECG recordings and measurements of CK-MB and cTnT. Fifty-four patients in the study group were additionally examined with MPS preoperatively and 2-4 days and 6 weeks postoperatively. RESULTS: The study showed a highly significant (p < 0.001) improvement in myocardial radionuclide uptake from preoperatively to 2-4 days postoperatively. Judged from ECG and enzymatic changes, two control patients and one study patient only had PMI and no additional cases of PMI were demonstrated by MPS. CONCLUSION: MPS at rest showed that CABG significantly improved myocardial perfusion, by demonstrating an increase in radionuclide uptake. In diagnosing PMI, we found that MPS provided no additional information beyond cardiac biochemical markers and ECG changes.     

Can preoperative myocardial perfusion scintigraphy predict changes in left ventricular perfusion and function after coronary artery bypass graft surgery?

OBJECTIVES We wanted to evaluate whether preoperative myocardial perfusion scintigraphy (MPS) could predict changes in cardiac symptoms and postoperative myocardial perfusion and left ventricular function after coronary artery bypass grafting (CABG). METHODS Ninety-two patients with stable angina pectoris (and at least one occluded coronary artery) underwent MPS before, and 6 months after, undergoing CABG. The result of the MPS was kept secret from the surgeons. RESULTS Before CABG, 90% of the patients had angina. After CABG, 97% of the patients were without symptoms. Overall graft patency was 84%. Before CABG, one patient had normal perfusion; in the rest of them the defects were classified as follows: reversible (60%), partly reversible (27%) and irreversible (12%). Following CABG, 33% had normal perfusion; in the rest the defects were reversible in 29%, partly reversible in 12% and irreversible in 26%. Left ventricular ejection fraction (LVEF), which was normal before operation in 45%, improved in 40% of all patients. The increase in LVEF was not related to the preoperative pattern of perfusion defects. Of 30 patients with normalized perfusion after CABG, 29 (97%) had reversible defects and one patient had partly reversible defects. Of 83 perfusion defects, which were normalized after CABG, 67 were reversible (81%) or partly reversible (12%). Seventy-five percent of all reversible coronary artery territories before CABG were normalized after operation. CONCLUSIONS Our results indicate that reversible or partly reversible perfusion defects at a preoperative MPS have a high chance of normalized myocardial perfusion assessed by MPS 6 months after operation. Normal perfusion is obtained almost exclusively in territories with reversible ischaemia. Symptoms improved in nearly all patients and LVEF in a significant fraction of the patients, not related to preoperative MPS.     

Preoperative evaluation of cardiac risk using dobutamine-thallium imaging in vascular surgery

Coronary artery disease is frequently present in patients undergoing evaluation for reconstructive peripheral vascular surgery. Dobutamine-thallium imaging has been shown to be a reliable and sensitive noninvasive method for the detection of significant coronary artery disease. Eighty-seven candidates for vascular reconstruction underwent dobutamine-thallium imaging. Forty-eight patients had an abnormal dobutamine-thallium scan. Twenty-two patients had infarct only, while 26 had reversible ischemia demonstrated on dobutamine-thallium imaging. Fourteen of 26 patients with reversible ischemia underwent cardiac catheterization and 11 showed significant coronary artery disease. Seven patients underwent preoperative coronary artery bypass grafting or angioplasty. There were no postoperative myocardial events in this group. Three patients were denied surgery on the basis of unreconstructible coronary artery disease, and one patient refused further intervention. Ten patients with reversible myocardial ischemia on dobutamine-thallium imaging underwent vascular surgical reconstruction without coronary revascularization and suffered a 40% incidence of postoperative myocardial ischemic events. Five patients were denied surgery because of presumed significant coronary artery disease on the basis of the dobutamine-thallium imaging and clinical evaluation alone. Thirty-nine patients with normal dobutamine-thallium scans underwent vascular reconstructive surgery with a 5% incidence of postoperative myocardial ischemia. Dobutamine-thallium imaging is a sensitive and reliable screening method which identifies those patients with coronary artery disease who are at high risk for perioperative myocardial ischemia following peripheral vascular surgery. Presented at the Annual Meeting of the Peripheral Vascular Surgery Society, New York, New York, June 17, 1989.     

CARDIAC ARRHYTHMIAS AND SILENT MYOCARDIAL ISCHEMIA DURING HEMODIALYSIS

Cardiac arrhythmias are noted in a significant proportion of chronic renal failure (CRF) patients on hemodialysis (HD), and may contribute to cardiovascular mortality. A number of factors have been implicated in the genesis of these arrhythmias. The role of silent myocardial ischemia (SMI), however, has not been evaluated systematically. We prospectively studied 38 unselected CRF patients on regular HD by continuous Holter monitoring starting 24 hours before HD, lasting through the dialysis session and continued for 20 hours thereafter. The recordings were analyzed for frequency, timing and severity of supraventricular and ventricular arrhythmias and SMI as identified by ST-segment depression. Ventricular arrhythmias during HD were noted in 11 (29%) patients (group I), and were potentially life-threatening (Lown Class III and IVa) in 13%. The remaining 27 patients (group II) had no ventricular arrhythmias during HD. There was no difference in the age, sex ratio, duration of HD, blood pressure, fluctuations in weight, hematocrit, predialysis creatinine, sodium, potassium, calcium or inorganic phosphate levels between patients in the two groups. The number of patients with clinical ischemic heart disease was significantly greater in group I. SMI was noted in 72% and 33% of group I and II patients respectively (p =0.026). 46% of those with and 25% of those without ST changes during HD developed ventricular arrthythmias during HD. Both SMI and ventricular arrhythmias were noted most frequently during the last hour of dialysis. Hypertension, diabetes mellitus and ischemic heart disease were observed more frequently amongst patients with SMI. Ventricular arrhythmias are detected in a significant proportion of CRF patients on HD. These are probably related to coronary artery disease since silent myocardial ischemia is also noted more frequently during HD in these patients. Further studies incorporating coronary angiography are needed in a larger number of patients to establish a definite causal relationship.     

Cardiac arrhythmias and silent myocardial ischemia during hemodialysis

Cardiac arrhythmias are noted in a significant proportion of chronic renal failure (CRF) patients on hemodialysis (HD), and may contribute to cardiovascular mortality. A number of factors have been implicated in the genesis of these arrhythmias. The role of silent myocardial ischemia (SMI), however, has not been evaluated systematically. We prospectively studied 38 unselected CRF patients on regular HD by continuous Holter monitoring starting 24 hours before HD, lasting through the dialysis session and continued for 20 hours thereafter. The recordings were analyzed for frequency, timing and severity of supraventricular and ventricular arrhythmias and SMI as identified by ST-segment depression. Ventricular arrhythmias during HD were noted in 11 (29%) patients (group I), and were potentially life-threatening (Lown Class III and IVa) in 13%. The remaining 27 patients (group II) had no ventricular arrhythmias during HD. There was no difference in the age, sex ratio, duration of HD, blood pressure, fluctuations in weight, hematocrit, predialysis creatinine, sodium, potassium, calcium or inorganic phosphate levels between patients in the two groups. The number of patients with clinical ischemic heart disease was significantly greater in group I. SMI was noted in 72% and 33% of group I and II patients respectively (p = 0.026). 46% of those with and 25% of those without ST changes during HD developed ventricular arrhythmias during HD. Both SMI and ventricular arrhythmias were noted most frequently during the last hour of dialysis. Hypertension, diabetes mellitus and ischemic heart disease were observed more frequently amongst patients with SMI. Ventricular arrhythmias are detected in a significant proportion of CRF patients on HD. These are probably related to coronary artery disease since silent myocardial ischemia is also noted more frequently during HD in these patients. Further studies incorporating coronary angiography are needed in a larger number of patients to establish a definite causal relationship.     

Cardiac Risk Assessment in Kidney Transplant Candidates: Clinical Usefulness of Different Guidelines

Although cardiovascular (CV) assessment is recommended to minimize perioperative risk in all potential kidney transplant recipients, the utility and reliability of various assessment methods are not well established. In this study, we investigated the CV evaluations and outcomes of standardized CV assessment protocols (Lisbon and American Society of Transplantation [AST]) in potential kidney transplant recipients. Data were analyzed for 266 end-stage renal disease patients (mean age 45.4 ± 13 years, female-to-male ratio 126:140) accepted for kidney transplantation wait-listing. Patients were classified as low and high cardiac risk according to their first cardiac evaluation. Major cardiovascular events (CVEs) and deaths were recorded. At the end of follow-up (median 639 days), 72 (27.1%) patients underwent kidney transplantation. A total of 49 patients (18.4%) had CVEs and 42 (15.8%) patients died. Being over 45 years of age and having dialysis vintage over 1 year were found to be independent risk factors for CVEs. Forty-eight out of 60 high-risk patients evaluated with noninvasive tests had negative results. Twelve out of these 48 patients had a CVE in due course. Among 10 patients who underwent coronary angiography, 1 had a CVE and 1 died. The sensitivity and specificity of the AST guidelines (area under the curve = 0.647, P = .005, sensitivity 83%, specificity 54%) were higher than Lisbon. In conclusion, the predictive risk factors for CVEs were age over 45 years and dialysis vintage over a year. Our results also suggest that exercise electrocardiography and myocardial perfusion scintigraphy for cardiac evaluation are less sensitive in CVE prediction. We recommend clinicians to use the AST guidelines and to prioritize coronary angiography in pretransplant CV assessment.     

Two-year assessment by exercise thallium scintigraphy of myocardial revascularization using bilateral internal mammary and gastroepiploic arteries.

OBJECTIVE: To assess the blood flow supply offered to the myocardium by surgical revascularization using bilateral internal mammary (IMAs) and gastroepiploic (GEA) arteries. METHODS: Two-year assessment by exercise thallium myocardial scintigraphy without medical treatment was performed in 122 patients (mean age 61 +/- 9 years) who underwent coronary artery bypass grafting (CABG) with exclusive use of IMAs and GEA. Usually, the right IMA was used to bypass the left anterior descending coronary artery, and the left IMA to bypass the diagonal and the marginal arteries as a sequential graft if required. The GEA was used to bypass the right coronary artery (RCA) in 50 patients and its posterior branches in 72 patients. RESULTS: During maximal or submaximal exercise stress testing, 119 patients (98%) were asymptomatic and 26 patients (21%) exhibited moderate ischemic ECG modifications which were correlated (P < 0.01) with incomplete revascularization and with the use of GEA to bypass the RCA. A third of patients had moderate ischemic thallium defects on exercise reversible after redistribution (anterior, 10; lateral, 2; inferior, 28). Silent residual myocardial ischemia detected by thallium scintigraphy was correlated (P < 0.001) with ECG modifications and incomplete revascularization; and inferior thallium defects were more frequent when GEA bypassed the RCA (P < 0.05). However, 26% of patients had residual ischemia despite a complete revascularization, and in at least 18% of cases for GEA and 8% for right IMA, arterial graft blood flow was insufficient at maximum exercise level and caused silent residual myocardial ischemia detected by thallium scintigraphy. CONCLUSIONS: Myocardial revascularization using bilateral IMAs and GEA offers a satisfactory myocardial perfusion in the majority of cases; however silent residual myocardial ischemia was detected in a third of patients and was related to incomplete revascularization and to insufficient blood flow supply probably due to small diameter of the arterial grafts.     

Measurement of coronary artery calcification with multi-slice spiral computed tomography and the associated factors in maintenance hemodialysis patients

Objective To investigate the factors correlated to coronary artery calcification (CAC) in maintenance hemodialysis (MHD) patients. Methods This study included 132 patients(54 females, 78 males), aged 26-94 years, who were on hemodialysis for 10-204 months(median dialysis duration 51.00 months). The parameters including calcium, phosphorus, parathyroid hormone, total cholesterol, low density lipoprotein, triglycerides, C - reactive protein (CRP), klotho, and so on were assessed. Quantification of CAC was determined by multi-slice spiral computed tomography (MSCT), known as the coronary artery calcification score (CACs). Results Ninety-two patients (69.70%) had CAC, with CACs ranging from 0 to 13 450.20. More than 30% patients experienced one even a variety of cardiovascular and cerebrovascular diseases. A positive correlation was observed between the degree of CAC and the incidence of cardiovascular and cerebrovascular diseases. Whereas a positive correlation existed between CACs and age (r=0.347, P=0.000), duration of hemodialysis (r=0.245, P= 0.005), systolic blood pressure (r=0.184, P=0.034), diabetes history (r=0.211, P=0.015), phosphorus (r= 0.262, P=0.002), calcium-phosphorus product (r=0.247, P=0.004); and a negative correlation between CACs and klotho level (r=-0.294, P=0.001). Multivariate logistic regression analysis showed that the main factor influencing the degree of CAC in MHD patients was age. Conclusions CAC is common and widespread in hemodialysis patients, who are often accompanied by cardiovascular and cerebrovascular diseases. The prevalence rate of cardiovascular and cerebrovascular diseases increases with the aggravation of CAC degree. Age, duration of hemodialysis, systolic blood pressure, diabetes history, disturbance of calcium and phosphorus metabolism and klotho are correlated with the severity of CAC. Age is an independent risk factor of CAC degree.     

Use of multidetector computed tomography for evaluating coronary artery disease in patients undergoing dialysis

Aim: Cardiovascular disease is the most common cause of death in patients undergoing dialysis. The accuracy of multidetector computed tomography (MDCT) for detecting coronary disease has not been determined, and little information is available regarding the performance of MDCT in patients undergoing dialysis. Methods: Twenty‐nine patients undergoing dialysis were analyzed and MDCT and coronary angiography (CAng) were performed consecutively. The coronary arteries were divided into four segments for analysis. We compared the significant stenosis lesions (≥50% luminal narrowing) identified by MDCT with those found by CAng. The total coronary artery calcium (CAC) score was determined by summing the individual lesion scores from each of the coronary branches. Results: One hundred and sixteen coronary artery branches in 29 patients were analyzed. The sensitivity, specificity, and positive and negative predictive values of MDCT for detecting significant coronary artery stenosis (≥50% stenosis) were 68%, 94%, 71% and 93%, respectively. The CAC scores were significantly higher in subjects with coronary artery disease (CAD) (514.0 ± 493.6 vs 254.3 ± 375.3, P = 0.05). The severe CAC score (>500) was related to the presence of significant CAD (P = 0.05) and the sensitivity and specificity for detecting significant CAD were 50% and 80%, respectively. Conclusion: MDCT is a useful and non‐invasive approach for detecting or excluding CAD in patients undergoing dialysis.     

Off-pump coronary artery bypass grafting as re-do surgery in two cases in which the right gastroepiploic artery was grafted to the right coronary artery

Transdiaphragmatic off-pump coronary artery bypass grafting (OPCAB) to the right coronary artery, is an effective way to reduce the risks of second bypass surgery as well as the risk of graft injury after coronary artery bypass grafting (CABG). We report two cases of successful OPCAB as re-do surgery in which the right gastroepiploic artery (RGEA) was grafted to the right coronary artery. The first case was a 58-year-old woman, who underwent CABG 10 years ago. OPCAB (RGEA to right coronary artery) was performed since myocardial perfusion scintigraphy revealed ischemia in the inferior wall. The second case was a 67-year-old man who had hypertension, hyperlipidemia, peripheral arterial disease, and was undergoing dialysis (for 6 years). Six years previously, he developed a mycotic aneurysm of the right coronary artery and underwent open-heart surgery. He often had episodes of angina at night or during dialysis, and then developed congestive heart failure and was hospitalized. Since ischemia was considered to be in the inferior wall, the RGEA was grafted to the right coronary artery.     

High Parathyroid Hormone Level and Osteoporosis Predict Progression of Coronary Artery Calcification in Patients on Dialysis

Coronary artery calcifications (CACs) are observed in most patients with CKD on dialysis (CKD-5D). CACs frequently progress and are associated with increased risk for cardiovascular events, the major cause of death in these patients. A link between bone and vascular calcification has been shown. This prospective study was designed to identify noninvasive tests for predicting CAC progression, including measurements of bone mineral density (BMD) and novel bone markers in adult patients with CKD-5D. At baseline and after 1 year, patients underwent routine blood tests and measurement of CAC, BMD, and novel serum bone markers. A total of 213 patients received baseline measurements, of whom about 80% had measurable CAC and almost 50% had CAC Agatston scores>400, conferring high risk for cardiovascular events. Independent positive predictors of baseline CAC included coronary artery disease, diabetes, dialysis vintage, fibroblast growth factor-23 concentration, and age, whereas BMD of the spine measured by quantitative computed tomography was an inverse predictor. Hypertension, HDL level, and smoking were not baseline predictors in these patients. Three quarters of 122 patients completing the study had CAC increases at 1 year. Independent risk factors for CAC progression were age, baseline total or whole parathyroid hormone level greater than nine times the normal value, and osteoporosis by t scores. Our results confirm a role for bone in CKD–associated CAC prevalence and progression.     

Comparison of active and passive coronary perfusion in off-pump coronary artery bypass grafting

The myocardial protective effects of active and passive coronary perfusion were compared during off-pump coronary artery bypass grafting (OPCAB) in coronary stenosis model. An internal shunt tube was placed in the proximal left anterior descending arteries of adult dogs to produce a 75% coronary stenosis model. In 10 animals passive coronary perfusion was performed using an internal shunt tube placed in a pseudo-anastomotic site, and active coronary perfusion was performed through an external shunt tube. Ischemia was examined at normal and low blood pressure, based on hemodynamics, regional myocardial blood flow, and oxygen and lactate extraction in the perfused area. With passive perfusion, regional myocardial blood flow decreased and oxygen extraction and regional lactate production increased at normal blood pressure, indicating myocardial ischemia. Regional myocardial blood flow further decreased at low blood pressure. In contrast, regional myocardial blood flow with active perfusion did not change at normal or low blood pressure, and oxygen and lactate extraction were unchanged, indicating prevention of myocardial ischemia. Myocardial ischemia can occur with passive perfusion even at normal blood pressure. Active coronary perfusion that provides sufficient regional perfusion prevents myocardial ischemia during coronary artery anastomosis in OPCAB.     

Scintigraphic demonstration of myocardial perfusion and ischaemia associated with coronary artery bypass grafting

Objectives. To assess if myocardial perfusion scintigraphy (MPS) at rest can be of value in elucidating myocardial perfusion, ischaemia and perioperative myocardial infarction (PMI) associated with coronary artery bypass graft (CABG) surgery. Design. This was a prospective randomized study of patients undergoing elective CABG. Forty-eight patients in the control group underwent serial ECG recordings and measurements of CK-MB and cTnT. Fifty-four patients in the study group were additionally examined with MPS preoperatively and 2–4 days and 6 weeks postoperatively. Results. The study showed a highly significant (p?<?0.001) improvement in myocardial radionuclide uptake from preoperatively to 2–4 days postoperatively. Judged from ECG and enzymatic changes, two control patients and one study patient only had PMI and no additional cases of PMI were demonstrated by MPS. Conclusion. MPS at rest showed that CABG significantly improved myocardial perfusion, by demonstrating an increase in radionuclide uptake. In diagnosing PMI, we found that MPS provided no additional information beyond cardiac biochemical markers and ECG changes.     

Sustained-release diltiazem reduces myocardial ischemic episodes in end-stage renal disease: a double-blind,randomized, crossover,placebo-controlled trial

End-stage renal disease (ESRD) patients receiving maintenance hemodialysis and suffering from coronary artery disease (CAD) often receive doses of calcium channel antagonists that are too low. This may be the result of physician's desire to avoid adverse side effects during hemodialysis. The aim of this study was the assessment of the safety and efficacy of incremental doses of diltiazem for the treatment of myocardial ischemia in ERSD patients with CAD to identify the optimal dose of the drug. A total of 196 chronic hemodialysis patients were enrolled with CAD showing more than 5 min of transient myocardial ischemia during a 48-h Holter ECG monitoring. A double-blind, randomized, crossover, placebo-controlled trial design was used. Incremental doses of diltiazem (120 to 240 mg/d) were administered in 4 mo. With a dose of 120 and 180 mg/d, a significant reduction in the number and duration of total and symptomatic ischemic episodes was observed (P < 0.001), but the number and the duration of silent ischemic episodes were not reduced. Conversely, the efficacy on silent myocardial ischemia was obtained with a dosage of diltiazem of 240 mg/d (P < 0.001). In addition, with a sustained-release formulation (120 mg twice daily), the efficacy was similar to that obtained with four 60-mg tablets, but the safety was improved, especially during hemodialytic session. The circadian variations analysis of transient ischemic episodes showed a significant reduction in both ischemic peaks observed at baseline only with 240 mg/d of diltiazem. The findings emphasize that sustained-release diltiazem (120 mg twice daily) can be largely useful in uremic patients with CAD on maintenance dialysis. Diltiazem reduces the number and the duration of silent ischemic episodes, has a good tolerability, and positively modifies the circadian pattern of ischemic episodes.