Muharrem Akin

Diagnostic accuracy of cadmium-zinc-telluride-based myocardial perfusion SPECT: impact of attenuation correction using a co-registered external computed tomography

INTRODUCTION Computed tomography (CT)-based attenuation correction (AC) improves the accuracy of standard myocardial perfusion SPECT. Most dedicated cadmium-zinc-telluride (CZT) SPECT cameras are not equipped with an integrated CT component. We aimed to determine the impact of AC on diagnostic performance of CZT SPECT using co-registration with an external low-dose CT. METHODS Sixty patients underwent CZT SPECT (GE Discovery 530c) with (99m)Tc-sestamibi at rest and following regadenoson stress. Using commercial software, SPECT images were co-registered with a low-dose CT acquired on a separate system (GE Discovery 670NMCT). Attenuation corrected and non-corrected (NC) images were reconstructed using an iterative algorithm. Accuracy was measured in 44 patients who had undergone invasive angiography within 6 months. Normalcy was compared in the remaining 16 patients who had a low pre-test likelihood (<5%) of coronary artery disease (CAD). RESULTS Summed stress and rest scores were significantly lower in AC images (9 ± 8 vs. 13 ± 9 and 6 ± 7 vs. 10 ± 9, P = 0.01), while summed difference score did not differ. According to angiography, 38 patients had significant CAD in 71 vascular territories. Attenuation correction improved accuracy globally (P = 0.03) and in RCA territory (P = 0.008). Specificity improved both globally (100 vs. 40%, P < 0.05) and in each individual territory (LAD: 63 vs. 36%, LCX: 70 vs. 33%, RCA: 81 vs. 19%, P < 0.01). Normalcy was 100% for AC and 62.5% for NC images (P < 0.05). CONCLUSION Attenuation correction with a co-registered external CT is feasible using CZT cameras and improves diagnostic accuracy mostly by improving specificity over uncorrected images.

Use of New Oral Anticoagulants in the Treatment of Venous Thromboembolism and Thrombotic Prophylaxis

Thrombo-embolism of the venous system consisting of deep vein thrombosis (DVT) and pulmonary embolism (PE) is common and associated with high morbidity and mortality. Symptomatic venous thromboembolism (VTE) manifests in about 1/3 of cases as PE and 2/3 as DVT. There is a strongly compound between early mortality after venous VTE and PE, age, malignancies and cardiovascular diseases. Anticoagulation therapy is the main therapeutic approach for the treatment of acute VTE and to prevent recurrent VTE events. For decades classic anticoagulants like heparin, low-molecular-weight heparins (LMWHs), fondaparinux, and vitamin K antagonists have been the gold standards in therapy and are widely used. Novel oral anticoagulants (NOAC) like the direct thrombin inhibitor (dabigatran etexilate) and the direct factor Xa inhibitors (e.g. rivaroxaban, apixaban, and edoxaban) have been introduced to overcome the drawbacks of vitamin K antagonists. The efficacy and safety of these NOAC have been investigated in several randomized trials. Here we want to give an overview about the NOACS in the treatment of acute and chronic VTE and their use for primary prevention of acute VTE.

Evaluation of a novel 2D perfusion angiography technique independent of pump injections for assessment of interventional treatment of peripheral vascular disease

To evaluate a novel 2D-perfusion angiography (2D-PA) technique allowing pro- and retrospective flow analysis based on a proximal reference region of interest (ROI) and distal target ROI in patients treated for peripheral arterial disease. 2D-PA allows quantifying blood flow by post-processing of digital subtraction angiography (DSA). 2D-PA was performed pre and post interventional treatment of peripheral arterial disease (PAD; n = 24; 13 angioplasties, 11 stents) in 21 patients (17 men, 72 ± 9y) with Fontaine stage IIB / III. Time-to-peak (TTP), peak density (PD) and area-under-the-curve (AUC) were calculated. Ratios reference/target ROI (TTPOUTFLOW/TTPINFLOW; PDOUTFLOW/PDINFLOW; AUCOUTFLOW/AUCINFLOW) were calculated and correlated to changes in the ankle-brachial-index (ABI). 2D-PA was technically feasible in all cases. A significant increase in ABI was seen after interventional treatment (+39%; p < 0.0001). ABI increase was accompanied by an increase of 36% of PDOUTFLOW/PDINFLOW (p < 0.0001), a 52% decrease of TTPOUTFLOW/TTPINFLOW (p = 0.0007) and a 69% increase of AUCOUTFLOW/AUCINFLOW (p < 0.0001). The difference of TTP pre- and post-intervention showed a correlation with the difference in ABI (r = −0.53, p = 0.0081). The other measured parameters failed to demonstrate significant correlation with improved ABI. The presented 2D-PA technique allows quantitative assessment of arterial flow before, during and after interventional treatment in PAD.

Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9): Impact of PCSK9 on Major Adverse Cardiac and Cerebrovascular Events.

Statins are the most widely prescribed drugs to reduce serum low density lipoprotein cholesterol (LDL-C) by inhibiting 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) reductase. LDL-C reduction is associated with a decreased risk of atherosclerotic cardiovascular disease (ASCVD), including cardiovascular disease (CVD) and stroke. Statins reduce LDL-C by 30 to 40%, and the combination with other lipid-lowering agents such as ezetimibe leads to a further reduction by 20 to 25%. However, even the combination of these two agents might not be sufficient in high risk patients to require aggressive LDL-C reduction. Therefore, starting from observations on individuals with loss-of-function in proprotein convertase subtilisin/kexin type 9 (PCSK9), which was associated with lower LDL-C levels and CVD rates, monoclonal antibodies (mAbs) against PCSK9 were developed. To date, two mAbs, alirocumab and evolocumab, have received approval by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA). In the present review we give an overview about pathophysiological and clinical aspects as well as evidence for these drugs with respect to cerebrovascular events.

Angiographic detection of fatal acute aortic dissection Stanford type A under resuscitation

After resuscitation for out-of-hospital cardiac arrest (OHCA), emergent cardiac catheterization is recommended in patients with ST-segment elevation, and should be considered early in those without [1, 2]. Here, we present a patient with OHCA and inferior ST-segment elevation who inadvertently had fatal acute aortic dissection, which is only rarely documented by angiography. A 77-year-old female with know atrial fibrillation on phenprocoumon and arterial hypertension was admitted to our emergency department after cardiopulmonary resuscitation (CPR) for OHCA. The patient had suffered from angina for 24 h and collapsed in the waiting room, while expecting an appointment with a general practitioner. After 20 min of CPR for asystole, spontaneous circulation returned. Electrocardiogram (ECG) demonstrated ST-segment elevation in leads II, III, aVF and V6. The ventilated patient, who was then stable with vasopressors, was immediately transferred to our hospital. After arrival in the emergency department, ECG confirmed ST-segment elevations, Q waves in leads II, III, aVF and V6, and incomplete right bundle branch block (Fig. 1A). Fast-track echocardiography showed mild aortic regurgitation but no pericardial effusion or severe right ventricular dysfunction. Therefore, the patient was transferred to the cathlab. On the way, hypotension occurred and CPR was performed with a mechanical resuscitation device (LUCAS, Physio-Control). Aortography revealed acute aortic dissection Stanford type A (AADA) extending to both iliac arteries, with the brachiocephalic trunk and the left carotid artery originating from the false lumen (Fig. 1B, C; Supplementary Video 1 — see journal website). Due to prolonged resuscitation and fatal neurological prognosis, resuscitation was terminated. Autopsy confirmed AADA with an entry in the aortic bulb (Fig. 1D) without affecting the right coronary artery ostium, as well as an aneurysm of the abdominal aorta (Fig. 1E). Prognosis of AADA is poor with 50% mortality after 48 h without surgery and 17.1% mortality after 30 days with surgery [3]. In our case, the clinical picture and ECG findings were indeed suggestive of inferior myocardial infarction, and typical echocardiographic signs of AADA, such as pericardial effusion or relevant aortic regurgitation were missing. Incidence of AADA is low compared to that of ST-segment elevation myocardial infarction, but is probably underestimated [4]. The prevalence of ST-segment elevation in AADA is 3.2% [5], and fast rule-out echocardiography in patients with ST-segment elevation in inferior leads is useful [6] and allowed by current guidelines, as long as it does not delay angiography [1, 7]. The present case prototypically illustrates fatal AADA and reminds us of considering AADA in cases of chest pain and ST-segment elevation in inferior leads, and further points to the eminent role of computed tomography in cases of successful resuscitation for OHCA [1]. clinical cardiology