Value of routine investigations to predict loop diuretic down-titration success in stable heart failure.

AIMS: Guidelines advocate down-titration of loop diuretics in chronic heart failure (CHF) when patients have no signs of volume overload. Limited data are available on the expected success rate of this practice or how routine diagnostic tests might help steering this process. METHODS AND RESULTS: Fifty ambulatory CHF-patients on stable neurohumoral blocker/diuretic therapy for at least 3months without any clinical sign of volume overload were prospectively included to undergo loop diuretic down-titration. All patients underwent a similar pre-down-titration evaluation consisting of a dyspnea scoring, physical examination, transthoracic echocardiography (diastolic function, right ventricular function, cardiac filling pressures and valvular disease), blood sample (serum creatinine, plasma NT-pro-BNP and neurohormones). Loop diuretic maintenance dose was subsequently reduced by 50% or stopped if dose was ≤40mg furosemide equivalents. Successful down-titration was defined as a persistent dose reduction after 30days without weight increase >1.5kg or new-onset symptoms of worsening heart failure. At 30-day follow-up, down-titration was successful in 62% (n=31). In 12/19 patients exhibiting down-titration failure, this occurred within the first week. Physical examination, transthoracic echocardiography and laboratory analysis had limited predictive capability to detect patients with down-titration success/failure (positive likelihood-ratios below 1.5, or area under the curve [AUC] non-statically different from AUC=0.5). CONCLUSION: Loop diuretic down-titration is feasible in a majority of stable CHF patients in which the treating clinician felt continuation of loops was unnecessary to sustain euvolemia. Importantly, routine diagnostics which suggest euvolemia, have limited diagnostic impact on the post-test probability.

Loop diuretic down-titration in stable chronic heart failure is often achievable, especially when urinary chloride concentration is low.

BACKGROUND: This study investigates spot urinary chloride concentration in euvolemic chronic heart failure (CHF) patients. METHODS: This prospective cohort study included 50 ambulatory CHF patients on maintenance loop diuretics without recent hospital admission, clinical signs of volume overload, or adjustment in neurohumoral blocker or diuretic therapy. Spot urinary samples were collected immediately after loop diuretic intake. Subsequently, loop diuretic dose was reduced with 50% or stopped if ≤40 mg furosemide equivalents. Successful down-titration was defined as persistent dose reduction after 7 d without body weight increase >1.5 kg. RESULTS: Urinary chloride concentration was 3045 ± 1271 mg/L overall. Patients with higher versus lower urinary chloride concentrations took the same dose of loop diuretics [40 mg (20-40 mg) furosemide equivalents; p value = .509] and had similar plasma NT-proBNP levels [1179 ng/L (311-2195 ng/L) versus 900 ng/L (255-1622 ng/L), respectively; p value = .461]. Down-titration was successful in 72% versus 76%, respectively (p value = 1.000). At 30 d, loop diuretic dose remained reduced in 59% versus 76% of patients, respectively (p value = .238). The proportion of patients free from diuretic therapy was 45% versus 62% in the high versus low chloride concentration group (p value = .265). CONCLUSIONS: Loop diuretic down-titration was successful in 3 out of 4 euvolemic CHF patients, irrespectively of urinary chloride concentration on spot samples collected after diuretic intake.

Comparison of LDPI to SPECT perfusion imaging using (99m)Tc-sestamibi and (99m)Tc-pyrophosphate in a murine ischemic hind limb model of neovascularization.

BACKGROUND: We aimed to determine the accuracy of laser Doppler perfusion imaging (LDPI) in an animal model for hind limb ischemia. METHODS: We used a murine (C57Bl/6 mice) ischemic hind limb model in which we compared LDPI with the clinically used (99m)Tc-sestamibi SPECT perfusion imaging (n = 7). In addition, we used the SPECT tracer (99m)Tc-pyrophosphate ((99m)Tc-PyP) to image muscular damage (n = 6). RESULTS: LDPI indicated a quick and prominent decrease in perfusion immediately after ligation, subsequently recovering to 21.9 and 25.2 % 14 days later in the (99m)Tc-sestamibi and (99m)Tc-PyP group, respectively. (99m)Tc-sestamibi SPECT scans also showed a quick decrease in perfusion. However, nearly full recovery was reached 7 days post ligation. Muscular damage, indicated by the uptake of (99m)Tc-PyP, was highest at day 3 and recovered to baseline levels at day 14 post ligation. Postmortem histology supported these findings, as a significantly increased collateral diameter was found 7 and 14 days after ligation and peak macrophage infiltration and TUNEL positivity was found on day 3 after ligation. CONCLUSIONS: Here, we indicate that LDPI strongly underestimates perfusion recovery in a hind limb model for profound ischemia.