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Age- and gender related differences in QTc-interval are most likely the result of changes in sex-specific hormones. Although the exact mechanisms and pathophysiology of sex hormones on the QTc-interval are not known, testosterone appears to shorten the QTc-interval. In females, however, there is a more complex interaction between progesterone and e...
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... and progesterone levels fluctuate during the men- strual cycle. Estrogen and progesterone levels are lowest at the onset of menses (menstrual phase). After the cessation of the menstrual flow, there is a gradual increase in estrogen (follicular phase). Estrogen levels peak in the middle of the menstrual phase during ovulation (ovulation phase) and after ovulation the estrogen levels gradually decrease during the luteal phase. Progesterone levels, in contrast, are low during the menstrual and follicular phase and increase after ovula- tion through the luteal phase (Fig. 2). In healthy females, there are no clear QTc-interval differences between the different phases of the menstrual cycle [55][56][57][58][59]. Hulot et al. [55] found no relationship between the level of estrogen and the length of the QTc-interval (P ? 0.92). In the study by Nakagawa et al. [56], the uncorrected QT-interval was shorter in the luteal phase compared to the follicular phase, although no difference in QTc-interval was seen. They found no statistically significant difference in estrogen level between these phases, while progesterone (P o 0.001) and noradrena- line levels (P o 0.05) were higher in the luteal phase suggest- ing a role of progesterone and/or autonomic tone on the uncorrected QT-interval. When double autonomic blockade was given consisting of atropine and propranolol adminis- tration, QTc-interval differences between the phases of the menstrual cycle were seen. Burke et al. [57] found a shorter QTc-interval in the luteal phase compared to the menstrual and follicular phase, whereas Endres et al. [58] observed a significantly longer QTc-interval during the follicular phase compared to the menstrual and luteal phase. Both studies indicate the important role of autonomic tone in alternations in the QTc-interval during the menstrual cycle. Rodrigues et al. [59] showed that ibutilide infusion, a known I Kr blocker mimicking LQTS, causes differences in QTc-interval between the phases of the menstrual cycle, whereas the luteal phase seemed to be protective against the drug-induced QTc-inter- val prolongation. Hence, since there is an effect of the menstrual cycle on the QTc-interval during administration of QTc-interval prolonging medication, it could be argued that this effect also is present in patients with ...
Citations
... Moreover, female gender is well recognized in the literature to be an independent risk factor for LQTS. Additionally, females with LQTS, whether inquired or congenital have a higher risk of tachyarrhythmias and SCD 12,13 . Although an association between QT-interval and mortality has been established in North American Indigenous people 14 , there is a scarcity of literature examining the outcomes of LQTS amongst Indigenous women specifically. ...
... At assessment, sex (female to male, 415 to 401 ms) was a strong covariate, while phosphate levels were a weak (Spearman 0.151, p < 0.05) covariate of the QT c-Bazett time interval. Both can be expected, as it is generally known that both sex and electrolytes, including calcium/phosphate balance, have been reported as significant covariates of the QT c-Bazett time interval, as also reflected in the FDA guidance and EMA guidelines [14,15,18]. Although evidence is inconsistent, a higher BMI in adults was associated with a longer QT c-Bazett in some studies [19,20]. ...
Introduction:
Although relevant for precision pharmacovigilance, there are conflicting data on whether former preterm birth is associated with QTc-Bazett prolongation in later life.
Methods:
To explore QTc-Bazett interval differences between former preterm and/or extremely low birth weight (ELBW) cases and term-born controls in adolescence and young adulthood, we analyzed pooled individual data after a structured search on published cohorts. To test the absence of a QTc-Bazett difference, a non-inferiority approach was applied (one-sided, upper limit of the 95% confidence interval [CI] mean QTc-Bazett difference, 5 and 10 ms). We also investigated the impact of characteristics, either perinatal or at assessment, on QTc-Bazett in the full dataset (cases and controls). Data were reported as median and range.
Results:
The pooled dataset contained 164 former preterm and/or ELBW (cases) and 140 controls born full-term from three studies. The median QTc-Bazett intervals were 409 (335-490) and 410 (318-480) ms in cases and controls. The mean QTc-Bazett difference was 1 ms, with an upper 95% CI of 6 ms (p > 0.05 and p < 0.01 for 5 and 10 ms, respectively). In the full dataset, females had a significantly longer QTc-Bazett than males (415 vs. 401 ms; p < 0.0001).
Conclusions:
QTc-Bazett intervals are not significantly different between former preterm and/or ELBW cases and term-born controls, and we rejected a potential prolongation > 10 ms in cases. When prescribing QTc-prolonging drugs, pharmacovigilance practices in this subpopulation should be similar to the general public (NCT05243537).
... It is known that, in patients with LQT-2, cardiac events are characteristically triggered by situations involving sudden heart rate acceleration 1 and that women with LQTS have a higher risk for cardiac events during adulthood compared with men with LQTS. 31 Hence, this implies a potential role for the standing test in the risk stratification of patients with LQTS. ...
Background
An elegant bedside provocation test has been shown to aid the diagnosis of long‐QT syndrome (LQTS) in a retrospective cohort by evaluation of QT intervals and T‐wave morphology changes resulting from the brief tachycardia provoked by standing. We aimed to prospectively determine the potential diagnostic value of the standing test for LQTS.
Methods and Results
In adults suspected for LQTS who had a standing test, the QT interval was assessed manually and automated. In addition, T‐wave morphology changes were determined. A total of 167 controls and 131 genetically confirmed patients with LQTS were included. A prolonged heart rate–corrected QT interval (QTc) (men ≥430 ms, women ≥450 ms) at baseline before standing yielded a sensitivity of 61% (95% CI, 47–74) in men and 54% (95% CI, 42–66) in women, with a specificity of 90% (95% CI, 80–96) and 89% (95% CI, 81–95), respectively. In both men and women, QTc≥460 ms after standing increased sensitivity (89% [95% CI, 83–94]) but decreased specificity (49% [95% CI, 41–57]). Sensitivity further increased ( P <0.01) when a prolonged baseline QTc was accompanied by a QTc≥460 ms after standing in both men (93% [95% CI, 84–98]) and women (90% [95% CI, 81–96]). However, the area under the curve did not improve. T‐wave abnormalities after standing did not further increase the sensitivity or the area under the curve significantly.
Conclusions
Despite earlier retrospective studies, a baseline ECG and the standing test in a prospective evaluation displayed a different diagnostic profile for congenital LQTS but no unequivocal synergism or advantage. This suggests that there is markedly reduced penetrance and incomplete expression in genetically confirmed LQTS with retention of repolarization reserve in response to the brief tachycardia provoked by standing.
... There is solid evidence showing that adequate and regular physical activity can have positive cardiovascular, endocrine, metabolic and neurological effects. 19,20 However, it has also been shown that excessive and strenuous physical training forms can generally damage the cardiovascular system. 21 In our study, hemoglobin level was found to be significantly higher in the group with pathology. ...
... 22 Also, in our study, it was found that QTc shortening with increasing age was consistent with the literature. 20 Therefore, it can be said that age is an independent risk factor for athletes. However, it was understood that these findings did not predict the important pathologies that would prevent the individuals from continuing their sports life. ...
... Although the exact mechanism and pathophysiology of sex hormones on the QT interval is unknown, testosterone appears to shorten the QT interval in males. And in women there is a more complex interaction between progesterone and estrogen due to the influence of the menstrual cycle, pregnancy and menopause (Vink et al., 2018). ...
The QT interval is a picture of the activity of the heart's ventricles, starting from depolarization to ventricular repolarization which can be influenced by several factors, namely drugs, gender, inflammatory conditions, obesity, heart failure, and others. Basic Health Research Data in 2018, states that in Indonesia there are around 2,784,064 individuals who suffer from heart disease and every year this number will continue to increase. The purpose of this study was to find out whether there was a relationship between sex and intravenous administration of drugs with QT prolongation. This research is a type of descriptive research. With a total sample of 118 respondents, it was carried out by observing medical records. The results of statistical tests on the sex variable with QT prolongation showed ρ = 0.007, and on the intravenous drug administration variable with QT prolongation showed ρ = 0.002. The conclusion of this study was that there was a relationship between gender and intravenous drug administration with QT prolongation. It is necessary to pay attention to the side effects of drug administration given to patients. And for future researchers, it is hoped that this study can become a reference by using other variables related to QT interval prolongation such as drug side effects and conditions of electrolyte disturbances.
... Additionally, we performed the statistical analysis of sex differences of EH administration, and there was no significant sex difference in the toxic influence of EH on monkeys the same as other anticoagulants (Agewall, 2017;Carnicelli et al., 2022;Seki et al., 2008). In contrast with humans (Sedlak et al., 2012;Vink et al., 2018), there are no significant differences of QT interval between male and female monkeys (Seki et al., 2008). However, this might result from individual difference in such few samples that the male QT seemed to be longer than the female QT in this acute toxicity study. ...
In this study, the toxicity effects on circulatory system and respiratory system, and the acute toxicity test of recombinant neorudin (EPR-hirudin, EH) in cynomolgus monkeys were evaluated to provide reference information for clinical studies. Eighteen cynomolgus monkeys were randomly divided into three groups for single intravenous administration of 3, 30 mg/kg EH and normal saline, respectively. The changes of respiratory frequency, respiratory intensity, blood pressure and electrocardiogram before and after administration were recorded. In acute toxicity test, six cynomolgus monkeys were intravenously received EH at a single dose of 171, 257, 385, 578, 867 and 1300 mg/kg respectively. The vital signs, hematology, serum biochemistry, coagulation indexes and electrocardiogram indexes of the animals were determined before administration and on the 7th and 14th day after administration. As the results showed that there were no significant abnormal changes in respiratory frequency, respiratory intensity, blood pressure or electrocardiogram in cynomolgus monkeys after receiving EH at 3 mg/kg and 30 mg/kg, and there was no statistical difference between the treated groups and normal saline group. In the acute toxicity test, no significant abnormalities were observed in vital signs, hematology, serum biochemistry, coagulation indexes and electrocardiogram indexes of six cynomolgus monkeys at day 7 and 14 after EH administration. Furthermore, autopsies of all cynomolgus monkeys showed no abnormalities. The results of toxicokinetics showed that AUClast of the drug increased in proportion to the EH dose in the range of 171-578 mg/kg, and increased in over proportion to the EH dose in the range of 578-1300 mg/kg. The variation of Cmax was basically consistent with AUClast. In a sum, A single intravenous injection of 3 and 30 mg/kg of EH did not affect the circulatory system and respiratory system in cynomolgus monkeys and the maximum tolerated dose of EH in cynomolgus monkey is over 1300 mg/kg (equivalent to 619-1300 times of the proposed clinical equivalent dose).
... As a first step in building the proposed scheme, we look for fiducial points that are the least sensitive to privacy leakage by reorganizing our database. Electrocardiogram intervals are one of the fiducial points that are essential for personal identification, but they also contain sufficient private information to classify diseases [42,43]. Instead of using such fiducial points, we find eight new fiducial points (i.e., the 37-th ∼45-th fiducial points listed in Table 2), which eliminate the possibility of information leakage. ...
Authentications using biometrics, such as fingerprint recognition and electrocardiogram (ECG), have been actively used in various applications. Unlike traditional authentication methods, such as passwords or PINs, biometric-based authentication has an advantage in terms of security owing to its capability of liveness detection. Among the various types of biometrics, ECG-based authentication is widely utilized in many fields. Because of the inherent characteristics of ECG, however, the incautious design of ECG-based authentication may result in serious leakage of personal private information. In this paper, we extensively investigate ECG-based authentication schemes previously proposed in the literature and analyze possible privacy leakages by employing machine learning and deep learning techniques. We found that most schemes suffer from vulnerabilities that lead to the leakage of personal information, such as gender, age, and even diseases. We also identified some privacy-insensitive ECG fiducial points by utilizing feature selection algorithms. Based on these features, we present a privacy-preserving ECG-based authentication scheme.
... The most common type of LQTS is divided into three sub-categories (LQT1-3). A study 16 noted the variations in QTc with respect to age and gender in these three classes of LQTS volunteers. It found three major findings based on three different classes of different age groups in male and females. ...
Introduction: In an Electrocardiogram (ECG), QT Interval (QTI) has gained a major role as an indicator; its prolongation leads to ventricular arrhythmias. QTI varies with RR Interval (RRI) as the Heart Rate (HR) changes which motivate to measure corrected QT (QTc) interval for different HR.
Objective: To develop a new QTc formula optimal for different HRs and compare its performance with previously developed QTc formulas.
Methods: ECGs were recorded from 220 volunteers (110 females) in Sinus Rhythm (SR), Sinus Tachycardia (ST) and Sinus Bradycardia (SB) conditions. HR, RRI and QTI were extracted from the lead II. A New QTc formula was developed by taking the mean value of slopes between RRI and QTI in SR, ST, and SB. The QTc values were calculated using a newly developed formula, and the performance was compared with previously developed QTc formulas.
Results: In SR, ST, and SB, the QTI mean values for lead II were 358 ms, 316 ms, and 440 ms and the mean slope values between RRI and QTI were 0.132, 0.214, and 0.137, respectively. The new QTc (QTcN) formula was developed by taking the mean of the above slope values as 0.161 and mentioned as QTcN[Formula: see text]QT[Formula: see text]0.161(1000−RRI).
Conclusion: The least slope value of the QTI/RRI plot gave the best correction formula. Using statistical analysis, it was noted that Frederica QTc formula showed the best results for SR and SB and Hodge’s formula in ST. To overcome the limitation of QTc formulas for different HR, a QTcN formula was developed to reduce over/under estimation of QTI.
... Either azithromycin or quinine may induce QT interval prolongation, even when administered for short periods of time [20,[31][32][33][34][35]. QT interval prolongation appears to resolve with termination of either drug, and the overall risk of torsade de pointes is low [30,[35][36][37]. Patients at increased risk of QTc interval prolongation include elderly women, persons with advanced heart disease, and those taking medications that prolong the QT interval or have the potential to inhibit important drug elimination mechanisms [32,33,37]. ...
... QT interval prolongation appears to resolve with termination of either drug, and the overall risk of torsade de pointes is low [30,[35][36][37]. Patients at increased risk of QTc interval prolongation include elderly women, persons with advanced heart disease, and those taking medications that prolong the QT interval or have the potential to inhibit important drug elimination mechanisms [32,33,37]. In the current study, all 13 patients in whom QTc interval prolongation developed had ≥1 risk factor. ...
Background
Human babesiosis is a worldwide emerging tick-borne disease caused by intraerythrocytic protozoa. Most patients experience mild to moderate illness, but life-threatening complications can occur. Although cardiac complications are common, the full spectrum of cardiac disease and the frequency, risk factors, and outcomes in patients experiencing cardiac complications are unclear. Accordingly, we carried out a record review of cardiac complications among patients with babesiosis admitted to Yale–New Haven Hospital over the last decade to better characterize cardiac complications of babesiosis.
Methods
We reviewed the medical records of all adult patients with babesiosis admitted to Yale–New Haven Hospital from January 2011 to October 2021, confirmed by identification of Babesia parasites on thin blood smear and/or by polymerase chain reaction. The presence of Lyme disease and other tick-borne disease coinfections were recorded.
Results
Of 163 enrolled patients, 32 (19.6%) had ≥1 cardiac complication during hospitalization. The most common cardiac complications were atrial fibrillation (9.4%), heart failure (8.6%), corrected QT interval prolongation (8.0%), and cardiac ischemia (6.8%). Neither cardiovascular disease risk factors nor preexisting cardiac conditions were significantly associated with the development of cardiac complications. The cardiac complication group had a greater prevalence of high-grade parasitemia (>10%) (P < .001), longer median length of both hospital (P < .001) and intensive care unit stay (P < .001), and a higher mortality rate (P = .02) than the group without cardiac complications.
Conclusions
Cardiac complications of acute babesiosis are common and occurred in approximately one-fifth of this inpatient sample. Further investigation is needed to elucidate the relationship between babesiosis severity and cardiac outcomes.
... In the multivariate analysis, age did not impact the predictive value of AccurKardia's technology even though age-related changes in QT interval have been previously reported [29]. ...
Background
Abnormal prolongation or shortening of the QT interval is associated with increased risk for ventricular arrhythmias and sudden cardiac death. For continuous monitoring, widespread use, and prevention of cardiac events, advanced wearable technologies are emerging as promising surrogates for conventional 12‑lead electrocardiogram (ECG) QT interval assessment. Previous studies have shown a good agreement between QT and corrected QT (QTc) intervals measured on a smartwatch ECG and a 12-lead ECG, but the clinical accuracy of computerized algorithms for QT and QTc interval measurement from smartwatch ECGs is unclear.
Objective
The prospective observational study compared the smartwatch-recorded QT and QTc assessed using AccurKardia’s AccurBeat platform with the conventional 12‑lead ECG annotated manually by a cardiologist.
Methods
ECGs were collected from healthy participants (without any known cardiovascular disease) aged >22 years. Two consecutive 30-second ECG readings followed by (within 15 minutes) a 10-second standard 12-lead ECG were recorded for each participant. Characteristics of the participants were compared by sex using a 2-sample t test and Wilcoxon rank sum test. Statistical comparisons of heart rate (HR), QT interval, and QTc interval between the platform and the 12-lead ECG, ECG lead I, and ECG lead II were done using the Wilcoxon sign rank test. Linear regression was used to predict QTc and QT intervals from the ECG based on the platform’s QTc/QT intervals with adjustment for age, sex, and difference in HR measurement. The Bland-Altman method was used to check agreement between various QT and QTc interval measurements.
Results
A total of 50 participants (32 female, mean age 46 years, SD 1 year) were included in the study. The result of the regression model using the platform measurements to predict the 12-lead ECG measurements indicated that, in univariate analysis, QT/QTc intervals from the platform significantly predicted QT/QTc intervals from the 12-lead ECG, ECG lead I, and ECG lead II, and this remained significant after adjustment for sex, age, and change in HR. The Bland-Altman plot results found that 96% of the average QTc interval measurements between the platform and QTc intervals from the 12-lead ECG were within the 95% confidence limit of the average difference between the two measurements, with a mean difference of –10.5 (95% limits of agreement –71.43, 50.43). A total of 94% of the average QT interval measurements between the platform and the 12-lead ECG were within the 95% CI of the average difference between the two measurements, with a mean difference of –6.3 (95% limits of agreement –54.54, 41.94).
Conclusions
QT and QTc intervals obtained by a smartwatch coupled with the platform’s assessment were comparable to those from a 12-lead ECG. Accordingly, with further refinements, remote monitoring using this technology holds promise for the identification of QT interval prolongation.
