Widened QRS-T Angle May Be a Measure of Poor Ventricular Stretch During Exercise Among On-duty Firefighters

A Scoping Review of Varying Mobile Electrocardiographic Devices

The electrocardiogram (ECG) can now be measured using mobile devices. Mobile ECG devices, which are defined as devices capable of recording and transmitting non-standard ECGs, offer numerous advantages such as cost-effectiveness and being user-friendly. Mobile ECG can also extend recording lengths (e.g., 2 days, 14 days), which is necessary to capture important intermittent events (e.g., cardiac arrhythmias) and evaluate prognostic risk markers (e.g., prolonged corrected QT (QTc) interval). Some mobile ECG devices can even connect to broadband networks allowing patients to remotely transmit their ECG to a clinician. This article systematically examines different mobile ECG devices used in prior studies and provides a detailed assessment of five diverse yet commonly used mobile ECG devices: AliveCor KardiaMobile; AliveCor KardiaMobile 6L; iRhythm ZioPatch; Apple Smartwatch ECG; and CardioSecur System. These mobile ECG devices are diverse in the number of leads measured and the duration of monitoring. Similar to their diversity, there has been a wide range of clinical applications of mobile ECG devices. Despite significant progress, questions regarding data quality, and clinican and patient acceptance and compliance persist.

The Effect of Mandatory Fitness Requirements on Cardiovascular Events: A State-by-State Analysis Using a National Database

BACKGROUND

Cardiovascular events are known to be the leading cause of death among on-duty firefighters. Implementing fitness standards may help reduce the incidence of cardiovascular deaths; however, standards vary between firefighter type and states. We aimed to investigate the rate of cardiovascular events among firefighters across states.

METHODS

Using publicly available data from the United States Fire Administration, we explored the rates of cardiovascular deaths between firefighter type (e.g., career, volunteer, and wildland) and state. Specifically, we examined rates of cardiovascular deaths between California and Tennessee, which have fitness standards for all firefighters, and New York, which does not have fitness standards for volunteer firefighters. We used descriptive statistics and trend analysis to examine the data.

FINDINGS

Most cardiovascular events occur among volunteer firefighters (60.6%, n = 877). Volunteer firefighters had 7.5 (95% CI = [4.8, 11.7], p < .001) greater odds of cardiovascular events compared to wildland firefighters, who had the lowest incidence of cardiovascular events (1.7%, n = 24). New York reported the most cardiovascular events (n = 161), primarily among volunteer firefighters (73.9%, n = 119). After the passage of legislation mandating fitness standards in California, a downtrend in the number of volunteer firefighter fatalities is observed. However, a null effect was observed in Tennessee after the passage of similar fitness standards as in California.

CONCLUSIONS/APPLICATIONS TO PRACTICE

Volunteer firefighters are significantly more likely to die of a cardiovascular event than career and wildland firefighters, both of which have stricter fitness standards. However, the effect of legislation mandating stricter fitness standards among volunteers did not produce a clear benefit for preventing fatalities. Nurses need to promote cardiovascular health among volunteer firefighters.

Correlates of Autonomic Function, Hemodynamics, and Physical Activity Performance During Exercise Stress Testing Among Firefighters

BACKGROUND

Autonomic dysfunction is an important propagator of cardiometabolic disease and can be measured using multiple metrics such as heart rate variability (HRV) and heart rate recovery (HRR). The relationships between HRV and HRR have not been fully examined, nor have the relationships between HRV, HRR, and other physiological measures linked to cardiometabolic disease (e.g., blood pressure recovery). Evaluation of these additional relationships may provide new insights into the association between autonomic function and cardiometabolic disease especially among high-risk groups like firefighters.

METHODS

92 firefighters (96% male, 81% white) without overt cardiovascular disease underwent exercise testing with continuous heart rate (HR) and blood pressure (BP) monitoring. HRR was the difference between maximal HR and HR 1-minute post-exercise; BP recovery (BPR) was the difference between maximal BP and BP 2-minute post-exercise. Afterwards, participants underwent 24-hour electrocardiographic monitoring to measure HRV. Unadjusted Spearman correlations and adjusted partial Spearman correlations were computed. Between group analyses were also conducted with Kruskal-Wallis test.

RESULTS

Associations between HRV and HRR poorly converged (RMSSD and HRR, unadjusted = 0.235; adjusted = 0.144). SDNN Index exhibited the strongest association with parasympathetic tone exhibited by overall lower HRs (unadjusted = -0.600; adjusted = -0.631). HRR demonstrated stronger associations with systolic and diastolic BP responses during exercise (SBP Recovery unadjusted = 0.267; adjusted = 0.297; DBP Recovery unadjusted = -0.276; adjusted = -0.232).

CONCLUSIONS

Overall, while HRV metrics converged and were associated with lower resting heart rates, HRV and HRR poorly converged. Interestingly, HRR was related with measures of hemodynamics indicating a potential relationship with vascular function during both maximal exercise and exercise recovery.

The Relationship between the Frontal QRS-T Angle on ECG and Physical Activity Level in Young Adults

BACKGROUND

The heart's electrical activity has been the subject of numerous research concerning various physiological parameters. The frontal QRS-T angle (FQRST) is an advanced ECG variable with clinical epidemiological utility. This study aimed to determine the relationship between FQRST and physical activity exposure among young adults.

METHODS

We recorded the ECG with 12 leads of 124 participants (mean age 20.28 ± 2.23 years, age range 18-27 years). Next, we measured their physical activity level (PAL) with the International Physical Activity Questionnaire-Short Form (IPAQ), which categorizes activity into three classes: low, moderate, or high.

RESULTS

An inferential analysis, based on the Kruskal-Wallis H test and Mann-Whitney U test, revealed a statistically significant difference in FQRST between the three groups of subjects, classified by their PAL (p < 0.001). We also identified a significant regression model between the body mass index (BMI) and the FQRST (p < 0.001).

CONCLUSIONS

The physical activity regime of young adults significantly influences the concordance between ventricular depolarization and repolarization, reflected in the FQRST's width. Also, we found a regression model between FQRST and BMI with statistical significance.

Severity of Myocardial Ischemia Is Related to Career Length Rather Than Age Among Professional Firefighters

BACKGROUND

Ischemic heart disease (IHD) is the major cause of duty-related fatalities in the fire service. Age and career length are not only important risk factors associated with IHD, but are also highly correlated. The aim of this secondary analyses was to assess the relationship between age, career length, and IHD, based on ischemic severity, to identify whether age or career length had a stronger relationship to IHD.

METHODS

This was a secondary, correlational analysis of on-duty firefighters without known cardiovascular or respiratory disease who underwent exercise treadmill testing with 12-lead electrocardiography. Ischemia was defined based on current guidelines. Maximum ST-segment depression was measured to determine IHD ischemic severity. Age, years of employment, demographics, weight, blood pressure were recorded. Multiple correlations were computed between age, career length, and IHD.

FINDINGS

Twenty-two firefighters were included (96% male, 82% White, 82% overweight or obese, 77% hypertensive). The partial correlation between maximum ST-segment depression and age controlled for career length was not significant (r = -.392, p = .079). The partial correlation between maximum ST-segment depression and career length controlled for age was statistically significant (r = .466, p = .033).

CONCLUSION/APPLICATION TO PRACTICE

Career length, not age, moderately correlates with IHD ischemic severity among firefighters. Career length is a proxy measure of occupational exposures which contributes to IHD. When assessing IHD risk in firefighters, health practitioners should consider incorporating the occupational exposure history (i.e., career length) in addition to age when providing risk reduction services.

[Diagnostic and prognostic significance of QRS-T angle]

The angle between theQRSandTvectors reflects the consistency or inconsistency of the processes of de- and repolarization of the ventricles of the heart and is considered one of the indicators of global electrical heterogeneity of myocardium. In recent years, the prognostic value of theQRS-Tangle has been demonstrated in relation to total and cardiovascular mortality, both in the population and in various groups of patients. The mechanisms of this phenomenon are not completely clear. The review analyses studies published over the past five years on the relationship between theQRS-Tangle and mortality, as well as coronary heart disease and heart failure. Possible mechanisms for increasing theQRS-Tangle are discussed. Data are given on the use of theQRS-Tangle in diagnostic and prognostic scales, including in combination with other indicators of global electrical heterogeneity of myocardium.

Exercise-Induced Premature Ventricular Contractions Are Associated With Myocardial Ischemia Among Asymptomatic Adult Male Firefighters: Implications for Enhanced Risk Stratification

BACKGROUND

Exercise-induced premature ventricular contractions (EI-PVCs) are associated with an increased risk of cardiovascular disease among asymptomatic adult males, but the underlying mechanisms remain understudied. Myocardial ischemia due to cardiovascular disease reduces coronary blood flow, may impair exercise performance, and initiates EI-PVCs; thus, EI-PVCs may be an early indicator of cardiovascular disease.

OBJECTIVE

The objective of this study was to determine whether EI-PVCs are associated with myocardial ischemia and reduced exercise performance among asymptomatic adult firefighters.

METHODS

Asymptomatic adult firefighters free of known cardiovascular disease underwent exercise treadmill testing. A 12-lead electrocardiography was placed on participants for 24 hr afterward to measure EI-PVCs in recovery. Univariate and multivariate binary logistic regression models were used to assess the odds of myocardial ischemia. Sensitivity and specificity analyses were conducted. Statistical significance was set at p < .05.

RESULTS

Participants comprised 86 asymptomatic adult males. The prevalence of myocardial ischemia was 30.8%. A single EI-PVC was associated with myocardial ischemia (χ² = 8.98; p = .003). EI-PVC remained a significant predictor despite adjustment for other cardiovascular risks (odds ratio = 4.281, p = .038). Although not statistically significant, the EI-PVC group achieved lower total exercise time (11.4 ± 2.9 vs. 12.4 ± 3.0 min, p = .13), lower metabolic equivalent of tasks (METs; 11.6 ± 2.6 vs. 12.8 ± 2.3 METs, p = .06), and a lower maximum exercise speed (4.4 ± 0.7 vs. 4.7 ± 0.8 miles/hr, p = .07).

DISCUSSION

EI-PVCs are associated with myocardial ischemia among asymptomatic male firefighters, providing additional evidence of the association between EI-PVCs and myocardial ischemia and suggesting EI-PVCs as an early indicator of cardiovascular disease.

Obesity and hypertension contribute to prolong QRS complex duration among middle-aged adults

BACKGROUND

Obesity and hypertension are comorbid diseases, which influence cardiac structure, and are associated with increased risk for cardiovascular events. The QRS duration (QRSd) reflects ventricular depolarization, and increased QRSd is associated with poor cardiovascular outcomes. QRS duration may be influenced by obesity and HTN, and reflect the increased risk factor for poor cardiovascular outcomes. The purpose of this analysis was to assess the relations between obesity, hypertension, and the interaction between them on QRSd.

METHODS

In this secondary data analysis, firefighters without documented cardiovascular disease in normal sinus rhythm were included. Twelve-lead 24-hr ECG Holter monitors measured mean QRSd. Body mass index (BMI) and resting blood pressure (BP) were measured and categorized. Univariate linear regression models were produced using BMI, BP, and the interaction between BMI and BP as factors associated with QRSd. Multivariate models adjusting for multiple covariates were also produced.

RESULTS

Seventy-seven firefighters were included and most (89.4%) were overweight or obese. After covariate adjustment, BMI (p = 0.028), BMI categorization (p = 0.020), and the interaction between BMI and systolic BP (p = 0.021) were associated with prolong QRSd.

CONCLUSIONS

Increased BMI and an interaction between BMI and systolic BP were independently associated with prolongation of the QRS complex. Determination of the underlying cardiac structures responsible prolongation of the QRSd is recommended for further research.