Christopher Semsarian

Christopher Semsarian

MBBS, PhD, MPH, FAHMS, FRACP, FRCPA, FCSANZ, FESC, FAHA, FHRS

Cardiologist

23 Years’ Experience Overall

Male📍 Sydney

About of Christopher Semsarian

Christopher Semsarian is a cardiologist based in Missenden Rd, Sydney, NSW 2050. He works with people who have heart conditions that can run in families, as well as a range of other heart and rhythm problems.


Cardiac issues can be scary, especially when they involve things like abnormal heart rhythms, fainting, heart failure, or problems with how the heart muscle works. In many cases, he helps work out what’s going on, what might be causing it, and what treatment options could fit best. He also supports families when there’s a higher chance of certain inherited heart conditions.


Over time, he’s built up a lot of experience, with 23 years’ experience overall. His background covers both cardiology and research, so he’s used to thinking carefully about symptoms, test results, and long-term risk. At times, patients may be dealing with sudden warning signs such as fast or irregular heartbeats, episodes of feeling faint, or concerns picked up after tests.


Christopher holds an MBBS from the University of Sydney (1989). He also completed a PhD at the same university in 1999, and later an MPH in 2014. His advanced training includes fellowships such as FRACP (1996) and cardiology-related qualifications including FCSANZ (2005), plus other fellowships and memberships listed in his qualifications.


Research is part of his work as well. He stays across new findings that can help with diagnosis and care, especially for inherited heart conditions and unusual rhythm disorders. He may be involved in clinical trials and research studies when they’re relevant to patient care and better understanding of these conditions.


If you’re looking for a cardiologist in Sydney who focuses on heart health and also takes family history seriously, Christopher Semsarian is based at his practice on Missenden Rd. He works with patients and their families in a practical way, aiming to make the next steps clear, whether that’s planning tests, discussing treatment, or understanding long-term outlook.

Education

  • MBBS at University of Sydney, 1989
  • PhD at University of Sydney, 1999
  • MPH at University of Sydney, 2014
  • FRACP (Fellow of the Royal Australasian College of Physicians), 1996
  • FCSANZ (Fellow of the Cardiac Society of Australia and NZ), 2005
  • FAHA (Fellow of American Heart Association USA), 2009
  • FHRS (Fellow of Heart Rhythm Society USA), 2013
  • FAHMS (Fellow of Australian Academy of Health and Medical Sciences), 2015
  • FRCPA (Honorary Fellow of the Royal College of Pathologists Australasia), 2017
  • FESC (Fellow of European Society of Cardiology), 2022

Services & Conditions Treated

Cardiac ArrestCardiomyopathyFamilial Hypertrophic CardiomyopathyHypertrophic Cardiomyopathy (HCM)Endocardial FibroelastosisFamilial Ventricular TachycardiaLong QT SyndromeVentricular FibrillationArrhythmiasBrugada SyndromeCatecholaminergic Polymorphic Ventricular TachycardiaDilated Cardiomyopathy (DCM)Familial Dilated CardiomyopathyParoxysmal Supraventricular Tachycardia (PSVT)Sudden Infant Death Syndrome (SIDS)Ventricular TachycardiaAlternating Hemiplegia of ChildhoodAndersen-Tawil SyndromeAtrial FibrillationAtrial Septal Defect (ASD)Bicuspid Aortic ValveCAPOS SyndromeCongenital Coronary Artery MalformationCongenital Heart Disease (CHD)Coronary Heart DiseaseDrug Induced DyskinesiaEpilepsyEpilepsy in ChildrenFaintingFamilial HypercholesterolemiaFriedreich AtaxiaGrass AllergyHeart BlockHeart FailureHeart TransplantHemiplegiaHereditary AtaxiaHolt-Oram SyndromeHypertensionMarfan SyndromeMitral Valve ProlapseMyoclonic EpilepsyPatent Foramen OvaleRestrictive Cardiomyopathy (RCM)Sick Sinus SyndromeSpinocerebellar Degeneration and Corneal DystrophyWildervanck Syndrome

Publications

5 total
Correction to: Low Penetrance Sarcomere Variants Contribute to Additive Risk in Hypertrophic Cardiomyopathy.

Circulation • March 17, 2025

Joshua Meisner, Aaron Renberg, Eric Smith, Yao-chang Tsan, Brynn Elder, Abbey Bullard, Owen Merritt, Sean Zheng, Neal Lakdawala, Anjali Owens, Thomas Ryan, Erin Miller, Joseph Rossano, Kimberly Lin, Brian Claggett, Euan Ashley, Michelle Michels, Rachel Lampert, John Stendahl, Dominic Abrams, Christopher Semsarian, Victoria Parikh, Matthew Wheeler, Jodie Ingles, Iacopo Olivotto, Sharlene Day, Sara Saberi, Mark Russell, Michael Previs, Carolyn Ho, James Ware, Adam Helms

In the article by Meisner et al, “Low Penetrance Sarcomere Variants Contribute to Additive Risk in Hypertrophic Cardiomyopathy,” which published online on December 5, 2024, and appears in the March 18, 2025, issue of the journal (Circulation. 2025;151:783–798. DOI: 10.1161/CIRCULATIONAHA.124.069398), a correction to the author list is needed. The authors notified the Editorial office that an author was mistakenly omitted from the author list. Iacopo Olivotto, MD has been added as an author. Dr Olivotto is a consultant for Bristol Myers Squibb, Amicus, Sanofi, Cytokinetics, Bayer, Tenaya, Rocket Pharma, and Lexeo. All authors were notified of the updated author list.

Association of Pathogenic/Likely Pathogenic Genetic Variants for Cardiomyopathies With Clinical Outcomes: A Multiancestry Analysis in the All of Us Research Program.

Circulation. Genomic And Precision Medicine • May 28, 2025

This study aimed to evaluate the prevalence of pathogenic/likely pathogenic cardiomyopathy variant carriers in a multiancestry US population and examine the risk of adverse clinical outcomes. This retrospective cohort study included multiancestry US adults aged ≥18 years with sequencing data from the All of Us Research Program. Pathogenic/likely pathogenic variants in cardiomyopathy genes were identified using the ClinVar database. The primary outcome was heart failure. Secondary outcomes included cardiomyopathy and arrhythmia. Outcomes were identified from electronic health records. Interval-censored Cox models, taking age on the timescale, were used to assess the risk of outcomes in pathogenic/likely pathogenic variant carriers with noncarriers as the reference group. Among 167 435 individuals (median age, 55.2 [39.5-66.3] years; 61.7% female; 40.7% non-European ancestry) included, the proportion of pathogenic/likely pathogenic cardiomyopathy variant carriers was 0.7% of the overall population and 0.8%, 0.8%, 0.5%, and 1.2% of European, African, East Asian, and South Asian ancestry individuals, respectively. Over the lifetime, there were 12 867 heart failure events (205 in carriers and 12 662 in noncarriers), with an incidence rate of 3.05 (95% CI, 2.66-3.49) per 1000 person-years in carriers and 1.37 (95% CI, 1.35-1.40) in noncarriers (HRadj, 2.30 [95% CI, 2.04-2.60]). Cardiomyopathy occurred in 5164 (161 in carriers and 5003 in noncarriers), with an incidence rate of 2.38 (95% CI, 2.04-2.78) per 1000 person-years among carriers and 0.54 (95% CI, 0.53-0.56) in noncarriers (HRadj, 4.31 [95% CI, 3.73-4.97]). There were 19 405 arrhythmia events (263 in carriers and 19 142 in noncarriers), with an incidence rate of 3.93 (95% CI, 3.48-4.44) per 1000 person-years among carriers and 2.09 (95% CI, 2.06-2.12) in noncarriers (HRadj, 2.12 [95% CI, 1.78-2.53]). Pathogenic/likely pathogenic cardiomyopathy variant carriers have an increased risk of heart failure, cardiomyopathy, and arrhythmias. Despite the modest overall prevalence, the associated risks suggest potential benefits of targeted genetic screening for early detection and management.

FirstCPR: A pragmatic community organisation-based cluster randomised trial to increase community training and preparedness to respond to out-of-hospital cardiac arrest.

Resuscitation Plus • March 24, 2025

Sonali Munot, Julie Redfern, Janet Bray, Blake Angell, Andrew Coggins, Alan Denniss, Garry Jennings, Sarah Khanlari, Pramesh Kovoor, Saurabh Kumar, Kevin Lai, Simone Marschner, Paul Middleton, Ian Oppermann, Zoe Rock, Christopher Semsarian, Matthew Vukasovic, Adrian Bauman, Clara Chow

Bystander cardiopulmonary resuscitation (CPR) and defibrillation improve out-of-hospital cardiac arrest survival. However, basic life support (BLS) skills are low. The FirstCPR cluster randomised controlled trial aimed to test the effectiveness of a community organisation-targeted BLS education and training approach. Clusters (community organisations with 50+ members) were randomly allocated to intervention (12-month period of opportunities to access BLS education and training) or control (no intervention). Outcomes were assessed via surveys at 12 months and pre-specified analysis involved hierarchical mixed-models. Of 165 randomised clusters (82 intervention), 58% were sports and 42% were social/faith-based. Most of the intervention clusters (74/82) participated in at least one intervention activity (15 in all activities). Factors such as the COVID-19 pandemic and organisation support impacted intervention uptake. Overall 924 members, across 93 clusters (407 from 57 intervention clusters; 517 from 36 control clusters), completed surveys. At 12-months, intervention organisation surveyed members reported higher rates of: being trained and willing to perform CPR on a stranger (primary outcome: 63.8% vs 46.9 %; Adjusted Odds Ratio (AOR) 2.22, 95% confidence interval (CI):1.50-3.30), confidence to use an automated external defibrillator (AED) (48.4% vs 26.4%; AOR:3.23, 95%CI:2.22-4.71) and willingness to use AEDs on a stranger (73.9% vs 62.9%; AOR:1.84, 95%CI:1.22-2.80). The results should be interpreted cautiously as the survey response rates were very low. However, survey respondents showed desired outcomes and key learnings for future research were gained.

Sex-Specific Clinical and Genetic Factors Associated With Adverse Outcomes in Hypertrophic Cardiomyopathy.

Circulation. Genomic And Precision Medicine • January 24, 2025

Alexandra Butters, Clare Arnott, Joanna Sweeting, Brian Claggett, Anna Cuomo, Dominic Abrams, Euan Ashley, Sharlene Day, Adam Helms, Rachel Lampert, Kim Lin, Michelle Michels, Erin Miller, Iacopo Olivotto, Anjali Owens, Victoria Parikh, Alexandre Pereira, Joseph Rossano, Thomas Ryan, Sara Saberi, John Stendahl, James Ware, John Atherton, Christopher Semsarian, Neal Lakdawala, Carolyn Ho, Jodie Ingles

Females with hypertrophic cardiomyopathy present at a more advanced stage of the disease and have a higher risk of heart failure and death. The factors behind these differences are unclear. We aimed to investigate sex-related differences in clinical and genetic factors affecting adverse outcomes in the Sarcomeric Human Cardiomyopathy Registry. Cox proportional hazard models were fit with a sex interaction term to determine if significant sex differences existed in the association between risk factors and outcomes. Models were fit separately for females and males to find the sex-specific hazard ratio (HR). After a mean follow-up of 6.4 years, females had a higher risk of heart failure (HR, 1.51 [95% CI, 1.21-1.88]; P=0.0003) but a lower risk of atrial fibrillation (HR, 0.74 [95% CI, 0.59-0.93]; P<0.0001) and ventricular arrhythmia (HR, 0.60 [95% CI, 0.38-0.94]; P=0.027) than males. No sex difference was observed for death (P=0.84). Sarcomere-positive males had higher heart failure (HR, 1.34 [95% CI, 1.06-1.69]) and death risks (HR, 1.48 [95% CI, 1.08-2.04]) not seen in females (HR, 0.85 [95% CI, 0.66-1.08] versus HR, 0.86 [95% CI, 0.71-1.21]). MYBPC3 variants lowered heart failure risk in females (HR, 0.56 [95% CI, 0.41-0.77]) but not in males (HR, 1.29 [95% CI, 0.99-1.67]). A sex difference appeared in moderate (4% to <6%) versus low risk (<4%) European Society of Cardiology hypertrophic cardiomyopathy risk score, with females at moderate risk more prone to ventricular arrhythmia (HR, 3.57 [95% CI, 1.70-7.49]), unobserved in males (HR, 1.13 [95% CI, 0.63-2.03]). We found that clinical and genetic factors contributing to adverse outcomes in hypertrophic cardiomyopathy affect females and males differently. Thus, research to inform sex-specific management of hypertrophic cardiomyopathy could improve outcomes for both sexes.

Low Penetrance Sarcomere Variants Contribute to Additive Risk in Hypertrophic Cardiomyopathy.

Circulation • December 05, 2024

Joshua Meisner, Aaron Renberg, Eric Smith, Yao-chang Tsan, Brynn Elder, Abbey Bullard, Owen Merritt, Sean Zheng, Neal Lakdawala, Anjali Owens, Thomas Ryan, Erin Miller, Joseph Rossano, Kimberly Lin, Brian Claggett, Euan Ashley, Michelle Michels, Rachel Lampert, John Stendahl, Dominic Abrams, Christopher Semsarian, Victoria Parikh, Matthew Wheeler, Jodie Ingles, Iacopo Olivotto, Sharlene Day, Sara Saberi, Mark Russell, Michael Previs, Carolyn Ho, James Ware, Adam Helms

Classically, hypertrophic cardiomyopathy (HCM) has been viewed as a single-gene (monogenic) disease caused by pathogenic variants in sarcomere genes. Pathogenic sarcomere variants are individually rare and convey high risk for developing HCM (highly penetrant). Recently, important polygenic contributions have also been characterized. Low penetrance sarcomere variants (LowSVs) at intermediate frequencies and effect sizes have not been systematically investigated. We hypothesize that LowSVs may be common in HCM with substantial influence on disease risk and severity. Among all sarcomere variants observed in the Sarcomeric Human Cardiomyopathy Registry (SHaRe), we identified putative LowSVs defined by (1) population frequency greater than expected for highly penetrant (monogenic) HCM (allele frequency >5×10-5 in the Genome Aggregation Database, gnomAD) and (2) moderate enrichment (>2×) in patients with HCM compared with gnomAD. LowSVs were examined for their association with disease severity and clinical outcomes. Functional effects of selected LowSVs were assessed using induced pluripotent stem cell-derived cardiomyocytes. Association of LowSVs with HCM-adjacent traits in the general population was tested using UK Biobank cardiac magnetic resonance imaging data. Among 6045 patients and 1159 unique variants in sarcomere genes, 12 LowSVs were identified. LowSVs were collectively common in the general population (1:350) and moderately enriched in HCM (aggregate odds ratio, 14.9 [95% CI, 12.5-17.9]). Isolated LowSVs were associated with an older age of HCM diagnosis and fewer adverse events. However, LowSVs in combination with a pathogenic sarcomere variant conferred higher morbidity (eg, composite adverse event hazard ratio, 5.4 [95% CI, 3.0-9.8] versus single pathogenic sarcomere variant, 2.0 [95% CI, 1.8-2.2]; P<0.001). An intermediate functional impact was validated for 2 specific LowSVs-MYBPC3 c.442G>A (partial splice gain) and TNNT2 c.832C>T (intermediate effect on contractile mechanics). Cardiac magnetic resonance imaging analysis of the general population revealed 5 of 12 LowSVs were significantly associated with HCM-adjacent traits without overt HCM. This study establishes a new class of low penetrance sarcomere variants that are relatively common in the population. When penetrant, isolated LowSVs cause mild HCM. In combination with pathogenic sarcomere variants, LowSVs markedly increase disease severity, supporting a clinically significant additive effect. Last, LowSVs also contribute to age-related remodeling even in the absence of overt HCM.

Clinical Trials

1 total

Exercise in Genetic Cardiovascular Conditions (Lifestyle and Exercise in Hypertrophic Cardiomyopathy LIVE-HCM/Lifestyle and Exercise in the Long QT Syndrome LIVE-LQTS

Completed

The goal is to determine how lifestyle and exercise impact the well-being of individuals with hypertrophic cardiomyopathy (HCM) and long QT syndrome (LQTS). Ancillary study Aim: To understand how the coronavirus epidemic is impacting psychological health and quality of life in the LIVE population

Participants: 4299

Frequently Asked Questions

What services does Dr Christopher Semsarian offer?
Dr Semsarian provides a range of cardiology services including arrhythmias, cardiomyopathy, heart failure, coronary disease and congenital heart conditions. He also covers genetic heart conditions and various heart rhythm disorders.
Which conditions does he treat?
He treats conditions such as atrial fibrillation, heart failure, cardiomyopathy (including hypertrophic and dilated), Brugada syndrome, long QT syndrome, paroxysmal supraventricular tachycardia (PSVT) and other arrhythmias, as well as congenital heart disease and related disorders.
Where is Dr Semsarian based and how can I book an appointment?
He practices in Sydney, at Missenden Road. To book an appointment, please contact the clinic directly for available times and referrals if needed.
What should I bring to my first appointment?
Bring any relevant medical records, current medications, and a list of symptoms or concerns. If you have prior tests or imaging, bring those results as well.
Does he work with patients of all ages?
Dr Semsarian’s work covers a wide range of heart conditions; for specific age-related services, please check with the clinic during appointment booking.
What is Dr Semsarian’s training and experience?
He is a cardiologist with MBBS, PhD, MPH and fellowships in several professional bodies. He has many years of experience in heart rhythm disorders, heart disease and related conditions.

Contact Information

Missenden Rd, Sydney, NSW 2050, Australia

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Memberships

  • European Society of Cardiology
  • European Heart Rhythm Association (EHRA)