Comparison of single-dose and repeated levosimendan infusion in patients with acute exacerbation of advanced heart failure

Background

Acute decompensation of chronic heart failure (HF) is a life-threatening situation with a short-term mortality of approximately 30% [1]. Intravenous positive inotropic agents play an important role in the treatment of acute decompensation in patients with systolic HF. Although traditional inotropic agents such as, β-adrenergic agonists and phosphodiesterase inhibitors appear effective for short-term improvement of symptoms, previous studies demonstrated that these agents increase morbidity and mortality by elevating intracellular cyclic adenosine monophosphate (cAMP) and calcium (Ca+2) levels [2,3]. Despite optimum traditional treatment strategies, frequent hospitalization due to acute decompensation leads to worsening of the disease [4].

Levosimendan (LS) is a Ca+2 sensitizer for the treatment of decompensated HF that increases troponin-C sensitivity against cytoplasmic Ca+2 without any modification of intracellular Ca+2 density [5]. LS’s sensitizing effect is dependent on the Ca+2 concentration, thus its affinity to cardiac myofilaments increases during systole and improves cardiac contractility [6]. During diastole, due to a decrease in the Ca+2 concentration, LS does not cause deterioration in diastolic functions [6]. LS improves cardiac contractility, increases cardiac output and stroke volume, and decreases pulmonary capillary wedge pressure, pulmonary artery pressure, and systemic and vascular resistance [7–9].

Cardiac remodelling is an important mechanism in the development and progression of HF [10]. Neurohormonal activation and proinflammatory cytokines play key roles in this process [10]. In severe HF, despite optimum medical treatment, elevated plasma brain natriuretic peptide (BNP), and interleukin levels were reported to be independent risk factors for both morbidity and mortality [11]. LS treatment decreased the BNP and interleukin levels [12]. Although previous studies displayed beneficial effects of both single-dose and repeated LS treatment on hemodynamics, symptoms, and inflammatory markers in patients with acute decompensated HF, there was no consensus on the frequency of its use. No data in the current literature exist concerning optimal dosing of LS in patients with acute decompensated HF.

In this study, we researched the impact of single-dose versus repeated LS infusion on cardiac performance, immune reaction, and neurohormonal activation in patients with acute decompensated HF.

Material and Methods

PATIENTS:

The present study included patients hospitalized at Cukurova University Faculty of Medicine Cardiology Clinic upon diagnosis of acute decompensated HF, with an ejection fraction less than 35%, and who were severely symptomatic (New York Heart Association [NYHA]-III/IV) although taking intravenous diuretic and vasodilator therapy. A total of 29 patients who met the inclusion criteria were included in the study and divided into 2 groups consecutively (1:1). A single-dose LS was given to patients in the first group and repeated LS was given to patients in the second group. The patients’ clinical conditions and echocardiographic and laboratory findings were assessed at the start of the study and at 3 days and 6 months after treatment.

The following patients were excluded from the study:

All subjects gave informed consent and the study was approved by the local ethics committee.

STUDY PROTOCOL:

LS infusion in addition to standardized treatment was performed with a loading dose of 6 μg/kg for 10 min following a 24-h infusion of 0.1 μg/kg/min. LS was readministered in the first and third months to patients in the repeated treatment group. Clinical characteristics, echocardiographic measurements, and laboratory variables prior to treatment were evaluated after 1 dose and after 6 months. Patients in group 2 were hospitalized for LS infusion at 1 and 3 months. However, patients in group 1 were assessed at an outpatient clinic during follow-up without hemodynamic monitoring. The study end-points were changes in clinical, biochemical, and echocardiographic variables at 6 month in both groups.

ECHOCARDIOGRAPHIC MEASUREMENTS:

Transthoracic echocardiographic examination was conducted on all patients using an Acuson Sequola C 256 model (Acuson Corporation, Mountain View, CA, USA) and a transducer with 3.5-mHz frequency along with ECG monitoring. All echocardiograms were performed by 2 echocardiographers blinded to the study. Examination was performed by finding convenient echocardiographic windows when the patient was in the decubitus position or lying on their left side. Left ventricular systolic and end-diastolic interior dimensions were measured from the obtained cross-sections and the left ventricular ejection fraction was calculated automatically. Moreover, left atrial systolic and end-diastolic sizes as well as septum and posterior wall thicknesses were measured from the same window. According to the Modified Simpson method, left ventricular systolic and end-diastolic volumes and ejection fraction (EF) were calculated [13].

Doppler velocity curves were recorded at a horizontal sweep speed of 100 mm/s while the patient held their breath after exhalation. An average of 3 consecutive cycles was used for the analysis. Sample volume was placed between the tips of the mitral leaflets at apical 4 chambers and left ventricular filling variants were measured by pulse wave Doppler echocardiography technique. Based on the records obtained, left ventricle diastolic early (A wave) and late (E wave) peak velocities and mitral deceleration time (DT) were measured and the E/A ratio was calculated. Isovolumetric relaxation time (IVRT) obtained by placing the sample volume of continuous wave (CW) Doppler in the left ventricle outflow tract to simultaneously display the end of aortic ejection, and the onset of mitral inflow was measured as the interval in between. Time elapsed from the point where the mitral A wave finished to a point where the mitral E wave started (a), and left ventricle ejection time (b) was measured. Difference between the 2 measurements (a−b) was considered as the total of isovolumetric contract and IVRT. The myocardial performance index was then calculated using the (a−b)/b formula.

During tissue Doppler measurements, specific attention was paid to ensuring that the ultrasonographic beams were parallel to the lateral and septal mitral annulus. Peak systolic mitral annuler (Sm), early diastolic (Em), and late diastolic (Am) velocities were measured with the sample volume placed at the junction of the LV wall and the mitral annulus of the septal and lateral myocardial segments from the 4-chamber view. The Sm velocity occurs during the ejection period, while the Em and Am velocities correspond to passive ventricular filling and atrial contraction. For assessment of left ventricular systolic function, Sm velocity was used.

Echocardiographic measurements were repeated in 5 subjects the next day by the same investigator. Additionally, transthoracic echocardiography was performed by a second observer for the same 5 patients after the first echocardiogram to assess the intra- and interobserver variability. Intraobserver and interobserver variability for lateral wall MPI were 0.03 and 0.06, respectively.

LABORATORY MEASUREMENTS OF INFLAMMATORY CYTOKINES:

Blood samples were taken from all patients from the antecubital vein for the measurement of BNP, interleukin (IL)-1β, IL-2, IL-6, and tumour necrosis factor (TNF)-α before and after LS infusion and at 6-month follow-up. The samples were collected in tubes containing EDTA, then centrifuged at 1500 rpm for a period of 5 min and stored at −40°C until needed. After dissolution of serum samples, BNP level was measured by use of the electrochemiluminescent immunoassay method using Phoenix Pharmaceuticals (Burlingame, CA, USA) commercial kits, and IL-1β, IL-2, IL-6, and TNF-α levels measured using the Biosource (Grand Island, NY, USA) commercial kit.

STATISTICAL ANALYSIS:

The study assay was performed using the SPSS 14.0 statistical software package. Continuous variations in group data are presented as means ± standard deviation. Categorical data were compared by the use of the chi-square test. Subjects’ data prior to treatment and at 3 days and 6 months post-treatment were compared using Wilcoxon’s signed-rank test. Non-parametric data are expressed as percentages. A p-value <0.05 was considered to indicate statistical significance.

Results

Our study consisted of 29 patients divided into 2 groups (mean age 60.2±7.4 years; 20 males, 9 females) with severe cardiac failure (NYHA-III/IV) who were administered a single dose or repeated dose of LS. Patient demographic characteristics are summarized in Table 1. Functional capacities of patients prior to treatment according to NYHA were similar in both groups (3.8±0.4 vs. 3.7±0.4, p=0.5). At the end of the follow-up period, a more robust recovery was observed in group 2 (Δ NYHA 1.5±0.7 vs. 0.9±0.6; p=0.03; Figure 1).

The baseline echocardiographic indices were similar in both groups. The beneficial effects of LS on left ventricular parameters such as systolic volume, ejection fraction, myocardial performance index, and Sm was evident beginning on the third day after administration of the initial dose of LS (Table 2). Left ventricular systolic volume, ejection fraction, and myocardial performance index improvement continued to 6 months only in group 2 (Table 2 and Figure 2). In addition, left ventricular end-diastolic volume decreased during follow-up only in group 2.

The patients’ baseline BNP, IL-1, IL-2, IL-6, and TNF-α concentrations were elevated in both groups (Table 3). Seventy-two hours after LS infusion, a marked decline was detected in BNP, IL-6, and TNF-α concentrations. Decreased levels of BNP, IL-6, and TNF-α remained at 6 months only in group 2.

All patients tolerated the treatment and were able to complete the infusion without adverse events. During the 6-month follow-up, no atrial fibrillation, ventricular tachycardia, or fibrillation developed and no patient died. LS infusion was shortly interrupted 11 times (20%) during infusion upon development of hypotension.

Discussion

LIMITATIONS:

The major limitation of this study was the small population size. Additionally, this was not a randomized and controlled study; no comparison was made with placebo or dobutamine. Patients in the single-dose group were not evaluated echocardiographically and biochemical measurements were not performed during the first and third months. Thus, the effects of repeated LS on biochemical and echocardiographic measures could not be compared. Results of this study should be confirmed in larger, prospective, randomized trials. Finally, the small sample size in this study precludes any valid subgroup analysis, thus we did not identify any confounders that may have interacted with treatment assignment and thus affect the outcome.

Conclusions

In this study we showed that repeated LS treatment in patients with severe cardiac failure when compared to single-dose administration of LS, caused regulation and recovery of clinical symptoms and findings, hemodynamics, and inflammatory variants. The results suggest that repeated LS application in advanced HF is advantageous when compared to single-dose LS administration.