Effects of low-dose dobutamine on coronary hemodynamics, myocardial metabolism, and anginal threshold in patients with coronary artery disease

Ivabradine treatment prevents dobutamine-induced increase in heart rate in patients with acute decompensated heart failure

BACKGROUND

Ivabradine is a heart rate (HR)-lowering agent acting by inhibiting the If-channel. Dobutamine does increase the HR and has some deleterious effects on myocardium. So, we aimed to evaluate whether ivabradine treatment blunts a dobutamine-induced increase in HR.

METHODS

The main study population consisted of 58 acute decompensated heart failure patients requiring inotropic support with left-ventricular ejection fraction below 35%, who were randomized to ivabradine (n = 29) or control (n = 29). All patients underwent Holter recording for 6 h and then dobutamine was administered at incremental doses of 5, 10 and 15 μg/kg/min, with 6-h steps. Holter recording was continued during dobutamine infusion. Ivabradine 7.5 mg was given at the initiation of dobutamine and readministered at 12 h of infusion. Also, a nonrandomized beta-blocker group with 15 patients receiving beta-blocker was included in the analysis. Control and beta-blocker groups did not receive ivabradine.

RESULTS

In the control group, mean HR gradually and significantly increased at each step of dobutamine infusion (81 ± 11, 90 ± 16, 97 ± 14 and 101 ± 16 b.p.m., respectively; P = 0.001), whereas no significant increase in HR was observed in the ivabradine group (82 ± 17, 82 ± 15, 85 ± 14 and 83 ± 12 b.p.m., respectively; P = 0.439). Mean HR was also found to significantly increase during dobutamine infusion in the beta-blocker group (75 ± 13, 82 ± 13, 86 ± 14 and 88 ± 13 b.p.m., respectively; P = 0.001). The median increase in HR from baseline was significantly higher in the control group compared to those in the ivabradine group (5 vs. 2 b.p.m.; P = 0.007 at first step, 13 vs. 5 b.p.m.; P = 0.001 at second step and 18 vs. 6 b.p.m.; P = 0.0001 at third step of dobutamine, respectively).

CONCLUSIONS

Ivabradine treatment prevents dobutamine-induced increase in HR and may be useful in reducing HR-related adverse effects of dobutamine.

Ischemia-modified albumin levels in patients with acute decompensated heart failure treated with dobutamine or levosimendan: IMA-HF study

OBJECTIVE

Ischemia-modified albumin (IMA) is a sensitive biomarker of myocardial ischemia. However, data on IMA levels in acute heart failure (HF) are still lacking. In this study, we aimed to evaluate serum IMA levels in acute decompensated HF and the effects of dobutamine and levosimendan treatments on IMA levels.

METHODS

This was a prospective, multicenter study that included 70 patients hospitalized with acute decompensated HF and left ventricular ejection fraction < 35%. Blood samples for IMA measurements were obtained on admission and 24-48 h after the initiation of HF therapy. Twenty-nine patients were treated with standard HF therapy, 18 received levosimendan, and 23 received dobutamine in addition to standard of care. A single serum specimen was also collected from 32 healthy individuals each. IMA concentrations were measured by the albumin cobalt binding colorimetric assay, and the results were given in absorbance units (AU). Independent and paired sample t-tests, Mann-Whitney U test, and Wilcoxon signed-rank test were used for the analysis.

RESULTS

In patients with acute decompensated HF, the serum concentration of IMA was significantly higher than those of healthy subjects (0.894 ± 0.23 AU vs. 0.379 ± 0.08 AU, p < 0.001). Overall, the IMA levels significantly decreased after 24-48 h of HF therapy (0.894 ± 0.23 AU and 0.832 ± 0.18 AU, p = 0.013). Furthermore, the IMA levels were also found to significantly decrease with standard HF therapy (1.041 ± 0.28 vs. 0.884 ± 0.15 AU, p = 0.041), with levosimendan (0.771 ± 0.18 vs. 0.728 ± 0.18 AU, p = 0.046) and also with dobutamine (0.892 ± 0.18 vs. 0.820 ± 0.13 AU, p = 0.035).

CONCLUSION

Patients with acute decompensated HF had elevated IMA levels, and appropriate HF therapy significantly reduced the serum IMA levels. Dobutamine or levosimendan did not increase the IMA levels, suggesting a lower potential in inducing myocardial ischemia when used in recommended doses.

Levosimendan versus dobutamine in critically ill patients: a meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the clinical efficacy of levosimendan versus dobutamine in critically ill patients requiring inotropic support.

METHODS

Clinical trials were searched in PubMed, EMBASE, and the Cochrane Central Registry of Clinical Trials, as well as Web of Science. Studies were included if they compared levosimendan with dobutamine in critically ill patients requiring inotropic support, and provided at least one outcome of interest. Outcomes of interest included mortality, incidence of hypotension, supraventricular arrhythmias, and ventricular arrhythmias.

RESULTS

Data from a total of 3052 patients from 22 randomized controlled trials (RCTs) were included in the analysis. Overall analysis showed that the use of levosimendan was associated with a significant reduction in mortality (269 of 1373 [19.6%] in the levosimendan group, versus 328 of 1278 [25.7%] in the dobutamine group, risk ratio (RR)=0.81, 95% confidence interval (CI) 0.70-0.92, P for effect=0.002). Subgroup analysis indicated that the benefit from levosimendan could be found in the subpopulations of cardiac surgery, ischemic heart failure, and concomitant β-blocker therapy in comparison with dobutamine. There was no significant difference in the incidence of hypotension, supraventricular arrhythmias, or ventricular arrhythmias between the two drugs.

CONCLUSIONS

In contrast with dobutamine, levosimendan is associated with a significant improvement in mortality in critically ill patients requiring inotropic support. Patients having cardiac surgery, with ischemic heart failure, and receiving concomitant β-blocker therapy may benefit from levosimendan. More RCTs are required to address the questions about no positive outcomes in the subpopulation in a cardiology setting, and to confirm the advantages in long-term prognosis.

Safety of contrast administration for endocardial enhancement during stress echocardiography compared with noncontrast stress

The aim was to evaluate the safety of stress echocardiography using contrast (CE) for endocardial enhancement compared with a noncontrast (NCE) cohort in a large nonselect population. The recent Food and Drug Administration warning cited lack of data for safety regarding the use of contrast in conjunction with stress echocardiography. A detailed record review was performed for 5,069 consecutive patients who underwent stress echocardiography (58% pharmacologic, 42% exercise) during an 8-year period. Contrast use, hemodynamics, and adverse clinical and electrocardiographic events were evaluated until time of discharge from the laboratory. Contrast was administered to 2,914 patients (58%) and was higher in in-patients (66%) and during dobutamine stress (67%). Compared with the NCE group, the CE group was older (median age 61 vs 58 years) and had more depressed left ventricular ejection fraction <50% (14% vs 11%; all p <0.001). The CE group experienced more chest pain (11% vs 8%; p = 0.001), back pain (0.6% vs 0.05%; p <0.001), and premature ventricular contractions (odds ratio 1.42, 95% confidence interval 1.19 to 1.69, p <0.001). There was no sustained ventricular tachycardia, ventricular fibrillation, cardiac arrest, or death in either group. One uncomplicated acute myocardial infarction and 1 anaphylactoid reaction occurred in the CE group, and none occurred in the NCE group (p = 0.51). Rates of clinically significant arrhythmias were similar in both groups (CE 2.1% vs NCE 1.9%; p = 0.8). In conclusion, although CE of echocardiographic images was used more often in patients with a higher cardiac risk profile, the risk of major adverse events was very small in both the CE and NCE stress echocardiography cohorts.

The use of levosimendan in comparison and in combination with dobutamine in the treatment of decompensated heart failure

Levosimendan is a new calcium sensitizer with inotropic and vasodilatory actions mediated by the sensitization of contractile proteins to calcium, opening of potassium channels and inhibition of phosphodiesterase-3. Its alternative mechanisms of action to those of other traditional inotropes provide a new approach in the management of decompensated heart failure. In contrast to dobutamine, levosimendan does not increase myocardial oxygen demand and, therefore, it is thought to have a lower potential to induce increases in myocardial ischemia and cardiac arrhythmias. The commonly used inotropic agent dobutamine increases myocardial contractility at the expense of increased myocardial oxygen consumption and, therefore, it can result in poor outcomes. Although dobutamine may also have favorable hemodynamic and symptomatic effects, levosimendan has been shown to be superior to dobutamine in increasing cardiac output and decreasing pulmonary capillary wedge pressure in patients with decompensated heart failure. In the presence of concomitant beta-blocker therapy, these favorable effects were present or even more pronounced during treatment with levosimendan, but not dobutamine. However, the mortality benefit of levosimendan observed in earlier trials has not been confirmed in recent, larger clinical trials. A distinct advantage of levosimendan over dobutamine is its prolonged hemodynamic effects, which last for up to 7-9 days. There are more data on the safety of levosimendan in ischemic patients than with any other inotropic drug and, therefore, levosimendan seems to be safe and effective in patients with ischemic heart disease when used at the recommended doses. Despite advances in heart failure therapy, many patients experience clinical deterioration, or do not respond to a single inotropic drug. Increasing evidence suggests the use of levosimendan in combination with dobutamine in patients with decompensated heart failure that is refractory to dobutamine alone.

Outpatient dobutamine therapy: the rhyme and the riddle

Advances in critical care medicine have increased survival for victims of myocardial infarction and other acute cardiac events so that increasingly patients are receiving long-term, labor-intensive, and costly medical care. Innovations in drug delivery systems and skyrocketing health care costs have fostered the growth of home health care which has blossomed into a $2.8 billion industry. There is evidence that outpatient dobutamine therapy produces definite physical and possibly psychological improvements of variable degree and duration. Hemodynamic improvements are generally associated with improvement in functional class, and the financial savings are recognizably substantial. However, three major problems confront therapies with beta-adrenergic agonists: tendency for tolerance, ventricular arrhythmias, and increased myocardial oxygen consumption. There is a dire need for establishment of exclusionary patient criteria and for risk stratification, as well as for development of a portable radionuclide nonimaging monitor. Given the current fund of knowledge, outpatient dobutamine therapy should be undertaken cautiously after meticulous patient selection reflecting an awareness of the tremendous complexities and inherent risks. The therapeutic implications are dependent on the nature of the underlying cardiomyopathy and the fact that beta-adrenergic receptor desensitization is unlikely to be overcome by progressive dosage increases. Therapy is initiated with the understanding that treatment will remain blindly empirical and conjectural in the absence of a continuous physiologic monitor and an expanded comprehension of the molecular pathophysiology of the failing ventricle.

Dipyridamole radionuclide ventriculography in patients with coronary artery disease: comparison with ergometer exercise

Intravenous administration of dipyridamole during radionuclide ventriculography (RNV) was performed in 26 consecutive patients with symptomatic coronary artery disease. The authors compared the results of dipyridamole-RNV with those of ergometer exercise-RNV in detecting myocardial ischemia. During exercise, ST depression, regional wall motion (RWM) abnormalities, and decreased left ventricular ejection fraction (LVEF) were observed in 21 (81%), 23 (88%), and 20 (77%) patients, respectively. However, after intravenous dipyridamole, ST depression, RWM abnormalities, and decreased LVEF were observed in 14 (54%), 15 (58%), and 2 (8%) patients, respectively. Although LVEF usually decreases during myocardial ischemia, LVEF did not decrease (57 +/- 11% to 58 +/- 10%), even in patients with ST depression, after intravenous dipyridamole. Maintained left ventricular ejection fraction is considered to be a hemodynamic effect of the potent arterial vasodilatation induced by dipyridamole. These results from dipyridamole-RNV in myocardial ischemia seem to conflict with the results from dipyridamole-thallium studies carried out to determine the capacity to detect coronary artery disease. Unknown mechanisms of dipyridamole other than the coronary steal phenomenon may be operative in the genesis of myocardial ischemia.

Radionuclide assessment of left ventricular function during dobutamine infusion in patients with coronary artery disease: comparison with ergometer exercise

The effects of dobutamine on left ventricular function were assessed employing radionuclide ventriculography (RNV) in 7 normal subjects (Group 1) and 21 patients with coronary artery disease (Group 2). After routine bicycle ergometer exercise RNV, dobutamine infusion was started at 5 micrograms/kg/min and the dosage was increased by 5 micrograms/kg/min every 4 minutes to a total of 15 micrograms/kg/min. In Group 1, left ventricular ejection fraction (LVEF) increased by both ergometer exercise and dobutamine infusion. In Group 2, LVEF did not increase during exercise, but increased during dobutamine infusion without evidence of significant myocardial ischemia. Only 2 patients in Group 2 had new regional wall motion abnormality. Left ventricular end-diastolic volume (LVEDV) in Group 2 increased from 191 +/- 19 to 210 +/- 18 ml during ergometer exercise, but decreased from 193 +/- 18 to 153 +/- 19 ml during dobutamine infusion. Short-term low-dose infusion of dobutamine may be used in patients without evidence of significant myocardial ischemia, but probably cannot be substituted for exercise testing in patients with mild to moderate coronary artery disease.

Congestive heart failure

A review of the epidemiology, pathophysiology, and treatment of congestive heart failure is presented, with particular attention given to newer modalities of therapy.

Effects of indomethacin on coronary hemodynamics, myocardial metabolism and anginal threshold in coronary artery disease

The effects of orally administered indomethacin or placebo on coronary hemodynamics were studied in 23 patients with coronary artery disease. After indomethacin administration the systemic arterial pressure increased by 12 +/- 4% and the myocardial oxygen consumption by 24 +/- 11%. Coronary sinus flow did not change and coronary vascular resistance increased slightly. Oxygen saturation of the arterial blood did not change, but coronary sinus saturation decreased substantially. Hemodynamic values returned to normal 150 minutes after administration of indomethacin. During rapid atrial pacing, coronary sinus flow increased 79 +/- 14% above the rest value when pacing was done before indomethacin administration; only a 56 +/- 12% increase was seen when pacing was repeated after indomethacin. Peak heart rate achieved during atrial pacing, severity of angina and the degree of ST-segment depression were not altered by indomethacin treatment. Orally administered indomethacin has a mild coronary vasoconstrictive effect that does not interfere substantially with the expected increase in myocardial blood flow during rapid atrial pacing. Anginal threshold is not altered by orally administered indomethacin.