Contrast FFR plus intracoronary injection of nitro-glycerine accurately predicts FFR for coronary stenosis functional assessment.

BACKGROUND: Fractional flow reserve (FFR) is the "gold standard" for assessing the physiological significance of coronary disease. In the last decade, several alternative adenosine-free indexes have been proposed in order to facilitate the dissemination of the functional evaluation of coronary stenosis. Our aim was to investigate whether radiographic contrast plus intracoronary nitroglycerin (cFFR-NTG) can predict functional assessment of coronary stenosis offering superior diagnostic agreement with FFR compared to non-hyperemic indexes and contrast mediated FFR (cFFR). METHODS: Three hundred twenty-nine lesions evaluated with pressure wire in 266 patients were prospectively included in this multicenter study. RESULTS: The ROC curves for cFFR-NTG using an FFR≤0.80 showed a higher accuracy in predicting FFR (AUC=0.97) than resting Pd/Pa (AUC=0.90, P<0.01) and cFFR (AUC=0.93.5, P<0.01). A significant (P<0.01) strong correlation was found between FFR and the four analyzed indexes: Pd/Pa (r=0.78); iFR/RFR (r=0.73); cFFR(r=0.89) and cFFR-NTG (r=0.93). cFFR-NTG showed the closest agreement at Bland-Altman analysis. The cFFR-NTG cut off value >0.84 showed the highest negative predictive value (88%), specificity (91%), sensitivity (94%) and accuracy (92%) of the studied indexes. CONCLUSIONS: Submaximal hyperemic adenosine-free indexes are an efficient alternative to adenosine for the physiological assessment of epicardial coronary disease. The most accurate index in predicting the functional significance of coronary stenosis using FFR as reference was cFFR-NTG.

Invasive assessment of coronary flow reserve impairment in severe aortic stenosis and ecochadiographic correlations.

OBJECTIVES AND BACKGROUND: Patients with aortic stenosis (AS) may have impaired coronary flow reserve (CFR) despite angiographically normal coronary arteries. This is the first report of invasive thermodilution-derived CFR and IMR in patients with AS and their associations with echocardiographic parameters for AS assessment. METHODS: Thirty-six consecutive severe AS patients and ten patients without AS underwent prospectively cardiac catheterization and coronary physiological parameters were determined in the left anterior descending (LAD). Mean transit time (Tmn), a surrogate of absolute coronary flow, was obtained from the coronary thermodilution curve. RESULTS: In AS patients we found a high LAD flow at rest (Tmn rest 0.55±0.3 vs 0.99±0.4, p=0.01) and a low flow at hyperemia (Tmnhyp 0.44±0.2 vs 27.7±0.1, p=0.02) and consequently a severe CFR impairment (1.4±0.4 vs 3.8±1.4, p<0.001) compared with controls. An elevated index of microvascular resistance (IMR) (32.7±16 vs 17.8±6.5, p=0.01) and a low baseline microvascular coronary resistance (48.1±29 vs 84±34, p=0.02) were also found. In AS patients there were significant correlations between CFR and left ventricular mass index (r=-0.32; p=0.02), and the ratio of acceleration time to ejection time (AT/ET) (r=-0.4; p=0.01) a non-flow dependent echocardiographic parameter for AS assessment. Multiple linear stepwise regression analysis showed that AT/ET (ß=-0.441, p=0.019) was the only independently variable associated with CFR CONCLUSIONS: In severe AS, invasive CFR shows a progressive decrease with AS severity and a good correlation with echocardiographic parameters of AS, especially with flow-independent ones.

Invasive assessment of coronary microvascular dysfunction in hypertrophic cardiomyopathy: the index of microvascular resistance.

We present a review of microvascular dysfunction in hypertrophic cardiomyopathy (HCM) and an interesting case of a symptomatic familial HCM patient with inducible ischemia by single photon emission computed tomography. Coronary angiography revealed normal epicardial arteries. Pressure wire measurements of fractional flow reserve (FFR), coronary flow reserve (CFR) and index of microvascular resistance (IMR) demonstrated a significant microcirculatory dysfunction. This is the first such case that documents this abnormality invasively using the IMR. The measurement of IMR, a novel marker of microcirculatory dysfunction, provides novel insights into the pathophysiology of this condition.