The evaluation and management of drug effects on cardiac conduction (PR and QRS intervals) in clinical development

PR prolongation as a predictor of atrial fibrillation onset: A state-of-the-art review

First-degree atrioventricular block (1-AVB), characterized by a PR interval exceeding 200 milliseconds, has traditionally been perceived as a benign cardiac condition. Recently, this perception has been challenged by investigations that indicate a potential association between PR prolongation and an elevated risk of atrial fibrillation (AF). To consolidate these findings, we performed a comprehensive review to assess the available evidence indicating a relationship between these two conditions. We searched MEDLINE and EMBASE databases as well as manually searched references of retrieved articles. We selected 18 cohort studies/meta-analyses involving general and special populations. Consistent findings across expansive cohort studies reveal that incremental increases in the PR interval may serve as an independent risk factor for AF. However, our analyses underscore the need for further research into the association between 1-AVB, defined by a specified PR interval cutoff, and the risk of AF.

Heart rate stability in a clinical setting and after a short exercise in healthy male volunteers

INTRODUCTION

Limited data exist on heart rate stabilization in the domiciled nature of phase I clinical studies, particularly when frequent measurements of QT intervals are involved. The present analysis aimed to evaluate heart rate stability in the domiciled nature of, and stabilization after a short exercise.

METHODS

Fifty-six healthy male subjects were included in this analysis. Data during a domiciled clinical setting and after a short exercise were analysed. Mean values of 30 s intervals of collected electrocardiographical data (PR, RR, QT and QTcF intervals) during a 10-min supine resting period in a domiciled nature or after walking up and down three stories (100 steps) were compared to baseline values using paired t-tests or compared to the intrasubject standard deviation.

RESULTS

Stable heart rates and stable QTcF intervals observed immediately upon assuming a supine position in the domiciled clinical setting. After the short exercise, PR interval and RR interval were significantly (p < 0.05) shorter for up to 120 s (mean value -9.8 ± 7.2 ms) and 30 s (-160 ± 165 ms, p < 0.05), respectively. QT and QTcF intervals were significantly (p < 0.05) shorter for up to 90 and 120 s postexercise, respectively. Both QT and QTcF intervals stabilized after 2 min, but QT interval remained prolonged while QTcF interval returned to baseline levels.

CONCLUSION

In a clinical setting, male volunteers do not require a waiting period for electrocardiographic parameter normalization. However, accurate measurement of these parameters following a short exercise necessitates a minimum 2-min resting interval.

False Negative ECG Device Results May Increase the Risk of Adverse Events in Clinical Oncology Trials

Background

Sites participating in clinical trials may not have the expertise and infrastructure to accurately measure cardiac intervals on 12-lead ECGs and rely heavily on the automated ECG device generated results for clinical decision-making.

Methods

Using a dataset of over 260,000 ECGs collected in clinical oncology studies, we investigated the mean difference and the rate of false negative results between the digital ECG machine QTc and QRS measurements compared to those obtained by a centralized ECG core lab.

Results

The mean differences between the core lab and the automated algorithm QTcF and QRS measurements were + 1.8 ± 16.0 ms and − 1.0 ± 8.8 ms, respectively. Among the ECGs with a centralized QTcF value > 450 or > 470 ms, 39.5% and 47.8% respectively had a device reported QTcF value ≤ 450 ms or ≤ 470 ms. Among the ECGs with a centrally measured QTcF > 500 ms, 55.8% had a device reported value ≤ 500 ms. Automated QTcF measurements failed to detect a QTcF increase > 60 ms for 53.9% of the ECGs identified by the core lab. Automated measurements also failed to detect QRS prolongation, though to a lesser extent than failures to detect QTc prolongation. Among the ECGs with a centrally measured QRS > 110 or 120 ms, 7.9% and 7.3% respectively had a device reported QRS value ≤ 110 ms or ≤ 120 ms.

Conclusion

Relying on automated measurements from ECG devices for patient inclusion and treatment (dis)continuation decisions poses a potential risk to patients participating in oncology studies.

Cardiac sodium channel inhibition by lamotrigine: in vitro characterization and clinical implications

Lamotrigine, approved for use as an antiseizure medication as well as the treatment of bipolar disorder, inhibits sodium channels in the brain to reduce repetitive neuronal firing and pathological release of glutamate. The shared homology of sodium channels and lack of selectivity associated with channel blocking agents can cause slowing of cardiac conduction and increased proarrhythmic potential. The Vaughan‐Williams classification system differentiates sodium channel blockers using biophysical properties of binding. As such, Class Ib inhibitors, including mexiletine, do not slow cardiac conduction as measured by the electrocardiogram, at therapeutically relevant exposure. Our goal was to characterize the biophysical properties of Na_V1.5 block and to support the observed clinical safety of lamotrigine. We used HEK‐293 cells stably expressing the hNa_V1.5 channel and voltage clamp electrophysiology to quantify the potency (half‐maximal inhibitory concentration) against peak and late channel current, on‐/off‐rate binding kinetics, voltage‐dependence, and tonic block of the cardiac sodium channel by lamotrigine; and compared to clinically relevant Class Ia (quinidine), Ib (mexiletine), and Ic (flecainide) inhibitors. Lamotrigine blocked peak and late Na_V1.5 current at therapeutically relevant exposure, with rapid kinetics and biophysical properties similar to the class Ib inhibitor mexiletine. However, no clinically meaningful prolongation in QRS or PR interval was observed in healthy subjects in a new analysis of a previously reported thorough QT clinical trial (SCA104648). In conclusion, the weak Na_V1.5 block and rapid kinetics do not translate into clinically relevant conduction slowing at therapeutic exposure and support the clinical safety of lamotrigine in patients suffering from epilepsy and bipolar disorder.

Evaluation of cardiotoxicity in Amazonian fish Bryconops caudomaculatus by acute exposure to aluminium in an acidic environment

Aluminium (Al) is soluble in acidic waters and may become toxic to organisms. In this study, the acute effects of two Al concentrations were evaluated in the Amazonian fish Bryconops caudomaculatus. Antioxidant responses and lipid damage were assessed in gills, liver and muscle, along with the electrocardiography (ECG) and characterization of cardiac complex and wave intervals. Fish were essayed as follows: two control groups at neutral and acidic pH and two exposure groups at acidic pH (0.3 mg/L and 3.0 mg/L Al). Water samples were collected at 0h, 24h and 48h, for chloride (Cl^-), fluoride (F^-) and sulphate (SO₄^2-) ion analyses, while total Al was quantified in muscle. Concentrations of Cl^- and SO₄^2- were constant over time whereas F^- was not detected. Total Al concentrations in water and muscle were concentration-dependent. Antioxidant responses, total antioxidant capacity against peroxyl radicals (ACAP) and glutathione S-transferase were not triggered in fish tissues exposed to 0.3 mg/L Al; however, fish exposed to 3.0 mg/L Al presented increased and reduced ACAP in gills and liver, respectively. No changes in lipoperoxidation levels occurred among groups. Fish exposed to 0.3 mg/L Al showed prolonged intervals in ECG as a reflection of low heart rate (HR), with sinus bradycardia. Moreover, there was a marked prolongation of the PQ interval (time between the atrial activity and the start of ventricular activity), indicating interference on the cardiac cell automaticity. Fish exposed to the highest concentration of Al showed reduced wave intervals as a consequence of increased HR, with sinus arrhythmia, while ECG tracings did not present P waves (atrial contraction), indicating an atrioventricular blockade. In conclusion, 48h exposure sufficed to cause cardiotoxicity in B. caudomaculatus at either Al concentration. However, as oxidative stress was not observed, such cardiac alterations seem to be reversible under the experimental conditions established herein.

Determinants of left ventricular function improvement for cardiac resynchronization therapy candidates

AIMS

A waiting period of more than 3 months is recommended for patients before undergoing cardiac resynchronization therapy (CRT). However, due to an anticipated high mortality rate, early implementation of CRT might be beneficial for some patients. We aimed to evaluate the rate and the probability of left ventricular (LV) function improvement and their predictors in patients with heart failure (HF) with indications for CRT.

METHODS AND RESULTS

From March 2011 to February 2014, a total of 5625 hospitalized patients for acute HF were consecutively enrolled in 10 tertiary hospitals. Among them, we analysed 1792 patients (mean age 63.96 ± 15.42 years, female 63.1%) with left ventricular ejection fraction (LVEF) ≤ 35% at the baseline echocardiography and divided them into three groups: 144 with left bundle branch block (LBBB), 136 with wide QRS complexes without LBBB, and 1512 not having these findings (control). We compared and analysed these three groups for improvement of LV function at follow-up echocardiography. In patients who met CRT indications (patients with LBBB or wide QRS complexes without LBBB), logistic regression was performed to identify risk factors for no improvement of LV. No improvement of LV was defined as LVEF ≤ 35% at follow-up echocardiography or the composite adverse outcomes: death, heart transplantation, extracorporeal membrane oxygenation, or use of a ventricular assist device before follow-up echocardiography. A classification tree was established using the binary recursive partitioning method to predict the outcome of patients who met CRT indications. In a median follow-up of 11 months, LVEF improvement was observed in 24.3%, 15.4%, and 40.5% of patients with LBBB, wide QRS complexes without LBBB, and control, respectively. Patients meeting CRT indications had higher 3 month mortality rates than the control (24.6% vs. 17.7%, P = 0.002). Multivariable logistic regression analysis revealed that large LV end-systolic dimension [odds ratio (OR) 1.10, 95% confidence interval (CI) 1.05-1.15, P < 0.001], low LVEF (OR 0.92, 95% CI 0.87-0.98, P = 0.006), diabetes requiring insulin (OR 6.49, 95% CI 2.53-19.33, P < 0.001), and suboptimal medical therapy (OR 6.85, 95% CI 3.21-15.87, P < 0.001) were significant factors predictive of no improvement. A decision tree analysis was consistent with these results.

CONCLUSIONS

Patients with CRT indications had higher mortality during their follow-up compared with control. LV function improvement was rare in this population, especially when they had some risk factors. These results suggest that the uniform waiting period before CRT implantation could be reconsidered and individualized.

The association between body temperature and electrocardiographic parameters in normothermic healthy volunteers

Background

Previous studies reported that hypo‐ and hyperthermia are associated with several atrial and ventricular electrocardiographical parameters, including corrected QT (QTc) interval. Enhanced characterization of variations in QTc interval and normothermic body temperature aids in better understanding the underlying mechanism behind drug induced QTc interval effects. The analysis’ objective was to investigate associations between body temperature and electrocardiographical parameters in normothermic healthy volunteers.

Methods

Data from 3023 volunteers collected at our center were retrospectively analyzed. Subjects were considered healthy after review of collected data by a physician, including a normal tympanic body temperature (35.5‐37.5°C) and in sinus rhythm. A linear multivariate model with body temperature as a continuous was performed. Another multivariate analysis was performed with only the QT subintervals as independent variables and body temperature as dependent variable.

Results

Mean age was 33.8 ± 17.5 years and mean body temperature was 36.6 ± 0.4°C. Body temperature was independently associated with age (standardized coefficient [SC] = −0.255, P < .001), female gender (SC = +0.209, P < .001), heart rate (SC = +0.231, P < .001), P‐wave axis (SC = −0.051, P < .001), J‐point elevation in lead V4 (SC = −0.121, P < .001), and QTcF duration (SC = −0.061, P = .002). In contrast, other atrial and atrioventricular (AV) nodal parameters were not independently associated with body temperature. QT subinterval analysis revealed that only QRS duration (SC = −0.121, P < .001) was independently associated with body temperature.

Conclusion

Body temperature in normothermic healthy volunteers was associated with heart rate, P‐wave axis, J‐point amplitude in lead V4, and ventricular conductivity, the latter primarily through prolongation of the QRS duration.

Speckle-Tracking Echocardiography for Cardioncological Evaluation in Bevacizumab-Treated Colorectal Cancer Patients

Angiogenesis inhibitor Bevacizumab (BVZ) may lead to the development of adverse effects, including hypertension and cardiac ischemia. Whether assessment of changes in myocardial strain by two-dimensional speckle-tracking echocardiography (2D-STE) can be of value in detecting BVZ-mediated cardiotoxicity at an earlier stage is not known. We investigated whether 2D-STE can non-invasively detect early evidence of cardiotoxicity in metastatic colorectal cancer (mCRC) patients treated with BVZ. Between January and June 2019, 25 consecutive patients (71.8 ± 7.5 year/old, 17 males) with mCRC were prospectively enrolled. Patients underwent physical examination, blood tests, and conventional 2D-transthoracic echocardiography implemented with 2D-STE analysis, at baseline and at 3 and 6 months following treatment with BVZ (15 mg/kg every 15 days) + 5-fluorouracil/folinic acid plus oxaliplatin (FOLFOX i.v.). At 6-month follow-up, we assessed occurrence of global longitudinal strain (GLS) impairment (> 15% decrease in GLS compared with baseline) as primary end-point and a new-onset systemic hypertension (secondary end-point). On average, GLS showed a progressive significant impairment after BVZ, from - 17.4 ± 3.2% at baseline to - 16 ± 2.9% (p = 0.003) at 6-month follow-up; > 15% decrease in GLS (primary end-point) was detected in 9 patients (36%). All other strain parameters remained unchanged. New-onset systemic hypertension (secondary end-point) was diagnosed in five patients (20%). No significant changes were observed in serial high-sensitivity cardiac troponin I measurements. No patient developed significant changes in LV size or LV ejection fraction; no case of clinically symptomatic HF was observed during BVZ-treatment. Measurement of GLS by 2D-STE analysis can effectively detect BVZ-mediated cardiotoxicity at an early stage.

Electrophysiological responses in Amazonian fish species Bryconops caudomaculatus (Osteichthyes: Characiformes) as biomarkers of xenobiotic toxicity

Sublethal exposures to environmental pollutants may cause changes in physiological parameters. Thus, knowledge of basal physiological rates of the species and the development of methods to quantify these rates are extremely important. Considering the scarcity of cardiac and muscle physiological studies in native Amazonian fish species and that no evaluation of electrophysiological responses by exposure to a stressor has been reported in Bryconops caudomaculatus, the aim of this study was to develop techniques of electromyographic and electrocardiographic recordings of normal responses, during toxicity induction and short-term recovery. A total of 9 animals were used, divided into two groups: control group (n = 4) and treated group (n = 5), with records lasting 5 min. The results showed that the basal electromyographic records indicate that the studied species has a very intense swimming activity, whereas the basal cardiac parameters clearly showed the patterns in P wave tracing, QRS complex, T wave and Q-T and R-R intervals. During exposure to the stressor, muscle activity ceased presenting intense decrease and myorelaxant effect expected. Electrocardiographic responses confirmed cardiotoxicity with intense bradycardia, ventricular bigeminism, prolongation of QRS complex duration and cardiac arrhythmias, indicating cardiac dysfunction. It was concluded that the electrophysiological responses are excellent biomarkers and showed the susceptibility of the species to the tested substance. In addition, the electrocardiogram and the electromyogram are excellent techniques to reflect the degree of environmental stress when organisms are exposed to toxic substances in the environment.

Prognostic Value of QRS Duration among Patients with Cardiogenic Shock Complicating Acute Heart Failure: Data from the Korean Acute Heart Failure (KorAHF) Registry

Background and Objectives

Prolonged QRS duration is associated with poor outcomes in patients with chronic heart failure (HF). However, the prognostic value of QRS duration in patients with cardiogenic shock complicating acute HF remains unknown. We evaluated the hypothesis that prolonged QRS duration may be associated with short-term mortality among acute HF patients with cardiogenic shock (CS).

Methods

From March 2011 through December 2013, a total of 5,625 acute HF patients were consecutively enrolled in ten tertiary university hospitals. Among them, we analyzed patients who presented with CS. Patients were divided into three groups by QRS duration cutoff values of 130 and 150 ms. The primary endpoint was 30-day in-hospital mortality.

Results

Two hundred eleven patients presented with CS at admission and those with available electrocardiograms were included in this analysis. There were 35 patients with QRS durations of 150 ms or above, 30 patients with QRS durations between 130 ms and 150 ms, and 146 patients with QRS durations below 130 ms. The 30-day all cause in-hospital mortality rates were 43.7%, 33.1%, and 24.9%, respectively. After multivariate adjustment, severe prolonged QRS duration was a significant prognostic factor for 30-day in-hospital mortality (hazard ratio, 1.909; 95% confidence interval, 1.024–3.558; p=0.042).

Conclusions

Prolonged QRS duration was associated with a higher risk of 30-day in-hospital mortality among patients with acute HF who presented with CS.

Trial Registration

ClinicalTrials.gov Identifier: NCT01389843

Rapamycin Treatment Reduces Acute Myocarditis Induced by Trypanosoma cruzi Infection

Chagas disease affects millions of people mainly in Latin America and is a protozoan illness caused by the parasite Trypanosoma cruzi. Chagasic cardiomyopathy is the leading cause of mortality of infected patients, due to compromised electrical and mechanical cardiac function induced by tissue remodeling, especially fibrosis, and lymphocytic infiltration. Some cellular biochemical pathways can be protective to the heart, and we tested if the in vivo activation of the autophagic machinery by rapamycin could reduce parasite-induced myocarditis. Regarding the expression of LC3, an autophagy marker, we observed its upregulation in the cardiac tissue of infected untreated mice. However, after rapamycin treatment, an autophagy inducer, infected mice showed reduced electrical cardiac dysfunctions, myocarditis, cardiac damage, and reduced production of pro-inflammatory cytokines by the heart. On the other hand, the parasite's life cycle was not affected, and we observed no modulations in cardiac tissue or blood parasitemia. Our data indicate that, at least partially, autophagy induction controls inflammation in the heart¸ illustrating the complexity of the pathways that concur to the development of the infection.

Impaired Recovery of Left Ventricular Function in Patients With Cardiomyopathy and Left Bundle Branch Block

BACKGROUND

Patients with left bundle branch block (LBBB) often respond to cardiac resynchronization therapy (CRT) with left ventricular ejection fraction (LVEF) improvement. Guideline-directed medical therapy (GDMT), not CRT, is first-line therapy for patients with reduced LVEF with LBBB. However, there are little data on how patients with reduced LVEF and LBBB respond to GDMT.

OBJECTIVES

This study examined patients with cardiomyopathy and sought to assess rates of LVEF improvement for patients with LBBB compared to other QRS morphologies.

METHODS

Using data from the Duke Echocardiography Laboratory Database, the study identified patients with baseline electrocardiography and LVEF ≤35% who had a follow-up LVEF 3 to 6 months later. The study excluded patients with severe valve disease, a cardiac device, left ventricular assist device, or heart transplant. QRS morphology was classified as LBBB, QRS duration <120 ms (narrow QRS duration), or a wide QRS duration ≥120 ms but not LBBB. Analysis of variance testing compared mean change in LVEF among the 3 groups with adjustment for significant comorbidities and GDMT.

RESULTS

There were 659 patients that met the criteria: 111 LBBB (17%), 59 wide QRS duration ≥120 ms but not LBBB (9%), and 489 narrow QRS duration (74%). Adjusted mean increase in LVEF over 3 to 6 months in the 3 groups was 2.03%, 5.28%, and 8.00%, respectively (p < 0.0001). Results were similar when adjusted for interim revascularization and myocardial infarction. Comparison of mean LVEF improvement between patients with LBBB on GDMT and those not on GDMT showed virtually no difference (3.50% vs. 3.44%). The combined endpoint of heart failure hospitalization or mortality was highest for patients with LBBB.

CONCLUSIONS

LBBB is associated with a smaller degree of LVEF improvement compared with other QRS morphologies, even with GDMT. Some patients with LBBB may benefit from CRT earlier than guidelines currently recommend.

Assessment of Multi-Ion Channel Block in a Phase I Randomized Study Design: Results of the CiPA Phase I ECG Biomarker Validation Study

Balanced multi‐ion channel‐blocking drugs have low torsade risk because they block inward currents. The Comprehensive In Vitro Proarrhythmia Assay (CiPA) initiative proposes to use an in silico cardiomyocyte model to determine the presence of balanced block, and absence of heart rate corrected J‐T_peak (J‐T_peakc) prolongation would be expected for balanced blockers. This study included three balanced blockers in a 10‐subject‐per‐drug parallel design; lopinavir/ritonavir and verapamil met the primary end point of ΔΔJ‐T_peakc upper bound < 10 ms, whereas ranolazine did not (upper bounds of 8.8, 6.1, and 12.0 ms, respectively). Chloroquine, a predominant blocker of the potassium channel encoded by the ether‐à‐go‐go related gene (hERG), prolonged ΔΔQTc and ΔΔJ‐T_peakc by ≥ 10 ms. In a separate crossover design, diltiazem (calcium block) did not shorten dofetilide‐induced ΔQTc prolongation, but shortened ΔJ‐T_peakc and prolonged ΔT_peak‐T_end. Absence of J‐T_peakc prolongation seems consistent with balanced block; however, small sample size (10 subjects) may be insufficient to characterize concentration‐response in some cases.

Echocardiographic Assessment for the Detection of Cardiotoxicity Due to Vascular Endothelial Growth Factor Inhibitor Therapy in Metastatic Renal Cell and Colorectal Cancers

BACKGROUND

Cardio-oncology is a recently established discipline that focuses on the management of patients with cancer who are at risk for developing cardiovascular complications as a result of their underlying oncologic treatment. In metastatic colorectal cancer (mCRC) and metastatic renal cell carcinoma (mRCC), vascular endothelial growth factor inhibitor (VEGF-i) therapy is commonly used to improve overall survival. Although these novel anticancer drugs may lead to the development of cardiotoxicity, whether early detection of cardiac dysfunction using serial echocardiography could potentially prevent the development of heart failure in this patient population requires further study. The aim of this study was to investigate the role of two-dimensional speckle-tracking echocardiography in the detection of cardiotoxicity due to VEGF-i therapy in patients with mCRC or mRCC.

METHODS

Patients with mRCC or mCRC were evaluated using serial echocardiography at baseline and 1, 3, and 6 months following VEGF-i treatment.

RESULTS

A total of 40 patients (34 men; mean age, 63 ± 9 years) receiving VEGF-i therapy were prospectively recruited at two academic centers: 26 (65%) were receiving sunitinib, eight (20%) pazopanib, and six (15%) bevacizumab. The following observations were made: (1) 8% of patients developed clinically asymptomatic cancer therapeutics-related cardiac dysfunction; (2) 30% of patients developed clinically significant decreases in global longitudinal strain, a marker for early subclinical cardiac dysfunction; (3) baseline abnormalities in global longitudinal strain may identify a subset of patients at higher risk for developing cancer therapeutics-related cardiac dysfunction; and (4) new or worsening hypertension was the most common adverse cardiovascular event, afflicting nearly one third of the study population.

CONCLUSIONS

Cardiac dysfunction defined by serial changes in myocardial strain assessed using two-dimensional speckle-tracking echocardiography occurs in patients undergoing treatment with VEGF-i for mCRC or mRCC, which may provide an opportunity for preventive interventions.

Refractory Arrhythmias in a Young Patient Poisoned by Imipramine

Tricyclic antidepressants are used to treat a variety of mental disorders, and are considered a common cause of fatal drug poisoning. This study reports a young woman with no history of cardiac diseases who presented to the emergency department with heart palpitation, weakness, and lethargy. After a short period of time, she became unconscious and experienced hypotension and refractory arrhythmia, finally being diagnosed with imipramine poisoning. Accurate history taking and the possible causes of these complications including cardio-toxic drug poisoning should be considered in such patients.

Dynamicity of hypothermia-induced J waves and the mechanism involved

BACKGROUND

J waves develop during hypothermia, but the dynamicity of hypothermia-induced J waves is poorly understood.

OBJECTIVE

The purpose of this study was to investigate the mechanism of the rate-dependent change in the amplitude of hypothermia-induced J waves.

METHODS

Nineteen patients with severe hypothermia were included (mean age 70 ± 12 years; 16 men [84.2%]). The rectal temperature at the time of admission was 27.8° ± 2.5°C. In addition to prolonged PR, QRS complex, and corrected QT intervals, the distribution of prominent J waves was widespread in all 19 patients.

RESULTS

Nine patients showed changes in RR intervals. When the RR interval shortened from 1353 ± 472 to 740 ± 391 ms (P = .0002), the J-wave amplitude increased from 0.50 ± 0.29 to 0.61 ±0.27 mV (P = .0075). The J-wave amplitude increased in 7 patients (77.8%) and decreased in 2 patients (22.2%) after short RR intervals. The augmentation of J waves at short RR intervals was associated with a significant prolongation of ventricular activation time (35 ± 5 ms vs 46 ± 5 ms; P = .0020), suggesting accentuated conduction delay. Increased conduction delay at short RR intervals was suggested to accentuate the phase 1 notch of the action potential and J waves in hypothermia. None developed ventricular fibrillation, and in 2 of 9 patients with atrial fibrillation, atrial fibrillation persisted after rewarming to normothermia.

CONCLUSION

J waves in severe hypothermia were augmented after short RR intervals in 7 patients as expected for depolarization abnormality, whereas 2 patients showed a bradycardia-dependent augmentation as expected for transient outward current-mediated J waves. Increased conduction delay at short RR intervals can be responsible for the accentuation of the transient outward current and J waves during severe hypothermia.

Cadmium stress assessment based on the electrocardiogram characteristics of zebra fish (Danio rerio): QRS complex could play an important role

The electrocardiogram (ECG) of zebra fish (Danio rerio) expresses cardiac features that are similar to humans. Here we use sharp microelectrode measurements to obtain ECG characteristics in adult zebra fish and analyze the effects of cadmium chloride (CdCl₂) on the heart. We observe the overall changes of ECG parameters in different treatments (0.1 TU, 0.5 TU and 1.0 TU CdCl₂), including P wave, Q wave, R wave, S wave, T wave, PR interval (atrial contraction), QRS complex (ventricular depolarization), ST segment, and QT interval (ventricular repolarization). The trends of the ECG parameters showed some responses to the concentration and exposure time of CdCl₂, but it was difficult to obtain more information about the useful indicators in water quality assessment depending on tendency analysis alone. A self-organizing map (SOM) showed that P values, R values, and T values were similar; R wave and T wave amplitude were similar; and most important, QRS value was similar to the CdCl₂ stress according to the classified data patterns including CdCl₂ stress (E) and ECG components based on the Ward linkage. It suggested that the duration of QRS complex was related to environmental stress E directly. The specification and evaluation of ECG parameters in Cd²⁺ pollution suggested that there is a markedly significant correlation between QRS complex and CdCl₂ stress with the highest r (0.729) and the smallest p (0.002) among all ECG characteristics. In this case, it is concluded that QRS complex can be used as an indicator in the CdCl₂ stress assessment due to the lowest AIC data abased on the linear regression model between the CdCl₂ stress and ECG parameters.

Predicting QRS and PR interval prolongations in humans using nonclinical data

BACKGROUND AND PURPOSE

Risk of cardiac conduction slowing (QRS/PR prolongations) is assessed prior to clinical trials using in vitro and in vivo studies. Understanding the quantitative translation of these studies to the clinical situation enables improved risk assessment in the nonclinical phase.

EXPERIMENTAL APPROACH

Four compounds that prolong QRS and/or PR (AZD1305, flecainide, quinidine and verapamil) were characterized using in vitro (sodium/calcium channels), in vivo (guinea pigs/dogs) and clinical data. Concentration-matched translational relationships were developed based on in vitro and in vivo modelling, and the in vitro to clinical translation of AZD1305 was quantified using an in vitro model.

KEY RESULTS

Meaningful (10%) human QRS/PR effects correlated with low levels of in vitro Na_v 1.5 block (3-7%) and Ca_v 1.2 binding (13-21%) for all compounds. The in vitro model developed using AZD1305 successfully predicted QRS/PR effects for the remaining drugs. Meaningful QRS/PR changes in humans correlated with small effects in guinea pigs and dogs (QRS 2.3-4.6% and PR 2.3-10%), suggesting that worst-case human effects can be predicted by assuming four times greater effects at the same concentration from dog/guinea pig data.

CONCLUSION AND IMPLICATIONS

Small changes in vitro and in vivo consistently translated to meaningful PR/QRS changes in humans across compounds. Assuming broad applicability of these approaches to assess cardiovascular safety risk for non-arrhythmic drugs, this study provides a means of predicting human QRS/PR effects of new drugs from effects observed in nonclinical studies.

Modeling hypothermia induced effects for the heterogeneous ventricular tissue from cellular level to the impact on the ECG

Hypothermia has a profound impact on the electrophysiological mechanisms of the heart. Experimental investigations provide a better understanding of electrophysiological alterations associated with cooling. However, there is a lack of computer models suitable for simulating the effects of hypothermia in cardio-electrophysiology. In this work, we propose a model that describes the cooling-induced electrophysiological alterations in ventricular tissue in a temperature range from 27°C to 37°C. To model the electrophysiological conditions in a 3D left ventricular tissue block it was essential to consider the following anatomical and physiological parameters in the model: the different cell types (endocardial, M, epicardial), the heterogeneous conductivities in longitudinal, transversal and transmural direction depending on the prevailing temperature, the distinct fiber orientations and the transmural repolarization sequences. Cooling-induced alterations on the morphology of the action potential (AP) of single myocardial cells thereby are described by an extension of the selected Bueno-Orovio model for human ventricular tissue using Q10 temperature coefficients. To evaluate alterations on tissue level, the corresponding pseudo electrocardiogram (pECG) was calculated. Simulations show that cooling-induced AP and pECG-related parameters, i.e. AP duration, morphology of the notch of epicardial AP, maximum AP upstroke velocity, AP rise time, QT interval, QRS duration and J wave formation are in good accordance with literature and our experimental data. The proposed model enables us to further enhance our knowledge of cooling-induced electrophysiological alterations from cellular to tissue level in the heart and may help to better understand electrophysiological mechanisms, e.g. in arrhythmias, during hypothermia.

PR Interval Prolongation and Cryptogenic Stroke: A Multicenter Retrospective Study

BACKGROUND

Atrial dysfunction or "cardiopathy" has been recently proposed as a mechanism in cryptogenic stroke. A prolonged PR interval may reflect impaired atrial conduction and thus may be a biomarker of atrial cardiopathy. We aim to compare the prevalence of PR interval prolongation in patients with cryptogenic stroke (CS) when compared with known non-cryptogenic non-cardioembolic stroke (NCNCS) subtypes.

METHODS

We used prospective ischemic stroke databases of 3 comprehensive stroke centers to identify patients 18 years or older with a discharge diagnosis of ischemic non-cardioembolic stroke between December 1, 2013 and August 31, 2015. The main outcome was ischemic stroke subtype (CS versus NCNCS). We compared PR intervals as a continuous and categorical variable (<200 milliseconds; ≥200 milliseconds) and other clinical and demographic factors between the 2 groups and used multivariate regression analyses to determine the association between PR interval prolongation and CS.

RESULTS

We identified 644 patients with ischemic non-cardioembolic stroke (224 CS and 420 NCNCS). Patients with CS were more likely to have a PR of 200 milliseconds or greater when compared with those with NCNCS (23.2% versus 13.8%, P = .009). After adjusting for factors that were significant in univariate analyses, a PR of 200 milliseconds or greater was independently associated with CS (odds ratio [OR] 1.70, 95% CI 1.08-2.70). The association was more pronounced when excluding patients on atrioventricular nodal blocking agents (OR 2.64, 95% CI 1.44-4.83).

CONCLUSIONS

A PR of 200 milliseconds or greater is associated with CS and may be a biomarker of atrial cardiopathy in the absence of atrial fibrillation. Prospective studies are needed to confirm this association.

Electrocardiogram QRS duration and associations with telomere length: A cross-sectional analysis in Australian rural diabetic and non-diabetic population

Prolonged electrocardiogram QRS durations are often present in aging populations. Shorter telomere length is considered a biomarker of cellular aging. Decreased telomere length has been associated with coronary artery risk, and ventricular remodeling. However, the association between telomeres and cardiac conduction abnormalities, such as increased QRS duration are not well understood. A retrospective cross-sectional population was obtained from the CSU Diabetes Screening Research Initiative database where 273 participants had both ECG-derived QRS duration and DNA to permit leukocyte telomere length (LTL) determination. Telomere length was determined using the monochrome multiplex quantitative PCR method to measure mean relative LTL. Resting 12-lead electrocardiograms were obtained from each subject using a Welch Allyn PC-Based ECG system. Relative LTL was moderately negatively associated with QRS duration in type 2 diabetes mellitus (T2DM) patients (R²=0.055), compared to controls (R²=0.010). In general linear models with no adjustments a significant interaction between QRS duration and LTL is observed for a combined population of T2DM and non-diabetics. When we compared T2DM to non-diabetics, we found that T2DM increased the effect size for relative LTL on QRS duration in comparison to controls. Hence, for each 0.1 unit of relative LTL attrition, QRS duration in T2DM patients increased by 3.24ms (95% CI, -63.00 to -1.84), compared to 1.65ms in controls (95% CI, -40.44 to 7.40). In summary we have observed an association between LTL in a rural aging mixed population of T2DM and non-diabetes. We have observed an unadjusted association between QRS duration and LTL in T2DM. We noted that the control group demonstrated no such association. This highlights the complexity of T2DM when exploring disease phenotype-telomere interactions.

Electrocardiographic assessments and cardiac events after fingolimod first dose - a comprehensive monitoring study

Background

First dose observation for cardiac effects is required for fingolimod, but recommendations on the extent vary. This study aims to assess cardiac safety of fingolimod first dose. Individual bradyarrhythmic episodes were evaluated to assess the relevance of continuous electrocardiogram (ECG) monitoring.

Methods

START is an ongoing open-label, multi-center study. At the time of analysis 3951 patients were enrolled. The primary endpoints are the incidence of bradycardia (heart rate < 45 bpm) and second-/third-degree AV blocks during treatment initiation. The relevance of Holter was assessed by matching ECG findings with the occurrence of clinical symptoms as well as by rigorous analysis of AV blocks with regard to the duration of pauses and the minimal heart rate recorded during AV block.

Results

Thirty-one patients (0.8%) developed bradycardia (<45 bpm), 62 patients (1.6%) had second-degree Mobitz I and/or 2:1 AV blocks with a lowest reading (i.e. mean of ten consecutive beats) of 35 bpm and the longest pause lasting for 2.6 s. No Mobitz II or third-degree AV blocks were observed. Only one patient complained about mild chest discomfort and fatigue. After 1 week, there was no second-/third-degree AV block.

Conclusions

Continuous Holter ECG monitoring in this large real-life cohort revealed that bradycardia and AV conduction abnormalities were rare, transient and benign. No further unexpected abnormalities were detected. The data presented here give an indication that continuous Holter ECG monitoring does not add clinically relevant value to patients’ safety.

Trial registration

NCT01585298; registered April 23, 2012.

Cardiac Electrical and Structural Changes During Bacterial Infection: An Instructive Model to Study Cardiac Dysfunction in Sepsis

BACKGROUND

Sepsis patients with cardiac dysfunction have significantly higher mortality. Although several pathways are associated with myocardial damage in sepsis, the precise cause(s) remains unclear and treatment options are limited. This study was designed to develop a new model to investigate the early events of cardiac damage during sepsis progression.

METHODS AND RESULTS

Francisella tularensis subspecies novicida (Ft.n) is a Gram-negative intracellular pathogen causing severe sepsis syndrome in mice. BALB/c mice (N=12) were sham treated or infected with Ft.n through the intranasal route. Serial electrocardiograms were recorded at multiple time points until 96 hours. Hearts were then harvested for histology and gene expression studies. Similar to septic patients, we illustrate both cardiac electrical and structural phenotypes in our murine Ft.n infection model, including prominent R' wave formation, prolonged QRS intervals, and significant left ventricular dysfunction. Notably, in infected animals, we detected numerous microlesions in the myocardium, previously observed following nosocomial Streptococcus infection and in sepsis patients. We show that Ft.n-mediated microlesions are attributed to cardiomyocyte apoptosis, increased immune cell infiltration, and expression of inflammatory mediators (tumor necrosis factor, interleukin [IL]-1β, IL-8, and superoxide dismutase 2). Finally, we identify increased expression of microRNA-155 and rapid degradation of heat shock factor 1 following cardiac Ft.n infection as a primary cause of myocardial inflammation and apoptosis.

CONCLUSIONS

We have developed and characterized an Ft.n infection model to understand the pathogenesis of cardiac dysregulation in sepsis. Our findings illustrate novel in vivo phenotypes underlying cardiac dysfunction during Ft.n infection with significant translational impact on our understanding of sepsis pathophysiology.

The Cardiac Safety Research Consortium enters its second decade: An invitation to participate

The Cardiac Safety Research Consortium (CSRC), a transparent, public-private partnership established in 2005 as a Critical Path Program and formalized in 2006 under a Memorandum of Understanding between the United States Food and Drug Administration and Duke University, is entering its second decade. Our continuing goal is to advance paradigms for more efficient regulatory science related to the cardiovascular safety of new therapeutics, both in the United States and globally, particularly where such safety questions add burden to innovative research and development. Operationally, CSRC brings together a broad base of stakeholders from academia, industry, and government agencies in a collaborative forum focused on identifying barriers and then creating novel solutions through shared data, expertise, and collaborative research. This white paper provides a brief overview of the Consortium's activities in its first decade and a context for some of our current activities and future directions. The growth and success of the CSRC have been primarily driven by members' active participation and the development of goodwill and trust throughout our membership, which have facilitated novel collaborations across traditionally competitive or contentious stakeholder boundaries. The continued expansion of our base of participating academicians, industry experts, and regulators will define the Consortium's success in our second decade. It is our hope that sharing our endeavors to date will stimulate additional participation in the CSRC and also provide a model for other groups starting to develop similar collaborative forums.

PKPD modelling of PR and QRS intervals in conscious dogs using standard safety pharmacology data

INTRODUCTION

Pharmacokinetic-pharmacodynamic (PKPD) modelling can improve safety assessment, but few PKPD models describing drug-induced QRS and PR prolongations have been published. This investigation aims to develop and evaluate PKPD models for describing QRS and PR effects in routine safety studies.

METHODS

Exposure and telemetry data from safety pharmacology studies in conscious beagle dogs were acquired. Mixed effects baseline and PK-QRS/PR models were developed for the anti-arrhythmic compounds AZD1305, flecainide, quinidine and verapamil and the anti-muscarinic compounds AZD8683 and AZD9164. RR interval correction and circadian rhythms were investigated for predicting baseline variability. Individual PK predictions were used to drive the pharmacological effects evaluating linear and non-linear direct and effect compartment models.

RESULTS

Conduction slowing induced by the tested anti-arrhythmics was direct and proportional at low exposures, whilst time delays and non-linear effects were evident for the tested anti-muscarinics. AZD1305, flecainide and quinidine induced QRS widening with 4.2, 10 and 5.6% μM(-1) unbound drug. AZD1305 and flecainide also prolonged PR with 13.5 and 11.5% μM(-1). PR prolongations induced by the anti-muscarinics and verapamil were best described by Emax models with maximal effects ranging from 55 to 95%. RR interval correction and circadian rhythm improved PR but not QRS modelling. However, circadian rhythm had minor impact on estimated drug effects.

DISCUSSION

Baseline and drug-induced effects on QRS and PR intervals can be effectively described with PKPD models using routine data, providing quantitative safety information to support drug discovery and development.

Central Autonomic Dysfunction Delays Recovery of Fingolimod Induced Heart Rate Slowing

BACKGROUND

In multiple sclerosis (MS) patients, Fingolimod may induce prolonged heart-rate slowing which might be caused by MS-related central autonomic lesions.

OBJECTIVES

To evaluate whether MS-patients with prolonged heart-rate slowing (> six hours) upon Fingolimod show cardiovascular-autonomic dysfunction before Fingolimod-initiation.

METHODS

Before Fingolimod-initiation, we recorded electrocardiographic RR-intervals (RRIs) and blood-pressure (BP) at rest, upon standing-up, during metronomic deep-breathing, Valsalva-maneuver, and "sustained-handgrip-exercise" in 21 patients with relapsing-remitting MS, and 20 healthy persons. We calculated sympathetic and parasympathetic cardiovascular parameters, including low- (LF) and high-frequency (HF) powers of RRI- and BP-oscillations, RRI-RMSSDs, RRI- and BP-changes during handgrip-exercise, parasympathetic heart-rate-slowing in relation to BP-overshoot after Valsalva-strain-release. We compared values of healthy persons and patients with and without prolonged heart-rate slowing after Fingolimod-initiation (ANOVA; significance: p<0.05).

RESULTS

Upon Fingolimod-initiation, 7/21 patients had prolonged HR-slowing. Before Fingolimod, these patients had higher resting BP and higher BP increase during handgrip-exercise than had the other participants (p<0.05). They did not reduce parasympathetic HR-parameters upon standing-up. After Valsalva-strain-release, their parasympathetic HR-slowing in response to BP-overshoot was four times higher than in the other participants (p<0.05).

CONCLUSIONS

The autonomic cardiovascular dysfunction in MS-patients with delayed HR-re-acceleration upon Fingolimod-initiation suggests that MS-related central autonomic lesions compromise HR-re-acceleration upon Fingolimod.

TRIAL REGISTRATION

German Clinical Trial Register DRKS00004548 http://drks-neu.uniklinik-freiburg.de/drks_web/setLocale_EN.do.

Considerations for assessing the potential effects of antidiabetes drugs on cardiac ventricular repolarization: A report from the Cardiac Safety Research Consortium

Thorough QT studies conducted according to the International Council on Harmonisation E14 guideline are required for new nonantiarrhythmic drugs to assess the potential to prolong ventricular repolarization. Special considerations may be needed for conducting such studies with antidiabetes drugs as changes in blood glucose and other physiologic parameters affected by antidiabetes drugs may prolong the QT interval and thus confound QT/corrected QT assessments. This review discusses potential mechanisms for QT/corrected QT interval prolongation with antidiabetes drugs and offers practical considerations for assessing antidiabetes drugs in thorough QT studies. This article represents collaborative discussions among key stakeholders from academia, industry, and regulatory agencies participating in the Cardiac Safety Research Consortium. It does not represent regulatory policy.

In Vitro Early Safety Pharmacology Screening: Perspectives Related to Cardiovascular Safety

In vitro screening for cardiovascular safety liabilities of novel drug candidates presents a challenge for the pharmaceutical industry. Such approaches rely on detecting pharmacologic effects on key components of complex integrated system early in drug discovery to define potential safety liabilities. Key to such studies are the concepts of hazard identification vs. risk assessment, drug specificity vs. selectivity, and an appreciation of the challenges faced when attempting to translate in vitro findings to preclinical in vivo as well as clinical effects. This chapter defines some key aspects of early safety pharmacology screening for cardiovascular liabilities, citing studies of two key depolarizing cardiac currents (fast sodium current and L-type calcium current) as examples linked to effects on cardiac conduction and repolarization.

Effect of ceralifimod (ONO-4641) on lymphocytes and cardiac function: Randomized, double-blind, placebo-controlled trial with an open-label fingolimod arm

This randomized, double-blind, placebo-controlled, 6-arm, parallel-design study investigated cardiac and hematological pharmacodynamic effects of ceralifimod (ONO-4641), a selective sphingosine-1-phosphate (S1P) receptor modulator, over a broad dose range in direct comparison with the nonselective S1P modulator fingolimod. Healthy subjects were assigned to ceralifimod (0.01, 0.025, 0.05, or 0.10 mg), fingolimod (0.5 mg), or placebo once daily for 14 days (n = 24 per group). After 14 days of treatment, mean absolute lymphocyte count percentage change from baseline was greatest in the fingolimod (-62%) and ceralifimod 0.10 mg (-56%) groups. On treatment cessation, lymphocyte recovery was faster in the ceralifimod versus the fingolimod group. Ceralifimod showed dose- and concentration-dependent chronotropic effect. Cardiac effects in the fingolimod group were dependent on fingolimod-P concentrations. Maximum mean heart rate (HR) effect on day 1 was larger with fingolimod (placebo-adjusted change from time-matched baseline HR [ΔΔHR], -14.9 beats per minute [bpm]) versus ceralifimod (ΔΔHR, -6.2 and -12.0 bpm for the 0.05- and 0.10-mg doses, respectively). Ceralifimod's effect on the PR interval was minor. Safety biomarker results suggest that potential therapeutic doses of ceralifimod, in particular the 0.05-mg dose, might result in reduced occurrence of bradycardia, atrioventricular block absolute lymphocyte count and grade 3/4 lymphopenia compared with fingolimod 0.5 mg.

Evaluation of Melissa officinalis (Lemon Balm) Effects on Heart Electrical System

Background:

Melissa officinalis, an herbal drug, is well known and frequently applied in traditional and modern medicine. Yet, there is inadequate information regarding its effects on electrical properties of the heart. The present study attempted to elucidate the effects of Melissa officinalis aqueous extract on electrocardiogram (ECG) in rat.

Objectives:

ECG is an easy, fast and valuable tool to evaluate the safety of used materials and drugs on heart electrical and conductivity properties. Many drugs with no cardiovascular indication or any overt cardiovascular effects of therapeutic dosing become cardiotoxic when overdosed (16). On the other hand, there are numerous substances and drugs that can cause ECG changes, even in patients without a history of cardiac disease. Therefore, this study was conducted to elucidate safety and outcome of one-week administration of M. officinalis aqueous extract on blood pressure and ECG parameters of rats.

Materials and Methods:

Four animal groups received tap water (control group), aqueous extracts of Melissa officinalis 50 (M50), 100 (M100) and 200 (M200) mg/kg/day, respectively and orally for a week. ECG and blood pressure were recorded on the eighth day of experiment.

Results:

Consumption of Melissa officinalis extract associated with prolonged QRS interval (P < 0.05 for M50 and M100 groups and P < 0.01 for M200 group versus the control group, respectively), prolonged QTc and JT intervals (P < 0.01 for different M groups versus the control group) and prolonged TpTe interval (P < 0.001 when M groups compared with the control group) of ECG. However, different doses of the extract had no significant effect on RR interval, PR interval, amplitudes of ECG waves, heart rate and blood pressure.

Conclusions:

For the first time, this study revealed that consumption of Melissa officinalis extract is associated with significant ECG alterations in rat. Future studies are necessary to determine potential clinical outcomes.

Modeling and Simulation Approaches for Cardiovascular Function and Their Role in Safety Assessment

Systems pharmacology modeling and pharmacokinetic-pharmacodynamic (PK/PD) analysis of drug-induced effects on cardiovascular (CV) function plays a crucial role in understanding the safety risk of new drugs. The aim of this review is to outline the current modeling and simulation (M&S) approaches to describe and translate drug-induced CV effects, with an emphasis on how this impacts drug safety assessment. Current limitations are highlighted and recommendations are made for future effort in this vital area of drug research.

The PR interval and QRS duration could be predictors of renal function decline

OBJECTIVE

Previous studies have implicated PR interval (iPR) and QRS duration (dQRS) obtained by electrocardiography in independent predictors of cardiovascular disease, which often precedes renal dysfunction. The aim of this study was to examine whether iPR or dQRS could be a predictor of renal function decline in a community-based cohort.

METHODS

We enrolled 1149 healthy subjects, and retrospectively evaluated the relationships between iPR or dQRS and renal function decline, observation period of which was 3 years, and assessed whether iPR or dQRS could predict renal function decline.

RESULTS

The iPR (r=-0.102, p=0.0006) or dQRS (r=-0.097, p=0.0010) was negatively associated with a rate of decline in estimated glomerular filtration rate (eGFR). Multiple regression analyses revealed that iPR (β=-0.095, p=0.0023) or dQRS (β=-0.069, p=0.0351) was an independent determinant of the rate of decline in eGFR after adjustment for covariates. Logistic regression analyses demonstrated that the longest iPR (odds ratios (OR), 2.03; 95% confidence intervals (CI), 1.49 to 2.76; p<0.0001) or dQRS (OR, 1.62; 95% CI, 1.16 to 2.25; p=0.0043) tertile showed an increased OR for prevalence of the rate of decline in eGFR≤1 ml/min/1.73 m2/year compared to the shortest iPR or dQRS tertile after adjustment for covariates.

CONCLUSION

The iPR and dQRS could be independent predictors of renal function decline in healthy subjects.

Arterial blood gas analysis and the outcome of treatment in tricyclic antidepressants poisoned patients with benzodiazepine coingestion

Background. Poisoning with tricyclic antidepressants (TCAs) is still a major concern for emergency physicians and intensivists. Concomitant ingestion of other psychoactive drugs especially benzodiazepines with TCAs may make this clinical situation more complex. This study aimed to compare the arterial blood gas (ABG) values and the outcome of treatment in patients with coingestion of TCA and benzodiazepine (TCA + BZD) poisoning and TCA poisoning alone. Methods. In this cross-sectional study which was carried out in a tertiary care university hospital in Iran, clinical and paraclinical characteristics of one hundred forty TCA only or TCA + BZD poisoned patients (aged 18-40 years) were evaluated. ABG analysis was done on admission in both groups. Outcomes were considered as survival with or without complication (e.g., intubation) and the frequency of TCA poisoning complications. Results. Arterial pH was significantly lower in TCA + BZD poisoning group compared with TCA only poisoning group (7.34 ± 0.08 and 7.38 ± 0.08, resp.; P = 0.02). However, other complications such as seizure, and the need for the endotracheal intubation were not significantly different. All patients in both groups survived. Conclusions. Concomitant TCA plus BZD poisoning may make the poisoned patients prone to a lower arterial pH level on hospital admission which may potentially increases the risk of cardiovascular complications in TCA poisoning.

Alterations of Blood Pressure and ECG following Two-Week Consumption of Berberis integerrima Fruit Extract

In light of the popularity and also the various nutritional and medicinal properties of Berberis integerrima, this study was conducted to assess the influence of its aqueous extract on hemodynamic and electrocardiogram (ECG) indices of rat. Animals were divided to control (CTL), B50, B100, and B200 groups that orally received tap water, aqueous extracts of B. integerrima fruit 50, 100, and 200 mg/kg/day, respectively, for two weeks and on day 15, data were recorded. Different doses of barberry fruit extract had no significant effect on blood pressure, heart rate, RR interval, P duration, and Q wave amplitude of electrocardiogram. Extract administration was associated with an incremental trend in PR interval that was not statistically significant. Higher doses (100 and 200 mg/kg) of extract significantly increased the QRS interval (P < 0.01 versus CTL and B50 groups) but decreased the QTc interval (P < 0.01 versus CTL group and P < 0.001 versus B50 group), the JT interval, and TpTe interval (P < 0.001 versus CTL and B50 groups). The results suggest that high doses of barberry extract definitely prolong the depolarization phase and shorten the repolarization phase of ventricular muscle and hence induce alteration in heart electrical conductivity.

An open-label study to investigate the cardiac safety profile of cabazitaxel in patients with advanced solid tumors

PURPOSE

This study assessed the cardiovascular safety of cabazitaxel, based on thorough evaluation of QT and non-QT variables, and the relationship between pharmacokinetic and pharmacodynamic electrocardiographic (ECG) profiles and the occurrence of Grade ≥3 cardiovascular adverse events.

METHODS

Patients with advanced solid tumors were treated with cabazitaxel 25 mg/m(2) every 3 weeks. Digital ECG recordings were obtained during Cycle 1 over 24 h after dosing. The primary end point was effect of cabazitaxel on QT interval corrected by the Fridericia formula (QTcF). Secondary end points were additional ECG parameters (QT, PR and QRS intervals, and heart rate), plasma pharmacokinetics of cabazitaxel and overall clinical safety.

RESULTS

The pharmacodynamic (ECG) population included 94 patients. In 63 patients with a full 24-h ECG evaluation, the maximum upper bound of 90 % confidence interval (CI) for mean QTcF change from baseline was 7.46 ms (mean 4.8 ms), occurring at 1 h 30 min post-infusion. The slope of QTcF change from baseline versus cabazitaxel concentration was slightly negative (-0.012 [95 % CI -0.017; -0.008], equivalent to a 1.2 ms decrease per 100 ng/mL increase in cabazitaxel concentration). For non-QT variables, no effect was noted. No Grade ≥3 cardiac adverse events were observed; Grade ≥3 hypotension and lymphocele occurred in two patients and one patient, respectively.

CONCLUSION

These results suggest that cabazitaxel has no clinically significant cardiovascular adverse effects in patients with advanced solid tumors.