Enzastaurin cardiotoxicity: QT interval prolongation, negative inotropic responses and negative chronotropic action

Several clinical trials observed that enzastaurin prolonged QT interval in cancer patients. However, the mechanism of enzastaurin-induced QT interval prolongation is unclear. Therefore, this study aimed to assess the effect and mechanism of enzastaurin on QT interval and cardiac function. The Langendorff and Ion-Optix MyoCam systems were used to assess the effects of enzastaurin on QT interval, cardiac systolic function and intracellular Ca²⁺ transient in guinea pig hearts and ventricular myocytes. The effects of enzastaurin on the rapid delayed rectifier (I_Kr), the slow delayed rectifier K⁺ current (I_Ks), transient outward potassium current (I_to), action potentials, Ryanodine Receptor 2 (RyR2) and the sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a (SERCA2a) expression and activity in HEK 293 cell system and primary cardiomyocytes were investigated using whole-cell recording technique and western blotting. We found that enzastaurin significantly prolonged QT interval in guinea pig hearts and increased the action potential duration (APD) in guinea pig cardiomyocytes in a dose-dependent manner. Enzastaurin potently inhibited I_Kr by binding to the human Ether-à-go-go-Related gene (hERG) channel in both open and closed states, and hERG mutant channels, including S636A, S631A, and F656V attenuated the inhibitory effect of enzastaurin. Enzastaurin also moderately decreased I_Ks. Additionally, enzastaurin also induced negative chronotropic action. Moreover, enzastaurin impaired cardiac systolic function and reduced intracellular Ca²⁺ transient via inhibition of RyR2 phosphorylation. Taken together, we found that enzastaurin prolongs QT, reduces heart rate and impairs cardiac systolic function. Therefore, we recommend that electrocardiogram (ECG) and cardiac function should be continuously monitored when enzastaurin is administered to cancer patients.

Longitudinal Association of Arterial Stiffness and Pressure Wave Reflection with Decline of the Cardiac Systolic Performance in Healthy Men

AIMS

This prospective observational study aimed to examine the individual longitudinal associations of the increases in the arterial stiffness and pressure wave reflection with the decline in the cardiac systolic performance during the study period in healthy middle-aged Japanese men.

METHODS

In 4016 middle-aged Japanese healthy men (43±9 years), the brachial-ankle pulse wave velocity (baPWV), radial augmentation index (rAI), and pre-ejection period/ejection time (pre-ejection period (PEP)/ET) were measured annually during a 9-year study period.

RESULTS

The baPWV, rAI, and PEP/ET showed steady annual increases during the study period. According to the results of multivariate linear regression analyses, both the baPWV and rAI measured at the baseline showed significant independent associations with the PEP/ET measured at the baseline (baPWV: beta=0.17, p＜0.01 and rAI: beta=0.11, p＜0.01), whereas neither showed any association with the PEP/ET measured at the end of the study period. The results of the mixed-model linear regression analysis of the repeated-measures data collected over the 9-year study period revealed that the baPWV, but not the rAI, showed a significant longitudinal association with the PEP/ET (estimate=0.69 x 10^－4, p＜0.01).

CONCLUSION

In apparently healthy middle-aged Japanese men, the annual increase of the arterial stiffness, rather than the annual increase of the pressure wave reflection, appears to be more closely associated with the annual decline of the cardiac systolic performance as assessed by the systolic time interval.

Mediation of Arterial Stiffness for Hyperuricemia-Related Decline of Cardiac Systolic Function in Healthy Men

Background: This prospective observational study examined whether hyperuricemia may be associated with impaired left ventricular (LV) systolic function and increased cardiac load resulting from increased arterial stiffness.

Methods and Results: In 1,880 middle-aged (mean [±SD] age 45±9 years) healthy men, serum uric acid (UA) levels, pre-ejection period/ejection time (PEP/ET) ratio, serum N-terminal pro B-type natriuretic peptide (NT-proBNP) levels, and brachial-ankle pulse wave velocity (baPWV) were measured at the start and end of the 3-year study period. Linear regression analysis revealed that serum UA levels measured at baseline were significantly associated with the PEP/ET ratio, but not with serum NT-proBNP levels, measured at baseline (β=0.73×10⁻¹, P<0.01) and at the end of the study period (β=0.68×10⁻¹, P<0.01). The change in the PEP/ET ratio during the study period was significantly greater in the High-UA (UA >7 mg/dL in 2009 and 2012) than Low-UA (UA ≤7 mg/dL in 2009 and 2012) group. Mediation analysis demonstrated both direct and indirect (via increases in baPWV) associations between serum UA measured at baseline and the PEP/ET ratio measured at the end of the study period.

Conclusions: In healthy middle-aged Japanese men, hyperuricemia may be associated with an accelerated decline in ventricular systolic function, both directly and indirectly, via increases in arterial stiffness.

Index of microcirculatory resistance predicts long term cardiac systolic function in patients with STEMI undergoing primary PCI

Background

To evaluate the predictive value of the index of microcirculatory resistance (IMR) for long-term cardiac systolic function after primary percutaneous coronary intervention (pPCI) in patients with acute anterior wall ST-segment elevation myocardial infarction (STEMI).

Methods

A total of 53 acute anterior wall STEMI patients were included and followed up within 1-year. IMR was measured to evaluate the immediate intraoperative reperfusion. IMR > 40 U was defined as the high IMR group and ≤ 40 U was defined as the low IMR group. Left ventricular ejection fraction (LVEF) was measured by echocardiography at 24 h, 1 month, 3 months, and 1 year after PCI to analyze the correlation between IMR and cardiac systolic function. Heart failure was estimated according to classification within one year.

Results

The ratio of TMPG (TIMI myocardial perfusion grade) 3 (85.7% vs. 52%, p = 0.015) and STR (ST-segment resolution) > 70% (82.1% vs. 48%, p = 0.019) were significantly higher in the low IMR group. The LVEF in the low IMR group was significantly higher than that in the high IMR group at 3 months (43.06 ± 2.63% vs. 40.20 ± 2.67%, p < 0.001) and 1 year (44.16 ± 2.40% vs. 40.13 ± 3.48%, p < 0.001). IMR was negatively correlated with LVEF at 3 months (r = − 0.1014, p = 0.0040) and 1 year (r = − 0.1754, p < 0.0001).

Conclusions

The IMR showed significant negative correlation with the LVEF value after primary PCI. The high IMR is a strong predictor of heart failure within 1 year after anterior myocardial infarction.

Combination of Linagliptin and Empagliflozin Preserves Cardiac Systolic Function in an Ischemia-Reperfusion Injury Mice With Diabetes Mellitus

Background

Sodium-glucose co-transporter 2 inhibitor (SGLT2i) and dipeptidyl peptidase 4 inhibitor (DPP4i) are oral hypoglycemic agents. Although SGLT2i has been shown having the beneficial effects on heart failure in basic and clinical studies, the combined effects of SGLT2i and DPP4i have not been established well. We investigated the effects of SGLT2i and DPP4i against diabetes mice model of myocardial ischemia-reperfusion injury.

Methods

Streptozotocin-induced diabetic C57BL/6J mice were divided into control (vehicle), empagliflozin (30 mg/kg/day), linagliptin (3 mg/kg/day) and combination (30 mg/kg/day and 3 mg/kg/day, respectively) groups. After 7 days of drug administration, 30 min of myocardial ischemia was performed. We investigated body weight, heart weight, blood glucose, and cardiac functions by pressure-volume Millar catheter followed by 28 days of additional drug administration.

Results

Blood glucose levels, body weight, and heart weight were not significantly different between the groups. In Millar catheter analysis, left ventricular volume at the peak left ventricular ejection rate which is one of the cardiac systolic parameters in combination group was significantly preserved than that in control (P = 0.036). The cardiac index in the combination group tended to be preserved compared to that in the control (P = 0.06). The pathological fibrotic area in the left ventricle in the combination group also tended to be smaller (P = 0.08).

Conclusions

Combination therapy with linagliptin and empagliflozin preserved cardiac systolic function on the diabetes mice model of myocardial ischemia-reperfusion injury independent of blood glucose levels.

Influence of cigarette smoking on biventricular systolic function independent of respiratory function: a cross-sectional study

Background

Cigarette smoking harms nearly every organ, including the heart and lungs. A comprehensive assessment of both cardiac and respiratory function is necessary for evaluating the direct effects of tobacco on the heart. However, few previous studies examining the effects of cigarette smoking on cardiac function included an assessment of lung function. This cross-sectional study investigated the influence of cigarette smoking on cardiac function, independent of respiratory function.

Methods

We retrospectively reviewed the medical records of 184 consecutive cases that underwent both spirometry and transthoracic echocardiography around the same time (within 1 month) in one hospital from April 2019 to March 2020. Participants were classified into three groups based on lifetime smoking exposure (pack-years): non-smoker (n = 49), low exposure (1–20 pack-years, n = 40), and high exposure (≥ 20 pack years, n = 95). Multiple linear regression analysis was used to assess the relationship among cigarette smoking, and cardiac and respiratory functions. The relationship between selected dependent variables and lifetime pack-years was assessed in two models with multiple linear regression analysis. Model 1 was adjusted for age and male sex; and Model 2 was adjusted for Model 1 plus forced expiratory volume percentage in 1 s and forced vital capacity percentage.

Results

Compared with the non-smokers, the participants with high smoking exposure had lower left ventricular (LV) systolic function and larger LV size. Multiple linear regression analysis revealed a negative association of cumulative lifetime pack-years with LV and right ventricular (RV) systolic functions, even after adjustment for age, sex, and spirometric parameters (forced expiratory volume percentage in 1 s and forced vital capacity percentage). Meanwhile, there was no significant association of smoking exposure with LV diastolic function (E/e′ and E/A) and RV diastolic function (e′t and e′t/a′t).

Conclusions

Cumulative smoking exposure was associated with a negative effect on biventricular systolic function in patients with relatively preserved cardiac function, independent of respiratory function.

A systematic review of randomised controlled trials examining the therapeutic effects of adult bone marrow-derived stem cells for non-ischaemic dilated cardiomyopathy

BACKGROUND

Certain early-phase clinical trials have suggested that bone marrow-derived stem cell transplantation might improve left ventricular function in patients with non-ischaemic dilated cardiomyopathy (NIDCM), whereas others trials have revealed no benefit from this approach. We sought to evaluate the therapeutic effects of bone marrow-derived stem cell therapy on NIDCM.

METHODS

We searched the PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases (through February 2016) for randomised controlled clinical trials that reported on bone marrow-derived stem cell transplantation for patients with NIDCM with a follow-up period ≥12 months. The co-primary endpoints were changes in mortality rate and left ventricular ejection fraction (LVEF); the secondary endpoints were changes in the 6-minute-walk test (6MWT) and left ventricular chamber size. Seven trials involving bone marrow-derived stem cell therapy that included 482 patients satisfied the inclusion and exclusion criteria.

RESULTS

Subjects who received bone marrow-derived stem cell therapy exhibited a significant reduction in mortality rate (19.7% in the cell group vs. 27.1% in the control group; 95% confidence interval (CI) -0.16 to -0.00, I 2 = 52%, p = 0.04). Bone marrow-derived stem cell therapy tended to produce LVEF improvement within 6 months (1.83% increase; 95% CI -0.27 to 3.94, I 2 = 74%, p = 0.09) and significantly improved LVEF after mid-term (6-12 months) follow-up (3.53% increase; 95% CI 0.76 to 6.29, I 2 = 88%, p = 0.01). However, this therapy produced no significant benefit in the 6MWT (p = 0.18). Finally, the transplantation of increased numbers of stem cells resulted in no observable additional benefit with respect to LVEF.

CONCLUSIONS

Bone marrow-derived stem cell therapy might have improved prognoses and appeared to provide moderate benefits in cardiac systolic function at mid-term follow-up. However, this therapy produced no observed improvement in exercise tolerance.

Emerging role of echocardiographic strain/strain rate imaging and twist in systolic function evaluation and operative procedure in patients with aortic stenosis

Systolic function of the left ventricle is vital for patients with aortic stenosis. Unfortunately, the most widely used clinical parameter, the left ventricular ejection fraction, is not sensitive enough, especially for patients with left ventricular hypertrophy. Echocardiographic strain/strain rate and twist are emerging parameters for left ventricular systolic and diastolic function evaluation. Aortic stenosis could reduce strain/strain rate while magnifying twist. Furthermore, strain/strain rate correlates well with the prognosis of patients with aortic stenosis. Most importantly the circumferential strain, strain rate and twist also play a role in differentiating cardiac compensation or decompensation. In any case, these parameters could normalize after successful surgical aortic valve replacement or transcatheter aortic valve replacement. Regardless of these advantages, clinical evidence is needed to ensure their usefulness.