Modification of ventriculo-arterial coupling by spironolactone in nonischemic dilated cardiomyopathy

Aims

We sought to clarify the role of ventriculo–arterial (V–A) coupling in the treatment of nonischemic dilated cardiomyopathy (NIDCM) by adding a mineralocorticoid receptor antagonist (MRA) to conventional anti‐failure therapy.

Methods and results

We employed cardiac magnetic resonance imaging to quantify left ventricular (LV) contractility and V–A coupling in normal subjects at rest (n = 11) and in patients with NIDCM (n = 12) before and after long term anti‐failure therapy, in which MRA was added to conventional anti‐failure therapy. After ≥6 months' treatment in NIDCM patients, LV volumes and mass decreased, and the LV ejection fraction increased from a median of 24% (17, 27) (interquartile range IQR) to 47 (42, 52) (P < 0.002), with a marked reduction in arterial elastance (Ea) from 2.89 mmHg/mL (2.34, 4.0) to 1.50 (1.29, 1.95) (P < 0.002), similar to Ea of normal subjects, 1.53 (1.34, 1.67) (P > 0.05). The V–A coupling ratio, Ea/end‐systolic elastance (single‐beat method), decreased by −1.08 (−1.96, −0.55), (P = 0.003), as did Ea/end‐systolic pressure/end‐systolic pressure ratio, −0.54 (0.35, 0.87), (P = 0.002). The preload recruitable stroke work (PRSW) increased as did PRSW indexed for Ea (both P = 0.002), which reflected ‘total circulatory performance’.

Conclusions

In NIDCM, adding MRA to conventional anti‐failure therapy markedly improved LV ejection fraction and reduced peripheral vascular resistance, due to both improved LV contractility and especially to enhanced V–A coupling, as Ea decreased to normal. Total circulatory performance was a sensitive indicator of both LV pump performance and the arterial loading conditions.

Timing of Left Ventricular Remodeling in Nonischemic Dilated Cardiomyopathy

BACKGROUND

Mineralocorticoid receptor antagonist (MRA) treatment produces beneficial left ventricular (LV) remodeling in nonischemic dilated cardiomyopathy (NIDCM). This study addressed the timing of maximal beneficial LV remodeling in NIDCM when adding MRA.

MATERIALS AND METHODS

We studied 12 patients with NIDCM on stable β-blocker and angiotensin-converting enzyme inhibitor/angiotensin receptor-blocking therapy who underwent cardiac magnetic resonance imaging before and after 6-31 months of continuous MRA therapy.

RESULTS

At baseline, the LV ejection fraction (LVEF) was 24% (19-27); median [interquartile range]. The LV end-systolic volume index (LVESVI) was 63 ml (57-76) and the LV stroke volume index (LVSVI) was 19 ml (14-21), all depressed. After adding MRA to the HF regimen, the LVEF increased to 47% (42-52), with a decrease in LVESVI to 36 ml (33-45) and increase in LVSVI to 36 ml (28-39) (for each, P  < 0 .0001). Using generalized least squares analysis, the maximal beneficial remodeling (defined by maximal increase in LVEF, the maximal decrease in LVESVI and maximal increase in LVSVI) was achieved after approximately 12-16 months of MRA treatment.

CONCLUSIONS

Adding MRA to a standard medical regimen for NIDCM resulted in beneficial LV remodeling. The maximal beneficial remodeling was achieved with 12-16 months of MRA therapy. These results have implications for the timing of other advanced therapies, such as placing internal cardioverter-defibrillators.

High reproducibility of adenosine stress cardiac MR myocardial perfusion imaging in patients with non-ischaemic dilated cardiomyopathy

OBJECTIVE

To evaluate the reproducibility of first-pass contrast-enhanced cardiac MR (CMR) myocardial perfusion imaging in patients with non-ischaemic dilated cardiomyopathy (NIDCM).

DESIGN

Prospective observational study.

SETTING

Single centre, tertiary care hospital.

PARTICIPANTS

6 outpatient participants with NIDCM.

OUTCOME

Reproducibility of semiquantitative myocardial perfusion analysis by CMR.

METHOD

6 patients with NIDCM were studied twice using first-pass of contrast transit through the left ventricular (LV) myocardium with a saturation-recovery gradient echo sequence at rest and during adenosine-induced hyperaemia. The anterior wall was divided into endocardial (Endo) and epicardial (Epi) segments. The Myocardial Perfusion Index (MPI) was calculated as the myocardial signal augmentation rate normalised to the LV cavity rate. The Myocardial Perfusion Reserve Index (MPRI) was calculated as hyperaemic/resting MPI.

RESULTS

Between study 1 and 2, median MPI was similar for resting Endo (0.076 vs 0.077), hyperaemic Endo (0.143 vs 0.143), resting Epi (0.073 vs 0.074), and hyperaemic Epi (0.135 vs 0.134). Median MPRI was similar for Endo (1.84 vs 1.87) and Epi (1.90 vs 2.00). Combining Endo and Epi MPI (N=12), there was excellent agreement between Study 1 and 2 for resting MPI (r=0.998, intraclass correlation coefficient (ICC) 0.998, coefficients of variation (CoV) 1.4%), hyperaemic MPI (r=0.979, ICC 0.963, CoV 3.3%) and MPRI (r=0.989, ICC 0.94, CoV 3.8%).

CONCLUSIONS

Resting and hyperaemic myocardial perfusion using a normalised upslope analysis during adenosine CMR is a highly reproducible technique in patients with NIDCM.

TRIAL REGISTRATION NUMBER

Clinical Trials.Gov ID NCT00574119.

Antifailure therapy including spironolactone improves left ventricular energy supply-demand relations in nonischemic dilated cardiomyopathy

BACKGROUND

Left ventricular (LV) energy supply-demand imbalance is postulated to cause "energy starvation" and contribute to heart failure (HF) in nonischemic dilated cardiomyopathy (NIDCM). Using cardiac magnetic resonance (CMR) and [(11)C] acetate positron emission tomography (PET), we evaluated LV perfusion and oxidative metabolism in NIDCM and the effects of spironolactone on LV supply-demand relations.

METHODS AND RESULTS

Twelve patients with NIDCM underwent CMR and PET at baseline and after ≥6 months of spironolactone therapy added to a standard HF regimen. The myocardial perfusion reserve index (MPRI) was calculated after gadolinium injection during adenosine, as compared to rest. The monoexponential clearance rate of [(11)C] acetate (kmono) was used to calculate the work metabolic index (WMI), an index of LV mechanical efficiency, and kmono/RPP (rate-pressure product), an index of energy supply/demand. At baseline, the subendocardium was hypoperfused versus the subepicardium (median MPRI, 1.63 vs. 1.80; P<0.001), but improved to 1.80 (P<0.001) after spironolactone. The WMI increased (P=0.001), as did kmono/RPP (P=0.003). These improvements were associated with reverse remodeling, increased LV ejection fraction, and decreases in LV mass and systolic wall stress (all P<0.002).

CONCLUSIONS

NIDCM is associated with subendocardial hypoperfusion and impaired myocardial oxidative metabolism, consistent with energy starvation. Antifailure therapy improves parameters of energy starvation and is associated with augmented LV performance.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov/ Unique identifier: ID NCT00574119.

Impairment of subendocardial perfusion reserve and oxidative metabolism in nonischemic dilated cardiomyopathy

BACKGROUND

Cardiac magnetic resonance (CMR) and [(11)C]acetate positron emission tomography (PET) were used to assess the hypothesis that patients with nonischemic dilated cardiomyopathy (NIDCM) have decreased subendocardial perfusion reserve and impaired oxidative metabolism, consistent with the concept of "energy starvation" in heart failure (HF).

METHODS AND RESULTS

CMR myocardial perfusion was evaluated in 13 NIDCM patients and 15 control subjects with coronary risk factors and normal myocardial perfusion. The NIDCM patients underwent [(11)C]acetate PET. The myocardial perfusion index (MPI) was calculated as the normalized rate of myocardial signal augmentation following gadolinium contrast injection. Hyperemic transmural, subendocardial, and subepicardial MPI were reduced in NIDCM compared with control subjects [0.13 vs 0.18 (P < .001), 0.13 vs 0.17 (P < .001), and 0.13 vs 0.17 (P = .008), respectively]. The subendocardial perfusion reserve was 1.59 ± 0.21 vs 1.86 ± 0.32 for the subepicardium (P = .002), demonstrating reduced perfusion reserve. The myocardial oxidative metabolic rate (kmono) per unit demand (rate-pressure product) was reduced in proportion to perfusion reserve (P = .02) CONCLUSIONS: Impaired subendocardial perfusion reserve in NIDCM confirmed results previously attained only in animal models. Impaired perfusion and impaired oxidative metabolism are consistent with subendocardial energy starvation in HF.