Jayaprakash Shenthar

The Tpeak – Tend interval as an electrocardiographic risk marker of arrhythmic and mortality outcomes: a systematic review and meta-analysis

BACKGROUNDnThe Tpeak - Tend interval (the interval from the peak to the end of the T wave), an electrocardiographic marker reflecting transmural dispersion of repolarization, has been used to predict ventricular tachycardia/fibrillation (VT/VF) and sudden cardiac death in different clinical settings.nnnOBJECTIVEnThis systematic review and meta-analysis evaluated the significance of the Tpeak - Tend interval in predicting arrhythmic and/or mortality end points.nnnMETHODSnPubMed, Embase, Cochrane Library, and CINAHL Plus databases were searched through November 30,xa02016.nnnRESULTSnOf the 854 studies identified initially, 33 observational studies involving 155,856 patients were included in our meta-analysis. Tpeak - Tend interval prolongation (mean cutoff value 103.3 ± 17.4 ms) was a significant predictor of the arrhythmic or mortality outcomes (odds ratio [OR] 1.14; 95% confidence interval [CI] 1.11-1.17; P < .001). When different end points were analyzed, the ORs were as follows: VT/VF, 1.10 (95% CI 1.06-1.13; P < .0001); sudden cardiac death, 1.27 (95% CI 1.17-1.39; P < .0001); cardiovascular death, 1.40 (95% CI 1.19-1.64; P < .0001); and all-cause mortality, 4.56 (95% CI 0.62-33.68; P < .0001). Subgroup analysis for each disease revealed that the risk of VT/VF or death was highest for Brugada syndrome (OR 5.68; 95% CI 1.57-20.53; P < .01), followed by hypertension (OR 1.52; 95% CI 1.26-1.85; P < .0001), heart failure (OR 1.07; 95% CI 1.04-1.11; P < .0001), and ischemic heart disease (OR 1.06; 95% CI 1.02-1.10; P = 0.001).nnnCONCLUSIONnThe Tpeak - Tend interval is a useful risk stratification tool in different diseases and in the general population.

MRI scanning in patients with new and existing CapSureFix Novus 5076 pacemaker leads: Randomized trial results

BACKGROUNDnMagnetic resonance imaging (MRI) can be safely performed in patients with magnetic resonance (MR)-conditional pacemaker systems but remains relatively contraindicated with non-MR-conditional pacemaker systems.nnnOBJECTIVEnThe purpose of this study was to evaluate the safety of MRI without positioning restrictions in patients with an MR-conditional pacemaker and currently a non-MR-conditional Medtronic CapSureFix Novus 5076 lead(s).nnnMETHODSnThe study randomized 266 patients in a 2:1 ratio to the MRI group (177 patients) or to the control group (89 patients). At 9-12 weeks postimplant, the MRI group underwent MRI at 1.5 T. Primary end points were MRI-related complication-free rate and noninferiority of the MRI group compared to the control group with regard to the proportion of patients with an increase of ≤0.5 V in right atrial (RA) and right ventricular (RV) pacing capture thresholds from immediately before MRI to 1-month after MRI.nnnRESULTSnNo MRI-related complications occurred in 156 MRI-scanned patients who were followed through 1-month post-MRI. Differences in the proportion of patients with ≤0.5 V pacing capture threshold changes from pre-MRI to 1-month post-MRI were minimal between the groups for RA (proportions of 100% in both groups; a P value cannot be calculated) and RV leads (proportions of 99.3% in the MRI group and 100% in the control group; noninferiority test, P < .0001). Proportions of patients with acceptable sensing amplitude changes from pre-MRI to 1-month post-MRI were also similar between the 2 groups for RA and RV leads (noninferiority test, P < .0001 and P = .0004, respectively). No arrhythmias occurred during MRI.nnnCONCLUSIONnMRI scans can be performed safely without positioning restrictions in patients with Medtronic CapSureFix Novus 5076 leads connected to an MR-conditional pacemaker.

Prolonged Tpeak-end and Tpeak-end/QT ratio as predictors of malignant ventricular arrhythmias in the acute phase of ST-segment elevation myocardial infarction: A prospective case-control study

BACKGROUNDnProlonged Tpeak-end (the interval from the peak of the T wave to the end of the T wave) and Tpeak-end/QT ratio have been shown to be markers of arrhythmogenesis in various cardiac disorders.nnnOBJECTIVESnThe purpose of this study was to evaluate the utility of Tpeak-end and Tpeak-end/QT ratio at admission in patients with acute ST-segment elevation myocardial infarction (STEMI) in predicting malignant ventricular arrhythmias.nnnMETHODSnThe study group included 50 patients presenting with STEMI, in whom Tpeak-end and Tpeak-end/QT ratio were measured at admission; these patients were monitored for arrhythmias with a continuous electrocardiogram in the intensive care unit for 48 hours, and 50 healthy individuals acted as controls.nnnRESULTSnThe Tpeak-end (0.11 ± 0.04 seconds vs 0.08 ± 0.006 seconds; P < .0010) and Tpeak-end/QT ratio (0.30 ± 0.06 vs 0.21 ± 0.02; P < .001) were prolonged in patients with STEMI. Three patients with STEMI who sustained ventricular fibrillation (VF) within 24 hours of admission had prolonged corrected QT interval (0.39 ± 0.04 seconds vs 0.46 ± 0.13 seconds; P = .019), Tpeak-end (0.10 ± 0.02 seconds vs 0.20 ± 0.11 seconds; P < .001), and Tpeak-end/QT ratio (0.26 ± 0.05 vs 0.41 ± 0.09; P < .001) as compared with patients with STEMI without VF. Tpeak-end > 0.1 seconds and Tpeak-end/QT ratio > 0.3 predicted VF with a sensitivity of 100%. However, the Tpeak-end/QT ratio had a higher specificity (82.9% for Tpeak-end/QT ratio vs 44.7% for Tpeak-end) and accuracy (84% for Tpeak-end/QT ratio vs 48% for Tpeak-end).nnnCONCLUSIONnTpeak-end and Tpeak-end/QT ratio are prolonged in patients with STEMI compared with healthy individuals, and Tpeak-end > 0.1 and Tpeak-end/QT ratio > 0.3 predict malignant ventricular arrhythmias within 24 hours of STEMI.

Suicidal zinc phosphide poisoning unmasking Brugada syndrome and triggering near fatal ventricular arrhythmia

Brugada syndrome (BrS) is an inherited channelopathy associated with increased incidence of ventricular arrhythmias and has many acquired triggers. Zinc phosphide (ZnP) is a rodenticide and is commonly implicated in suicidal poison ingestion. ZnP poisoning can cause myocardial toxicity and death. We report a case of ZnP poisoning that triggered a type I Brugada pattern and ventricular fibrillation in a 67‐year‐old male. He had no other features of toxicity and recovered later. As metal phosphide is the commonest toxin involved in suicidal poisoning in India and BrS being endemic here, this case highlights an important clinical problem.

Mutational analysis of SCN5A gene in long QT syndrome

The SCN5A gene encodes for the INa channel implicated in long QT syndrome type-3 (LQTS-type-3). Clinical symptoms of this type are lethal as most patients had a sudden death during sleep. Screening of SCN5A in South Indian cohort by PCR-SSCP analyses revealed five polymorphisms — A29A (exon-2), H558R (exon-12), E1061E and S1074R (exon-17) and IVS25 + 65G > A (exon-25) respectively. In-silico and statistical analyses were performed on all the polymorphisms. Exon-2 of SCN5A gene revealed A282G polymorphism (rs6599230), resulting in alanine for alanine (A29A) silent substitution in the N-terminus of SCN5A protein. Exon-12 showed A1868G polymorphism (H558R — rs1805124) and its ‘AA’ genotype and ‘A’ allele frequency were found to be higher in LQTS patients pointing towards its role in LQTS etiology. Two polymorphisms A3378G (E1061E) and the novel C3417A (S1074R) were identified as compound heterozygotes/genetic compounds in exon-17 of SCN5A located in the DIIS6–DIIIS1 domain of the SCN5A transmembrane protein. IVS25 + 65G > A was identified in intron-25 of SCN5A. The ‘G’ allele was identified as the risk allele. Variations were identified in in-silico analyses which revealed that these genetic compounds may lead to downstream signaling variations causing aberrations in sodium channel functions leading to prolonged QTc. The compound heterozygotes of SCN5A gene polymorphisms revealed a significant association which may be deleterious/lethal leading to an aberrant sodium ion channel causing prolonged QTc.

Transvenous permanent pacemaker implantation in dextrocardia: technique, challenges, outcome, and a brief review of literature

AIMSnDextrocardia is a rare congenital anomaly. Pacemaker implantation in dextrocardia can be challenging because of the distorted anatomy and associated anomalies. The literature regarding implantation of pacemaker in dextrocardia is scarce.nnnMETHODS AND RESULTSnThe study involved retrospective analysis of records of patients with dextrocardia who had undergone pacemaker implantation between January 2006 and July 2013 from a single centre. Six patients with dextrocardia (five males and one female) underwent permanent pacemaker implantation (PPI) between January 2006 and July 2013. Of them, three had situs solitus dextrocardia and three situs inversus dextrocardia. All three patients with situs solitus dextrocardia had associated corrected transposition of great arteries. The indication for pacemaker implantation was symptomatic complete atrioventricular (AV) block in four, high-grade AV block in one, and sinus node dysfunction in one patient. A favourable outcome was noted during a mean follow-up of 3.9 years (4 months to 7 years) with one patient needing a pulse generator replacement.nnnCONCLUSIONnPermanent pacemaker implantation in dextrocardia can be challenging because of the distorted anatomy. Use of a technique employing angiography to delineate chamber anatomy and relationship can assist the operator during such difficult PPIs. The medium- and long-term survival after a successful pacemaker implantation in dextrocardia is favourable.

A survey of cardiac implantable electronic device implantation in India: By Indian Society of Electrocardiology and Indian Heart Rhythm Society

Background There is limited data regarding the demographics and type of cardiac implantable electronic device (CIED) in India. Aim The aim of this survey was to define trends in CIED implants, which included permanent pacemakers (PM), intracardiac defibrillators (ICD), and cardiac resynchronization therapy pacemakers and defibrillators (CRT-P/D) devices in India. Methods The survey was the initiative of the Indian Society of Electrocardiology and the Indian Heart Rhythm Society. The type of CIED used, their indications, demographic characteristics, clinical status and co-morbidities were collected using a survey form over a period of 1 year. Results 2117 forms were analysed from 136 centers. PM for bradyarrhythmic indication constituted 80% of the devices implanted with ICDs and CRT-P/D forming approximately 10% each. The most common indication for PM implantation was complete atrio-ventricular block (76%). Single chamber (VVI) pacemakers formed 54% of implants, majority in males (64%). The indication for ICD implantation was almost equal for primary and secondary prevention. A single chamber ICD was most commonly implanted (65%). Coronary artery disease was the etiology in 58.5% of patients with ICD implants. CRT pacemakers were implanted mostly in patients with NYHA III/IV (82%), left ventricular ejection fraction <0.35 (88%) with CRT-P being most commonly used (57%). Conclusion A large proportion of CIED implants in India are PM for bradyarrhythmic indications, predominantly AV block. ICDs are implanted almost equally for primary and secondary prophylaxis. Most CRT devices are implanted for NYHA Class III. There is a male predominance for implantation of CIED.

An unusual case of complete atrioventricular block causing Takotsubo syndrome

Complete atrioventricular (AV) block in association with Takotsubo syndrome (TS) has been well recognized, but the cause and effect relationship has not been elucidated. We describe a 78-year-old female who presented with complete AV block but one week later developed new-onset, diffuse T-wave inversions, QT prolongation, and acceleration of junctional escape rate. Left ventriculogram revealed features typical of TS. One year after permanent pacemaker implantation, complete AV block persisted despite the reversal of wall motion defects implying that conduction abnormality was the trigger of TS rather than its consequence.

Evaluation of baseline ECG in patients undergoing Oral Flecainide Challenge test for suspected Brugada Syndrome: An analysis of lead II

Background and Objectives We analyzed Lead II in patients undergoing an Oral Flecainide Challenge test (FCT), to identify any pointers that could predict a positive FCT and thereby help in recognition of latent BS. Methods The following parameters in lead II were retrospectively analyzed from the pre-test ECG in 62 patients undergoing FCT for suspected BS: The presence or absence of S waves, S wave amplitude, duration and upslope duration; J point parameters- Early repolarization, QRS notch, and QRS Slur; ST segment parameters-lack of isoelectric ST segment, ST duration and QT interval. Results 48 had positive FCT (Group-1) while 14 were negative for FCT(Group-2). Lack of an isoelectric ST segment (50% vs 14.29%, p = 0.018) and slurring of QRS (33.33% vs 0%, p = 0.014) was more common in Group-1 than Group-2. Group-1 had shorter ST segment duration (median 81.5 (IQR 64–103.5) vs 110 (IQR 90–132), p = 0.002) and shorter ST: QT ratio (median 0.28 (IQR 0.22–0.35) vs 0.23 (0.18–0.27), p = 0.007). QRS notch/depressed J point (87.5%), QRS slur (100%), and lack of isoelectric ST segment (92.31%) had high sensitivity for predicting an inducible Type 1 Brugada pattern. Combining two parameters- ST: QT ratio<0.24 and lack of isoelectric ST segment-considerably improved the specificity (73.3%), and the positive predictive value of the test to 76%. The results remained accurate when validated in a small prospective cohort. Conclusion Shortened ST segment in Lead II, lack of isoelectric ST segment, slurred QRS and ST/QT ratio <0.24 are predictive of underlying Brugada pattern in baseline ECG.

Heat shock protein 70 gene polymorphisms' influence on the electrophysiology of long QT syndrome.

PurposeLong QT syndrome (LQTS) is a rare cardiac disorder caused due to mutations in genes encoding ion channels responsible for generation of electrical impulses. The heat shock protein (HSP)-70 gene, expressed under conditions of stress, plays a cardioprotective role when overexpressed and helps in the proper folding of the nascent proteins synthesized by the cellular machinery. We aimed to identify the role played by HSP-70 gene polymorphisms in the pathogenesis of LQTS.MethodsStudy included 49 LQTS patients, 71 family members, and 219 healthy individuals recruited from an ethnically matched population. Genotyping of the single-nucleotide polymorphisms (SNPs) rs1043618 (HSP-70-1, +190G/C), rs1061581 (HSP-70-2, +1267A/G), and rs2227956 (HSP-70-hom, +2437T/C) was performed by PCR-RFLP analysis, and the results were analyzed statistically at 95xa0% confidence interval and pu2009≤u20090. 05.ResultsThe “C” allele of HSP-70-1 (+190G/C) and “G” allele of HSP-70-2 (+1267A/G) showed strong association with LQTS phenotype. The haplotype group C-G-T consisting of two risk alleles was significantly associated with the disease condition. Multifactor dimensionality reduction analysis further substantiated that the three-allele model influences the outcome of the phenotype highlighting the effect of modifiers in the etiology of LQTS.ConclusionsAs HSP-70 influences the channel assembly and maturation/trafficking of the ion channel proteins, the alleles C of the HSP-70-1 and G of the HSP-70-2 loci and the haplotype group C-G-T could be considered a diagnostic biomarker in the identification of the LQTS phenotype with a potential to affect the progression and modification of the disease phenotype.