BACKGROUNDThe instantaneous wave-free ratio (iFR) is an index used to assess the severity of coronary-artery stenosis. The index has been tested against fractional flow reserve (FFR) in small trials, and the two measures have been found to have similar diagnostic accuracy. However, studies of clinical outcomes associated with the use of iFR are lacking. We aimed to evaluate whether iFR is noninferior to FFR with respect to the rate of subsequent major adverse cardiac events.
METHODSWe conducted a multicenter, randomized, controlled, open-label clinical trial using the Swedish Coronary Angiography and Angioplasty Registry for enrollment. A total of 2037 participants with stable angina or an acute coronary syndrome who had an indication for physiologically guided assessment of coronary-artery stenosis were randomly assigned to undergo revascularization guided by either iFR or FFR. The primary end point was the rate of a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization within 12 months after the procedure.
RESULTSA primary end-point event occurred in 68 of 1012 patients (6.7%) in the iFR group and in 61 of 1007 (6.1%) in the FFR group (difference in event rates, 0.7 percentage points; 95% confidence interval [CI], −1.5 to 2.8; P = 0.007 for noninferiority; hazard ratio, 1.12; 95% CI, 0.79 to 1.58; P = 0.53); the upper limit of the 95% confidence interval for the difference in event rates fell within the prespecified noninferiority margin of 3.2 percentage points. The results were similar among major subgroups. The rates of myocardial infarction, target-lesion revascularization, restenosis, and stent thrombosis did not differ significantly between the two groups. A significantly higher proportion of patients in the FFR group than in the iFR group reported chest discomfort during the procedure.
CONCLUSIONSAmong patients with stable angina or an acute coronary syndrome, an iFR-guided revascularization strategy was noninferior to an FFR-guided revascularization strategy with respect to the rate of major adverse cardiac events at 12 months. (Funded by Philips Volcano; iFR SWEDEHEART ClinicalTrials.gov number, NCT02166736.) a bs tr ac t
Overall, deferral of revascularization is equally safe with both iFR and FFR, with a low MACE rate of about 4%. Lesions were more frequently deferred when iFR was used to assess physiological significance. In deferred patients presenting with ACS, the event rate was significantly increased compared with SAP at 1 year.
A B S T R A C T We have investigated the relationship between pulmonary artery occlusion (PAO) and the surfactant system of the lung by studying the ultrastructural responses of type II alveolar pneumocytes to PAO of 4-12 h duration in 16 mongrel dogs. In six of these animals, the occluded lung was allowed to reperfuse for 6 h before killing and in four animals subjected to PAO of 4 h duration, the occluded lung was ventilated with 5% CO2 balance air. PAO by itself resulted in a dramatic 80% reduction in the volumetric density of lamellar bodies (LB) in the type II cells. This resulted predominantly from a decrease in volume of the individual LB. Although reperfusion was associated with an increase in LB volume density toward normal, 6 h of reperfusion was insufficient to re-establish normal type II cellular morphology. Ventilation of the occluded lung with 5% CO2 prevented LB depletion indicating that alveolar CO2 tension may affect the release and/or synthesis of LB in type II pneumocytes.
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