Instantaneous wave-free ratio compared with fractional flow reserve in PCI: A cost-minimization analysis.

BACKGROUND: Coronary physiology is a routine diagnostic tool when assessing whether coronary revascularization is indicated. The iFR-SWEDEHEART trial demonstrated similar clinical outcomes when using instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) to guide revascularization. The objective of this analysis was to assess a cost-minimization analysis of iFR-guided compared with FFR-guided revascularization. METHODS: In this cost-minimization analysis we used a decision-tree model from a healthcare perspective with a time-horizon of one year to estimate the cost difference between iFR and FFR in a Nordic setting and a United States (US) setting. Treatment pathways and health care utilizations were constructed from the iFR-SWEDEHEART trial. Unit cost for revascularization and myocardial infarction in the Nordic setting and US setting were derived from the Nordic diagnosis-related group versus Medicare cost data. Unit cost of intravenous adenosine administration and cost per stent placed were based on the average costs from the enrolled centers in the iFR-SWEDEHEART trial. Deterministic and probabilistic sensitivity analyses were carried out to test the robustness of the result. RESULTS: The cost-minimization analysis demonstrated a cost saving per patient of $681 (95% CI: $641 - $723) in the Nordic setting and $1024 (95% CI: $934 - $1114) in the US setting, when using iFR-guided compared with FFR-guided revascularization. The results were not sensitive to changes in uncertain parameters or assumptions. CONCLUSIONS: IFR-guided revascularization is associated with significant savings in cost compared with FFR-guided revascularization.

Quantitative flow ratio for immediate assessment of nonculprit lesions in patients with ST-segment elevation myocardial infarction-An iSTEMI substudy.

OBJECTIVES: We evaluated the diagnostic performance of quantitative flow ratio (QFR) assessment of nonculprit lesions (NCLs) based on acute setting angiograms obtained in patients with ST-segment elevation myocardial infarction (STEMI) with QFR, fractional flow reserve (FFR), and instantaneous wave-free ratio (iFR) in the staged setting as reference. BACKGROUND: QFR is an angiography-based approach for the functional evaluation of coronary artery lesions. METHODS: This was a post-hoc analysis of the iSTEMI study. NCLs were assessed with iFR in the acute setting and with iFR and FFR at staged (median 13 days) follow-up. Acute and staged QFR values were computed in a core laboratory based on the coronary angiography recordings. Diagnostic cut-off values were ≤0.80 for QFR and FFR, and ≤0.89 for iFR. RESULTS: Staged iFR and FFR data were available for 146 NCLs in 112 patients in the iSTEMI study. Among these, QFR analysis was feasible in 103 (71%) lesions assessed in the acute setting with a mean QFR value of 0.82 (IQR: 0.73-0.91). Staged QFR, FFR, and iFR were 0.80 (IQR: 0.70-0.90), 0.81 (IQR: 0.71-0.88), and 0.91 (IQR: 0.87-0.96), respectively. Classification agreement of acute and staged QFR was 93% (95%Cl: 87-99). The classification agreement of acute QFR was 84% (95%CI: 76-90) using staged FFR as reference and 74% (95%CI: 65-83) using staged iFR as reference. CONCLUSIONS: Acute QFR showed a very good diagnostic performance with staged QFR as reference, a good diagnostic performance with staged FFR as reference, and a moderate diagnostic performance with staged iFR as reference.

Assessment of increasing intravenous adenosine dose in fractional flow reserve.

BACKGROUND: Effects of increased adenosine dose in the assessment of fractional flow reserve (FFR) were studied in relation to FFR results, hemodynamic effects and patient discomfort. FFR require maximal hyperemia mediated by adenosine. Standard dose is 140 µg/kg/min administrated intravenously. Higher doses are commonly used in clinical practice, but an extensive comparison between standard intravenous dose and a high dose (220 µg/kg/min) has previously not been performed. METHODS: Seventy-five patients undergoing FFR received standard dose adenosine, followed by high dose adenosine. FFR, mean arterial pressure (MAP) and heart rate (HR) were analyzed. Patient discomfort measured by Visual Analogue Scale (VAS) was assessed. RESULTS: No significant difference was found between the doses in FFR value (0.85 [0.79-0.90] vs 0.85 [0.79-0.89], p = 0.24). The two doses correlated well irrespective of lesion severity (r = 0.86, slope = 0.89, p = <0.001). There were no differences in MAP or HR. Patient discomfort was more pronounced using high dose adenosine (8.0 [5.0-9.0]) versus standard dose (5.0 [2.0-7.0]), p = <0.001. CONCLUSIONS: Increased dose adenosine does not improve hyperemia and is associated with increased patient discomfort. Our findings do not support the use of high dose adenosine. TRIAL REGISTRATION: Retrospective Trial registration: Current Controlled Trials ISRCTN14618196 . Registered 15 December 2016.

Safety, Feasibility, and Hemodynamic Effects of Mild Hypothermia in Transcatheter Aortic Valve Replacement: The TAVR-CHILL Trial.

The safety, feasibility, and hemodynamic effects of mild hypothermia (MH) induced by transnasal cooling were studied in transcatheter aortic valve replacement (TAVR). MH is a common therapy following cardiac arrest and seems to have favorable effects in myocardial infarction and on hemodynamic stability. In TAVR, hemodynamic instability is common during rapid pacing. Twenty subjects undergoing TAVR were randomized 1:1 to hypothermia or normothermia. Hemodynamic endpoints were mean arterial blood pressure and required dosage of vasoactive and inotropic drugs. Patients were followed up at 6 months. All patients in the MH group (n=10) reached the target temperature of 34°C before first rapid pacing. Tympanic and urinary bladder temperature remained significantly lower in the MH group during the procedure. No adverse effects of cooling were observed. Mean arterial pressure was higher in the MH group (90±20 mm Hg) than in the control group (71±13 mm Hg) at the start of the procedure, at first rapid pacing (94±19 vs. 80±16 mm Hg), and at balloon aortic valvuloplasty (90±17 vs. 73±14 mm Hg). Less norepinephrine was administered to the hypothermia group. Transnasal cooling during TAVR was safe and well tolerated. We observed a more stable hemodynamic profile in the MH group, indicated by higher blood pressure and lower levels of vasoactive drugs required. A larger study of patients with severe ventricular dysfunction is required to more comprehensively investigate the hemodynamic effects of transnasal cooling in TAVR.