<div>Increasing Trend in Ventricular Tachycardia Related Mortality- Cause or
Effect?</div><div>Mahesh Balakrishnan, MBBS; Mathew D. Hutchinson, MD, FACC, FHRS</div><div>Banner University Medical Center-Tucson and University of Arizona
College of Medicine Tucson, Tucson, Arizona, USA</div><div>Word count: 1207</div><div>Funding: none</div><div>Conflict of Interest / Disclosures: none</div><div>Address for Correspondence:</div><div>Mathew D. Hutchinson, MD, FACC, FHRS</div><div>University of Arizona College of Medicine Tucson</div><div>1501N. Campbell Ave, 4142B</div><div>Tucson, AZ 85724, USA</div><div>Email: MathewHutchinson@shc.arizona.edu</div><div>Sudden cardiac death claims up to 350,000 lives every year in the United
States, and overall survival rates post arrest remain dismal [1].
Ventricular arrhythmias are a leading cause of sudden cardiac death
accounting for 24% of out of hospital cardiac arrests and portend a
more favorable recovery compared to non-shockable rhythms[2].
Although ischemic heart disease remains the leading cause of ventricular
arrhythmias, other forms of nonischemic cardiomyopathy associated with
myocardial fibrosis and hypertrophy are gaining prominence. Although
patients with severe LV dysfunction are at the highest risk for
ventricular arrhythmias[3], tomographic imaging has aided in in
identification of higher risk patients with occult structural heart
disease despite preserved LVEF [4]. Contemporary patients with heart
disease today benefit from a range of pharmacological and device-based
therapies that delay the progression of heart failure. It is reasonable
to speculate that as these patients survive longer that they may develop
arrhythmic complications. Thus, it is imperative that we periodically
reassess the relative contribution of arrhythmic versus non-arrhythmic
death in patients with heart disease.</div><div>In this issue of the Journal, Lee and colleagues contribute a research
letter that adds provocative new information regarding temporal
mortality trends associated with ventricular tachycardia. The authors
queried a CDC database to assess VT-associated mortality trends in
patients with underlying heart disease between 2007 and 2020. Patients
with VT listed as the proximate cause of death (ICD-10 code I47.2) who
had underlying cardiovascular diagnoses (ICD-10 codes I00-I78) were
included in the analysis. Age-adjusted mortality rates for ventricular
tachycardia and average annual percentage change were reported.</div><div>The study reports a significant increase in age-adjusted mortality
ascribed to ventricular tachycardia over the past 13 years. Adjusted
mortality was higher with increasing age, in men versus women, in black
compared to white Americans, and in the Southern versus non-Southern
regions of the United States. The authors attribute the increase in
mortality rate from ventricular tachycardia to the higher prevalence of
structural and ischemic heart disease in an increasingly aging
population. The authors also speculate an increase in the diagnosis of
ventricular tachycardia due to the increase in the use of invasive and
non-invasive cardiac rhythm monitoring devices over that period.
Gender-related differences in modality from ventricular tachycardia are
attributed to the higher prevalence of ischemic cardiomyopathy in men.
The higher mortality in the black Americans is attributed to their
higher prevalence of associated cardiovascular risk factors, as well as
socioeconomic factors that affect access to care.</div><div>The authors findings support and expand previous observations regarding
the influences of age, gender, ethnicity, and geography on
cardiovascular outcomes. Prospective cohort studies have shown that the
incidence of ventricular arrhythmias increases with age [0.5 vs 0.3
per 1000 population in age group &gt;65 years compared to
&lt;65 years] and are more prevalent in men [0.59% in men
compared to 0.2% in women over 65] [5]. In patients with
nonischemic cardiomyopathy, the prevalence of late gadolinium
enhancement is also higher in men compared to women [4, 6]. These
factors may explain the gender differences in mortality related to
ventricular tachycardia. Ethnic disparities in heart failure outcomes
have been documented in multiple studies including CARDIA and MESA, with
worse heart failure outcomes in black populations across age groups. The
authors are commended for examining outcome disparities related to
patient groups that are traditionally underrepresented in clinical
trials.</div><div>The study suggests that mortality trends from ventricular tachycardia
have worsened despite advances in medical therapy and widespread use of
implantable cardioverter defibrillators. The use of ICD-10 diagnosis of
VT to inform the mechanism of death is an obvious limitation of the
authors’ report. The specific diagnosis of monomorphic ventricular
tachycardia is assumed; however, the specific rhythm diagnosis was not
possible in these patients raising the possibility that other forms of
ventricular arrhythmias (e.g. polymorphic VT or ventricular
fibrillation) were also present. Furthermore, although VT may be seen at
the time of death, it is often triggered by other severe cardiovascular
or medical illnesses that are the true mortality drivers. It is
well-known that ventricular tachycardia is often seen in patients with
acute coronary syndrome, structural heart disease, heart failure,
metabolic abnormalities, infiltrative disorders of the heart etc., all
of which could potentially be responsible for mortality in these
patients. The study methodology is unable to differentiate mortality
resulting from ventricular tachycardia and ventricular tachycardia being
present in patients dying from other etiologies. Thus, the authors’
observations should not be interpreted as increasing “lethality” of VT
in these patients. The use of a broad range of ICD-10 codes to document
associated “cardiovascular disease” in the study cohort also raises
the possibility of multiple unmeasured confounding variables that may
have independently affected patient survival.</div><div>The prevalence of arrhythmias in patients infected with COVID-19 has
been well-documented. Studies have reported ventricular arrhythmias in
up to 5.9% of patients infected with COVID-19, particularly patients
with evidence of myocardial injury and myocarditis[7]. Patients with
cardiovascular comorbidities also have more severe disease course from
COVID infection. It is interesting to speculate whether the spike in
age-adjusted mortality in 2019-2020 may have been affected by
COVID-related illness.</div><div>The authors’ report offers hypothesis generating insights into
VT-related mortality in the contemporary era. Further studies are needed
to provide mechanistic insight into the observed association of VT and
death as either proximate cause or association. Dedicated studies in
underrepresented ethnic groups may allow identification of novel
clinical or biochemical risk factors that can modulate disease course.
Clearly there is more work to be done.</div><div>References:</div><div>1. Al-Khatib, S.M., et al., <i>2017 AHA/ACC/HRS Guideline for
Management of Patients With Ventricular Arrhythmias and the Prevention
of Sudden Cardiac Death: A Report of the American College of
Cardiology/American Heart Association Task Force on Clinical Practice
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C, Crouch A, Perez AB, Merritt R, Kellermann A; Centers for Disease
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Storm in Coronavirus Disease.</i> Case Rep Cardiol, 2022. <b>2022</b> : p.
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