ABSTRACT
Objective Fractional flow reserve (FFR) using adenosine has been the gold standard in the functional assessment of intermediate coronary stenoses in the catheterization laboratory. We aim to study the correlation of adenosine-free indices such as whole cycle Pd/Pa [the ratio of mean distal coronary pressure (Pd) to the mean pressure observed in the aorta (Pa)], instantaneous wave-free ratio (iFR), and contrast-induced submaximal hyperemia (cFFR) with FFR. Methods This multicenter, prospective, observational study included patients with stable angina or acute coronary syndrome (>48 h since onset) with discrete intermediate coronary lesions (40–70% diameter stenosis). All patients underwent assessment of whole cycle Pd/Pa, iFR, cFFR, and FFR. We then evaluated the correlation of these indices with FFR and assessed the diagnostic efficiencies of them against FFR ≤0.80. Results Of the 103 patients from three different centers, 83 lesions were included for analysis. The correlation coefficient (r value) of whole cycle Pd/Pa, iFR, and cFFR in relation to FFR were +0.84, +0.77, and +0.70 (all p values < 0.001), respectively, and the c-statistic against FFR ≤0.80 were 0.92 (0.86–0.98), 0.89(0.81–0.97), and 0.91 (0.85–0.97) (all p values < 0.001), respectively. The best cut-off values identified by receiver–operator characteristic curve for whole cycle Pd/Pa, iFR, and cFFR were 0.94, 0.90, and 0.88, respectively, for an FFR ≤0.80. By the concept of “adenosine-free zone” (iFR = 0.86–0.93), 59% lesions in this study would not require adenosine. Conclusion All the three adenosine-free indices had good correlation with FFR. There is no difference in the diagnostic accuracies among the indices in functional evaluation of discrete intermediate coronary stenoses. However, further validation is needed before adoption of adenosine-free pressure parameters into clinical practice.
ABSTRACT
Background Heart rate (HR) reduction is of benefit in chronic heart failure (HF). The effect of heart rate reduction using Ivabradine on various echocardiographic parameters in dilated cardiomyopathy has been less investigated. Methods Of 187 patients with HF (DCM, NYHA II–IV, baseline HR > 70/min), 125 patients were randomized to standard therapy (beta blockers, ACEI, diuretics, n = 62) or add-on Ivabradine (titrated to maximum 7.5 mg BD, n = 63). Beta-blockers were titrated in both the groups. Results At 3 months both groups had improvement in NYHA class, 6 min walk test, Minnesota Living With Heart Failure (MLWHF) scores and fall in BNP, however the magnitude of change was greater in Ivabradine group. Those on Ivabradine also had lower LV volumes, higher LVEF (28.8 ± 3.6 vs 27.2 ± 0.5, p = 0.01) and more favorable LV global strain (11 ± 1.7vs 12.2 ± 1.1, p = <0.001), MPI (0.72 ± 0.1 vs 0.6 ± 0.1, p = <0.001), LV mass (115.2 ± 30 vs 131.4 ± 35, p = 0.007), LV wall stress (219.8 ± 46 vs 238 ± 54) and calculated LV work (366 ± 101 vs 401 ± 102, p = 0.05). The benefit of Ivabradine was sustained at 6 months follow up. The % change in HR was significantly higher in Ivabradine group (−32.2% vs −19.3%, p = 0.001) with no difference in blood pressure. Resting HR < 70/min was achieved in 96.8% vs 27.9%, respectively in the two groups. Conclusion Addition of Ivabradine to standard therapy in patients with DCM and symptomatic HF and targeting a heart rate < 70/min improves symptoms, quality of life and various echocardiographic parameters.