Autonomic neuropathy and QT interval in hemodialysed patients

Abstract. Background QT interval prolongation increases the risk of ventricular arrhythmias and sudden death in diabetic autonomic neuropathy and ischemic heart disease. In end–stage renal disease (ESRD), the effects of hemodialysis on QT interval are diverse and the influence of autonomic neuropathy has yet to be clearly defined. Methods Sixty–nine ERSD patients (age 64 ± 14) were studied. Prior to the dialysis session, patients underwent four standard autonomic cardiovascular tests; before and after the dialysis session, a 12–lead ECG was recorded. Corrected QT intervals (QTc) were measured and QT dispersion (QTd) was calculated. Twelve subjects (age 59 ± 6) with normal renal function served as control group. Results Compared to controls, ESRD patients showed a longer QTc (434 ± 26 vs 414 ± 28ms; p = 0.016) and a similar QTd (35 ± 13 vs 37 ± 14ms; p = 0.54).QTc was > 440ms in 33.3% of the patients. No difference in the prevalence or score of autonomic neuropathy was observed between the subgroups with and without a prolonged QTc. After the hemodialysis session, QTc increased in 56% and decreased in 43% of the patients, and QTd increased in 45 % and decreased in 55% of the patients. QTc and QTd changes were not related to the presence of autonomic neuropathy. Conclusions A large variability in QTc and QTd response was observed after hemodialysis. Autonomic neuropathy did not contribute to QTc and QTd length, nor to QTc and QTd change after dialysis.     

Abnormalities of rate-corrected QT intervals in Parkinson's disease-a comparison with multiple system atrophy and progressive supranuclear palsy

A number of patients with Parkinson's disease (PD) and multiple system atrophy (MSA), in whom sudden death does occur occasionally, have QT or rate-corrected QT (QTc) interval prolongation on electrocardiogram (ECG). Although these QT or QTc interval abnormalities are likely related to autonomic dysfunction, the pathophysiology remains unknown. The aim of this study was to compare the degree of QTc interval prolongation among akinetic-rigid syndromes, namely PD and related disorders, and to evaluate the relationship between QTc prolongation and severity of autonomic dysfunction. Thirty-four patients with PD, 22 with MSA, 11 with progressive supranuclear palsy (PSP) and 30 healthy controls underwent standard autonomic function tests, and electrocardiography variables (RR, QT and QTc intervals) were measured by an ECG recorder with an automated analyzer. The relationship between QTc interval and cardiovascular reflex tests were also analyzed. Orthostatic hypotension and decreased heart rate in response to respiratory stimuli were prominent in MSA, while these were relatively mild in PD. Unlike the RR and QT intervals, the QTc interval significantly differed among all groups (p<0.01). The QTc interval was significantly prolonged in PD (409+/-17 ms; p<0.001) and MSA (404+/-14 ms; p<0.05) compared with healthy controls (394+/-19 ms). Neither autonomic dysfunction nor QTc interval prolongation was evident in PSP. QTc intervals and cardiovascular reflexes did not correlate, except for Valsalva ratio. The QTc interval was obviously prolonged in PD patients to an extent that could not be accounted for simply by autonomic dysfunction levels. MSA patients showed slightly prolonged QTc intervals in spite of marked cardiovascular autonomic dysfunction. Abnormalities of the QTc may reflect the degeneration of cardioselective sympathetic and parasympathetic neurons that cannot be fully captured by cardiovascular autonomic function tests.     

QTc interval, and autonomic and somatic nerve function in diabetic neuropathy

QTc intervals were measured using an electrocardiogram and other autonomic function tests, in 66 neuropathy patients with non-insulin-dependent diabetes mellitus (59.0±12.5 years; mean ± SD). The change in R-R interval did not influence the QTc interval, as calculated by the equation: QTc =QT+(1000-R-R)/7 (ms), compared with the conventional Bazett's equation which appeared to overcompensate in the case of a small R-R interval. The QTc interval in the diabetic patients was significantly longer than that in age-matched controls. The QTc interval showed an inverse correlation with the coefficient of variation of the R-R interval and skin blood flow at rest. However, no correlation was found between QTc interval and blood pressure change, change in heart rate on standing, or results of the sympathetic skin response. The QTc interval did not correlate significantly with motor or sensory nerve conduction parameters. We conclude that the QTc interval can be a simple and useful autonomic indicator for diabetic neuropathy relatively independent of other abnormalities of autonomic and somatic nervous system function. Clin Auton Res 8:139–143     

Prolonged Corrected QT Interval in Patients with Myotonic Dystrophy Type 1

Background and Purpose

Sudden cardiac death is one of the leading causes of death in patients with myotonic dystrophy type 1 (DM1). It has been proposed that a prolonged QT interval is associated with sudden cardiac death in several neurological diseases, including multiple system atrophy, idiopathic Parkinson''s disease, and diabetic autonomic neuropathy. However, analyses of the corrected QT (QTc) interval in DM1 patients are rare in the literature. The purposes of this study were to determine the association between the QT interval and DM1, and the affecting factors.

Methods

Thirty-nine patients diagnosed with DM1 through genetic testing were enrolled. The QTc interval (calculated using Bazett''s formula: QTc=QT/√RR) was compared between these patients and 39 normal healthy controls. The clinical and laboratory factors affecting QTc interval in the patient group were investigated.

Results

The QTc interval was significantly longer in the DM1 group (411.2±44.7 msec, mean±SD) than in the normal control group (355.6±20.6 msec). Intragroup analysis revealed that a prolonged QTc interval in DM1 patients was associated with being female and older, having a longer disease duration, and exhibiting abnormal electrocardiography findings.

Conclusions

The higher incidence of sudden cardiac death in the DM1 population is associated with the observed prolonged QTc interval in those patients.     

QT interval and QT dispersion in multiple system atrophy (Shy-Drager syndrome)

To evaluate the influence of autonomic function on the QT interval and QT dispersion, 18 patients (10 males and 8 females; mean age 61±9 years) with multiple system atrophy (MSA, Shy-Drager syndrome) were studied. Cardiovascular tests were performed to assess the degree of autonomic dysfunction. The QT interval, corrected QT (QTc), QT dispersion (QTd), corrected and adjusted QTd were calculated from a standard 12-lead electrocardiogram. Fifteen healthy subjects matched for sex and age were studied as controls. Nine MSA patients showed severe autonomic dysfunction with orthostatic hypotension. In the remaining patients definite autonomic impairment was found. No statistically significant difference was found in QTd and only a trend towards higher values of maximal QTc was found in patients compared with controls. QTc prolongation, defined as greater than the mean±2 SD of the controls, was detected only in three out of the 18 MSA patients (17%). No correlation was found between the severity of autonomic impairment and repolarization parameters. Our data suggest that chronic autonomic impairment in patients with MSA does not significantly affect ventricular repolarization and ventricular dispersion.     

Highly abnormal thermotests in familial dysautonomia suggest increased cardiac autonomic risk

OBJECTIVE—Patientswith familial dysautonomia have an increased risk of sudden death. Insome patients with familial dysautonomia, sympathetic cardiacdysfunction is indicated by prolongation of corrected QT (QTc)interval, especially during stress tests. As many patients do nottolerate physical stress, additional indices are needed to predictautonomic risk. In familial dysautonomia there is a reduction of bothsympathetic neurons and peripheral small nerve fibres which mediatetemperature perception. Consequently, quantitative thermal perceptiontest results might correlate with QTc values. If this assumption iscorrect, quantitative thermotesting could contribute to predictingincreased autonomic risk.
METHODS—To test thishypothesis, QTc intervals were determined in 12 male and eight femalepatients with familial dysautonomia, aged 10 to 41 years (mean 21.7 (SD10.1) years), in supine and erect positions and postexercise andcorrelated with warm and cold perception thresholds assessed at sixbody sites using a Thermotest.
RESULTS—Due toorthostatic presyncope, six patients were unable to undergo erect andpostexercise QTc interval assessment. The QTc interval was prolonged(>440 ms) in two patients when supine and in two additional patientswhen erect and postexercise. Supine QTc intervals correlatedsignificantly with thermal threshold values at the six body sites andwith the number of sites with abnormal thermal perception (Spearman'srank correlation p<0.05). Abnormal Thermotest results were morefrequent in the four patients with QTc prolongation and the sixpatients with intolerance to stress tests.
CONCLUSION—The resultssuggest that impaired thermal perception correlates with cardiacsympathetic dysfunction in patients with familial dysautonomia. Thusthermotesting may provide an alternative, albeit indirect, means ofassessing sympathetic dysfunction in autonomic disorders.

     

Antipsychotic drugs and QT interval prolongation

The QTc prolongation by antipsychotic drugs is of major concern, especially in light of the data indicating an increased risk of sudden death in psychiatric patients taking these drugs. Sudden death in psychiatric patients could be partially attributed to drug-induced torsades de pointes and for this reason careful evaluation of QTc prolonging properties of antipsychotic drugs is needed. Antipsychotic drugs prolong QT interval usually by blocking the potassium I_Kr current. Improved understanding of ion channel structure and kinetics and its role in repolarization has tremendous impact on understanding of the mechanisms of drug-induced QT prolongation and torsades de pointes. Proarrhythmia caused by a QT-prolonging drug occurs infrequently, and usually multiple factors need to operate to precipitate such an event including a combination of two or more drugs affecting the same pathway, hypokalemia, and possibly genetic predisposition. Currently prescribed antipsychotics might cause QT prolongation ranging from 4–6 ms for haloperidol and olanzapine to 35 ms for thioridazine. The response of a patient to a drug is very individual and therefore an individualized system of drug administration and monitoring needs to be developed which takes into account baseline QTc duration and its changes after a drug was introduced. A systematic approach while stratifying psychiatric patients as those with short QTc (QTc 0.41 sec), borderline QTc (QTC = 0.42–0.44 sec), and prolonged QTc ( 0.45 sec) is being proposed to improve the safety of administering antipsychotic drugs and to decrease the risk of drug-related sudden death in psychiatric patients.     

心电图QT间期与抗精神病药及代谢等的关系

目的：观察心电图叩间期与抗精神病药及代谢等的关系。方法：对390例应用抗精神病药至少6个月住院患者的代谢参数作评估，测量他们的校正QT间期（帆）。结果：25例（6．4％）出现QTc间期延长。联用与单一应用抗精神病药患者的QR间期差异无显著性（P=0．884）。服氯氮平患者的叽间期较其他药物明显延长。结论：QT间期延长并不多见，与三酰甘油相关，与其他代谢参数无显著相关。     

The influence of autonomic neuropathy on hypotension during hemodialysis

Many patients with chronic renal failure experience profound hypotension during hemodialysis. This phenomenon may be caused by hypovolemia, autonomic or cardiac dysfunction, vascular resistance defects or vasoactive substances such as nitric oxide or adrenomedullin. The aim of the study was to evaluate the influence of autonomic neuropathy on the occurrence of hypotension during hemodialysis. Fifty-three patients with chronic renal failure on maintenance hemodialysis underwent a standard battery of cardiovascular tests for the diagnosis of autonomic neuropathy. The study population was then divided into two groups, with (AN+) and without (AN−) autonomic neuropathy. Blood pressure (BP) was recorded before, during and after hemodialysis for 10 consecutive dialysis sessions and the mean value was calculated. Results Of the patients, 38 % were AN+. During hemodialysis, systolic BP was lower in AN+ than in AN− patients at the third hour (110.0 ± 17.5 vs 128.0 ± 26.2; p = 0.049). Systolic BP reduction during hemodialysis was greater in AN+ than AN− patients (−21.2 ± 10.9 vs −13.5 ± 10.6 % change, p = 0.013). Conclusion The presence of autonomic neuropathy is associated with a more severe BP fall during hemodialysis. Routine evaluation of autonomic function may be helpful in defining patients at risk for dialysis-induced hypotension. Received: 14 September 2001, Accepted: 19 February 2002     

Use of corrected QT interval in autonomic function testing: assessment of reproducibility

QT interval duration is influenced by the autonomic nervous system and has been proposed as an additional tool in the diagnosis of diabetic autonomic neuropathy. The study aimed to assess in normal subjects the reproducibility of QT interval duration compared with that of cardiovascular tests commonly used to explore the function of the autonomic nervous system. Fifty-nine healthy subjects (31 males, 28 females; mean age 35.1 ±17.7 years) performed five cardiovascular tests: deep breathing test (DBT), lying to standing test (LST), Valsalva manoeuvre (VM), postural blood pressure test (PBPT) and cough test (CT). QT interval duration was measured on an electrocardiogram (ECG) registered after a 15-min rest in the supine position. Corrected QT interval (QTc) was calculated according to Bazett's formula. The QTc interval duration for each subject was expressed as the mean of the QTc calculated by two observers. Each subject was submitted to the cardiovascular test battery and the ECG twice in 1 week. The coefficient of variation (CV) was calculated to assess the reproducibility. The observed CV values were as follows: DBT 15.8%, LST 8.0%, VM 9.5%, CT 7.2%, PBPT 176%, QTc 3.4%. Our data confirm the reproducibility of heart rate cardiovascular tests: the QTc interval is a reproducible, easily measurable parameter, which has the advantage of not requiring patient cooperation.     

The potential for QT prolongation by antiepileptic drugs in children

Cardiac arrhythmia may be one of the major causes of sudden unexpected death in children with epilepsy. We assessed drug-induced QT prolongation to establish whether the use of antiepileptic drugs contributes to sudden unexpected death. A total of 178 children with epilepsy (93 males and 85 females, with ages ranging from 1 month to 18.9 years; mean age 7.0 +/- 4.1 years) were involved in the study. The QT intervals were manually measured and corrected using Fridericia's formula (QTFc = QT/RR(1/3)). The mean corrected QT interval (QTc) of 152 children on antiepileptic drugs during the study period was 0.40 +/- 0.03 s, and for 26 age-matched, antiepileptic drug-free control patients it was 0.40 +/- 0.03 s. The mean QTc of the children with monotherapy was 0.40 +/- 0.03 s for the valproate group (n = 42), 0.39 +/- 0.02 s for the carbamazepine/oxcarbazepine group (n = 34), and 0.40 +/- 0.02 s for the topiramate group (n = 26), respectively. There was no statistically significant difference among the groups as assessed by analysis of variance. In addition, there was no significant difference between the monotherapy group (n = 109; 0.40 +/- 0.02 s) and the polytherapy group (n = 43; 0.39 +/- 0.03 s). Major antiepileptic drugs may not precipitate prolongation of the QT interval into sudden unexpected death in children with epilepsy, however further studies are required.     

Reduced functional connectivity between ventromedial prefrontal cortex and insula relates to longer corrected QT interval in HIV+ and HIV− individuals

Objective

Prolongation of the QT interval, i.e., measure of the time between the start of the Q wave and the end of the T wave, is a precursor to fatal cardiac arrhythmias commonly observed in individuals infected with the Human Immunodeficiency Virus (HIV), and is related to dysregulation of the autonomic nervous system. We investigated the relationship between QT interval length and resting state functional connectivity (rsFC) of the ventromedial prefrontal cortex (VMPFC), a core region of the brain that is involved with cardio-autonomic regulation.

A meta-analysis of heart rate and QT interval alteration in anorexia nervosa.

OBJECTIVE: Reports have suggested association between sudden death and QT prolongation in AN patients. Incidence and clinical consequences of cardiac abnormalities remain controversial. As the course of AN disease is long-lasting it remains unclear how often psychiatrists should send AN patients for somatic and especially cardiological investigation. The objective of the study was to aggregate the published data on HR and QT alteration and to perform a meta-analysis of the HR and QT alteration in patients with anorexia nervosa. METHODS: A Medline search of all English language studies from 1994 to 2005 was performed. The inclusion criteria were confirmed diagnosis of AN, measurement of QTc and mean heart rate. Data from 10 studies were analyzed using weighted linear regression model. RESULTS: Analysis showed that bradycardia and relationship between HR and BMI decreases as the disease continues. QTc interval in AN patients was within normal range although significantly longer than in controls. CONCLUSION: Further investigations of sudden death in patients with AN due to cardiac arrest are needed and a model of clinical monitoring of cardiovascular system should be elaborated. If QTc prolongation is detected even in the normal range further cardiological examination for risk assessment and systematic clinical surveillance of the cardiovascular system should be considered.     

Analysis of the QTc interval during olanzapine treatment of patients with schizophrenia and related psychosis

BACKGROUND: There may be a temporal association between some antipsychotics and prolongation of the heart-rate-corrected QT interval (QTc) representing a delay in ventricular repolarization. QTc prolongation significantly exceeding normal intra-individual and interindividual variation may increase the risk of ventricular tachydysrhythmias, especially torsade de pointes, and therefore, sudden cardiac death. METHOD: Electrocardiogram recordings obtained as part of the safety assessment of olanzapine in 4 controlled, randomized clinical trials (N = 2,700) were analyzed. These analyses were conducted to characterize any change in QTc temporally associated with olanzapine, compared with placebo, haloperidol, and risperidone, in acutely psychotic patients (DSM-III-R and DSM-IV) and to characterize variability and temporal course of the QTc in this patient population. Changes from baseline to minimum and maximum QTc were tested for significance, and baseline to acute-phase endpoint change in mean QTc was tested for significance within treatments and for differences between olanzapine and comparators. The possibility of a linear relationship between dose of olanzapine and mean change in QTc, as well as incidence of treatment-emergent prolongation of QTc (change from < 430 msec at baseline to > or =430 msec at endpoint), was tested. RESULTS: The incidence of maximum QTc > or = 450 msec during treatment was approximately equal to the incidence of QTc > or =450 msec at baseline. CONCLUSION: Results of these analyses suggest that olanzapine, as therapeutically administered to patients with schizophrenia and related psychoses, does not contribute to QTc prolongation resulting in potentially fatal ventricular arrhythmias.     

急性脑血管病患者心率和QT间期的研究

目的了解急性脑血管病患者心率和QT间期的变化,为急性脑血管病的合理干预提供依据。方法检测246例急性脑出血(Ⅰ组)、251例急性脑梗死患者(Ⅱ组)和300例正常对照组的标准12导联心电图,观察心率和QT间期的变化。结果与正常对照组相比,Ⅰ组和Ⅱ组窦性心动过速的发生率显著增加,Ⅰ组增加更明显,而窦性心动过缓的发生率低于对照组;2组平均心室率明显增快,尤以急性脑出血组为甚。Ⅰ组和Ⅱ组平均QTc间期较对照组明显延长,且QTc间期延长的发生率显著增高。结论急性脑血管病患者平均心室率增快,QT间期延长。     

Insular cortex lesion and autonomic instability in a herpes simplex virus encephalitis patient

The cardiovascular system is regulated by a central autonomic network (CAN) consisting of the insular cortex, anterior cingulate gyrus, and amygdala. Because the insular cortex often tends to be damaged in patients with herpes simplex virus (HSV) encephalitis, the autonomic instability observed in these patients was suggested to be moderated by an insular cortex lesion. Here, we report the case of a 51-year-old Japanese male who was hospitalized following a collapse 5 days earlier; he was diagnosed as herpes encephalitis. Diffusion-weighted MRI revealed asymmetric right greater hyperintensity throughout his insular cortex and anterior cingulate gyrus. At 1 week after admission, transthoracic echo showed diffuse hypokinesis in the left ventricle (LV). Cardiac ¹²³I-meta-iodobenzylguanidine uptake (¹²³I-MIBG) scintigraphy revealed reduced uptake in the inferior and posterior wall. Electrocardiograhy at rest showed that the coefficient variation of RR intervals (CVR-R) was reduced, and the corrected QT (QTc) interval length was prolonged. In this HSV encephalitis patient, signs of a right insular cortex lesion and autonomic instability were observed: LV hypokinesis, regional reduced ¹²³I-MIBG uptake, decreased CVR-R, and QTc interval prolongation. Our patient’s autonomic instability may thus be derived from disrupted autonomic balance due to the right insular cortex lesion.     

QTc-interval abnormalities in a forensic population

Background Antipsychotic drugs have been linked to sudden death among psychiatric patients, with a suggestion that prolongation of the QT‐interval detectable on a standard electrocardiogram may be linked to fatal cardiac arrhythmias in these circumstances. Patients in secure forensic psychiatric facilities may be particularly likely to be on high‐dose antipsychotic medication, and yet, as far as the authors are aware, no study of QT‐intervals among such patients has been reported. Aim To investigate the prevalence of QT‐interval abnormalities and associated known risk factors for fatal cardiac arrhythmias in a sample of forensic patients. Method Participants had a 12‐lead electrocardiogram taken at 50 mm/s. Information was collected on their age, gender, psychiatric diagnosis, history of cardiovascular, liver and kidney diseases, and smoking, on all medications and on history of seclusion over the previous 12 months. Analysis was carried out using binary logistic regression. Results Lower rates of QT‐interval abnormalities than might be expected for this population were found. It was also found that a high dose of antipsychotics was associated with QTc prolongation (Adjusted OR = 9.5, 95% CI 2.6–34.2), a result consistent with previous literature. Conclusion Forensic patients need not be at increased risk of QTc abnormality provided risk factors are properly managed. A high dose of antipsychotic medication increases the risk of QTc prolongation. Copyright © 2007 John Wiley & Sons, Ltd.     

蛛网膜下腔出血患者并发长QT间期综合征的危险因素探讨

目的：分析哪些因素与蛛网膜下腔出血患者伴发长QT间期综合征有关。方法：对98例发病2小时内人住我院的蛛网膜下腔出血患者分别记录了年龄、性别以及是否有糖尿病史,测定了每一例的心电图QT间期,用Bazettformula方法计算了经心率校正后的QT间期即QTc,并测定了每一例患者的血钠、血钾、血钙、血镁浓度和血糖水平。用多元线性回归方法分析了蛛网膜下腔出血患者的校正后QT间期即QTc与年龄、性别、血钠、血钾、血钙、血镁浓度及血糖水平的关系。结果：平均QTc间期为469．80±24．19ms。多元线性回归分析表明女性、低血钾及血糖为QTc间期延长的独立危险因素。女性相对于男性的相对危险度为4．23,低血钾(＜3．5mmol/L)者与正常血钾者比较相对危险度为2．86,高血糖(＞7．4mmol/L)患者相对于非高血糖患者(≤7．4mmol/L)的相对危险度为1．10。结论：女性、低血钾浓度及高血糖水平是蛛网膜下腔出血患者QTc延长的独立危险因素。     

New Generation Antipsychotic Drugs and QTc Interval Prolongation

BACKGROUND: Recent regulatory and clinical concerns have brought into sharp focus antipsychotic drug-induced QTc interval prolongation, torsades de pointes, and sudden cardiac death. Several new generation (atypical) antipsychotic drugs have either been withdrawn from clinical use or delayed in reaching the marketplace due to these concerns. Because torsades de pointes is rarely found, QTc interval prolongation serves as a surrogate marker for this potentially life-threatening arrhythmia. Current methods of calculating this electrocardiographic parameter have limitations. The primary care physician is a key member of the team managing a patient who requires administration of antipsychotic drugs. This article focuses on new generation antipsychotic drugs and principles useful to both the primary care physician and the psychiatrist. METHOD: PubMed was searched in September 2002 using the terms antipsychotic drug and QT interval. References were examined from review articles describing antipsychotic drugs and the QT interval. The author's files gathered over the past 20 years on the QT interval were also reviewed. RESULTS: Nine cases were available in which drug-induced QTc interval prolongation was associated with new generation antipsychotic drug administration. Eight cases were taken from the literature, and the author added one additional report. The newer agents involved were risperidone, quetiapine, and ziprasidone. In at least 8 cases, there was evidence of other risk factors associated with QTc interval prolongation. In one case frequently referenced in the literature, the authors misunderstood their own data showing that QTc interval prolongation did not relate to delayed ventricular repolarization. In another instance, 2 authors reported on the same patient, with important information missing from both articles. No evidence of torsades de pointes appeared in any of the 9 cases. CONCLUSIONS: No evidence is currently available in the literature implicating new generation antipsychotic drugs in the production of torsades de pointes. However, the absence of such evidence does not prove that newer antipsychotic drugs do not cause torsades de pointes. Among patients free of risk factors for QTc interval prolongation and torsades de pointes, current literature does not dictate any specific consultative or laboratory intervention before administering new generation antipsychotic drugs. When risk factors are present, evaluation and intervention specific to those risk factors should dictate the clinician's course of action. More specific guidelines for monitoring the QT interval and risk of torsades de pointes await improved methods of measuring the QTc interval relevant to each patient.     

Impact of Age and Sex on QT Prolongation in Patients Receiving Psychotropics

Objective:

To assess older age and female sex, 2 of the major risk factors for potentially fatal cardiac arrhythmias or sudden cardiac death in patients prescribed psychotropics, within the context of electrocardiographic evidence of time between start of Q wave and end of T wave (QT) interval prolongation, which is an indicator of an increased risk for potentially fatal cardiac arrhythmias.

Method:

The literature on the relation between age, sex, and QT interval with respect to psychotropic drugs was reviewed.

Results:

The QT interval must be corrected (QTc) for heart rate. Because slower heart rates prolong and faster heart rates shorten the QT interval, people with faster heart rates may have a prolonged QT interval that is not apparent until the correction is performed. QTc values for apparently healthy post-pubertal people are less than 450 ms for males and less than 470 ms for females. The longer QT intervals in women may account for their increased risk of potentially fatal cardiac arrhythmias on psychotropics. QTc increases with increasing age. Assessment of QTc in older people is especially important to identify people with a longer QTc who are more likely to attain a serious QT level with drugs that prolong QTc. The age-related increase in QTc is more evident in men than women, suggesting that male sex does not afford protection against potentially fatal arrhythmias at older age.

Conclusion:

The association of increasing age and female sex with greater QT intervals indicates the need to have an increased awareness of the QTc prior to use of these psychotropics and to evaluate the QTc after initiation of therapy.