Whole genome sequencing of families diagnosed with cardiac channelopathies reveals structural variants missed by whole exome sequencing.

Cardiac channelopathies are a group of heritable disorders that affect the heart's electrical activity due to genetic variations present in genes coding for ion channels. With the advent of new sequencing technologies, molecular diagnosis of these disorders in patients has paved the way for early identification, therapeutic management and family screening. The objective of this retrospective study was to understand the efficacy of whole-genome sequencing in diagnosing patients with suspected cardiac channelopathies who were reported negative after whole exome sequencing and analysis. We employed a 3-tier analysis approach to identify nonsynonymous variations and loss-of-function variations missed by exome sequencing, and structural variations that are better resolved only by sequencing whole genomes. By performing whole genome sequencing and analyzing 25 exome-negative cardiac channelopathy patients, we identified 3 pathogenic variations. These include a heterozygous likely pathogenic nonsynonymous variation, CACNA1C:NM_000719:exon19:c.C2570G:p. P857R, which causes autosomal dominant long QT syndrome in the absence of Timothy syndrome, a heterozygous loss-of-function variation CASQ2:NM_001232.4:c.420+2T>C classified as pathogenic, and a 9.2 kb structural variation that spans exon 2 of the KCNQ1 gene, which is likely to cause Jervell-Lange-Nielssen syndrome. In addition, we also identified a loss-of-function variation and 16 structural variations of unknown significance (VUS). Further studies are required to elucidate the role of these identified VUS in gene regulation and decipher the underlying genetic and molecular mechanisms of these disorders. Our present study serves as a pilot for understanding the utility of WGS over clinical exomes in diagnosing cardiac channelopathy disorders.

Knowledge and Skills in Cardiopulmonary Resuscitation and Effect of Simulation Training on it among Healthcare Workers in a Tertiary Care Center in India.

Aim and background: High-quality cardiopulmonary resuscitation (CPR) is associated with improved patient outcomes, but healthcare workers (HCWs) may be frequently undertrained. This study aimed to assess baseline knowledge and skills among HCWs about basic and advanced life support and the effect of simulation-based training on it. Methods: It was a single-center prospective quasi-interventional study among resident doctors and nurses at a Tertiary Center in New Delhi, India. A questionnaire-based assessment was done to assess baseline knowledge. The participants then underwent simulation-based training followed by questionnaire-based knowledge assessment and skill assessment. A repeat questionnaire-based assessment was done 6 months post-training to assess knowledge retention. Results: A total of 82 HCWs (54 doctors and 28 nurses) were enrolled. The participants scored 22.28 ± 6.06 out of 35 (63.65%) in the pre-training knowledge assessment, with low scores in post-cardiac arrest care, advanced life support, and defibrillation. After the training, there was a significant rise in scores to 28.32 ± 4.08 out of 35 (80.9%) (p < 0.01). The retention of knowledge at 6 months was 68.87% (p < 0.01). The participants scored 92.61 ± 4.75% marks in skill assessment with lower scores in chest compressions and team leadership roles. There was a positive correlation (r = 0.35) between knowledge and skills scores (p < 0.01). Conclusion: There is a progressive decrease in baseline knowledge of HCWs with the further steps in the adult chain of survival. The simulation training program had a positive impact on the knowledge of HCWs. The training programs should focus on defibrillation, advanced life support, post-cardiac arrest care, and leadership roles. How to cite this article: Agarwal A, Baitha U, Ranjan P, Swarnkar NK, Singh GP, Baidya DK, et al. Knowledge and Skills in Cardiopulmonary Resuscitation and Effect of Simulation Training on it among Healthcare Workers in a Tertiary Care Center in India. Indian J Crit Care Med 2024;28(4):336-342.

1029 genomes of self-declared healthy individuals from India reveal prevalent and clinically relevant cardiac ion channelopathy variants.

BACKGROUND: The prevalence and genetic spectrum of cardiac channelopathies exhibit population-specific differences. We aimed to understand the spectrum of cardiac channelopathy-associated variations in India, which is characterised by a genetically diverse population and is largely understudied in the context of these disorders. RESULTS: We utilised the IndiGenomes dataset comprising 1029 whole genomes from self-declared healthy individuals as a template to filter variants in 36 genes known to cause cardiac channelopathies. Our analysis revealed 186,782 variants, of which we filtered 470 variants that were identified as possibly pathogenic (440 nonsynonymous, 30 high-confidence predicted loss of function ). About 26% (124 out of 470) of these variants were unique to the Indian population as they were not reported in the global population datasets and published literature. Classification of 470 variants by ACMG/AMP guidelines unveiled 13 pathogenic/likely pathogenic (P/LP) variants mapping to 19 out of the 1029 individuals. Further query of 53 probands in an independent cohort of cardiac channelopathy, using exome sequencing, revealed the presence of 3 out of the 13 P/LP variants. The identification of p.G179Sfs*62, p.R823W and c.420 + 2 T > C variants in KCNQ1, KCNH2 and CASQ2 genes, respectively, validate the significance of the P/LP variants in the context of clinical applicability as well as for large-scale population analysis. CONCLUSION: A compendium of ACMG/AMP classified cardiac channelopathy variants in 1029 self-declared healthy Indian population was created. A conservative genotypic prevalence was estimated to be 0.9-1.8% which poses a huge public health burden for a country with large population size like India. In the majority of cases, these disorders are manageable and the risk of sudden cardiac death can be alleviated by appropriate lifestyle modifications as well as treatment regimens/clinical interventions. Clinical utility of the obtained variants was demonstrated using a cardiac channelopathy patient cohort. Our study emphasises the need for large-scale population screening to identify at-risk individuals and take preventive measures. However, we suggest cautious clinical interpretation to be exercised by taking other cardiac channelopathy risk factors into account.

A unique location of the accessory pathway in a child with permanent junctional reciprocating tachycardia.

Permanent junctional reciprocating tachycardia (PJRT) is a rare supra ventricular tachycardia (SVT) due to an accessory pathway (AP), characterized by slow and decremental retrograde conduction, which is predominantly seen in infants and children. Although the typical site of AP in PJRT is a right posteroseptal region around or just within the coronary sinus (CS), atypical sites of AP have been described. We report a rare case of PJRT in a 7-year-old girl with an AP located in the superio-paraseptal (Para-Hsian) region that was successfully ablated through a non-coronary sinus.

Early repolarization syndrome, epilepsy, and atrial fibrillation in a young girl with novel KCND3 mutation managed with quinidine.

A 6-year-old girl presented with a difficult to control epilepsy syndrome. On evaluation, additional presyncope episodes associated with polymorphic ventricular tachycardia were also noted. A diagnosis of early repolarization syndrome (ERS) was made with an early repolarization pattern on electrocardiogram, documented VT episodes, and clinical presyncope (proposed Shanghai score 7). Paroxysmal atrial fibrillation (AF) was also noted on 24-h Holter recordings. The child was stabilized with isoprenaline infusion and was later discharged with arrhythmia control on quinidine and cilostazol. The genetic evaluation revealed a potassium channel KCND3 gene missense mutation. The case highlights the association of epilepsy syndrome and AF with ERS; the possible association of KCND3 gene mutation with a malignant phenotype; and management issues in a small child.

Comparing two different schedules of online learning for updated cardiopulmonary resuscitation guidelines in Covid-19 patients: A randomized study.

Background Coronavirus disease 2019 (Covid-19) is an evolving disease with newly generated evidence related to the clinical management of Covid-19 patients. We aimed to compare two online learning schedules for disseminating new cardiopulmonary resuscitation (CPR) guidelines in terms of knowledge gain and acceptability among nurses. Methods In a prospective randomized controlled study, 61 nurses trained in comprehensive cardiopulmonary life support (CCLS) were randomized to synchronous (n=31) and asynchronous learning groups (n= 30). The enhanced training module on CPR (ETMCPR) prepared by a team of experts was used to impart training to the nurses. Baseline data and pre-intervention knowledge of participants were collected using a structured demographic sheet and knowledge questionnaire (25 items) in a google form. Nurses in the synchronous group were provided training using ETMCPR through a licensed Zoom platform, while the nurses in the asynchronous group had access to the uploaded ETMCPR module in the e-learning platform. At the end of the intervention, the knowledge of the nurses was assessed along with their acceptability to the online learning schedule. Results Both schedules of online learning were effective in improving the knowledge scores of the nurses (11.93 [3.26] v. 21.15 [1.90], p=0.01 and 11.71 [3.12] v. 20.32 [1.71], p=0.01). The mean acceptability scores of nurses in the asynchronous group were statistically lower than in the synchronous group (38.93 [2.50] v. 42.5 [3.08], p=0.007). Conclusion Both synchronous and asynchronous schedules of online learning were effective in disseminating updated CPR guidelines; however, nurses in the synchronous group were more satisfied with the learning schedule.

Resource and Infrastructure-Appropriate Management of ST-Segment Elevation Myocardial Infarction in Low- and Middle-Income Countries.

The 143 low- and middle-income countries (LMICs) of the world constitute 80% of the world's population or roughly 5.86 billion people with much variation in geography, culture, literacy, financial resources, access to health care, insurance penetration, and healthcare regulation. Unfortunately, their burden of cardiovascular disease in general and acute ST-segment-elevation myocardial infarction (STEMI) in particular is increasing at an unprecedented rate. Compounding the problem, outcomes remain suboptimal because of a lack of awareness and a severe paucity of resources. Guideline-based treatment has dramatically improved the outcomes of STEMI in high-income countries. However, no such focused recommendations exist for LMICs, and the unique challenges in LMICs make directly implementing Western guidelines unfeasible. Thus, structured solutions tailored to their individual, local needs, and resources are a vital need. With this in mind, a multicountry collaboration of investigators interested in LMIC STEMI care have tried to create a consensus document that extracts transferable elements from Western guidelines and couples them with local realities gathered from expert experience. It outlines general operating principles for LMICs focused best practices and is intended to create the broad outlines of implementable, resource-appropriate paradigms for management of STEMI in LMICs. Although this document is focused primarily on governments and organizations involved with improvement in STEMI care in LMICs, it also provides some specific targeted information for the frontline clinicians to allow standardized care pathways and improved outcomes.

Role of CMR feature-tracking derived left ventricular strain in predicting myocardial iron overload and assessing myocardial contractile dysfunction in patients with thalassemia major.

OBJECTIVE: Myocardial iron overload (MIO) in thalassemia major (TM) may cause subclinical left ventricular (LV) dysfunction which manifests with abnormal strain parameters before a decrease in ejection fraction (EF). Early detection of MIO using cardiovascular magnetic resonance (CMR)-T2* is vital. Our aim was to assess if CMR feature-tracking (FT) strain correlates with T2*, and whether it can identify early contractile dysfunction in patients with MIO but normal EF. METHODS: One hundred and four consecutive TM patients with LVEF > 55% on echocardiography were prospectively enrolled. Those fulfilling the inclusion criteria underwent CMR, with T2* being the gold standard for detecting MIO. Group 1 included patients without significant MIO (T2* > 20 ms) and group 2 with significant MIO (T2* < 20 ms). RESULTS: Eighty-six patients (mean age, 17.32 years, 59 males) underwent CMR. There were 68 (79.1%) patients in group 1 and 18 (20.9%) in group 2. Fourteen patients (16.3%) had mild-moderate MIO, and four (4.6%) had severe MIO. Patients in group 2 had significantly lower global radial strain (GRS). Global longitudinal strain (GLS) and global circumferential strain (GCS) did not correlate with T2*. T1 mapping values were significantly lower in patients with T2* < 10 ms than those with T2* of 10-20 ms; however, FT-strain values were not significantly different between these two groups. CONCLUSION: CMR-derived GRS, but not GLS and GCS, correlated with CMR T2*. GRS is significantly decreased in TM patients with MIO and normal EF when compared with those without. FT-strain may be a useful adjunct to CMR T2* and maybe an early marker of myocardial dysfunction in TM. KEY POINTS: • A global radial strain of < 29.3 derived from cardiac MRI could predict significant myocardial iron overload in patients with thalassemia, with a sensitivity of 76.5% and specificity of 66.7%. • Patients with any myocardial iron overload have significantly lower GRS, compared to those without, suggesting the ability of CMR strain to identify subtle myocardial contractile disturbances. • T1 and T2 mapping values are significantly lower in those with severe myocardial iron than those with mild-moderate iron, suggesting a potential role of T1 and T2 mapping in grading myocardial iron.

Utility of Caudal Angulation for Venous Access under Fluoroscopic Guidance during Cardiovascular Implantable Electronic Device Implantation.

BACKGROUND: Axillary venous access is preferred for CIED implantation. The procedure is usually performed under fluoroscopic guidance in anteroposterior (A-P) view. However, there is a lack of perception of depth in this view with a fear of creating complications. Caudal fluoroscopy (adding 30°-35° caudal angulation to A-P projection) has been proposed to circumvent this problem. OBJECTIVE: The aim of this study was to elucidate the advantages of caudal fluoroscopy using fluoroscopic images, contrast venograms, and CT angiography images of axillary vein. METHODS: The fluoroscopic images and contrast venograms obtained in the A-P view were compared with caudal fluoroscopy in patients undergoing CIED implantation at our centre. Also, the CT angiography images of axillary vein were reconstructed to understand the relative anatomy of the vein and the underlying lung parenchyma, simulating these 2 projections. RESULTS: The CT angiography images, contrast venograms, and fluoroscopic images confirmed that caudal fluoroscopy allows better visualization of the vein in relation to the lung parenchyma and rib cage. Analysis of fluoroscopic images revealed that the bend of the first rib formed a conical prominence in caudal fluoroscopy. This served as an important bony landmark for successful venous access, which was usually obtained while the needle was being directed towards this prominence in caudal fluoroscopy. CONCLUSIONS: The proposed advantages of caudal fluoroscopy for CIED implantation have been elucidated by analysis of CT angiography images, contrast venograms, and fluoroscopic images.

An unusual cause of changing QRS morphology.

A 7-day old term neonate with D-malposition of great arteries, large perimembranous ventricular septal defect (almost single ventricle), without pulmonary stenosis was admitted with cyanosis and congestive heart failure. ECG revealed supraventricular tachycardia with alternating QRS axis with every beat. We discuss our approach to this scenario, which leads us to a rather rare cause of changing QRS morphology.

Every face tells a story-unravelling a case of bidirectional ventricular tachycardia.

Bidirectional ventricular tachycardia is a rare form of tachycardia. We hereby report a case of bidirectional ventricular tachycardia in an 8-year-old boy wherein careful clinical exami-nation led to the diagnosis of Andersen Tawil syndrome. The case also demonstrates the efficacy of flecainide in managing bidirectional ventricular tachycardia in the setting of Andersen Tawil syndrome.

Fixed Low-Dose Triple Combination Antihypertensive Medication vs Usual Care for Blood Pressure Control in Patients With Mild to Moderate Hypertension in Sri Lanka: A Randomized Clinical Trial.

Importance: Poorly controlled hypertension is a leading global public health problem requiring new treatment strategies. Objective: To assess whether a low-dose triple combination antihypertensive medication would achieve better blood pressure (BP) control vs usual care. Design, Setting, and Participants: Randomized, open-label trial of a low-dose triple BP therapy vs usual care for adults with hypertension (systolic BP >140 mm Hg and/or diastolic BP >90 mm Hg; or in patients with diabetes or chronic kidney disease: >130 mm Hg and/or >80 mm Hg) requiring initiation (untreated patients) or escalation (patients receiving monotherapy) of antihypertensive therapy. Patients were enrolled from 11 urban hospital clinics in Sri Lanka from February 2016 to May 2017; follow-up ended in October 2017. Interventions: A once-daily fixed-dose triple combination pill (20 mg of telmisartan, 2.5 mg of amlodipine, and 12.5 mg of chlorthalidone) therapy (n = 349) or usual care (n = 351). Main Outcomes and Measures: The primary outcome was the proportion achieving target systolic/diastolic BP (<140/90 mm Hg or <130/80 mm Hg in patients with diabetes or chronic kidney disease) at 6 months. Secondary outcomes included mean systolic/diastolic BP difference during follow-up and withdrawal of BP medications due to an adverse event. Results: Among 700 randomized patients (mean age, 56 years; 58% women; 29% had diabetes; mean baseline systolic/diastolic BP, 154/90 mm Hg), 675 (96%) completed the trial. The triple combination pill increased the proportion achieving target BP vs usual care at 6 months (70% vs 55%, respectively; risk difference, 12.7% [95% CI, 3.2% to 22.0%]; P < .001). Mean systolic/diastolic BP at 6 months was 125/76 mm Hg for the triple combination pill vs 134/81 mm Hg for usual care (adjusted difference in postrandomization BP over the entire follow-up: systolic BP, -9.8 [95% CI, -7.9 to -11.6] mm Hg; diastolic BP, -5.0 [95% CI, -3.9 to -6.1] mm Hg; P < .001 for both comparisons). Overall, 419 adverse events were reported in 255 patients (38.1% for triple combination pill vs 34.8% for usual care) with the most common being musculoskeletal pain (6.0% and 8.0%, respectively) and dizziness, presyncope, or syncope (5.2% and 2.8%). There were no significant between-group differences in the proportion of patient withdrawal from BP-lowering therapy due to adverse events (6.6% for triple combination pill vs 6.8% for usual care). Conclusions and Relevance: Among patients with mild to moderate hypertension, treatment with a pill containing low doses of 3 antihypertensive drugs led to an increased proportion of patients achieving their target BP goal vs usual care. Use of such medication as initial therapy or to replace monotherapy may be an effective way to improve BP control. Trial Registration: anzctr.org.au Identifier: ACTRN12612001120864; slctr.lk Identifier: SLCTR/2015/020.

Consensus statement for implantation and follow-up of cardiac implantable electronic devices in India.

Cardiac implantable electronic device (CIED) procedures are being done by many operators/centers and it is projected that this therapy will remarkably increase in India in the coming years. This document by IHRS, aims at guiding the Indian medical community in the appropriate use and method of implantation with emphasis on implanter training and center preparedness to deliver a safe and effective therapy to patients with cardiac rhythm disorders and heart failure.

Correlation of pacing site in right ventricle with paced QRS complex duration.

BACKGROUND: Pacing from RV mid septum and outflow tract septum has been proposed as a more physiological site of pacing and narrower paced QRS complex duration. The paced QRS morphology and duration in different RV pacing sites is under continued discussion. Hence, this study was designed to address the correlation of pacing sites in right ventricle with paced QRS complex duration. METHODS: Two hundred fifty-two consecutive patients who underwent pacemaker implantation were enrolled. Baseline clinical characteristics were recorded for each patient. All patient underwent fluoroscopy, electrocardiogram and echocardiography post pacemaker implantation. Paced QRS duration was calculated from the leads with maximum QRS duration. RESULTS: Mean paced QRS (pQRS) duration was significantly higher in apical septum group with a mean of 148.9 ±â€¯14.8 m s compared to mid septum (139.6 ±â€¯19.9 m s; p-value 0.003) and RVOT septum (139.6 ±â€¯14.8 m s; p-value 0.002) groups, respectively. There was no significant difference between mid-septal and RVOT septal pQRS duration. On multivariate analysis, female gender, baseline QRS duration and RVOT septal pacing were the only predictors for narrow pQRS duration (<150 msec). CONCLUSION: RV mid-septal and RVOT septal pacing were associated with significantly lower pQRS duration as compared with apical pacing. Based on multivariate analysis RVOT septal pacing appears to be preferred and more physiological pacing site.

Strengths and Limitations of Using the Polypill in Cardiovascular Prevention.

PURPOSE OF REVIEW: Polypill and its role in cardiovascular disease (CVD) prevention has been extensively discussed and debated since the inception of the concept in 2003. This article reviews the subsequent accumulated research in this area. RECENT FINDINGS: Several short and intermediate to long-term studies with different brands of polypills have analysed the impact of polypill in phase II and III trials. The strengths of polypill that have emerged include better adherence, equivalent or better risk factor control and quality of life among polypill users as compared to usual care. The lurking limitations include difficulty with dose adjustment to targets, fear of mass medicalisation and low acceptability among physicians. The current literature supports polypill use in reducing blood pressure and cholesterol levels for CVD prevention with improvement in adherence to medication. However, the long-term outcome of polypill on CVD events and mortality are unavailable and are currently being studied in clinical trials.

Quantitative assessment of cardiac mechanical dyssynchrony and prediction of response to cardiac resynchronization therapy in patients with non-ischaemic dilated cardiomyopathy using equilibrium radionuclide angiography.

AIMS: The aim of this study was to evaluate equilibrium radionuclide angiography (ERNA) in prediction of response to cardiac resynchronization therapy (CRT) in non-ischaemic dilated cardiomyopathy (DCM) patients. METHODS AND RESULTS: Thirty-two patients (23 males, 57.5 ± 12.1 years) were prospectively included. Equilibrium radionuclide angiography and clinical evaluation were performed before and 3 months after CRT implantation. Standard deviation of left ventricle mean phase angle (SD LVmPA) and difference between LV and right ventricle mPA (LV-RVmPA) expressed in degrees (°) were used to quantify left intraventricular synchrony and interventricular synchrony, respectively. Left ventricular ejection fraction (LVEF) was also evaluated. At the baseline, mean NYHA class was 3.3 ± 0.5, LVEF 22.5 ± 5.6%, mean QRS duration 150.3 ± 18.2 ms, SD LVmPA 43.5 ± 18°, and LV-RVmPA 30.4 ± 15.6°. At 3-month follow-up, 22 patients responded to CRT with improvement in NYHA class ≥1 and EF >5%. Responders had significantly larger SD LVmPA (51.2 ± 13.9 vs. 26.5 ± 14°) and LV-RVmPA (35.8 ± 13.7 vs. 18.4 ± 13°) than non-responders. Receiver-operating characteristic curve analysis demonstrated 95% sensitivity and 80% specificity at a cut-off value of 30° for SD LVmPA, and 81% sensitivity and 80% specificity at a cut-off value of 23° for LV-RVmPA in prediction of response to CRT. CONCLUSION: Baseline SD LVmPA and LV-RVmPA derived from ERNA are useful for prediction of response to CRT in non-ischaemic DCM patients.

Comparison of left ventricular systolic function and mechanical dyssynchrony using equilibrium radionuclide angiography in patients with right ventricular outflow tract versus right ventricular apical pacing: A prospective single-center study.

BACKGROUND: Chronic ventricular pacing is known to adversely affect left ventricular (LV) function. Studies comparing right ventricular outflow tract (RVOT) pacing with RV apical (RVA) pacing have shown heterogeneous outcomes. Our aim was to objectively assess LV function and mechanical dyssynchrony in patients with RVOT and RVA pacing using equilibrium radionuclide angiography (ERNA). METHODS: Fifty-one patients who underwent permanent pacemaker implantation and had normal LV function were prospectively included. Twenty-nine patients had pacemaker lead implanted in the RVOT and 22 at the RVA site. All patients underwent ERNA within 5 days post-pacemaker implantation and follow-up studies at 6 and 12 months. Standard deviation of LV mean phase angle (SD LV mPA) expressed in degrees, which was derived by Fourier first harmonic analysis of phase images, was used to quantify left intraventricular dyssynchrony. RESULTS: No significant difference was observed between the two groups with respect to indication (P = .894), Type/mode (P = .985), and percentage of ventricular pacing (P = .352). Paced QRS duration was significantly longer in RVA group than RVOT group (P = .05). There was no statistically significant difference between the RVA and RVOT groups at baseline with respect to LVEF (P = .596) and SD LV mPA (P = .327). Within the RVA group, a significant decline in LVEF was observed over 12-month follow-up (from 57.3% ± 5.32% to 55.6% ± 6.25%; P = .012). In the RVOT group, the change in LVEF was not statistically significant (from 56.7% ± 4.08% to 54.3% ± 6.63%; P = .159). No significant change in SD LV mPA was observed over 12-month follow-up within the RVA group (from 10.5 ± 2.58° to 10.4 ± 3.54°; P = 1.000) as well as in the RVOT group (from 9.7 ± 3.28° to 9.4 ± 2.85°; P = .769). However, between the RVA and RVOT groups, no significant difference was observed at 12-month follow-up in terms of LVEF and dyssynchrony (LVEF P = .488; SD LV mPA P = .296). CONCLUSION: No significant difference was observed between RVOT and RVA groups with regard to LV function and synchrony over a 12-month follow-up. RVOT pacing offers may lead to better preservation of LV function on longer follow-up.

Does perfusion pattern influence stress-induced changes in left ventricular mechanical dyssynchrony on thallium-201-gated SPECT myocardial perfusion imaging?

BACKGROUND: The relationship between perfusion pattern and stress-induced changes in left ventricular mechanical dyssynchrony (LVMD) on stress-rest thallium-201-gated SPECT myocardial perfusion imaging (Tl-201 SPECT MPI) is not clear. The aim of the study is to assess the relation of perfusion pattern with stress-induced changes in LVMD on Tl-201 MPI. METHODS: Data of 194 patients who underwent exercise-rest Tl-201 MPI between January to December 2012 at our institute was retrospectively evaluated. Institute Ethical committee approval was obtained. Fifty patients who underwent Tl-201 MPI for suspected CAD and had normal LV perfusion and function on MPI were taken as normal group. Patients with perfusion abnormalities (n = 144) were divided into three groups: ischemia (n = 66), infarct (n = 32), and mixed group (n = 46; ischemia and infarct both). Summed stress score, summed rest score, summed difference score (SDS), and LV ejection fraction (EF) were evaluated. Two LVMD parameters, phase standard deviation (PSD) and phase histogram bandwidth (PHB), were assessed in post-stress and rest MPI images. ΔPSD (post-stress PSD - rest PSD) and ΔPHB (post-stress PHB - rest PHB) were calculated to measure stress-induced changes in LVMD. RESULTS: In all the groups, mean post-stress LVMD parameters were lower as compared to LVMD parameters at rest. Post-stress PSD was significantly lower than rest PSD in all groups. Similar trend was noted with PHB values also, but it was statistically significant in the normal and ischemia group only. Post-stress worsening of at least one of the LVMD parameters was noted in 28 patients and all these patients had perfusion abnormalities. But on subgroup analysis, no difference was found in proportion of patients showing post-stress worsening of LVMD between ischemia (13.6%), infarct (25%), and mixed (23.6%) groups. No significant correlation was found between ΔPSD/ΔPHB and ΔLVEF/SDS in any group. CONCLUSION: LV mechanical dyssynchrony parameters are smaller in post-exercise stress as compared to rest on Tl-201 MPI, regardless of perfusion pattern. Stress-induced worsening of LV dyssynchrony was observed only in patients with perfusion abnormalities, but this is not related to the type of perfusion abnormality.