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Effective management of long Q-T syndrome with amiodarone

Gururaj AK, Ainon S

J Singapore Paediatr Soc, 1990;32(1-2):50-2.
PMID: 2259197

It is well known that episodic loss of consciousness and convulsions may have a cardiac rather than a cerebral origin (1). We report a case where these episodes were caused by recurrent ventricular tachycardia/ventricular fibrillation secondary to idiopathic long QT syndrome which was effectively treated with amiodarone.

Matched MeSH terms: Long QT Syndrome/complications; Long QT Syndrome/drug therapy*
Clinical and genetic analysis of long QT syndrome in two Malay children

Wong AR, Zilfalil BA, Bhuiyan ZA

Med J Malaysia, 2019 08;74(4):341-343.
PMID: 31424047

Long QT syndrome (LQTS) is predominantly a genetic cardiac arrhythmia disorder. We report here our study on long QT syndrome from two children from Kelantan, Malaysia. Clinical and genetic findings of these two unrelated Malay children with LQTS is discussed. We found a Long QT, type 1 causal mutation, p.Ile567Thr in the KCNQ1 gene in the first child. A pathogenic mutation could not be detected in the second child, explaining the heterogeneity of this disease.

Matched MeSH terms: Long QT Syndrome/congenital; Long QT Syndrome/diagnosis*; Long QT Syndrome/genetics*
Fulltext The effects of ageing and adrenergic challenge on electrocardiographic phenotypes in a murine model of long QT syndrome type 3

Chadda KR, Ahmad S, Valli H, den Uijl I, Al-Hadithi AB, Salvage SC, et al.

Sci Rep, 2017 09 11;7(1):11070.
PMID: 28894151 DOI: 10.1038/s41598-017-11210-3

Long QT Syndrome 3 (LQTS3) arises from gain-of-function Nav1.5 mutations, prolonging action potential repolarisation and electrocardiographic (ECG) QT interval, associated with increased age-dependent risk for major arrhythmic events, and paradoxical responses to β-adrenergic agents. We investigated for independent and interacting effects of age and Scn5a+/ΔKPQ genotype in anaesthetised mice modelling LQTS3 on ECG phenotypes before and following β-agonist challenge, and upon fibrotic change. Prolonged ventricular recovery was independently associated with Scn5a+/ΔKPQ and age. Ventricular activation was prolonged in old Scn5a+/ΔKPQ mice (p = 0.03). We associated Scn5a+/ΔKPQ with increased atrial and ventricular fibrosis (both: p

Matched MeSH terms: Long QT Syndrome/diagnosis*; Long QT Syndrome/physiopathology*
Fulltext Torsade de pointes and syncopal attacks in a 26-year old woman with congenital complete heart block and prolonged QT interval

Quek DK, Ong SB

Singapore Med J, 1990 Apr;31(2):185-8.
PMID: 2371586

A 26-year old woman with congenital complete heart block and prolonged QT interval presented for the first time with syncopal attacks associated with torsade de pointes in adulthood. Cardioversion followed by overdrive pacing was needed to finally control the unstable rhythm. During episodes of non-capture, paraoxysms of torsade de pointes leading to ventricular flutter were recorded by a 24-hour ambulatory electrocardiographic monitoring. Beta-blockade and permanent ventricular pacing finally abolished both the syncopal attacks and the torsade phenomena. The prognosis of congenital complete heart block associated with QT prolongation resembles that of the Romano-Ward syndrome. Recognition of this variant would facilitate earlier treatment of this rare but potentially lethal disorder.

Matched MeSH terms: Long QT Syndrome/complications*; Long QT Syndrome/diagnosis
Fulltext Ion channels, long QT syndrome and arrhythmogenesis in ageing

Jeevaratnam K, Chadda KR, Salvage SC, Valli H, Ahmad S, Grace AA, et al.

Clin Exp Pharmacol Physiol, 2017 12;44 Suppl 1:38-45.
PMID: 28024120 DOI: 10.1111/1440-1681.12721

Ageing is associated with increased prevalences of both atrial and ventricular arrhythmias, reflecting disruption of the normal sequence of ion channel activation and inactivation generating the propagated cardiac action potential. Experimental models with specific ion channel genetic modifications have helped clarify the interacting functional roles of ion channels and how their dysregulation contributes to arrhythmogenic processes at the cellular and systems level. They have also investigated interactions between these ion channel abnormalities and age-related processes in producing arrhythmic tendency. Previous reviews have explored the relationships between age and loss-of-function Nav 1.5 mutations in producing arrhythmogenicity. The present review now explores complementary relationships arising from gain-of-function Nav 1.5 mutations associated with long QT3 (LQTS3). LQTS3 patients show increased risks of life-threatening ventricular arrhythmias, particularly after 40 years of age, consistent with such interactions between the ion channel abnormailities and ageing. In turn clinical evidence suggests that ageing is accompanied by structural, particularly fibrotic, as well as electrophysiological change. These abnormalities may result from biochemical changes producing low-grade inflammation resulting from increased production of reactive oxygen species and superoxide. Experimental studies offer further insights into the underlying mechanisms underlying these phenotypes. Thus, studies in genetically modified murine models for LQTS implicated action potential recovery processes in arrhythmogenesis resulting from functional ion channel abnormalities. In addition, ageing wild type (WT) murine models demonstrated both ion channel alterations and fibrotic changes with ageing. Murine models then suggested evidence for interactions between ageing and ion channel mutations and provided insights into potential arrhythmic mechanisms inviting future exploration.

Matched MeSH terms: Long QT Syndrome/genetics*; Long QT Syndrome/metabolism; Long QT Syndrome/epidemiology; Long QT Syndrome/physiopathology
Smartphone electrocardiogram for QT interval monitoring in Coronavirus Disease 2019 (COVID-19) patients treated with Hydroxychloroquine

Andy Ko TY, Chen LS, Pang IX, Ling HS, Wong TC, Sia Tonnii LL, et al.

Med J Malaysia, 2021 03;76(2):125-130.
PMID: 33742617

INTRODUCTION: The global pandemic of Corona Virus Disease 2019 (COVID-19) has led to the re-purposing of medications, such as hydroxychloroquine and lopinavir-ritonavir in the treatment of the earlier phase of COVID-19 before the recognized benefit of steroids and antiviral. We aim to explore the corrected QT (QTc) interval and 'torsadogenic' potential of hydroxychloroquine and lopinavir-ritonavir utilising a combination of smartphone electrocardiogram and 12-lead electrocardiogram monitoring.
MATERIALS AND METHODS: Between 16-April-2020 to 30-April- 2020, patients with suspected or confirmed for COVID-19 indicated for in-patient treatment with hydroxychloroquine with or without lopinavir-ritonavir to the Sarawak General Hospital were monitored with KardiaMobile smartphone electrocardiogram (AliveCor®, Mountain View, CA) or standard 12-lead electrocardiogram. The baseline and serial QTc intervals were monitored till the last dose of medications or until the normalization of the QTc interval.
RESULTS: Thirty patients were treated with hydroxychloroquine, and 20 (66.7%) patients received a combination of hydroxychloroquine and lopinavir-ritonavir therapy. The maximum QTc interval was significantly prolonged compared to baseline (434.6±28.2msec vs. 458.6±47.1msec, p=0.001). The maximum QTc interval (456.1±45.7msec vs. 464.6±45.2msec, p=0.635) and the delta QTc (32.6±38.5msec vs. 26.3±35.8msec, p=0.658) were not significantly different between patients on hydroxychloroquine or a combination of hydroxychloroquine and lopinavir-ritonavir. Five (16.7%) patients had QTc of 500msec or more. Four (13.3%) patients required discontinuation of hydroxychloroquine and 3 (10.0%) patients required discontinuation of lopinavirritonavir due to QTc prolongation. However, no torsade de pointes was observed.
CONCLUSIONS: QTc monitoring using smartphone electrocardiogram was feasible in COVID-19 patients treated with hydroxychloroquine with or without lopinavir-ritonavir. The usage of hydroxychloroquine and lopinavir-ritonavir resulted in QTc prolongation, but no torsade de pointes or arrhythmogenic death was observed.

Matched MeSH terms: Long QT Syndrome/chemically induced; Long QT Syndrome/diagnosis*
Fulltext Anaesthesia for a patient with long QT syndrome undergoing renal transplantation

Lim KY, Lim TA, Wong WH

Med J Malaysia, 2005 Dec;60(5):647-9.
PMID: 16515119

Anaesthetizing patients with Long QT Syndrome is a major challenge, as the potential for sudden catastrophic cardiovascular collapse is well known. We present a 15-year-old boy with Long QT Syndrome who presented for an elective renal transplant. All electrolyte concentration abnormalities were corrected preoperative and adequate beta-blockade was maintained. The patient was given a target controlled infusion of propofol, together with opioids and atracurium. Anaesthesia was uneventful and the patient was extubated at the end of the surgical procedure.

Matched MeSH terms: Long QT Syndrome/surgery*
QT prolongation associated with hydroxychloroquine and protease inhibitors in COVID-19

Koh HM, Chong PF, Tan JN, Chidambaram SK, Chua HJ

J Clin Pharm Ther, 2021 Jun;46(3):800-806.
PMID: 33768612 DOI: 10.1111/jcpt.13356

WHAT IS KNOWN AND OBJECTIVE: Hydroxychloroquine and protease inhibitors were widely used as off-label treatment options for COVID-19 but the safety data of these drugs among the COVID-19 population are largely lacking. Drug-induced QTc prolongation is a known adverse reaction of hydroxychloroquine, especially during chronic treatment. However, when administered concurrently with potential pro-arrhythmic drugs such as protease inhibitors, the risk of QTc prolongation imposed on these patients is not known. We aim to investigate the incidence of QTc prolongation events and potential factors associated with its occurrence in COVID-19 population.
METHODS: We included 446 SARS-CoV-2 RT-PCR-positive patients taking at least one treatment drug for COVID-19 within a period of one month (March-April 2020). In addition to COVID-19-related treatment (HCQ/PI), concomitant drugs with risks of QTc prolongation were considered. We defined QTc prolongation as QTc interval of ≥470 ms in postpubertal males, and ≥480 ms in postpubertal females.
RESULTS AND DISCUSSION: QTc prolongation events occurred in 28/446 (6.3%) patients with an incidence rate of 1 case per 100 person-days. A total of 26/28 (93%) patients who had prolonged QTc intervals received at least two pro-QT drugs. Multivariate analysis showed that HCQ and PI combination therapy had five times higher odds of QTc prolongation as compared to HCQ-only therapy after controlling for age, cardiovascular disease, SIRS and the use of concurrent QTc-prolonging agents besides HCQ and/or PI (OR 5.2; 95% CI, 1.11-24.49; p = 0.036). Independent of drug therapy, presence of SIRS resulted in four times higher odds of QTc prolongation (OR 4.3; 95% CI, 1.66-11.06; p = 0.003). In HCQ-PI combination group, having concomitant pro-QT drugs led to four times higher odds of QTc prolongation (OR 3.8; 95% CI, 1.53-9.73; p = 0.004). Four patients who had prolonged QTc intervals died but none were cardiac-related deaths.
WHAT IS NEW AND CONCLUSION: In our cohort, hydroxychloroquine monotherapy had low potential to increase QTc intervals. However, when given concurrently with protease inhibitors which have possible or conditional risk, the odds of QTc prolongation increased fivefold. Interestingly, independent of drug therapy, the presence of systemic inflammatory response syndrome (SIRS) resulted in four times higher odds of QTc prolongation, leading to the postulation that some QTc events seen in COVID-19 patients may be due to the disease itself. ECG monitoring should be continued for at least a week from the initiation of treatment.

Matched MeSH terms: Long QT Syndrome/chemically induced*
Fulltext QTc Interval Prolongation and Hemorrhagic Stroke: Any Difference Between Acute Spontaneous Intracerebral Hemorrhage and Acute Non-traumatic Subarachnoid Hemorrhage?

Amin OSM, Al-Bajalan SJ, Mubarak A

Med Arch, 2017 Jun;71(3):193-197.
PMID: 28974832 DOI: 10.5455/medarh.2017.71.193-197

BACKGROUND: A variety of ECG changes occur as an aftermath of stroke. Prolongation of the QTc interval is a well-documented change. We analyzed QTc interval prolongation among patients with acute hemorrhagic strokes.
METHODS: This observational study was conducted at the Emergency Department of Sulaymaniyah General Teaching Hospital and Shar Hospital from September 1st, 2014 to August 31st, 2015. Fifty patients who developed acute spontaneous hypertensive intracerebral hemorrhage (ICH) and 50 patients who developed acute non-traumatic subarachnoid hemorrhage (SAH) were included in the study. All patients underwent resting 12-lead ECG within half an hour of admission. The QTc interval was calculated and analyzed in those 100 patients.
RESULTS: Females (62%) outnumbered males (38%) with a female to male ratio of 1.6:1. Forty percent of the patients were between 60-69 years of age. Hypertension was seen in 82% of patients while left ventricular hypertrophy was documented in 40% of patients. The QTc was prolonged in 38 patients (17 patients in the ICH group and 21 patients in the SAH group). In both groups, males demonstrated QTc prolongation more than females. However, there were no statistically significant gender difference between both groups and within the same group. There was a statistically significant association between SAH and QTc prolongation (p-value<0.001); the ICH group did not demonstrate any significant relationship with QTc prolongation.
CONCLUSION: Prolongation in the QTc interval was "statistically" associated with acute SAH only. No gender difference was noted; whether this observation is clinically significant or not, it needs further analytic studies.

Matched MeSH terms: Long QT Syndrome/etiology*
Genetic polymorphisms in KCNQ1, HERG, KCNE1 and KCNE2 genes in the Chinese, Malay and Indian populations of Singapore

Koo SH, Ho WF, Lee EJ

Br J Clin Pharmacol, 2006 Mar;61(3):301-8.
PMID: 16487223

To determine the genetic variability of long QT syndrome (LQTS)-associated genes (KCNQ1, HERG, KCNE1 and KCNE2) among three distinct ethnic groups in the Singapore population.

Matched MeSH terms: Long QT Syndrome/genetics