Research Appraisals
Evidence-based critical appraisals of the latest medical research, systematically evaluated using Oxford CEBM methodology.
Showing 3 appraisals
The Journal of clinical endocrinology and metabolism
The effects of glucose-dependent insulinotropic polypeptide on net splanchnic blood flow in lean humans.
CONTEXT: Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone with potent vasoactive and metabolic effects in adipose tissue, but its effects on splanchnic blood flow (SBF) in humans remain unclear. Investigating potential regional differences is important for understanding the vascular actions of GIP in humans. OBJECTIVE: The aim of this study was to examine the effects of GIP on SBF, both independently and in combination with hyperglycemia and hyperinsulinemia. METHODS: In a randomized, controlled crossover study, 8 healthy, lean male participants underwent 4 separate experimental conditions. The interventions included intravenous infusions of either GIP at a rate of 1.5 pmol-1 kg-1 minute-1 or saline, administered alone or in combination with a hyperglycemic and hyperinsulinemic clamp, respectively. Splanchnic blood flow was measured by Fick's Principle after catheterization of a hepatic vein, using indocyanine green as indicator. RESULTS: Splanchnic blood flow remained comparable across all experimental conditions, including GIP and saline infusions, both with and without the hyperglycemic and hyperinsulinemic clamp (P = .42). CONCLUSION: Under the applied conditions, GIP does not appear to play a substantial role in the acute regulation of net SBF, either alone or in combination with induced hyperglycemia and hyperinsulinemia.
17 July 2026
Read appraisal →Circulation
Determining the Physiological Threshold for Angina (ORBITA-FIRE): A Double-Blind, Randomized, Placebo-Controlled Study
BACKGROUND: In stable coronary artery disease, the primary goal of percutaneous coronary intervention (PCI) is symptom relief. Fractional flow reserve (FFR) and nonhyperemic pressure ratios such as resting full-cycle ratio (RFR) are used to guide revascularization. Although these indices correlate with myocardial ischemia, they have never been validated against the onset of angina. The physiological thresholds for angina, FFRangina and RFRangina, angina (FFRangina at rest and during exercise remain undefined. METHODS: ORBITA-FIRE (Finding the Invasive Threshold for Symptom Relief in Exertional Angina) was a multicenter, double-blind, randomized, placebo-controlled study in patients with stable angina and single-vessel coronary artery disease. After imaging-guided PCI, an in-stent balloon was incrementally inflated until angina occurred at rest. This angina threshold was verified against placebo inflation, and corresponding FFRangina and RFRangina values were recorded at symptom onset. The protocol was repeated during low- and high-intensity exercise to assess changes in angina thresholds with increasing cardiac workload. RESULTS: Sixty-five patients were enrolled (mean age, 63.9±8.7 years; 74% male; 69% hypertensive; 23% diabetic; 91% with Canadian Cardiovascular Society class II-III angina). Median pre-PCI FFR was 0.59 (interquartile range [IQR], 0.46-0.70) and RFR was 0.61 (IQR, 0.40-0.82). Median FFRangina at rest was 0.29 (IQR, 0.23-0.35), increasing to 0.38 (IQR, 0.30-0.48) during low-intensity exercise and 0.45 (IQR, 0.36-0.55) during high-intensity exercise. RFRangina similarly increased from 0.22 (IQR, 0.16-0.30) at rest to 0.26 (IQR, 0.18-0.36) and 0.32 (IQR, 0.23-0.46) during low- and high-intensity exercise. All thresholds were significantly lower than clinical diagnostic cut points (P<0.001). Lower FFRangina and RFRangina thresholds were associated with greater symptom reproducibility across rest, low- and high-intensity exercise conditions (FFRangina: P=0.008, P<0.001, P<0.001, respectively; RFRangina: P=0.015, P<0.001, P=0.002, respectively). Lower angina thresholds across all conditions predicted higher baseline angina burden and greater symptom relief with PCI (probability of interaction >0.999). CONCLUSIONS: Physiological thresholds for angina, FFRangina and RFRangina, are highly individualized, vary with cardiac workload, and are consistently lower than the universal ischemia-based thresholds used to guide revascularization. These findings support integrating personalized, symptom-linked physiology to refine patient selection and to improve symptomatic response to PCI.
9 June 2026
Read appraisal →Nature communications
Measuring multi-site pulse transit time with an AI-enabled mmWave radar
Pulse Transit Time (PTT) is a measure of arterial stiffness and a physiological marker associated with cardiovascular function, with an inverse relationship to diastolic blood pressure (DBP). We present an AI-enabled mmWave system for contactless multi-site PTT measurement using a single radar. By leveraging radar beamforming and deep learning algorithms our system simultaneously measures PTT and estimates diastolic blood pressure at multiple sites. The system was evaluated across three physiological pathways - heart-to-radial artery, heart-to-carotid artery, and mastoid area-to-radial artery - achieving correlation coefficients of 0.75-0.86 compared to contact-based reference sensors for measuring PTT. Furthermore, the system demonstrated correlation coefficients of 0.90-0.91 for estimating DBP, and achieved a mean error of -0.62-0.06 mmHg and standard deviation of 4.54-5.20 mmHg, meeting the FDA's AAMI guidelines for non-invasive blood pressure monitors. These results suggest that our proposed system has the potential to provide a non-invasive measure of cardiovascular health across multiple regions of the body.
27 May 2026
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