RegressionExplorer: Interactive Exploration of Logistic Regression Models with Subgroup Analysis.

We present RegressionExplorer, a Visual Analytics tool for the interactive exploration of logistic regression models. Our application domain is Clinical Biostatistics, where models are derived from patient data with the aim to obtain clinically meaningful insights and consequences. Development and interpretation of a proper model requires domain expertise and insight into model characteristics. Because of time constraints, often a limited number of candidate models is evaluated. RegressionExplorer enables experts to quickly generate, evaluate, and compare many different models, taking the workflow for model development as starting point. Global patterns in parameter values of candidate models can be explored effectively. In addition, experts are enabled to compare candidate models across multiple subpopulations. The insights obtained can be used to formulate new hypotheses or to steer model development. The effectiveness of the tool is demonstrated for two uses cases: prediction of a cardiac conduction disorder in patients after receiving a heart valve implant and prediction of hypernatremia in critically ill patients.

Intracoronary hypothermia for acute myocardial infarction in the isolated beating pig heart.

Hypothermia may attenuate reperfusion injury and thereby improve acute myocardial infarction therapy. Systemic cooling trials failed to reduce infarct size, perhaps because the target temperature was not reached fast enough. The use of selective intracoronary hypothermia combined with intracoronary temperature monitoring allows for titrating to target temperature and optimizing the cooling rate. We aimed to the test the feasibility of intracoronary cooling for controlled, selective myocardial hypothermia in an isolated beating pig heart. In five porcine hearts the left anterior descending artery (LAD) was occluded by an over-the-wire balloon (OTWB). After occlusion, saline at 22°C was infused through the OTWB lumen for 5 minutes into the infarct area at a rate of 30 ml/min. Thereafter the balloon was deflated but infusion continued with saline at 4°C for 5 minutes. Distal coronary temperature was continuously monitored by a pressure/temperature guidewire. Myocardial temperature at several locations in the infarct and control areas was recorded using needle thermistors. In the occlusion phase, coronary temperature decreased by 11.4°C (range 9.4-12.5°C). Myocardial temperature throughout the infarct area decreased by 5.1°C (range 1.8-8.1°C) within three minutes. During the reperfusion phase, coronary temperature decreased by 6.2°C (range 4.1-10.3°C) and myocardial temperature decreased by 4.5°C (range 1.5-7.4°C). Myocardial temperature outside the infarct area was not affected. In the isolated beating pig heart with acute occlusion of the LAD, we were able to rapidly "induce, maintain, and control" a stable intracoronary and myocardial target temperature of at least 4°C below body temperature without side effects and using standard PCI equipment, justifying further studies of this technique in humans.

Long-term comparison of sirolimus-eluting and bare-metal stents in ST-segment elevation myocardial infarction.

OBJECTIVES: We aimed to investigate, in patients with ST-segment elevation myocardial infarction (STEMI), whether the previously reported clinical benefits of sirolimus-eluting stent(s) (SES) in terms of reducing a major adverse cardiac and cerebrovascular event (MACCE) compared with bare-metal stent(s) (BMS) were maintained over a 5-year time period. BACKGROUND: In the prospective single-centre randomized DEBATER trial, SES significantly reduced the rate of MACCE in STEMI patients within 1 year compared with BMS, mainly driven by a reduction of target lesion revascularization. Randomized data on the long-term safety and efficacy of SES in STEMI patients are conflicting and limited. PATIENTS AND METHODS: Between January 2006 and May 2008, a total of 907 STEMI patients were randomized to receive SES or BMS. The primary endpoint was MACCE defined as the composite of death, myocardial infarction, stroke, repeat revascularization and bleeding. Five-year follow-up data were collected by reviewing hospital records, telephone calls and a written questionnaire. RESULTS: At 5 years, the rate of MACCE between the SES group and the BMS group was no longer significantly different (33.3 vs. 39.3%, P=0.12). The cumulative incidence of death and myocardial infarction was similar in both groups (11.0 vs. 9.7%, P=0.51). Repeat revascularization was performed in 21.1 and 25.8% of patients, respectively (P=0.12). The rate of very late stent thrombosis (1-5 years of follow-up) was very low in both groups (2.0 vs. 0.7%, P=0.12). CONCLUSION: The benefits of SES in STEMI patients in terms of reducing MACCE faded over time. We found no safety concerns in terms of SES in the long term, with extremely low rates of very late stent thrombosis.

New image processing and noise reduction technology allows reduction of radiation exposure in complex electrophysiologic interventions while maintaining optimal image quality: a randomized clinical trial.

BACKGROUND: Despite their carcinogenic potential, X-rays remain indispensable for electrophysiologic (EP) procedures. OBJECTIVE: The purpose of this study was to evaluate the dose reduction and image quality of a novel X-ray technology using advanced image processing and dose reduction technology in an EP laboratory. METHODS: In this single-center, randomized, unblinded, parallel controlled trial, consecutive patients undergoing catheter ablation for complex arrhythmias were eligible. The Philips Allura FD20 system allows switching between the reference (Allura Xper) and the novel X-ray imaging technology (Allura Clarity). Primary end-point was overall procedural patient dose, expressed in dose area product (DAP) and air kerma (AK). Operator dose, procedural success, and necessity to switch to higher dose settings were secondary end-points. RESULTS: A total of 136 patients were randomly assigned to the novel imaging group (n = 68) or the reference group (n = 68). Baseline characteristics were similar, except patients in the novel imaging group were younger (58 vs 65 years, P < .01). Median DAP and AK were 43% and 40% lower in the novel imaging group, respectively (P < .0001). A 50% operator dose reduction was achieved in the novel imaging group (P < .001). Fluoroscopy time, number of exposure frames, and procedure duration were equivalent between the two groups, indicating that the image quality was similarly adequate in both groups. Procedural success was achieved in 91% of patients in both groups; one pericardial tamponade occurred in the novel imaging group. CONCLUSION: The novel imaging technology, Allura Clarity, significantly reduces patient and operator dose in complex EP procedures while maintaining image quality.