Cardiorespiratory Fitness and the Risk of Serious Ventricular Arrhythmias: A Prospective Cohort Study

Hemodynamic gain index and risk of ventricular arrhythmias: a prospective cohort study

Objectives: Hemodynamic gain index (HGI), a novel hemodynamic index obtained from cardiopulmonary exercise testing (CPX), is associated with adverse cardiovascular outcomes. However, its specific relationship with ventricular arrhythmias (VAs) is unknown. We aimed to assess the association of HGI with risk of VAs in a prospective study. Design: Hemodynamic gain index was estimated using heart rate and systolic blood pressure (SBP) responses ascertained in 1945 men aged 42-61 years during CPX from rest to maximum exercise, using the formula: [(Heart ratemax x SBPmax) - (Heart raterest x SBPrest)]/(Heart raterest x SBPrest). Cardiorespiratory fitness (CRF) was measured using respiratory gas exchange analysis. Hazard ratios (HRs) (95% confidence intervals, CIs) were estimated for VAs. Results: Over a median follow-up duration of 28.2 years, 75 cases of VA were recorded. In analysis adjusted for established risk factors, a unit (bpm/mmHg) higher HGI was associated with a decreased risk of VA (HR 0.72, 95% CI: 0.55-0.95). The results remained consistent on adjustment for lifestyle factors and comorbidities (HR 0.72, 95% CI: 0.55-0.93). Comparing the top versus bottom tertiles of HGI, the corresponding adjusted HRs (95% CIs) were 0.51 (0.27-0.96) and 0.52 (0.28-0.94), respectively. The associations were attenuated on addition of CRF to the model. HGI improved risk discrimination beyond established risk factors but not CRF. Conclusions: Higher HGI is associated with a reduced risk of VAs in middle-aged and older Caucasian men, but dependent on CRF levels. Furthermore, HGI improves the prediction of the long-term risk for VAs beyond established risk factors but not CRF.

Unraveling the link between cardiorespiratory fitness and cancer: a state-of-the-art review

Cardiorespiratory fitness (CRF) not only reflects an individual's capacity to perform physical activities but also encapsulates broader effects on the basic biology of aging. This review aims to summarize the evidence on the influence of CRF on overall and site-specific cancer risks. It delves into the biological mechanisms through which CRF may exert its effects, explores the clinical implications of these findings, identifies gaps in the current evidence base, and suggests directions for future research. The synthesis of findings reveals that higher CRF levels (general threshold of > 7 METs) are consistently associated with a reduced risk of a range of cancers, including head and neck, lung, breast, gastrointestinal, particularly pancreatic and colorectal, bladder, overall cancer incidence and mortality, and potentially stomach and liver, bile duct, and gall bladder cancers. These inverse associations between CRF and cancer risk do not generally differ across age groups, sex, race, or adiposity, suggesting a universal protective effect of CRF. Nonetheless, evidence linking CRF with skin, mouth and pharynx, kidney, and endometrial cancers is limited and inconclusive. Conversely, higher CRF levels may be potentially linked to an increased risk of prostate cancer and hematological malignancies, such as leukemia and myeloma, although the evidence is still not conclusive. CRF appears to play a significant role in reducing the risk of several cancers through various biological mechanisms, including inflammation reduction, immune system enhancement, hormonal regulation, and metabolic improvements. Overall, enhancing CRF through regular physical activity offers a vital, accessible strategy for reducing cancer risk and extending the health span. Future research should aim to fill the existing evidence gaps regarding specific cancers and elucidate the detailed dose-response relationships between CRF levels and cancer risk. Studies are also needed to elucidate the causal relationships and mechanistic pathways linking CRF to cancer outcomes.

The evolving role of cardiopulmonary exercise testing in ischemic heart disease - state of the art review

PURPOSE OF REVIEW

Cardiopulmonary exercise testing (CPET) is the gold standard for directly assessing cardiorespiratory fitness (CRF) and has a relatively new and evolving role in evaluating atherosclerotic heart disease, particularly in detecting cardiac dysfunction caused by ischemic heart disease. The purpose of this review is to assess the current literature on the link between cardiovascular (CV) risk factors, cardiac dysfunction and CRF assessed by CPET.

RECENT FINDINGS

We summarize the basics of exercise physiology and the key determinants of CRF. Prognostically, several studies have been published relating directly measured CRF by CPET and outcomes allowing for more precise risk assessment. Diagnostically, this review describes in detail what is considered healthy and abnormal cardiac function assessed by CPET. New studies demonstrate that cardiac dysfunction on CPET is a common finding in asymptomatic individuals and is associated with CV risk factors and lower CRF. This review covers how key CPET parameters change as individuals transition from the asymptomatic to the symptomatic stage with progressively decreasing CRF. Finally, a supplement with case studies with long-term longitudinal data demonstrating how CPET can be used in daily clinical decision making is presented.

SUMMARY

In summary, CPET is a powerful tool to provide individualized CV risk assessment, monitor the effectiveness of therapeutic interventions, and provide meaningful feedback to help patients guide their path to improve CRF when routinely used in the outpatient setting.

Hemodynamic Gain Index Is Associated With Cardiovascular Mortality and Improves Risk Prediction: A PROSPECTIVE COHORT STUDY

PURPOSE

The hemodynamic gain index (HGI) and cardiorespiratory fitness (CRF) are parameters assessed during cardiopulmonary exercise testing (CPX). The association between the HGI and cardiovascular disease (CVD) mortality is uncertain. We evaluated the association between the HGI and CVD mortality risk using a prospective study.

METHODS

The HGI was calculated using heart rate (HR) and systolic blood pressure (SBP) measured in 1634 men aged 42-61 yr during CPX, using the formula: [(HR peak × SBP peak ) - (HR rest × SBP rest )]/(HR rest × SBP rest ). Cardiorespiratory fitness was directly measured using a respiratory gas exchange analyzer.

RESULTS

During a median (IQR) follow-up of 28.7 (19.0, 31.4) yr, 439 CVD deaths occurred. The risk of CVD mortality decreased continuously with the increasing HGI ( P value for nonlinearity = .28). Each unit higher HGI (1.06 bpm/mm Hg) was associated with a decreased risk of CVD mortality (HR = 0.80: 95% CI, 0.71-0.89), which was attenuated after further adjustment for CRF (HR = 0.92: 95% CI, 0.81-1.04). Cardiorespiratory fitness was associated with CVD mortality and the association remained after adjustment for the HGI: (HR = 0.86: 95% CI, 0.80-0.92) per each unit (MET) higher CRF. Addition of the HGI to a CVD mortality risk prediction model improved risk discrimination (C-index change = 0.0285; P < .001) and reclassification (net reclassification improvement = 8.34%; P < .001). The corresponding values for CRF were a C-index change of 0.0413 ( P < .001) and a categorical net reclassification improvement of 14.74% ( P < .001).

CONCLUSIONS

The higher HGI is inversely associated with CVD mortality in a graded fashion, but the association is partly dependent on CRF levels. The HGI improves the prediction and reclassification of the risk for CVD mortality.

Interplay Between Fitness, Systolic Blood Pressure and Sudden Cardiac Death (from a Cohort Study)

Modifiable risk factors, such as blood pressure and cardiorespiratory fitness (CRF) play a role in the genesis of sudden cardiac death (SCD). However, data on their joint contributions to SCD risk are scarce. We aimed to evaluate the interplay between systolic blood pressure (SBP), CRF, and SCD risk in a cohort of men. Resting SBP was measured using a random-zero sphygmomanometer and CRF was assessed using a respiratory gas exchange analyzer during clinical exercise testing at baseline in 2,291 men aged 42 to 61 years. SBP was classified as normal and high (<140 and ≥140 mm Hg, respectively) and CRF as low, medium, and high. Cox regression analysis was used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for SCD. A total of 262 SCDs occurred during a median follow-up of 28.2 years. Comparing high versus normal SBP, the multivariable-adjusted HR (95% CI) for SCD was 1.35 (1.03 to 1.76). Comparing low versus high CRF levels, the corresponding adjusted HR (95% CI) for SCD was 1.81 (1.23 to 2.65). The HRs remained similar when SBP was further adjusted for CRF and CRF was further adjusted for SBP. Men with high SBP and low CRF compared with normal SBP and medium-high CRF, had an increased risk of SCD (HR 2.67, 95% CI 1.76 to 4.05), with no significant evidence of an association between men with high SBP and medium-high CRF and SCD risk (HR 1.38, 95% CI 0.84 to 2.26). There was modest evidence of an additive interaction between SBP and CRF in relation to SCD. In conclusion, there exists an interplay between SBP, CRF, and SCD risk in middle-aged and older men. Medium to high CRF levels may mitigate the increased risk of SCD in subjects with high SBP.

Cardiorespiratory Fitness and Risk of Aortic Stenosis (from a Prospective Cohort Analysis)

Cardiorespiratory fitness (CRF) is a major risk factor and predictor of atherosclerotic cardiovascular disease. However, the relationship between CRF and risk of aortic stenosis (AS) has not been previously investigated. Thus, we aimed to assess the prospective association between CRF and risk of AS. CRF, as measured by maximal oxygen uptake, was assessed using a respiratory gas exchange analyzer during cardiopulmonary exercise testing in 2,308 men aged 42 to 61 years recruited into the Kuopio Ischemic Heart Disease prospective cohort study. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated for AS. During a median follow-up of 27 years, 101 cases of AS occurred. Dose-response analysis suggested there might be a nonlinear relation between CRF levels and AS risk. In an analysis adjusted for age, body mass index, systolic blood pressure, total cholesterol, high-density lipoprotein cholesterol, smoking, history of type 2 diabetes mellitus, and coronary heart disease, the HRs 95% (CIs) of AS were 0.57 (0.34 to 0.96) and 0.91 (0.53 to 1.57) for participants in the middle and upper third of CRF levels, respectively, compared with participants in the bottom third. After further adjustment for alcohol consumption, the corresponding HRs (95% CIs) were 0.58 (0.34 to 0.97) and 0.91 (0.53 to 1.56), respectively. In conclusion, higher CRF levels may be associated with a lower incidence of AS in middle-aged and older Finnish men. Given the likely limitations of low statistical power, further research is needed to provide insights into the dose-response nature of any relationship between CRF and AS.

Haemodynamic Gain Index Is Associated with Risk of Sudden Cardiac Death and Improves Risk Prediction: A Cohort Study

INTRODUCTION

Haemodynamic gain index (HGI) is a novel haemodynamic parameter which can be obtained from cardiopulmonary exercise testing (CPX), but its association with sudden cardiac death (SCD) is not known. We aimed to assess the association of HGI with SCD risk in a long-term prospective cohort study.

METHODS

HGI was calculated using heart rate and systolic blood pressure (SBP) responses measured in 1897 men aged 42–61 years during CPX from rest to peak exercise. Cardiorespiratory fitness (CRF) was measured using respiratory gas exchange analysis. Multivariable adjusted hazard ratios (HRs) (95% confidence intervals [CIs]) were estimated for SCD.

RESULTS

During a median follow-up of 28.7 years, 205 SCDs occurred. The risk of SCD decreased gradually with increasing HGI (p value for non-linearity = 0.63). A unit (bpm/mm Hg) higher HGI was associated with a decreased risk of SCD (HR: 0.84; 95% CI: 0.71-0.99), which was attenuated following adjustment for CRF. CRF was inversely associated with SCD, which remained after further adjustment for HGI (HR: 0.85; 95% CI: 0.77-0.94) per each unit higher CRF. Addition of HGI to a SCD risk prediction model containing established risk factors improved risk discrimination (C-index change = 0.0096; p = 0.017) and reclassification (net reclassification improvement [NRI] = 39.40%, p = 0.001). The corresponding values for CRF were (C-index change = 0.0178; p = 0.007) and (NRI = 43.79%, p = 0.001).

CONCLUSION

Higher HGI during CPX is associated with a lower SCD risk, consistent with a dose-response relationship but dependent on CRF levels. Though HGI significantly improves the prediction and classification of SCD beyond common cardiovascular risk factors, CRF remains a stronger risk indicator and predictor of SCD compared to HGI.

Baseline and usual cardiorespiratory fitness and the risk of chronic kidney disease: A prospective study and meta-analysis of published observational cohort studies

Chronic kidney disease (CKD) is a global public health burden but is largely preventable. Few studies have reported an association between high levels of cardiorespiratory fitness (CRF) and decreased risk of CKD. However, some relevant aspects of the association, such as the dose-response relationship and the long-term relevance of CRF levels to CKD, have yet to be addressed. We, therefore, aimed to quantify the nature and magnitude of the association between CRF and CKD in a cohort of 2099 men aged 42-61 years with normal kidney function at baseline. CRF was directly measured using a respiratory gas exchange analyzer during cardiopulmonary exercise testing. Hazard ratios (HRs) (95% CIs) were estimated for the incidence of CKD. Correction for within-person variability was made using data from repeat measurements of CRF taken 11 years after baseline. A total of 197 CKD events were recorded during a median follow-up of 25.8 years. The age-adjusted regression dilution ratio for CRF was 0.59 (95% CI: 0.53-0.65). The risk of CKD decreased in a graded fashion with increasing CRF. Comparing extreme tertiles of CRF, the HR (95% CI) for CKD was 0.67 (0.46-0.97) following adjustment for several established and emerging risk factors. The corresponding adjusted HR (95% CI) was 0.51 (0.27-0.96) following correction for within-person variability. In a meta-analysis of five population-based cohort studies (including the current study) comprising 32,447 participants and 4,043 CKD cases, the fully-adjusted risk ratios (95% CIs) for CKD comparing extreme tertiles of baseline and long-term CRF values were 0.58 (0.46-0.73) and 0.40 (0.27-0.59), respectively. Findings from a new prospective study and pooled analysis of previous studies plus the new study indicate that high CRF levels are strongly and independently associated with a reduced risk of CKD and consistent with a linear dose-response relationship. Using single baseline measurements of CRF to investigate the association between CRF and CKD risk could considerably underestimate the true association.

Percentage of Age-Predicted Cardiorespiratory Fitness May Be a Stronger Risk Indicator for Incident Type 2 Diabetes Than Absolute Levels of Cardiorespiratory Fitness

PURPOSE

There are inverse and independent associations between cardiorespiratory fitness (CRF) and several adverse cardiometabolic outcomes. The percentage of age-predicted CRF (%age-predicted CRF) is comparable to absolute CRF as a risk indicator for some of these outcomes, but the association between %age-predicted CRF and risk of type 2 diabetes (T2D) has not been previously investigated. We aimed to assess the association between %age-predicted CRF and T2D in a prospective cohort study.

METHODS

Cardiorespiratory fitness, as measured directly by peak oxygen uptake, was assessed in 1901 men aged 42-60 yr who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (achieved CRF/age-predicted CRF) × 100. Hazard ratios (95% CI) were estimated for T2D.

RESULTS

During a median follow-up of 26.8 yr, 227 T2D cases were recorded. The risk of T2D decreased continuously with increasing %age-predicted CRF ( P value for nonlinearity = .30). A 1-SD increase in %age-predicted CRF was associated with a decreased risk of T2D in analysis adjusted for established risk factors (HR = 0.68: 95% CI, 0.59-0.79). The corresponding adjusted risk was (HR = 0.51: 95% CI, 0.35-0.75) comparing extreme tertiles of %age-predicted CRF. The respective estimates for the association between absolute CRF and T2D were-HR (95% CI)-0.71 (0.60-0.83) and 0.64 (0.44-0.95).

CONCLUSIONS

Percentage of age-predicted CRF is linearly, inversely, and independently associated with the risk of incident T2D and may be a stronger risk indicator for T2D compared to absolute CRF in a general population of middle-aged and older men.

High Fitness Levels Offset the Increased Risk of Chronic Kidney Disease due to Low Socioeconomic Status: A Prospective Study

BACKGROUND

Socioeconomic status (SES) and cardiorespiratory fitness (CRF) are each independently associated with chronic kidney disease. The interplay among SES, CRF, and chronic kidney disease is not well understood. We aimed to evaluate the separate and joint associations of SES and CRF with chronic kidney disease risk in a cohort of Caucasian men.

METHODS

In 2099 men aged 42-61 years with normal kidney function at baseline, SES was self-reported and CRF was directly measured using a respiratory gas exchange analyzer during cardiopulmonary exercise testing. Hazard ratios (HRs) (95% confidence interval) were estimated for chronic kidney disease.

RESULTS

A total of 197 chronic kidney disease events occurred during a median follow-up of 25.8 years. Comparing low versus high SES, the multivariable-adjusted HR (95% confidence interval) for chronic kidney disease was 1.55 (1.06-2.25), which remained consistent on further adjustment for CRF 1.53 (1.06-2.22). Comparing high versus low CRF, the multivariable-adjusted HR for chronic kidney disease was 0.66 (0.45-0.96), which persisted on further adjustment for SES 0.67 (0.46-0.97). Compared with high SES-high CRF, low SES-low CRF was associated with an increased risk of chronic kidney disease 1.88 (1.23-2.87), with no evidence of an association for low SES-high CRF and chronic kidney disease risk 1.32 (0.85-2.05). Positive additive (relative excess risk due to interaction = 0.31) and multiplicative (ratio of HRs = 1.14) interactions were found between SES and CRF in relation to chronic kidney disease risk.

CONCLUSIONS

In middle-aged and older males, SES and CRF are each independently associated with risk of incident chronic kidney disease. There exists an interplay among SES, CRF and chronic kidney disease risk, with high CRF levels appearing to offset the increased chronic kidney disease risk related to low SES.

Cardiorespiratory Fitness, Inflammation, and Risk of Chronic Obstructive Pulmonary Disease in Middle-Aged Men: A COHORT STUDY

PURPOSE

Chronic obstructive pulmonary disease (COPD) is characterized by chronic lung inflammation. The relationship between cardiorespiratory fitness (CRF) and COPD has not been well characterized. We aimed to evaluate the independent and joint associations of inflammation (high-sensitivity C-reactive protein [hsCRP]) and CRF with COPD risk in a cohort of White men.

METHODS

Among 2274 men aged 42-61 yr at baseline, serum hsCRP level was measured using an immunometric assay and CRF was assessed using a respiratory gas exchange analyzer. The level of hsCRP was categorized as normal and high (≤3 and >3 mg/L, respectively) and CRF as low and high. We corrected for within-person variability in exposures using repeat measurements taken several years apart.

RESULTS

A total of 116 COPD cases occurred during a median follow-up of 26.0 yr. The age-adjusted regression dilution ratio of hsCRP and CRF was 0.57 (95% CI, 0.50-0.64) and 0.58 (95% CI, 0.53-0.64), respectively. Comparing high versus normal hsCRP levels, the multivariable-adjusted HR for COPD was 1.79 (95% CI, 1.20-2.68). The COPD risk decreased linearly with increasing CRF. The multivariable-adjusted HR for COPD per 1-SD increase in CRF was 0.75 (95% CI, 0.60-0.95). Compared with men with normal hsCRP-low CRF, high hsCRP-low CRF was associated with an increased COPD risk, 1.80 (95% CI, 1.12-2.89), with no evidence of an association for high hsCRP-high CRF and COPD risk, 1.35 (95% CI, 0.68-2.69).

CONCLUSIONS

Both hsCRP and CRF are associated with COPD risk in middle-aged men. However, high CRF levels attenuate the increased COPD risk related to high hsCRP levels.

Objectively Assessed Cardiorespiratory Fitness and All-Cause Mortality Risk: An Updated Meta-analysis of 37 Cohort Studies Involving 2,258,029 Participants

OBJECTIVE

To detail the magnitude and specificity of the association between cardiorespiratory fitness (CRF) and all-cause mortality risk.

METHODS

Cohort studies with at least 1 year of follow-up were sought from inception until December 2021 in MEDLINE, Embase, Web of Science, and a manual search of relevant articles. Relative risks (RRs) with 95% CIs were pooled using random-effects models. Quality of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation tool.

RESULTS

A total of 37 unique studies comprising of 2,258,029 participants with 108,613 all-cause mortality events were eligible. The pooled multivariable-adjusted RR for all-cause mortality comparing the top vs bottom tertiles of CRF levels was 0.55 (95% CI, 0.50 to 0.61). When CRF was expressed in metabolic equivalent task (MET) units, the corresponding pooled RR was 0.56 (95% CI, 0.50 to 0.62). For every 1-MET increase in CRF, the RR for all-cause mortality was 0.89 (95% CI, 0.86 to 0.92). Strength of the association did not differ by publication year, age, sex, follow-up duration, CRF assessment method, or risk of bias.

CONCLUSION

Aggregate analysis of observational cohort studies confirms a strong inverse and independent association between CRF and all-cause mortality risk. The results suggest that guideline bodies should consider the inclusion of CRF in standard risk panels for mortality risk assessment.

Cardiorespiratory fitness does not offset the increased risk of chronic obstructive pulmonary disease attributed to smoking: a cohort study

Though evidence suggests that higher cardiorespiratory fitness (CRF) levels can offset the adverse effects of other risk factors, it is unknown if CRF offsets the increased risk of chronic obstructive pulmonary disease (COPD) due to smoking. We aimed to evaluate the combined effects of smoking status and CRF on incident COPD risk using a prospective cohort of 2295 middle-aged and older Finnish men. Peak oxygen uptake, assessed with a respiratory gas exchange analyzer, was used as a measure of CRF. Smoking status was self-reported. CRF was categorised as low and high based on median cutoffs, whereas smoking status was classified into smokers and non-smokers. Multivariable-adjusted hazard ratios with confidence intervals (CIs) were calculated. During 26 years median follow-up, 119 COPD cases were recorded. Smoking increased COPD risk 10.59 (95% CI 6.64–16.88), and high CRF levels decreased COPD risk 0.43 (95% CI 0.25–0.73). Compared with non-smoker-low CRF, smoker-low CRF was associated with an increased COPD risk in multivariable analysis 9.79 (95% CI 5.61–17.08), with attenuated but persisting evidence of an association for smoker-high CRF and COPD risk 6.10 (95% CI 3.22–11.57). An additive interaction was found between smoking status and CRF (RERI = 6.99). Except for CRF and COPD risk, all associations persisted on accounting for mortality as a competing risk event. Despite a wealth of evidence on the ability of high CRF to offset the adverse effects of other risk factors, it appears high CRF levels have only modest attenuating effects on the very strong association between smoking and COPD risk.

Obesity paradox in joint replacement for osteoarthritis - truth or paradox?

Obesity is associated with an increased risk of cardiovascular disease (CVD) and other adverse health outcomes. In patients with pre-existing heart failure or coronary heart disease, obese individuals have a more favourable prognosis compared to individuals who are of normal weight. This paradoxical relationship between obesity and CVD has been termed the 'obesity paradox'. This phenomenon has also been observed in patients with other cardiovascular conditions and diseases of the respiratory and renal systems. Taking into consideration the well-established relationship between osteoarthritis (OA) and CVD, emerging evidence shows that overweight and obese individuals undergoing total hip or knee replacement for OA have lower mortality risk compared with normal weight individuals, suggesting an obesity paradox. Factors proposed to explain the obesity paradox include the role of cardiorespiratory fitness ("fat but fit"), the increased amount of lean mass in obese people, additional adipose tissue serving as a metabolic reserve, biases such as reverse causation and confounding by smoking, and the co-existence of older age and specific comorbidities such as CVD. A wealth of evidence suggests that higher levels of fitness are accompanied by prolonged life expectancy across all levels of adiposity and that the increased mortality risk attributed to obesity can be attenuated with increased fitness. For patients about to have joint replacement, improving fitness levels through physical activities or exercises that are attractive and feasible, should be a priority if intentional weight loss is unlikely to be achieved.

Cardiorespiratory fitness is not associated with reduced risk of prostate cancer: A cohort study and review of the literature

BACKGROUND

Cardiorespiratory fitness (CRF) has a strong inverse relationship with several chronic disease outcomes, including some cancers. The association between CRF and prostate cancer is controversial. We aimed to assess the prospective association of CRF with prostate cancer risk using a cohort study and review of the literature.

MATERIAL AND METHODS

Cardiorespiratory fitness was assessed using a respiratory gas exchange analyser during exercise testing in 2204 cancer-free middle-aged men. Hazard ratios (HRs) with 95% confidence interval (CIs) were estimated. We corrected for within-person variability in CRF levels using repeat measurements.

RESULTS

During a median follow-up of 24.9 years, 216 prostate cancer cases occurred. The age-adjusted regression dilution ratio of CRF was 0.58 (95% CI: 0.53-0.64). The HR (95% CI) of prostate cancer per 1 standard deviation increase in CRF in age-adjusted analysis was 1.10 (0.95-1.27). The association remained consistent after further adjustment for several risk factors (HR 1.13; 95% CI 0.96-1.33). The corresponding adjusted HRs were 1.24 (95% CI: 0.87-1.77) and 1.28 (95% CI: 0.87-1.88), respectively, when comparing the extreme tertiles of CRF levels. Previous studies mostly reported no evidence of an association or an increased risk of prostate cancer in relation to high CRF. Studies reporting positive associations had short-term follow-up durations (<10 years).

CONCLUSIONS

Primary data and a review of previous studies suggest that elevated CRF is not associated with reduced prostate cancer risk. Previous findings of significant evidence of associations could be attributed to increased screening and detection as well as reverse causation bias.

Percentage of age-predicted cardiorespiratory fitness and risk of sudden cardiac death: A prospective cohort study

BACKGROUND

The inverse associations between cardiorespiratory fitness (CRF) and vascular outcomes have been established. However, there has been no prospective evaluation of the relationship between percentage of age-predicted cardiorespiratory fitness (%age-predicted CRF) and risk of sudden cardiac death (SCD).

OBJECTIVE

The purpose of this study was to assess the association of %age-predicted CRF with SCD risk in a long-term prospective cohort study.

METHODS

CRF was assessed using the gold standard respiratory gas exchange analyzer in 2276 men who underwent cardiopulmonary exercise testing. The age-predicted CRF estimated from a regression equation for age was converted to %age-predicted CRF using (Achieved CRF/Age-predicted CRF) × 100. Hazard ratios (HRs) [95% confidence intervals (CIs)] were calculated for SCD.

RESULTS

During median follow-up of 28.2 years, 260 SCDs occurred. There was a dose-response relationship between age-predicted CRF and SCD. A 1-SD increase in %age-predicted CRF was associated with a decreased risk of SCD in analysis adjusted for established risk factors (HR 0.60; 95% CI 0.53-0.70), which remained consistent on further adjustment for several potential confounders, including alcohol consumption, physical activity, socioeconomic status, and systemic inflammation (HR 0.73; 95% CI 0.62-0.85). The corresponding adjusted HRs were 0.34 (0.23-0.50) and 0.52 (0.34-0.79), respectively, when comparing extreme quartiles of %age-predicted CRF levels. HRs for the associations of absolute CRF levels with SCD risk in the same participants were similar.

CONCLUSION

Percentage of age-predicted CRF is continuously, strongly, and independently associated with risk of SCD and is comparable to absolute CRF as a risk indicator for SCD.

High fitness levels, frequent sauna bathing and risk of pneumonia in a cohort study: Are there potential implications for COVID-19?

BACKGROUND

There is an ongoing debate on a potential protective role of habitual physical activity and passive heat therapy on the risk of COVID-19, a respiratory infectious disease that can manifest as severe pneumonia. To explore these putative roles, we evaluated the independent and joint associations of cardiorespiratory fitness (CRF) and frequency of sauna bathing (FSB) with pneumonia risk in a prospective cohort study of 2275 men aged 42-61 years at recruitment.

MATERIAL AND METHODS

Objectively measured CRF and self-reported sauna bathing habits were assessed at baseline. CRF was categorized as low and high (median cut-offs) and FSB as low and high (defined as ≤1 and 2-7 sessions/wk, respectively). Multivariable-adjusted hazard ratios (HRs) with confidence intervals (CIs) were calculated for incident pneumonia.

RESULTS

During a median follow-up of 26.6 years, 529 cases of pneumonia occurred. Comparing high vs low CRF, the multivariable-adjusted HR (95% CIs) for pneumonia was 0.75 (0.61-0.91). Comparing high vs low FSB, the corresponding HR was 0.81 (0.68-0.97). Compared to men with low CRF & low FSB, the multivariable-adjusted HRs of pneumonia for the following groups: high CRF & low FSB; low CRF & high FSB; and high CRF & high FSB were 0.88 (0.65-1.20), 0.89 (0.71-1.13), and 0.62 (0.48-0.80) respectively.

CONCLUSIONS

In a general male Caucasian population, a combination of high fitness levels and frequent sauna baths is associated with a substantially lowered future pneumonia risk compared with each modality alone. The implications of these findings in altering COVID-19 disease or its severity deserve study.

Comparison of the Ekblom-Bak Submaximal Test to a Maximal Test in a Cohort of Healthy Younger and Older Adults in the United States

Cardiorespiratory fitness (CRF) is routinely investigated in diverse populations, including in older adults of varying physical activity levels. Commonly performed maximal exercise testing protocols might be contraindicated and/or inadequate for older individuals who have physical or cognitive impairment. Moreover, early termination of an attempted maximal exercise test could result in underestimation of CRF in this population. The goal of the current study was to compare CRF estimates using the Ekblom-Bak (EB) submaximal exercise test - previously validated in a cohort of Scandinavian adults - versus a subsequent maximal exercise test in a diverse, Midwestern United States cohort. Fifteen generally healthy individuals were included in this study who were either "Young" (25-34 years old) or "Older" (55-75 years old) as well as either sedentary or highly active. Participants completed the EB submaximal exercise test, followed immediately by a maximal exercise test. We found that all 15 individuals were able to successfully perform the EB submaximal testing method. Across the wide range of volumes of maximal oxygen consumption (VO2max; 12-52 ml/kg/min), the EB submaximal estimates of VO2max correlated highly with the maximal test based values (Pearson's r = 0.98), but with a small bias (6 ml/kg/min, 95% limits of agreement -1.06 and -11.29). Our results suggest that the EB submaximal testing method may be useful in identifying wide differences in CRF among a diverse cohort of older adults in the United States, but larger studies will be needed to determine the degree of its accuracy and precision in identifying smaller differences.

Joint effect of blood pressure and C-reactive protein and the risk of sudden cardiac death: A prospective cohort study

BACKGROUND

Both blood pressure and C-reactive protein (CRP) are each independently related to mortality risk. However, the combined effect of systolic blood pressure (SBP) and CRP on sudden cardiac death (SCD) risk has not been studied.

PATIENTS AND METHODS

We studied the joint impact of SBP and CRP and the risk of SCD in the Kuopio Ischemic Heart Disease prospective cohort study of 1953 men aged 42-61 years with no history of ischemic heart disease. Baseline investigations were conducted between March 1984 and December 1989. SBP and CRP were measured. SBP was divided based on median values to low and high (median cutoffs 132 mmHg) and CRP as low and high (median cut-off 1.30 mg/L). Hazard ratios (HRs) with confidence intervals (CIs) were calculated after multivariate adjustment.

RESULTS

Subjects were followed-up for 23.2 years, and 137 SCDs occurred. In this study, elevated SBP (>132 mmHg) combined with elevated (CRP >1.30 mg/L) were associated with SCD risk. Adjustment for age, examination year, alcohol consumption, BMI, energy expenditure during exercise, total cholesterol, HDL-cholesterol, type 2 diabetes, smoking, antihypertension medication and aspirin use, the risk of SCD remained statistically significant (HR, 2,73, 95% CI, 1.62-4.60, p < .001). Further adjustment for socio-economic status, years of education and history of cardiovascular disease in a family the results were only slightly changed (HR, 2.65, 95% CI, 1.57-4.49, p < .001).

CONCLUSIONS

In our male cohort study, the joint effect of high SBP together with increased CRP levels is a risk predictor of SCD compared with low SBP and CRP.

Factors associated with return of spontaneous circulation after out-of-hospital cardiac arrest in Poland: a one-year retrospective study

Background

Out-of-hospital cardiac arrest (OHCA) is a common reason for calls for intervention by emergency medical teams (EMTs) in Poland. Regardless of the mechanism, OHCA is a state in which the chance of survival is dependent on rapid action from bystanders and responding health professionals in emergency medical services (EMS). We aimed to identify factors associated with return of spontaneous circulation (ROSC).

Methods

The medical records of 2137 EMS responses to OHCA in the city of Wroclaw, Poland between July 2017 and June 2018 were analyzed.

Results

The OHCA incidence rate for the year studied was 102 cases per 100,000 inhabitants. EMS were called to 2317 OHCA events of which 1167 (50.4%) did not have resuscitation attempted on EMS arrival. The difference between the number of successful and failed cardiopulmonary resuscitations (CPRs) was statistically significant (p < 0.001). Of 1150 patients in whom resuscitation was attempted, ROSC was achieved in 250 (27.8%). Rate of ROSC was significantly higher when CPR was initiated by bystanders (p < 0.001). Patients presenting with asystole or pulseless electrical activity (PEA) had a higher risk of CPR failure (86%) than those with ventricular fibrillation/ventricular tachycardia (VF/VT). Patients with VF/VT had a higher chance of ROSC (OR 2.68, 1.86–3.85) than those with asystole (p < 0.001). The chance of ROSC was 1.78 times higher when the event occurred in a public place (p < 0.001).

Conclusions

The factors associated with ROSC were occurrence in a public place, CPR initiation by witnesses, and presence of a shockable rhythm. Gender, age, and the type of EMT did not influence ROSC. Low bystander CPR rates reinforce the need for further efforts to train the public in CPR.

The role of cardiorespiratory fitness on the risk of sudden cardiac death at the population level: A systematic review and meta-analysis of the available evidence

Cardiorespiratory fitness (CRF) has been widely studied as a powerful and independent predictor of all-cause and disease-specific mortality. Sudden cardiac death (SCD) is recognized as a significant cause of mortality among the general population, including the general population without previous symptoms of any coronary heart disease (CHD). Consequently, SCD is an important public health problem, which constitutes a clinical challenge. Thus, prevention of SCD by detecting early risk factors could be a useful tool, contributing to the American Heart Association's goal of decreasing the incidence of SCD at the population level. The identification of these risk factors for CVD would facilitate the large-scale screening of those participants at higher risk of SCD. This systematic review collects information about the role of CRF on the risk of SCD at the available evidence, and analyzes the long-term influence of CRF as a risk factor and independent predictor of SCD.