The Perfect Storm: Abnormal Baseline QT With Chronic Methadone Use and Serious Hypokalemia.

Methadone, a well-known drug used for pain control and as a treatment for opioid addiction, can cause arrhythmias, including torsades de pointes (TdP), which may progress to ventricular fibrillation and sudden death. We present a case of a middle-aged woman with a long history of methadone use who presented to the emergency department after experiencing cardiac arrest at home. During her hospitalization, she experienced multiple episodes of TdP that improved with isoproterenol and potassium correction. The initial diagnosis was methadone-induced prolonged QT. However, even with discontinuation of methadone, her QTc remained prolonged. Congenital long QT syndrome was suspected, and genetic testing was instructed to test in the outpatient setting. She was discharged on nadolol and a LifeVest.

A "one-step" approach to heart rate correction and statistical analysis applied to conscious dog QTc studies.

A "one-step" method which combined the heart rate correction and statistical analysis for conscious nonhuman primate (NHP) QTc assessment was recently published. The principles of this method are applicable to other species. In the current analysis, we demonstrate the utility of the technique in conscious dog QTc studies. Two studies in male dogs (n = 8 and n = 7) implanted with telemetry devices were used. In both studies, treatments were randomized and all animals received all treatments. In the primary study, the effect on QTc of moxifloxacin was compared with vehicle. Each treatment (vehicle and moxifloxacin) was given on two separate occasions. In the second study, dogs were given vehicle or dofetilide. Conventional QTc analysis was compared with the "one-step" method. The effect on QTc relative to vehicle was determined along with the median minimal detectable difference. As expected, both moxifloxacin and dofetilide gave QTc increases with a maximum of ~ 20 ms. There was a significant increase in the sensitivity to detect a QTc effect when using the "one-step" method. The minimal detectable difference was 1.6 ms for the "one-step" method compared with 6.2 ms for the conventional method. These analyses are consistent with the increased sensitivity described for the "one-step" method applied to studies in NHP. The increased sensitivity should enhance the ability to support an integrated assessment of the QTc prolongation liability for new drugs.

QTc prolongation across CDK4/6 inhibitors: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Cyclin-dependent kinases (CDK) 4/6 inhibitors have significantly improved outcomes for patients with ER+/HER2- breast cancer. Nevertheless, they differ from each other in terms of chemical, biological, and pharmacological features, as well as toxicity profiles. We aim to determine whether QTc prolongation is caused by CDK4/6i in general or if it is associated with ribociclib only. METHODS: We systematically searched PubMed, Embase, and Cochrane Library for randomized controlled trials (RCTs) comparing the prevalence of QTc prolongation as an adverse event in HR+ breast cancer patients treated with CDK4/6i vs those without CDK4/6i. We pooled relative risk (RR) and mean difference (MD) with 95% confidence interval (CI) for the binary endpoint of QT prolongation. RESULTS: We included 14 RCTs comprising 16 196 patients, of whom 8576 underwent therapy with CDK4/6i. An increased risk of QTc prolongation was associated with the use of CDK4/6i (RR = 2.35, 95% CI = 1.67 to 3.29, P < .001; I2 = 44%). Subgroup analyses revealed a significant increase in the QTc interval for the ribociclib and palbociclib cohorts. The ribociclib subgroup showed a relative risk of 3.12 (95% CI = 2.09 to 4.65, P < .001; I2 = 12%), whereas the palbociclib subgroup had a relative risk of 1.51 (95% CI = 1.05 to 2.15, P = .025; I2 = 0%). CONCLUSION: Palbociclib was associated with QTc prolongation; however, the relative risk for any grade QTc was quantitively twice with ribociclib. Furthermore, grade 3 QTc prolongations were observed exclusively with ribociclib. These results are important for guiding clinical decision-making and provide reassurance regarding the overall safety profile of this drug class.

Does IV fentanyl, frequently used in emergency departments, change QTC value? A prospective observational study.

BACKGROUND: Fentanyl is an opioid analgesic frequently used in the emergency department (ED) and is usually administered without knowing the QTC values of the patients or being monitored. However, the effect of fentanyl on QTC, prolongation or shortening, has not been elucidated. This study aimed to determine the effect of fentanyl on QTC. METHODS: This is a prospective observational study in the ED of a tertiary hospital on patients who received intravenous fentanyl for procedures other than intubation. ECG was performed before and at 1, 5, 15, 30, and 60 min after the initiation of fentanyl administration, and QTC value was calculated. Primary outcomes were QTC prolongation, defined as an increase in the QTC to ≥ 500 ms or any increase in QTC by ≥ 60 ms. RESULTS: The study included 109 patients. Of these, 60 patients were male, and the median age was 40. Compared with the baseline QTC value, statistically significant prolongation was detected at the 5th, 15th, 30th, and 60th minutes, with the maximum prolongation at 30 min, and the median was 13.08 ms. Most patients with QTC prolongation were female and over 40 years of age. Clinically, none of these patients developed malignant arrhythmias during the 60-minute monitored observation period. CONCLUSION: Fentanyl prolonged the QTC value statistically significantly. Although no patient developed malignant arrhythmia clinically, our results suggest that this QTC-prolonging effect should be considered when using fentanyl in patients at risk of torsades.

Early vs. delayed QTc prolongation in acute poisoning: A prognostic accuracy study-A case series.

Given the limited capacity of intensive care units in many countries, it is crucial to identify reliable prognostic markers to optimize poisoning patients management and improve outcomes. This study aimed to assess the predictive value of three variables, namely the initial QTc interval (iQTc) measured within two hours of admission, the delayed QTc interval (dQTc) measured between 6 and 12 hours of entry, and the QTc interval trend over time (ΔQTc), for mortality in patients with undifferentiated poisoning. A retrospective case series was conducted on 70 patients with undifferentiated poisoning admitted to the intensive care unit (ICU) of Afzalipour Hospital between March 21, 2021, and March 20, 2023. The results of the multivariate analysis revealed that dQTc, base deficit, and creatinine were independently associated with mortality (P value < 0.001). The dQTc had the highest predictive ability, with an area under the curve (AUC) of 0.84, followed by ΔQTc with an AUC of 0.76, and iQTc with an AUC of 0.67. Additionally, the results of the Generalized Estimating Equation model with repeated measurements revealed a higher odds ratio for dQTc (OR, 6.33; 95% CI, 2.54-15.79) compared to iQTc (OR, 4.92; 95% CI, 1.71-14.17). The study concluded that monitoring the dQTc interval could provide valuable prognostic information in acute poisoning cases.

The effect of intravenous ondansetron on QT interval in the emergency department.

OBJECTIVE: Ondansetron, a 5HT3 receptor antagonist, is commonly used in emergency departments to treat nausea and vomiting. In 2011, the Food and Drug Administration (FDA) issued a warning that this medicine may cause QT prolongation, potentially leading to deadly arrhythmias. The objective of this study was to characterize the QT interval prolongation associated with ondansetron use in the Emergency Department. METHODS: This was a prospective, observational cohort study of adult patients who presented to the emergency department during a one-year period and were treated with intravenous ondansetron. We investigated the QT prolongation associated with dosages. ECGs were obtained before the medication and 5, 15, and 30 minutes after IV drug administration. Every QT measurement was recorded and compared to the zero point. The severity of drug-induced QT prolongation was determined according to the recommendations of the International Conference on Compliance (ICH). QTc prolongation was categorized as 'negligible' (<5 ms), 'significant' (>20 ms), 'potential concern' (>30 ms), or 'definitely worrying' (>60 ms). RESULTS: Of the 435 patients enrolled in the study, 60% (261 patients) were female and the mean age was 39 (±18). The QT prolongation peaked at the fifth minute and remained consistent at the fifteenth and thirty-first minutes. The maximum prolongation of the mean QT duration occured at the fifth minute (7.9 ± 18.1 ms). No patient revealed any problems with cardiac conduction. The prolonged QT interval was not related to the dose of ondansetron, but QT measurements were higher in the 30th minute in patients treated with 8 mg of ondansetron. The effect of ondansetron administration on QT prolongation was found to be above the 'negligible' but below the 'significant' value, according to the ICH recommendations. DISCUSSION: In this study, QT prolongation due to ondansetron administration was below the 'important' value according to the recommendations of the ICH. No cases of cardiac arrhythmia were reported in any of the partients. Thus, routine ECG monitoring in patients given ondansetron due to the risk of QTc prolongation does not seem cost-effective when evaluated together with additional factors such as its negative impact on emergency patient flow, waste of personnel and time, and increase in healthcare costs. In the absence of a known risk of cardiac arrhythmia, IV administration of 4 mg and 8 mg of ondansetron doses no risk of QT prolongation in the emergency population.

An Updated Safety Review of the Relationship Between Atypical Antipsychotic Drugs, the QTc Interval and Torsades de Pointe As: Implications for Clinical Use.

INTRODUCTION: The rising prevalence of psychiatric disorders has resulted in a significant increase in the use of antipsychotic medications. These agents may prolong the corrected QT interval (QTc), running the risk of precipitating ventricular arrhythmias, notably Torsades de Pointes (TdP). Current recommendations vary regarding the optimal approach to safe prescribing practices and QTc surveillance for antipsychotics. This review summarizes the current literature addressing these clinical concerns. AREAS COVERED: The physiologic basis of the QTc interval, mechanisms underlying its susceptibility to pharmacological influence, specific risks associated with atypical antipsychotic agents, and recommendations for safe prescription practices. We performed a literature review using Pubmed and Embase databases, searching for 'antipsychotics' and 'torsades de pointes.' EXPERT OPINION: Finding a safe and universally accepted protocol for prescribing antipsychotics remains a persistent challenge in medicine. Predictive models that integrate clinical history with demographic and ECG characteristics can help estimate an individual's susceptibility to therapy-associated risks, including QTc prolongation. Agents such as ziprasidone and iloperidone are significantly more likely to prolong the QTc interval compared to others such as brexpiprazole, cariprazine, olanzapine, and clozapine. A personalized approach using low-risk medications when clinically feasible, and at the lowest efficacious dose, offers a promising path toward safer antipsychotic prescribing.

Antipsychotic medications are used to treat conditions such as schizophrenia and bipolar disorder; however, they can also affect cardiac electrical conduction. This effect on cardiac function increases the risk of a dangerous heart rhythm, which can potentially be fatal. Patients and doctors need to be aware of and monitor for these potential heart-related side effects, although antipsychotics can be very helpful for mental health conditions.

Clofazimine and QT prolongation in the treatment of rifampicin-resistant tuberculosis: Findings of aDSM in Taiwan.

BACKGROUND: Bedaquiline, delamanid and fluoroquinolones are associated with increased QTcF. Whether clofazimine is associated with QTcF prolongation is less clear. METHODS: All patients with rifampicin-resistant TB enrolled between May 2017 and Dec 2019 were included. ECGs were performed at baseline, month 1, month 3 and month 6 for patients treated with conventional regimens, and at additional timepoint for patients treated with bedaquiline, delamanid and short regimen. We estimated the maximum increase of QTcF and constructed cox proportional hazards models to assess factors associated with QTcF≥501ms. RESULTS: Among 321 patients, 59 (18.4%) patients had QTcF≥501ms during a mean follow-up of 242 days (median 189, range 4-1091). The median maximum increase of QTcF was 43.4 ms (IQR 31.3-65.9) in patients treated with clofazimine. Treatment with clofazimine was significantly associated with QTcF≥501ms as compared to without clofazimine (adjusted hazards ratio (adjHR) 4.35, 95% confidence interval (CI) 2.01-9.44). Among patients not treated with bedaquiline and delamanid, those treated with clofazimine and a fluoroquinolone (adjHR 3.43, 95% CI 1.61-7.34) and those treated with clofazimine and high dose moxifloxacin (adjHR 6.54, 95% CI 2.43-17.60) had a significantly higher risk of QTcF≥501ms as compared to those treated with a fluoroquinolone without other QTcF prolonging agents. Four (1.6%) patients had documented ventricular tachycardia, in which one was Torsade de pointes. One patient was found to have sudden death during hospitalization. CONCLUSIONS: Clofazimine was significantly associated with an increased risk of QTcF prolongation. QTcF≥501ms was potentially associated with fatal event and needed to be managed cautiously.

Drug-induced QT interval prolongation in patients with heart failure with preserved ejection fraction.

Heart failure (HF) with reduced ejection fraction (HFrEF) is a risk factor for drug-induced QT interval prolongation. It is unknown if HF with preserved ejection fraction (HFpEF) is also associated with an increased risk. Dofetilide and sotalol are potent QT interval-prolonging agents that are frequently used in patients with HFpEF, in whom atrial fibrillation is a common comorbidity. We tested the hypothesis that the risk of QT interval prolongation associated with dofetilide and sotalol is increased in patients with HFpEF. We conducted a retrospective cohort study conducted using electronic health records from the Indiana Network for Patient Care (January 31, 2010 -May 3, 2021). After removing patients with overlapping diagnoses of HFpEF and HFrEF, no diagnosis code, and absence of QT interval records, we identified patients taking dofetilide or sotalol among three groups: HFrEF (n = 138), HFpEF (n = 109), and no HF (n = 729). QT prolongation was defined as heart rate-corrected QT (QTc) > 500 ms during dofetilide/sotalol therapy. Unadjusted odds ratios (OR) for QT prolongation were determined by univariate analysis. Adjusted ORs were determined by generalized estimating equations (GEE) with logit link to account for an individual cluster with different times of hospitalization and covariates. QTc prolongation associated with dofetilide or sotalol occurred in 53.2%, 71.7% and 30.0% of patients with HFpEF, HFrEF, and patients with no HF, respectively. After adjusting for age, sex, race, serum potassium and magnesium concentrations, kidney function, concomitant drug therapy, and comorbid conditions, the adjusted odds of QTc prolongation were significantly higher in patients with HFpEF [OR = 1.98 (95% CI 1.17-3.33)], and in those with HFrEF [OR = 5.23, (3.15-8.67)], compared to those with no evidence of HF. The odds of QT prolongation among inpatients receiving dofetilide or sotalol were increased in patients with HFpEF and HFrEF compared to those who did not have HF.

The role of mitochondrial dysfunction in the association between trace metals and QTc prolongation in the aged population.

This study delves into the relationship between environmental metal exposure and QT interval corrected for heart rate (QTc) prolongation, a critical marker for cardiovascular risk in the elderly. Although the interplay between metal exposure and QTc prolongation is important for predicting sudden cardiac death, it remains underexplored. Our analysis of 6478 participants from the Shenzhen aging-related disorder cohort involved measuring urinary concentrations of 22 trace metals and using mitochondrial DNA copy number (mtDNA-CN) as an indicator of mitochondrial dysfunction. Utilizing Bayesian kernel machine regression, and structural equation modeling, we assessed the effects of mixed trace metals on QTc prolongation. Our findings indicated a direct association between certain metals (Sb, Cu, Zn) and a 7 % increase in QTc prolongation risk, while Li, V, and Rb were associated with a 5 % reduction in risk. Elevated levels of V, Ti, and Cr corresponded to higher mtDNA-CN. Notably, restricted cubic splines revealed a U-shaped, nonlinear relationship between mtDNA-CN and QTc prolongation. After adjusting for metal exposure, an inverse correlation was observed between mtDNA-CN and QTc prolongation, suggesting mitochondrial dysfunction as a partial mediator.

The evaluation of the short-term and long-term hydroxychloroquine therapy on ECG parameters.

Amidst the COVID-19 pandemic, hydroxychloroquine (HCQ) was widely administered despite limited data on its safety and efficacy. This study assesses the acute and chronic impacts of HCQ on electrocardiography (ECG) parameters alongside the effects of azithromycin and levofloxacin coadministration in patients with COVID-19. A comprehensive analysis was conducted on 109 COVID-19 patients receiving HCQ, with or without Azithromycin and/or Levofloxacin, and 51 long-term HCQ-treated Sjogren's syndrome (SS) patients. ECG parameters, including QTc interval, were meticulously evaluated against a control group of 109 COVID-19 patients without HCQ treatment. HCQ monotherapy, in combination with Levofloxacin, significantly prolonged the QTc interval in COVID-19 patients compared to controls. Notably, the combination of HCQ and Azithromycin demonstrated a mitigated impact on QTc prolongation. Long-term HCQ use in SS patients did not significantly affect QTc intervals, illustrating a distinct safety profile from short-term use in COVID-19 treatment. HCQ's impact on QTc prolongation is influenced by therapeutic context, coadministered drugs, and patient demographics. The findings underscore the necessity of cautious HCQ use, particularly in acute settings like COVID-19, where monitoring and consideration of drug interactions and patient-specific factors are critical.

Assessment of corrected JT-peak (JTpc) and Tpeak-to-Tend (TpTec) as proarrhythmia biomarkers in non-human primates: Outcome from a HESI consortium.

INTRODUCTION: Corrected QT interval (QTc)is an established biomarker for drug-induced Torsade de Pointe (TdP), but with concerns for a false positive signal. Clinically, JTpc and TpTec have emerged as ECG sub-intervals to differentiate predominant hERG vs. mixed ion channel blocking drugs that prolong QTc. METHODS: In a multicentric, prospective, controlled study, different proarrhythmic drug effects on QTc, JTpc and TpTec were characterized with cynomolgus monkeys using telemetry in a Lead II configuration for internal and external telemetry.Drugs and vehicle were administered orally (PO) to group size of 4 to 8 animals, in 4 laboratories. RESULTS: In monkeys, dofetilide (0.03-0.3 mg/kg) was associated with exposure dependent QTc and JTpc increase, but no significant TpTec effect. Similarly, quinidine (2-50 mg/kg) increased QTc and JTpc but did not change TpTec. Mexiletine (1-15 mg/kg) and verapamil (50 mg/kg) did not induce any significant effect on QTc, JTpc or TpTec. DISCUSSION: Clinically, predominant hERG blockers (dofetilide and quinidine) prolong QTc, JTpc and TpTec and are associated with increased risk for TdP. Results from this study demonstrate that ECG changes after dofetilide and quinidine administration to telemetered monkeys differ from the clinical response, lacking the expected effects on TpTec. Potential explanations for the lack of translation include physio-pharmacology species differences or ECG recording and analysis methodology variations. Mixed ion channel blockers verapamil and mexiletine administered to monkeys showed no significant QTc, JTpc or TpTec prolongation as expected based on the similar clinical response for these agents.

The Use of Drugs that Should be Avoided or Used with Caution in Patients Hospitalized for Acute Decompensated Heart Failure.

BACKGROUND: Heart failure (HF) is a pervasive global health concern, with acute decompensated heart failure (ADHF) contributing significantly to morbidity and mortality. Medications used in patients with HF may exacerbate HF or prolong the QT interval, posing additional risks. OBJECTIVE: The objective is to assess the prevalence and utilization patterns of medications known to cause or exacerbate HF and prolong the QT interval among patients with ADHF. Understanding these patterns is crucial for optimizing patient care and minimizing potential risks. METHODS: A retrospective chart review was conducted at Huntsville Hospital, Huntsville, USA, covering 602 patients with ADHF over a 40-month period. Inclusion criteria involved age ≥ 18 years, a history of HF, and ADHF admission. The 2016 American Heart Association Scientific Statement was used to identify drugs that may cause or exacerbate HF and those that could prolong the QT interval RESULTS: Among the 602 patients, 57.3% received medications causing or exacerbating HF, notably albuterol (34.9%) and diabetes medications (20.4%), primarily metformin, followed by urologic agents (14.3%), mostly tamsulosin, and nonsteroidal anti-inflammatory drugs (NSAIDs) (6.1%). Moreover, 82.9% were on medications prolonging the QT interval, with loop diuretics, amiodarone, ondansetron, and famotidine most prevalent. Furthermore, 42.1% of the patients received more than two concomitant medications that prolong the QT interval, which can further exacerbate the risk of torsades de pointes. CONCLUSION: This study underscores the high prevalence of HF-causing or HF-exacerbating medications and QT-prolonging drugs in patients with ADHF. Healthcare professionals must be cognizant of these patterns, advocating for safer prescribing practices to optimize patient outcomes and reduce the burden of HF-related hospitalizations.

Thorough QT/QTc study to evaluate the effect of a single supratherapeutic dose of islatravir on QTc interval prolongation in healthy adults.

Islatravir is a deoxynucleoside analog being developed for the treatment of HIV-1 infection. Clinical studies are being conducted to evaluate islatravir, administered in combination with other antiretroviral therapies, at doses of 0.25 mg once daily and 2 mg once weekly. In multiple previous clinical studies, islatravir was generally well tolerated, with no clear trend in cardiac adverse events. A trial was conducted to evaluate the effect of islatravir on cardiac repolarization. A randomized, double-blind, active- and placebo-controlled phase 1 trial was conducted, in which a single dose of islatravir 0.75 mg, islatravir 240 mg (supratherapeutic dose), moxifloxacin 400 mg (active control), or placebo was administered. Continuous 12-lead electrocardiogram monitoring was performed before dosing through 24 hours after dosing. QT interval measurements were collected, and safety and pharmacokinetics were evaluated. Sixty-three participants were enrolled, and 59 completed the study. Fridericia's QT correction for heart rate was inadequate; therefore, a population-specific correction was applied (QTcP). The placebo-corrected change from baseline in QTcP (ΔΔQTcP) interval at the observed geometric mean maximum plasma concentration associated with islatravir 0.75 mg and islatravir 240 mg was <10 ms at all time points. Assay sensitivity was confirmed because the use of moxifloxacin 400 mg led to a ΔΔQTcP >10 ms. The pharmacokinetic profile of islatravir was consistent with that of previous studies, and islatravir was generally well tolerated. Results from the current trial suggest that single doses of islatravir as high as 240 mg do not lead to QTc interval prolongation.

Feasibility and accuracy of mobile QT interval monitoring strategies in bedaquiline-enhanced prophylactic leprosy treatment.

Some anti-mycobacterial drugs are known to cause QT interval prolongation, potentially leading to life-threatening ventricular arrhythmia. However, the highest leprosy and tuberculosis burden occurs in settings where electrocardiographic monitoring is challenging. The feasibility and accuracy of alternative strategies, such as the use of automated measurements or a mobile electrocardiogram (mECG) device, have not been evaluated in this context. As part of the phase II randomized controlled BE-PEOPLE trial evaluating the safety of bedaquiline-enhanced post-exposure prophylaxis (bedaquiline and rifampicin, BE-PEP, versus rifampicin, SDR-PEP) for leprosy, all participants had corrected QT intervals (QTc) measured at baseline and on the day after receiving post-exposure prophylaxis. The accuracy of mECG measurements as well as automated 12L-ECG measurements was evaluated. In total, 635 mECGs from 323 participants were recorded, of which 616 (97%) were of sufficient quality for QTc measurement. Mean manually read QTc on 12L-ECG and mECG were 394 ± 19 and 385 ± 18 ms, respectively (p < 0.001), with a strong correlation (r = 0.793). The mean absolute QTc difference between both modalities was 11 ± 10 ms. Mean manual and automated 12L-ECG QTc were 394 ± 19 and 409 ± 19 ms, respectively (n = 636; p < 0.001), corresponding to moderate agreement (r = 0.655). The use of a mECG device for QT interval monitoring was feasible and yielded a median absolute QTc error of 8 ms. Automated QTc measurements were less accurate, yielding longer QTc intervals.

Low Risk of Cardiac Complications During Long-Term Follow-Up of Opioid Dependence.

OBJECTIVES: To prospectively assess rates of QT prolongation, arrhythmia, syncope, and sudden cardiac death (SCD) in a cohort of people with heroin dependence. METHODS: To estimate rates of QT prolongation, arrhythmia, and syncope, a subcohort (n = 130) from the Australian Treatment Outcomes Study, a prospective longitudinal cohort study of 615 people with heroin dependence, underwent medical history, venepuncture, and ECG at the 18- to 20-year follow-up.To estimate rates of SCD, probabilistic matching for the entire cohort was undertaken with the Australian Institute of Health and Welfare National Death Index. Deaths were classified into suicide, accidental overdose, trauma, unknown, and disease, which were then further subclassified by probability of SCD. SCD rate was the number of possible or probable SCDs divided by total patient years from the cohort. RESULTS: From the subcohort, 4 participants (3%) met the criteria for QT prolongation; 3 were prescribed methadone. Seven participants (5%) reported history of arrhythmia, including 2 transferred from methadone to buprenorphine. Thirty participants (23%) reported a previous syncopal event-14 diagnosed as nonarrhythmic syncope and 13 not investigated. In the previous 12 months, 66 participants (51%) reported heroin use; 55 participants (42%) were prescribed methadone. No participant had QTc greater than 500 milliseconds.There were 3 possible SCDs, translating to an estimated SCD rate of 0.29 (CI: 0.05, 0.8) events per 1000 patient years. More cohort members died of overdose (n = 50), suicide (n = 11), and hepatitis C (n = 4). CONCLUSIONS: Low rates of QT prolongation, arrhythmia, syncope, and SCD in the cohort despite high rates of heroin use and methadone treatment.

The NOS1AP gene rs10494366 common genetic variant does not modify the risk of sudden cardiac death in users of digoxin.

AIMS: Common genetic variations in the nitric oxide synthase-1 adaptor protein (NOS1AP) gene are associated with QT-interval prolongation. In a previous study, we observed an association between the rs10494366 variant of this gene and an increased QT-interval shortening in digoxin users. As QT-interval shortening is a risk factor for sudden cardiac death (SCD), in this study, we investigated whether the association between digoxin use and risk of SCD differs in participants with different NOS1AP rs10494366 genotypes. METHODS: We included 11 377 individuals from the prospective population-based cohort of the Rotterdam Study. We used Cox proportional hazard regression analysis with digoxin as time-dependent exposure to estimate the associations between current digoxin use and the risk of SCD among different rs10494366 genotype groups in the adjusted models. We also studied whether such an association was dose-dependent, comparing high dosage (≥ 0.250 mg), moderate dosage (0.125 mg ≤ dose< 0.250 mg) and low dosage (< 0.125 mg) digoxin users with non-users. RESULTS: The median baseline age of the total study population was 62 (interquartile range [IQR] 58-71) years. The cumulative incidence of SCD was 4.1% (469 cases), and among them, 74 (15.7%) individuals were current digoxin users at the time of death, during a median follow-up of 11.5 (IQR 6.5-17) years. Current digoxin users had an increased risk of SCD (multivariable adjusted model hazard ratio [HR]: 3.07; 95% confidence interval [CI]: 2.38-3.98), with no significant differences between the three genotype groups. The adjusted HRs were 4.03 [95% CI: 1.98-8.21] in the minor homozygous GG, 3.46 [95% CI: 2.37-5.04] in the heterozygous TG and 2.56 [95%CI: 1.70-3.86] in the homozygous TT genotype groups. Compared to low- and moderate-dose, high-dose digoxin users with GG genotype had the highest risk of SCD (HR: 5.61 [95% CI: 1.34-23.47]). CONCLUSIONS: Current use of digoxin is associated with a significantly increased risk of SCD. The NOS1AP gene rs10494366 variant did not modify the digoxin-associated risk of SCD in a population of European ancestry.

Sudden cardiac arrest occurring in temporal proximity to consumption of energy drinks.

BACKGROUND: Energy drinks potentially can trigger life-threatening cardiac arrhythmias. It has been postulated that the highly stimulating and unregulated ingredients alter heart rate, blood pressure, cardiac contractility, and cardiac repolarization in a potentially proarrhythmic manner. OBJECTIVE: The purpose of this study was to describe our experience regarding sudden cardiac arrest (SCA) occurring in proximity to energy drink consumption in patients with underlying genetic heart diseases. METHODS: The electronic medical records of all SCA survivors with proven arrhythmias referred to the Mayo Clinic Windland Smith Rice Genetic Heart Rhythm Clinic for evaluation were reviewed to identify those who consumed an energy drink before their event. Patient demographics, clinical characteristics, documented energy drink consumption, and temporal relationship of energy drink consumption to SCA were obtained. RESULTS: Among 144 SCA survivors, 7 (5%; 6 female; mean age at SCA 29 ± 8 years) experienced an unexplained SCA associated temporally with energy drink consumption. Of these individuals, 2 had long QT syndrome and 2 had catecholaminergic polymorphic ventricular tachycardia; the remaining 3 were diagnosed with idiopathic ventricular fibrillation. Three patients (43%) consumed energy drinks regularly. Six patients (86%) required a rescue shock, and 1 (14%) was resuscitated manually. All SCA survivors have quit consuming energy drinks and have been event-free since. CONCLUSION: Overall, 5% of SCA survivors experienced SCA in proximity to consuming an energy drink. Although larger cohort studies are needed to elucidate the incidence/prevalence and quantify its precise risk, it seems prudent to sound an early warning on this potential risk.