Selective adenosine agonists and myocardial perfusion imaging.

Selective adenosine receptor agonists have several advantages for use as stress agents in conjunction with myocardial perfusion imaging compared to the non selective agents such as adenosine and dipyridamole. This review will summarize the pre-clinical and clinical data on the selective adenosine agonist stress agents regadenoson (Lexiscan(®)), binodenoson (CorVue™) and apadenoson (Stedivaze™) that have been studied so far with focus on regadenoson that has the most clinical data published so far. The article will review the adenosine receptor types and properties. It will also review the various attributes of the selective adenosine agonists including their pharmacology, pharmacokinetics and pharmacodynamics, their coronary vasodilatory and hemodynamic effects, their safety and side effects, their interactions with other drugs and their use with myocardial perfusion imaging. The landmark trials of the selective adenosine agonists will be reviewed as well as their use in special patient populations undergoing stress myocardial perfusion imaging.

Oral antiplatelet therapy in diabetes mellitus and the role of prasugrel: an overview.

Diabetics have a prothrombotic state that includes increased platelet reactivity. This contributes to the less favorable clinical outcomes observed in diabetics experiencing acute coronary syndromes as well as stable coronary artery disease. Many diabetics are relatively resistant to or have insufficient response to several antithrombotic agents. In the setting of percutaneous coronary intervention, hyporesponsiveness to clopidogrel is particularly common among diabetics. Several strategies have been examined to further enhance the benefits of oral antiplatelet therapy in diabetics. These include increasing the dose of clopidogrel, triple antiplatelet therapy with cilostazol, and new agents such as prasugrel. The large TRITON TIMI 38 randomized trial compared clopidogrel to prasugrel in the setting of percutaneous coronary intervention for acute coronary syndromes. The diabetic subgroup (n = 3146) experienced considerable incremental benefit with a 4.8% reduction in cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke at 15-month follow-up with prasugrel treatment. Among diabetics on insulin this combined endpoint was reduced by 7.9% at 15 months. Major bleeding was not increased in the diabetic subgroup. This confirms the general hypothesis that more potent oral antiplatelet therapy can partially overcome the prothrombotic milieu and safely improve important clinical outcomes in diabetics.

The scope of coronary heart disease in patients with chronic kidney disease.

Chronic kidney disease (CKD) affects approximately 13% of the U.S. population and is associated with increased risk of cardiovascular complications. Once renal replacement therapy became available, it became apparent that the mode of death of patients with advanced CKD was more likely than not related to cardiovascular compromise. Further observation revealed that such compromise was related to myocardial disease (related to hypertension, stiff vessels, coronary heart disease, or uremic toxins). Early on, the excess of cardiovascular events was attributed to accelerated atherosclerosis, inadequate control of blood pressure, lipids, or inflammatory cytokines, or perhaps poor glycemia control. In more recent times, outcome research has given us further information that relates even lesser degrees of renal compromise to an excess of cardiovascular events in the general population and in those with already present atherosclerotic disease. As renal function deteriorates, certain physiologic changes occur (perhaps due to hemodynamic, inflammatory, or metabolic changes) that decrease oxygen-carrying capacity of the blood by virtue of anemia, make blood vessels stiffer by altering collagen or through medial calcinosis, raise the blood pressure, increase shearing stresses, or alter the constituents of atherosclerotic plaque or the balance of thrombogenesis and thrombolysis. At further levels of renal dysfunction, tangible metabolic perturbations are recognized as requiring specific therapy to reduce complications (such as for anemia and hyperparathyroidism), although outcome research to support some of our current guidelines is sorely lacking. Understanding the process by which renal dysfunction alters the prognosis of cardiac disease might lead to further methods of treatment. This review will outline the relationship of CKD to coronary heart disease with respect to the current understanding of the traditional and nontraditional risk factors, the role of various imaging modalities, and the impact of coronary revascularization on outcome.

Pretreatment with nitroprusside for microcirculatory protection in saphenous vein graft interventions.

OBJECTIVES: We hypothesized that the prophylactic administration of sodium nitroprusside (NTP) during saphenous vein graft (SVG) PCI would ameliorate the detrimental effects of distal embolization and reduce the frequency and magnitude of post-procedural myonecrosis. METHODS: Sixty-four consecutive patients with normal preprocedural cardiac enzymes underwent SVG PCI without embolic protection devices and received prophylactic intragraft NTP before initial device activation. For each case, 2 control patients were selected in reverse chronologic order and were matched for stent use, thromboatherectomy device use, clinical presentation, presence of thrombus and pre-PCI thrombolysis in myocardial infarction (TIMI) flow. RESULTS: Mean patient age was 66 +/- 10 years, 78% of whom were males. Stent and thromboatherectomy use was 95.3% and 3.1%, respectively in both groups (p = ns). Prior to intervention, TIMI < 3 flow was present in 26.6% of cases and in 24.2% of control patients (p = ns). Thrombus was present in 20.3% of cases and in 19.5% of controls (p = ns). Post-PCI creatinine kinase (CK)-MB elevation > 3 x the upper limit of normal (ULN) occurred in 6.3% of cases vs. 16.4% of controls (p = 0.049) and > 5 x ULN in 1.6% of cases vs.10.9% of controls (p = 0.022). In a multivariate regression model that included stent use, in-stent restenosis, thrombus presence, preprocedural TIMI 3 flow, MI as procedural indication, NTP and glycoprotein IIb/IIIa use, NTP was the only independent and significant predictor of reduced post-procedural CK-MB elevation > 5 x ULN. CONCLUSION: Prophylactic administration of intragraft NTP during SVG PCIs results in a lower frequency and magnitude of post-procedural cardiac enzyme elevation.

Hemodynamic evaluation of coronary artery bypass graft lesions using fractional flow reserve.

BACKGROUND: Coronary angiography is limited by its inability to assess the hemodynamic significance of a coronary artery stenosis. The assessment of the physiological significance of saphenous vein graft (SVG) lesions with a pressure wire to determine the fractional flow reserve (FFR) is lacking. METHODS: FFR was determined in 10 SVG lesions of 10 males who had stress myocardial perfusion imaging (MPI) prior to referral for percutaneous coronary intervention for clinical indications. RESULTS: All SVGs had a diameter stenosis (DS) > 50% and 30% had a DS > or = 70%. A significant FFR was present in 30% of patients. Ischemia along the territory of the SVG was present in 20% of patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FFR < 0.75 for the detection of ischemia on stress MPI were 50, 75, 33, 85, and 70%, respectively. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of FFR < 0.75 for detecting > or = 70% DS on angiography were 33, 71, 33, 71, and 60%, respectively. There was no significant correlation between FFR and % DS (R(2) = 0.1, P = 0.35). CONCLUSION: The use of FFR to assess the physiological significance of SVG lesions is feasible and provides an acceptable specificity and negative predictive value compared to stress MPI.

Subaortic stenosis missed by invasive hemodynamic assessment.

We present a case of 61-year-old man that was evaluated for possible aortic stenosis but did not show a left ventricular outflow gradient on invasive assessment in the catheterization laboratory. Transthoracic echocardiography showed subaortic stenosis secondary to a discrete membranous structure in the left ventricular outflow tract. This is the first case in the literature of a patient with discrete subaortic stenosis missed by invasive hemodynamic assessment.

The effects of medications on myocardial perfusion.

Antianginal and lipid-lowering medications may modify the results of stress myocardial perfusion imaging. Several studies have shown the beneficial potential of these agents in suppressing myocardial ischemia in patients with known coronary artery disease. The effects of nitrates, calcium-channel blockers, beta-blockers, and statins on myocardial perfusion imaging are likely attributable to changes in myocardial blood flow and myocardial oxygen supply-demand ratio. This comprehensive review examines relevant experimental and clinical published data. Technical issues in image interpretation specific to myocardial perfusion imaging and implications of use of cardiac medications to results of myocardial perfusion imaging are discussed.

Hypertrophic obstructive cardiomyopathy in liver transplant patients.

The optimal treatment strategy for patients with symptomatic hypertrophic obstructive cardiomyopathy (HOCM) and end-stage liver disease (ESLD) is not well defined. Although medical management is the accepted first line treatment, patients who are unresponsive to medication require further interventions. Since ESLD patients have a high operative risk for surgical myomectomy, alcohol septal ablation (ASA) emerges as a good alternative in these cases. The timing of ASA in relation to liver transplantation is still unclear. We report here on the first case of an orthotopic liver transplant-recipient undergoing ASA and the second of a cirrhotic patient requiring ASA as a bridge to liver transplantation. Both patients had a good clinical outcome and we argue that ASA in HOCM patients should be driven by symptom onset, and that in the asymptomatic patient it can be safely deferred until after liver transplantation.

Three-dimensional balloon catheter sizing identifies significant underdeployed stents using conventional methods in renal artery interventions.

BACKGROUND: Renal artery stent restenosis remains a significant impediment that in part is attributed to suboptimal stent deployment. We tested the hypothesis that optimal stent deployment during renal artery interventions can be achieved using the Metricath (MC) system, a balloon-catheter sizing device. METHODS: The MC low-pressure balloon derives accurate vessel lumen dimensions from the three-dimensional reconstruction of volume of fluid and pressure within the inflated balloon. We systematically compared the final visual assessment of renal artery intervention with a subsequent MC minimal lumen diameter (MLD) in patients undergoing renal artery stenting. RESULTS: Sixteen patients underwent angioplasty and stenting of 20 renal artery lesions. MC guidance resulted in adjunctive intervention in 90% of lesions, increasing MLD from 4.40 +/- 0.77 mm before to 5.17 +/- 0.82 mm (p < 0.001) after adjunctive intervention. The MC MLD to the angiographic reference vessel diameter improved from 77.4 +/- 15.2% to 91.2 +/- 17.5% (p < 0.001), and the MC MLD to the nominal stent diameter improved from 76.2 +/- 7.1% to 90.0 +/- 9.4% (p < 0.001) after adjunctive intervention. Stent expansion was more pronounced at its distal site compared to the lesion site where the postinterventional distal stent MLD was 5.52 +/- 0.93 mm (p = 0.23), and the lesion MLD was 5.17 +/- 0.82 (p = 0.001) compared to a nominal stent diameter of 5.78 +/- 0.88 mm. An MC MLD-to- nominal stent diameter ratio greater than or equal to 85% occurred in 10% of lesions before adjunctive dilatation and in 65% of lesions after adjunctive balloon post dilatation. CONCLUSIONS: MC guidance during renal interventions revealed a large proportion of underdeployed stents that were further optimized by adjunctive intervention.

Saphenous vein graft-to-left atrium fistula treated with percutaneous transcatheter embolization with coils.

Coronary artery fistulae are rare anomalies that are most commonly congenital and rarely acquired. We present a first case of a vein graft to the left atrium fistula that occurred post coronary artery bypass grafting and was treated with percutaneous transcatheter embolization with coiling. The coil was initially lost in the left atrium, but was successfully retrieved and the fistula was closed. We review the pertinent literature on acquired coronary artery fistulae and their management.

Predictors of survival in patients with end-stage renal disease evaluated for kidney transplantation.

Cardiovascular disease is the major cause of mortality in patients with end-stage renal disease (ESRD). This study examined the all-cause mortality in 3,698 patients with ESRD evaluated for kidney transplantation at our institution from 2001 to 2004. Mean age for the cohort was 48+/-12 years, and 42% were women. Stress myocardial perfusion imaging was done in 2,207 patients (60%) and coronary angiography in 260 patients (7%). There were 622 deaths (17%) during a mean follow-up period of 30+/-15 months. The presence and severity of coronary disease on angiography was not predictive of survival. Coronary revascularization did not impact survival (p=0.6) except in patients with 3-vessel disease (p=0.05). The best predictor of death was left ventricular ejection fraction, measured by gated myocardial perfusion imaging, with 2.7% mortality increase for each 1% ejection fraction decrease. In conclusion, left ventricular ejection fraction is a strong predictor of survival in patients with ESRD awaiting renal transplantation. Strategies to improve cardiac function or earlier renal transplantation deserve further studies.

Percutaneous aortic valvuloplasty as a bridge to a high-risk percutaneous coronary intervention.

We describe a novel approach of using percutaneous aortic valvuloplasty as a bridge to percutaneous coronary intervention in a patient with refractory congestive heart failure, severe aortic stenosis, severe left ventricular dysfunction and severe 3-vessel coronary artery disease who was not a surgical candidate for aortic valve replacement and coronary artery bypass grafting.

A novel method of clot extraction using a FilterWire EX in acute myocardial infarction.

We describe a novel approach for the use of a FilterWire EX distal protection device as a snaring device for clot extraction in a patient who sustained acute ST-elevation myocardial infarction due to occlusion of the right coronary artery.

Origin of all three major coronary arteries from the right sinus of Valsalva: clinical, angiographic, and magnetic resonance imaging findings and incidence in a select referral population.

OBJECTIVE: We sought to determine the incidence and imaging features by coronary angiography and cardiac magnetic resonance imaging (MRI) of anomalies in which the right, circumflex, and left anterior descending coronary arteries arise separately from the right sinus of Valsalva. BACKGROUND: The anomalous origin of all major coronary arteries from separate ostia in the right sinus of Valsalva has been reported as exceedingly rare, with mainly isolated cases reported. A knowledge of the origin and proximal courses of aberrant arteries is critical for patient management. METHODS: 42 consecutive patients without other congenital heart disease referred to our institution for MRI evaluation of anomalous coronary artery over a six year period were evaluated. Analysis of angiograms and MRI was done to determine the anatomic origin and proximal pathway of coronary arteries (determined by conventional angiography and MRI) and degree of any stenosis (by angiography). RESULTS: Seven of the 42 patients (17%) in this referral population had the described anatomy. Both conventional angiography and MRI depicted the origin and proximal courses of these arteries. In all patients, the circumflex passed behind the aorta. In three, the left anterior descending passed through the ventricular septum; in four, it passed anterior to the pulmonary trunk. CONCLUSIONS: This series is the largest ever reported on this complex anatomical variant and the first to give a systematic analysis of the anatomy by angiography and MRI. This constellation of multiple anomalous coronary arterial origins and proximal courses may not be as rare as previously reported.

Myocardial perfusion imaging after transient balloon occlusion during percutaneous coronary interventions.

BACKGROUND: Myocardial perfusion imaging (MPI) is highly sensitive in detecting rest ischemia when the radiotracer is injected during the episode of ischemia. The frequency of abnormal MPI results after resolution of ischemia is not well defined. The aim of this study was to determine how long MPI results remain abnormal after transient coronary artery occlusion. METHODS AND RESULTS: Patients undergoing single-vessel percutaneous coronary intervention were injected with technetium 99m sestamibi at 30 to 60 minutes (group 1) (n = 20) or 90 to 120 minutes (group 2) (n = 10) after the last balloon inflation and 24 hours later. There were 30 men aged 59 +/- 8 years. The culprit vessel was the left anterior descending artery in 14 patients and the right coronary artery in 13. The diameter stenosis was reduced from 76.1% +/- 8.7% to 3.0% +/- 6.4% (P < .001). The duration of balloon inflation was 40.3 +/- 12.5 seconds. Chest pain or ST shifts occurred in 66% of patients. A perfusion defect in the territory of the culprit artery was detected in 3 of 20 patients (15%) in group 1 and in 0 of 10 patients (0%) in group 2 (P = .3). One of those three patients had a perfusion defect on MPI done 24 hours later, along with a regional wall motion abnormality on the 2 sets of images. CONCLUSIONS: Abnormal perfusion is seen in a small percentage of patients at 30 to 60 minutes and in none at 90 to 120 minutes after a brief transient balloon occlusion. These results might have important implications in patient care.

The safety of bivalirudin during elective percutaneous coronary interventions in heart transplant patients.

BACKGROUND: Bivalirudin has been shown to be safe and effective during percutaneous coronary interventions (PCI) of native coronary arteries in the REPLACE 2 trial. The safety of bivalirudin during PCIs in heart transplant patients is not known. METHODS: Heart transplant patients who had undergone PCI of de novo lesions and received bivalirudin during the procedure were included in the study. Medical records were reviewed for the occurrence of death, myocardial infarction, target vessel revascularization or major bleeding up to 30 days after discharge. The results were compared with the REPLACE 2 trial and with a control group of heart transplant recipients who received heparin during their procedures. RESULTS: There were 51 separate PCIs performed in 30 patients in the study group. The mean age was 56 +/- 12 years and 6 (20%) were women. The control group consisted of 24 patients who had undergone 35 PCIs. There were no deaths, myocardial infarctions or target vessel revascularization during the follow-up period in the study group. The combined endpoint of death, myocardial infarctions, target vessel revascularization and major bleeding requiring two or more units of packed red blood cells occurred in 2 (3.9%) patients compared to 275 (9.2%) patients in the REPLACE 2 trial (p = 0.195) and 5 (14.3%) in the control group (p = 0.115). CONCLUSION: Bivalirudin is a safe antithrombotic medication to use during elective PCI in heart transplant patients with cardiac allograft vasculopathy. (Cardiol J 2007; 14: 458-462).

Transjugular biopsy of a right atrial mass under intracardiac echocardiographic guidance.

Biopsy of cardiac tumors to obtain a tissue diagnosis has been performed under echocardiographic (transthoracic or transesophageal) or fluoroscopic guidance. We report successful transjugular biopsy of a right atrial mass using intracardiac echocardiographic guidance.

Percutaneous balloon pericardiotomy for the treatment of infected pericardial effusion with tamponade.

Percutaneous balloon pericardiotomy has been used as an alternative for surgically created pericardial window mainly for the management of malignant pericardial effusions in critically ill patients. We describe a patient with purulent pericardial effusion and cardiac tamponade who was treated successfully and without complications with percutaneous balloon pericardiotomy.

Three-vessel coronary artery disease, aortic stenosis, and constrictive pericarditis 27 years after chest radiation therapy: a case report.

A patient with a history of Hodgkin's lymphoma presented with recurrent left pleural effusions and dyspnea on exertion 27 years after radiation therapy. Further evaluation disclosed suspected radiation-induced constrictive pericarditis, aortic stenosis and regurgitation, and severe coronary artery disease. He underwent successful 3-vessel coronary artery bypass grafting, aortic valve replacement, and pericardiectomy.