Optimizing the Technique for Invasive Fractional Flow Reserve to Assess Lesion-Specific Ischemia.

BACKGROUND: Invasive fractional flow reserve (FFRINV) is the standard technique for assessing myocardial ischemia. Pressure distortions and measurement location may influence FFRINV interpretation. We report a technique for performing invasive fractional flow reserve (FFRINV) by minimizing pressure distortions and identifying the proper location to measure FFRINV. METHODS: FFRINV recordings were obtained prospectively during manual hyperemic pullback in 100 normal and diseased coronary arteries with single stenosis, using 4 measurements from the terminal vessel, distal-to-the-lesion, proximal vessel, and guiding catheter. FFRINV profiles were developed by plotting FFRINV values (y-axis) and site of measurement (x-axis), stratified by stenosis severity. FFRINV≤0.8 was considered positive for lesion-specific ischemia. RESULTS: Erroneous FFRINV values were observed in 10% of vessels because of aortic pressure distortion and in 21% because of distal pressure drift; these were corrected by disengagement of the guiding catheter and re-equalization of distal pressure/aortic pressure, respectively. There were significant declines in FFRINV from the proximal to the terminal vessel in normal and stenotic coronary arteries (P<0.001). The rate of positive FFRINV was 41% when measured from the terminal vessel and 20% when measured distal-to-the-lesion (P<0.001); 41.5% of positive terminal measurements were reclassified to negative when measured distal-to-the-lesion. Measuring FFRINV 20 to 30 mm distal-to-the-lesion (rather than from the terminal vessel) can reduce errors in measurement and optimize the assessment of lesion-specific ischemia. CONCLUSIONS: Meticulous technique (disengagement of the guiding catheter, FFRINV pullback) is required to avoid erroneous FFRINV, which occur in 31% of vessels. Even with optimal technique, FFRINV values are influenced by stenosis severity and the site of pressure measurement. FFRINV values from the terminal vessel may overestimate lesion-specific ischemia, leading to unnecessary revascularization.

Outcomes of bare metal versus drug-eluting stents in allograft vasculopathy.

BACKGROUND: Because of improved outcomes with drug-eluting stents (DES), we examined angiographic and clinical outcomes of bare metal stents (BMS) vs DES for discrete lesions in chronic allograft vasculopathy. METHODS: Heart transplant patients who underwent percutaneous coronary intervention were divided into one of two groups: BMS or DES. Baseline clinical characteristics, rejection episodes and procedural details were compared. Distal arteriopathy was qualitatively compared using the Gao score. End-points included angiographic in-stent restenosis, acute coronary syndrome (ACS), ST-elevation myocardial infarction, heart failure admissions and cardiac death at 1 year. Student's t-test, chi-square test and the Mann-Whitney U-test were utilized to assess the results. Correlations were assessed using Pearson's correlation coefficient. RESULTS: Forty-two patients with 80 stents (56 DES, 24 BMS) were identified. Baseline clinical characteristics, immunosuppression regimen, cardiac risk factors, frequency of rejection and procedural details were similar. Distal arteriopathy was similar (p = 0.374), suggesting equally advanced vasculopathy. Twenty-nine patients (69%) and 46 lesions (58%) were available at 1 year for clinical and angiographic follow-up. One-year diameter stenosis (26.1 +/- 21.3% vs 31.7 +/- 38.3%; p = 0.602) and binary restenosis (22.6% vs 22.7%; p = 0.774) rates were similar for DES and BMS, respectively. There were no ST-elevation infarctions; ACS [9 (16%) vs 5 (21%) p = 0.638] and cardiac death (2 in both groups) were similar for DES and BMS, respectively. Heart failure admissions were more frequent in the DES group [18 (32%) vs 5 (21%); p = 0.016]. No clinical predictors were identified. CONCLUSIONS: In-stent stenosis, ACS and cardiac death at 1 year were similar for DES and BMS. The milieu of systemic immunosuppression in heart transplant decreases the advantages of DES in allograft vasculopathy.