Feasibility of assessment of coronary stent patency using 16-slice computed tomography

Intracoronary stent implantation is a frequently performed procedure in the treatment of stenoses in coronary arteries, but in-stent restenosis occurs in approximately 10% to 15% of patients. A noninvasive diagnostic procedure to evaluate in-stent restenosis would therefore be of great benefit. We investigated the feasibility of assessing stent patency with 16-slice computed tomography. Multislice computed tomography (MSCT) was performed in 22 patients with previously implanted stents. For each stent, assessability was determined and related to stent type and diameter. Subsequently, the presence of significant restenosis was determined in the evaluable stents. In addition, peristent lumina (5 mm proximal and distal to the stent) were evaluated. Conventional angiography in combination with quantitative coronary angiography served as the standard of reference. MSCT was performed successfully in all but 1 patient. Of 65 stents, 50 (77%) were determined assessable. Uninterpretable stents tended to have a thicker strut and/or a smaller diameter. In the evaluable stents, 7 of 9 stenoses were detected and the absence of restenosis was correctly identified in all 41 patent stents, resulting in a sensitivity and specificity of 78% and 100%, respectively. Sensitivity and specificity for the detection of peristent stenosis were 75% and 96%, respectively. In conclusion, MSCT may be useful in the assessment of stent patency and may function as a gatekeeper before invasive diagnostic procedures.     

Benefit of combined resynchronization and defibrillator therapy in heart failure patients with and without ventricular arrhythmias.

OBJECTIVES: We attempted to assess the efficacy of combined cardiac resynchronization therapy-implantable cardioverter-defibrillator (CRT-ICD) in heart failure patients with and without ventricular arrhythmias. BACKGROUND: Because CRT and ICDs both lower all-cause mortality in patients with advanced heart failure, combination of both therapies in a single device is challenging. METHODS: A total of 191 consecutive patients with advanced heart failure, left ventricular ejection fraction <35%, and a QRS duration >120 ms received CRT-ICD. Seventy-one patients had a history of ventricular arrhythmias (secondary prevention); 120 patients did not have prior ventricular arrhythmias (primary prevention). During follow-up, ICD therapy rate, clinical improvement after 6 months, and mortality rate were evaluated. RESULTS: During follow-up (18 +/- 4 months), primary prevention patients experienced less appropriate ICD therapies than secondary prevention patients (21% vs. 35%, p < 0.05). Multivariate analysis revealed, however, no predictors of ICD therapy. Furthermore, a similar, significant, improvement in clinical parameters was observed at 6 months in both groups. Also, the mortality rate in the primary prevention group was lower than in the secondary prevention group (3% vs. 18%, p < 0.05). CONCLUSIONS: As 21% of the primary prevention patients and 35% of the secondary prevention patients experienced appropriate ICD therapy within 2 years after implant, and no predictors of ICD therapy could be identified, implantation of a CRT-ICD device should be considered in all patients eligible for CRT.     

Assessment of myocardial viability by nuclear imaging techniques

The assessment of myocardial viability has become important in the diagnostic and prognostic work up of patients with ischemic cardiomyopathy. Patients with viable myocardium may benefit from revascularization in terms of improvement of function, symptoms, and prognosis. In contrast, patients without viable myocardium do not benefit and should be treated conservatively. Various nuclear imaging techniques are available.     

Lipoprotein(a) and Oxidized Phospholipids Promote Valve Calcification in Patients With Aortic Stenosis

Background

Lipoprotein(a) [Lp(a)], a major carrier of oxidized phospholipids (OxPL), is associated with an increased incidence of aortic stenosis (AS). However, it remains unclear whether elevated Lp(a) and OxPL drive disease progression and are therefore targets for therapeutic intervention.

Prediction of improvement of ventricular function after revascularization: 18F-fluorodeoxyglucose single-photon emission computed tomography vs low-dose dobutamine echocardiography

AIMS: To compare assessment of myocardial flow and glucose metabolismby single-photon emission computed tomography (SPECT) with low-dosedobutamine echocardiography in predicting improvement in regionaland global left ventricular function after coronary artery bypassgrafting. METHODS AND RESULTS: Thirty patients with regional wall motion abnormalities (meanejection fraction 32±19%) were studied with low-dosedobutamine echocardiography (5 and 10 µg . kg^–1.min^–1) and thallium-201/ ¹⁸F-fluorodeoxyglucose(FDG) SPECTprior to surgery. For comparative analysis, a 13-segment modelwas used. Postoperative improvement was predicted if the echocardiogramshowed that wall motion abnormalities were reversible duringthe dobutamine infusion and there was normal perfusion or relativelyincreased FDG uptake in perfusion defects (mismatch) in dyssynergicsegments on SPECT. After surgery, ventricular function was reassessed.An echocardiogram was taken at the 3 month follow-up with thepatient at rest. Regional wall motion had improved in 62/168(37%) revascularized segments. In predicting functional outcome,low-dose dobutamine echocardiography reached a sensitivity of89% and a specificity of 82%, with a positive predictive valueof 74% and a negative predictive value of 93%, whereas for thallium-201/FDGSPECT these values were 84%, 86%, 78% and 90%, respectively.In patients with more than two viable segments on either technique,the wall motion score index, a surrogate of global ventricularfunction, improved significantly. CONCLUSION: For the optimal prediction of functional out-come, combinedassessment of flow and FDG imaging is needed. Both thallium-201/FDGSPECT and low-dose dobutamine echocardiography appear comparableand similarly accurate in predicting improvement of left ventricularfunction after surgical revascularization.     

The effects of cardiac resynchronization therapy on left ventricular function, myocardial energetics, and metabolic reserve in patients with dilated cardiomyopathy and heart failure

OBJECTIVES: The effects of long-term cardiac resynchronization therapy (CRT) on left ventricular (LV) energetics and metabolic reserve were evaluated. BACKGROUND: Cardiac resynchronization therapy is a new therapy for patients with drug-refractory severe heart failure (HF). METHODS: Ten patients with idiopathic dilated cardiomyopathy who had undergone implantation of biventricular pacemaker 8 +/- 5 months earlier were studied during two conditions: CRT switched on, and after CRT was switched off for 24 h. Left ventricular function was measured using echocardiography and oxidative metabolism using [(11)C]acetate positron emission tomography. Both measurements were performed at rest and during dobutamine-induced stress (5 microg/kg/min). Basal- and adenosine-stimulated (140 microg/kg/min) myocardial blood flow were quantitated using [(15)O]water. RESULTS: During CRT off, LV stroke volume was significantly reduced at rest (72 +/- 18 ml vs. 63 +/- 15 ml, p < 0.05), but LV oxidative metabolism (K(mono)) remained unchanged (0.046 +/- 0.008 vs. 0.054 +/- 0.016 min(-1)) leading to a significant deterioration of myocardial efficiency of forward work (from 48.2 +/- 16.7 to 36.6 +/- 11.7 mm Hg.l/g, p < 0.05). During dobutamine-induced stress, stroke volume and K(mono) values were not different whether CRT was on or off. However, myocardial efficiency (56.1 +/- 16.1 vs. 49.8 +/- 18.0 mm Hg.ml.g(-1).min(-1), p = 0.099) and metabolic reserve, the response of K(mono) to dobutamine (0.023 +/- 0.014 vs. 0.013 +/- 0.014 min(-1), p = 0.09), tended to reduce when CRT was switched off. Cardiac resynchronization therapy had no effects on myocardial perfusion. Natriuretic peptides increased significantly during CRT-off period. CONCLUSIONS: Long-term CRT has beneficial effects on LV function and myocardial efficiency at rest in patients with HF. These effects are not associated with changes in myocardial perfusion or oxygen consumption. During dobutamine-induced stress, CRT does not affect functional parameters, but myocardial efficiency and metabolic reserve may be increased.     

Imaging the myocardial ischemic cascade

Non-invasive imaging plays a growing role in the diagnosis and management of ischemic heart disease from its earliest manifestations of endothelial dysfunction to myocardial infarction along the myocardial ischemic cascade. Experts representing the North American Society for Cardiovascular Imaging and the European Society of Cardiac Radiology have worked together to organize the role of non-invasive imaging along the framework of the ischemic cascade. The current status of non-invasive imaging for ischemic heart disease is reviewed along with the role of imaging for guiding surgical planning. The issue of cost effectiveness is also considered. Preclinical disease is primarily assessed through the coronary artery calcium score and used for risk assessment. Once the patient becomes symptomatic, other imaging tests including echocardiography, CCTA, SPECT, PET and CMR may be useful. CCTA appears to be a cost-effective gatekeeper. Post infarction CMR and PET are the preferred modalities. Imaging is increasingly used for surgical planning of patients who may require coronary artery bypass.