Relation of systemic blood pressure to sudden cardiac death

Characteristics of women with ischemic sudden cardiac death

BACKGROUND

Sudden cardiac death (SCD) is a significant mode of death causing 15-20% of all deaths in high-income countries. Coronary artery disease (CAD) is the most common cause of SCD in both sexes, and SCD is often the first manifestation of underlying CAD in women. This case-control study aimed to determine the factors associated with SCD due to CAD in women.

METHODS

The study group consisted of women with CAD-related SCD (N = 888) derived from the Fingesture study conducted in Northern Finland from 1998 to 2017. All SCDs underwent medicolegal autopsy. The control group consisted of women with angiographically verified CAD without SCD occurring during the 5-year-follow-up (N = 610). To compare these groups, we used medical records, autopsy findings, echocardiograms, and electrocardiograms (ECGs).

RESULTS

Subjects with SCD were older (73.2 ± 11.3 vs. 68.8 ± 8.0, p < 0.001) and were more likely to be smokers or ex-smokers (37.1% vs. 27.6%, p = 0.045) compared to control patients. The proportion of subjects with prior myocardial infarction (MI) was higher in controls (46.9% vs. 41.4% in SCD subjects, p = 0.037), but in contrast, SCD subjects were more likely to have underlying silent MI (25.6% vs. 2.4% in CAD controls, p < 0.001). Left ventricular hypertrophy (LVH) was more common finding in SCD subjects (70.9% vs. 55.1% in controls, p < 0.001). Various electrocardiographic abnormalities were more common in subjects with SCD, including higher heart rate, atrial fibrillation, prolonged QTc interval, wide or fragmented QRS complex and early repolarization. The prevalence of Q waves and T inversions did not differ between the groups.

CONCLUSIONS

Underlying LVH and previous MI with myocardial scarring are common and often undiagnosed in women with CAD-related SCD. These results suggest that untreated CAD with concomitant myocardial disease is an important factor in SCD in women.

Prevalence, Predictors, and Outcomes of Resistant Hypertension in Egyptian Population

Background

Hypertension is a leading problem; it affects around thirty million adult Egyptians, according to the last national registry. The exact prevalence of resistant hypertension (RH) in Egypt wasn't spotted before. The purpose of this study was to determine the prevalence, predictors, and impact on adverse cardiovascular outcomes among adult Egyptians with RH.

Methods

The present study examined a cohort of 990 hypertensive patients who were divided into two groups based on their blood pressure control; group I (n = 842) patients who achieved blood pressure control and group II (n = 148) patients who met the RH definition criteria. All patients underwent a close follow-up for one year to evaluate the major cardiovascular events.

Results

The prevalence of RH was 14.9%. The main predictors impacting the cardiovascular outcomes of RH were advanced age (≥65 years), the presence of chronic kidney diseases, a BMI ≥ 30 kg/m², and NSAID use. After one year of follow-up, the RH group displayed noticeably higher rates of major cardiovascular events, including new-onset atrial fibrillation (6.8% vs. 2.5%, P = 0.006), cerebral stroke (4.1% vs. 1.2%, P = 0.011), myocardial infarction (4.7% vs. 1.3%, P = 0.004), and acute heart failure (4.7% vs. 1.8%, P = 0.025).

Conclusion

The prevalence of RH in Egypt is moderately high. Patients with RH have a far higher risk of cardiovascular events than those whose blood pressure is within control.

Comorbid Hypertension Reduces the Risk of Ventricular Arrhythmia in Chronic Heart Failure Patients with Implantable Cardioverter-Defibrillators

AIMS

Low blood pressure (BP) has been shown to be associated with increased mortality in patients with chronic heart failure. This study was designed to evaluate the relationships between diagnosed hypertension and the risk of ventricular arrhythmia (VA) and all-cause death in chronic heart failure (CHF) patients with implantable cardioverter-defibrillators (ICD), including those with preserved left ventricular ejection fraction (HFpEF) and indication for ICD secondary prevention. We hypothesized that a stable hypertension status, along with an increasing BP level, is associated with a reduction in the risk of VA in this population, thereby limiting ICD efficacy.

METHODS

We retrospectively enrolled 964 CHF patients, with hypertension diagnosis and hospitalized BP measurements obtained before ICD implantation. The primary outcome measure was defined as the composite of SCD, appropriate ICD therapy, and sustained VT. The secondary endpoint was time to death or heart transplantation (HTx). We performed multivariable Cox proportional hazard regression and entropy balancing to calculate weights to control for baseline imbalances with or without hypertension. The Fine-Gray subdistribution hazard model was used to confirm the results. The effect of random BP measurements on the primary outcome was illustrated in the Cox model with inverse probability weighting.

RESULTS

The 964 patients had a mean (SD) age of 58.9 (13.1) years; 762 (79.0%) were men. During the interrogation follow-up [median 2.81 years (interquartile range: 1.32-5.27 years)], 380 patients (39.4%) reached the primary outcome. A total of 244 (45.2%) VA events in non-hypertension patients and 136 (32.1%) in hypertension patients were observed. A total of 202 (21.0%) patients died, and 31 (3.2%) patients underwent heart transplantation (incidence 5.89 per 100 person-years; 95% CI: 5.16-6.70 per 100 person-years) during a median survival follow-up of 4.5 (IQR 2.8-6.8) years. A lower cumulative incidence of VA events was observed in hypertension patients in the initial unadjusted Kaplan-Meier time-to-event analysis [hazard ratio (HR): 0.65, 95% confidence interval (CI): 0.53-0.80]. The protective effect was robust after entropy balancing (HR: 0.71, 95% CI: 0.56-0.89) and counting death as a competing risk (HR: 0.71, 95% CI: 0.51-1.00). Hypertension diagnosis did not associate with all-cause mortality in this population. Random systolic blood pressure was negatively associated with VA outcomes (p = 0.065).

CONCLUSIONS

In hospitalized chronic heart failure patients with implantable cardioverter-defibrillators, the hypertension status and higher systolic blood pressure measurements are independently associated with a lower risk of combined endpoints of ventricular arrhythmia and sudden cardiac death but not with all-cause mortality. Randomized controlled trials are needed to confirm the protective effect of hypertension on ventricular arrhythmia in chronic heart failure patients.

Exercise cardiac power and the risk of heart failure in men: A population-based follow-up study

BACKGROUND

Little is known about exercise cardiac power (ECP), defined as the ratio of directly measured maximal oxygen uptake with peak systolic blood pressure during exercise, on heart failure (HF) risk. We examined the association of ECP and the risk of HF.

METHODS

This was a population-based cohort study of 2351 men from eastern Finland. The average time to follow-up was 25 years. Participants participated at baseline in an exercise stress test. A total of 313 cases of HF occurred.

RESULTS

Men with low ECP (<9.84 mL/mmHg, the lowest quartile) had a 2.37-fold (95% confidence interval (95%CI): 1.68-3.35, p < 0.0001) hazards ratio of HF as compared with men with high ECP (>13.92 mL/mmHg, the highest quartile), after adjusting for age. Low ECP was associated with a 1.96-fold risk (95%CI: 1.38-2.78, p < 0.001) of HF after additional adjustment for conventional risk factors. After further adjustment for left ventricular hypertrophy, the results hardly changed (hazards ratio = 1.87, 95%CI: 1.31-2.66, p < 0.001). One SD increase in ECP (3.16 mL/mmHg) was associated with a decreased risk of HF by 28% (95%CI: 17%-37%).

CONCLUSION

ECP provides a noninvasive and easily available measure from cardiopulmonary exercise tests in predicting HF. However, ECP did not provide additional value over maximal oxygen uptake_.

The role of metabolic syndrome in sudden cardiac death risk: Recent evidence and future directions

Metabolic syndrome (MetS) is a frequent condition whose deleterious effects on the cardiovascular system are often underestimated. MetS is nowadays considered a real pandemic with an estimated prevalence of 25% in general population. Individuals with MetS are at high risk of sudden cardiac death (SCD) as this condition accounts for 50% of all cardiac deaths in such a population. Of interest, recent studies demonstrated that individuals with MetS show 70% increased risk of SCD even without previous history of coronary heart disease (CHD). However, little is known about the interplay between the two conditions. MetS is a complex disease determined by genetic predisposition, unhealthy lifestyle and ageing with deleterious effects on different organs. MetS components trigger a systemic chronic low-grade pro-inflammatory state, associated with excess of sympathetic activity, cardiac hypertrophy, arrhythmias and atherosclerosis. Thus, MetS has an important burden on the cardiovascular system as demonstrated by both preclinical and clinical evidence. The aim of this review is to summarize recent evidence concerning the association between MetS and SCD, showing possible common aetiological processes, and to indicate prospective for future studies and therapeutic targets.

Life's Simple 7 and the risk of stroke in Finnish men: A prospective cohort study

BACKGROUND

Population-wide preventive measures constitute important approaches towards reducing stroke risk and its associated burden. We sought to examine the association between American Heart Association's (AHA) Life's Simple7 (LS7) score and the risk of stroke in men.

METHODS

The study is based on the prospective population-based Kuopio Ischaemic Heart Disease cohort comprising men (42-60 years) without pre-existing history of stroke at baseline (1984-1989). LS7 was computed from AHA's cardiovascular health metrics for 2520 men and includes data on diet, physical activity, body mass index, smoking status, blood pressures, total cholesterol and blood glucose. Participants were classified into three LS7 groups based on the number of ideal metrics: low (0-2), medium (3-4) and high (5-7). Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of LS7 scores for total and ischaemic stroke.

RESULTS

During a median follow-up of 26 years, 428 total and 362 ischaemic incident stroke events were recorded. The risk of both stroke outcomes decreased continuously with increasing LS7 scores across the range 2-6. Men with high LS7 had 48% (HR: 0.52; 95%CI: 0.32-0.86) lower risk of total stroke when compared with those with low LS7. The association was similar for the risk of ischaemic stroke, with 50% (HR: 0.50; 95%CI: 0.29-0.87) lower risk among men with high LS7 compared with those with low LS7.

CONCLUSION

LS7 was strongly, inversely and linearly associated with risk of total and ischaemic strokes among a middle-aged male Finnish population.

Cardiovascular risk factors and blood pressure response to various types of exercise in veteran athletes

Aim. To study the main cardiovascular risk (CVR) factors and assess the blood pressure (BP) response to various types of exercise in veteran athletes.

Material and methods. In order to identify the main CVR factors, 234 competitive athletes and 29 persons practicing physical training were interviewed. We also measured their pre- and post-exercise BP. The previously diagnosed hypertension (HTN) was also taken into account.

Results. Among the participants, HTN was diagnosed in 48,5% of athletes, obesity — in 21%, smoking — in 22,9%, while 15,5% had a positive family history of coronary artery disease. The combination of two or more studied risk factors was observed in 35,7% of the subjects. The prevalence of the studied risk factors in participants significantly depended on the type of physical activity. The most unfavorable situation was obtained among hockey players. The highest pre-exercise diastolic BP values were registered in football players (p<0,05), while after exercise, in hockey and football players. In persons with obesity and HTN, the pre- and post-exercise systolic and diastolic BP, as well as the double product, were significantly (p<0,05) higher than in those without HTN and obesity.

Conclusion. Veteran athletes practically do not differ from the general population in prevalence of HTN, smoking, and obesity. Elevated pre-and post-exercise BP values (>139/89 mm Hg) was recorded in >40% of veteran athletes. The highest BP levels were found among volleyball and football players. The factors predisposing to such an increase in pre- and post-exercise BP in veteran athletes are obesity, diagnosed HTN, and a positive family history of coronary artery disease. There is reason to consider BP >139/89 mm Hg in the early recovery period as an unfavorable indicator.

Systolic Blood Pressure and Risk for Ventricular Arrhythmia in Patients With an Implantable Cardioverter Defibrillator

Low systolic blood pressure (SBP) was previously suggested to be a marker for heart failure and mortality in patients with low left ventricular ejection fraction. We aimed to explore the association of SBP on risk of ventricular tachyarrhythmias (VTA) and atrial arrhythmias as well as appropriate and inappropriate Implantable Cardioverter Defibrillator (ICD) therapy. The study population comprised 1,481 of 1,500 (99%) patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial - Reduce Inappropriate Therapy trial. Multivariate Cox proportional hazards regression modeling was used to identify the association of baseline SBP (recorded prior to ICD implantation) with the risk of VTA > 170 beats/min during follow-up (primary end point) and atrial arrhythmia, appropriate and inappropriate ICD therapy, hospitalization and death (secondary end points). SBP was dichotomized at 120 mm Hg (approximate mean and median) and was also assessed as a continuous measure. Multivariate analysis showed that each 10 mm Hg decrement in SBP was associated with corresponding 11% increased risk for VTA (p = 0.008). Low SBP (≤120 mm Hg) was associated with a significant 58% (p = 0.002) increased risk for VTA ≥170 beats/min; 53% (p = 0.019) increased risk for VTA ≥200 beats/min; and 65% (p = 0.001) increased risk for appropriate ICD therapy, as compared with SBP >120 mm Hg. Low SBP was not associated with increased risk of atrial arrhythmias, and inappropriate ICD therapy. In conclusion, in MADIT-RIT, SBP (≤120 mm Hg) predicted higher rates of VTA. These findings suggest that SBP may be utilized for VTA risk stratification in candidates for primary ICD therapy.

Certain beta blockers (e.g., bisoprolol) may be reevaluated in hypertension guidelines for patients with left ventricular hypertrophy to diminish the ventricular arrhythmic risk

Hypertensive left ventricular hypertrophy (HTN LVH) is associated with almost threefold increased risk of ventricular tachycardia (VT)/ventricular fibrillation (VF). Furthermore, HTN LVH increases the risk of sudden cardiac death (SCD). The reverse LV remodeling due to efficient antihypertensive therapy lowers the incidence rates of cardiovascular events and SCD and the vast majority of available arterial hypertension (HTN) guidelines recommend renin angiotensin system (RAS) blockers and calcium channel blockers (CCBs) for HTN LVH aiming for LVH regression. On the other hand, beta blockers (BBs) as a class are not recommended in HTN LVH due to their insufficient capacity to reverse LVH remodeling even though they are recommended as the first-line drugs for prevention/treatment of VT/VF (in general, unrelated to HTN LVH). Moreover, BBs are the best antiarrhythmic (against VT/VF) among antihypertensive drugs. Despite that, BBs are currently not recommended for LVH treatment in HTN Guidelines. It is important to prevent VT/VF in patients at high risk, such as those with HTN LVH. Therefore, certain BBs (such as Bisoprolol) may be reevaluated in guidelines for HTN (in the section of HTN LVH).

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.

Antihypertensive therapy and sudden cardiac death, should we expect the unexpected?

Hypertension (HTN) and sudden cardiac death (SCD) constitute major public health problems accounting for millions of deaths each year worldwide. Both HTN and HTN-induced left ventricular hypertrophy (LVH) have been shown to be independent risk factors for SCD. However, the association between antihypertensive pharmacotherapy and risk of SCD has been under-investigated. Given that antihypertensive pharmacotherapy effectively reduces overall cardiovascular mortality, it would be expected to protect patients from SCD. Nevertheless, available data demonstrate that antihypertensive medications (primarily thiazide diuretics), while effective in reducing the incidence of myocardial infarction, do not confer protection from SCD. The purpose of this review was to present the relationship between HTN, LVH, and SCD and to describe the potential association between antihypertensive pharmacotherapy and risk of SCD.

Blood pressure, hypertension and the risk of sudden cardiac death: a systematic review and meta-analysis of cohort studies

Cardiovascular disease is the leading cause of death worldwide, while sudden cardiac death (SCD) accounts for over 60% of all cardiovascular deaths. Elevated blood pressure and hypertension have been associated with increased risk of SCD, but the findings have not been consistent. To clarify whether blood pressure or hypertension is associated with increased risk of SCD and to quantify the size and the shape of any association observed. PubMed and Embase databases were searched for published prospective studies on blood pressure or hypertension and SCD up to 30 April 2018. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random effects model. The meta-analysis included 2939 SCDs among 418,235 participants from 18 studies. The summary RRs were 2.10 (95% CI 1.71-2.58, I² = 56.7%, p_{heterogeneity} = 0.018, n = 10) for prevalent hypertension, 1.28 (95% CI 1.19-1.38, I² = 45.5%, p_{heterogeneity} = 0.07, n = 10) per 20 mmHg increment in systolic blood pressure (SBP) and 1.09 (95% CI 0.83-1.44, I² = 83.4%, p_{heterogeneity} = 0.002, n = 3) per 10 mmHg increment in diastolic blood pressure (DBP). A nonlinear relationship was suggested between SBP and SCD. The results persisted in most subgroup and sensitivity analyses. There was no evidence of publication bias. This meta-analysis found an increased risk of SCD with hypertension diagnosis and increasing SBP. Future studies should clarify the association for DBP and the shape of the dose-response relationship between blood pressure and SCD.

Association of ADHD medications with the risk of cardiovascular diseases: a meta-analysis

This meta-analysis was conducted to evaluate the association between Attention deficit hyperactivity disorder (ADHD) medications and risk of sudden death/arrhythmia, stroke, myocardial infarction as well as all-cause death. We searched PubMed, Web of Science and China National Knowledge Infrastructure from 1950 to May 2018. All observational studies that the exposure of interest was ADHD medications, the outcome of interest was sudden death/arrhythmia, stroke, myocardial infarction as well as all-cause death, and the study reported relative risks (RRs) with 95% confidence intervals (95% CIs) were included. Pooled RRs were estimated by random-effects model. Subgroup analyses were conducted to examine the effects of study design, population, Country, follow-up duration, female proportion, covariates adjustment on the risk of sudden death/arrhythmia. Eight articles with ten studies (4,221,929 participants) were included in this meta-analysis about the association between ADHD medications and risk of sudden death/arrhythmia. The pooled RRs with 95% CIs of sudden death/arrhythmia for ADHD medications were 1.39 (1.06, 1.83). The result of the cohort study was 1.24 (0.84, 1.83). The pooled RRs between ADHD medications and stroke, myocardial infarction, all-cause death were 1.00 (0.74, 1.35), 0.91 (0.79, 1.05), 0.89 (0.54, 1.45), respectively. As for methylphenidate, the pooled RRs between methylphenidate and sudden death/arrhythmia, stroke, myocardial infarction, all-cause death were 1.46 (1.03, 2.07), 0.92 (0.70, 1.21), 0.97 (0.77, 1.23), 1.00 (0.49, 2.04), respectively. Based on the results of cohort studies, there was no correlation between ADHD medications and sudden death/arrhythmia, stroke, myocardial infarction and all-cause death. However, some of the confidence intervals do not exclude modest elevated risks, e.g., for sudden death/arrhythmia.

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.

Potential Protective Role of Blood Pressure-Lowering Drugs on the Balance between Hemostasis and Fibrinolysis in Hypertensive Patients at Rest and During Exercise

In patients with hypertension, the triad represented by endothelial dysfunction, platelet hyperactivity, and altered fibrinolytic function disturbs the equilibrium between hemostasis and fibrinolysis and translates into a hypercoagulable state, which underlies the risk of thrombotic complications. This article reviews the scientific evidence regarding some biological effects of antihypertensive drugs, which can protect patients from the adverse consequences of hypertensive disease, improving endothelial function, enhancing antioxidant activity, and restoring equilibrium between hemostatic and fibrinolytic factors. These protective effects appear not to be mediated through blood pressure reduction and are not shared by all molecules of the same pharmacological class.

Effects of long-term exercise on arrhythmogenesis in aged hypertensive rats

Chronic hypertension is a multifactorial disease that is highly associated with cardiovascular disorders. Physical activity, such as long-term exercise, is advocated as a treatment for hypertension, but the responses of different age groups to long-term exercise are unknown. We used aged spontaneous hypertensive rats (SHRs, 80 weeks old) to test the hypothesis that long-term exercise compensated for deficient autonomic control and reduced susceptibility to ventricular tachycardia (VT) and ventricular fibrillation (VF) in this animal model. The aged SHRs were divided into control and voluntary exercise groups. Ambulatory electrocardiography was recorded for the heart rate variability (HRV) analysis. Programmed stimulation was applied to exposed hearts to induce ventricular arrhythmia in situ. Then, the hearts were isolated for an optical mapping study. The results showed that increased HRV indices were broadly related to vagal dominance in the high-intensity exercise group. Exercise altered the electrical propagation dynamic properties, such as the action potential duration restitution (APDR). Furthermore, the VF inducibility decreased with increased exercise intensity. Taken together, our results suggest that long-term exercise reduces the risk of arrhythmogenesis in aged SHRs through enhanced vagal control and stabilized electrical dynamics.

Exercise cardiac power and the risk of coronary heart disease and cardiovascular mortality in men

PURPOSE

The aim of this study was to examine the relationship of exercise cardiac power (ECP), defined as a ratio of directly measured maximal oxygen uptake with peak systolic blood pressure during exercise, with the risk of mortality from coronary heart diseases (CHD) and cardiovascular diseases (CVD).

DESIGN

Population-based cohort study with an average follow-up of 25 years from eastern Finland. About 2358 men at baseline participated in exercise stress test and 182 CHD and 302 CVD deaths occurred.

RESULTS

Men with low ECP (< 8.7 mL/mmHg, lowest quartile) had a 3.5-fold (95% CI 2.1-5.8, p < 0.0001) risk of CHD mortality as compared with men with high ECP (>16.4 mL/mmHg, highest quartile) after adjusting for age and examination year. Low ECP was associated with a 2.8-fold risk of CHD and 2.4-fold for CVD mortality after additional adjustment for conventional risk factors. After further adjustment for leisure time physical activity, the results hardly changed (HR 2.5, 95% CI 1.71-3.67, p < 0.001).

CONCLUSION

ECP provides non-invasive and easily available measure for the prediction of CHD and CVD mortality. One of the most potential explanation for the association between ECP and the risk of CHD and CVD mortality is an elevated afterload and peripheral resistance indicated by hypertension. Key messages Index of exercise cardiac power defined as the ratio of directly measured maximal oxygen uptake (VO_2max) with peak systolic blood pressure gives prognostic information in coronary heart disease (CHD) and CVD mortality risk stratification. ECP provides non-invasive and easily available measure for the prediction of CHD and CVD mortality. One of the most potential explanation for the association between ECP and the risk of CHD and CVD mortality is an elevated afterload and peripheral resistance indicated by hypertension.

Cardiorespiratory Fitness and Risk of Sudden Cardiac Death in Men and Women in the United States: A Prospective Evaluation From the Aerobics Center Longitudinal Study

OBJECTIVES

To examine the relation between cardiorespiratory fitness (CRF) and sudden cardiac death (SCD) in a large US adult population and to study the effects of hypertension, obesity, and health status on the relation of CRF with SCD.

PATIENTS AND METHODS

A total of 55,456 individuals (mean age, 44.2 years; 13,507 women) from the Aerobics Center Longitudinal Study, a prospective observational investigation (from January 2, 1974, through December 31, 2002), were included. Cardiorespiratory fitness was assessed by a maximal treadmill test, and baseline assessment included an extensive set of measurements.

RESULTS

There were 109 SCDs. An inverse risk of SCD was found across incremental CRF levels after adjusting for potential confounders. Participants with moderate and high CRF levels had 44% (hazard ratio, 0.56; 95% CI, 0.35-0.90) and 48% (hazard ratio, 0.52; 95% CI, 0.30-0.92) significantly lower risk of SCD, respectively, than did those with low CRF levels (P<.001). The risk of SCD decreased by 14% (hazard ratio, 0.86; 95% CI, 0.77-0.96) per 1-metabolic equivalent increase in the fully adjusted model. Hypertensive, overweight, or unhealthy individuals with moderate to high CRF levels had lower risks of SCD (ranging from 58% to 72% of lower risk) than did those with the same medical conditions and low CRF levels.

CONCLUSION

The risk of SCD in US men and women could be partially reduced by ensuring moderate to high levels of CRF independently of other risk factors and especially in those who are hypertensive, overweight, or unhealthy.

Tools for risk stratification of sudden cardiac death: a review of the literature in different patient populations

While various modalities to determine risk of sudden cardiac death (SCD) have been reported in clinical studies, currently reduced left ventricular ejection fraction remains the cornerstone of SCD risk stratification. However, the absolute burden of SCD is greatest amongst populations without known cardiac disease. In this review, we summarize the evidence behind current guidelines for implantable cardioverter defibrillator (ICD) use for the prevention of SCD in patients with ischemic heart disease (IHD). We also evaluate the evidence for risk stratification tools beyond clinical guidelines in the general population, patients with IHD, and patients with other known or suspected medical conditions.

Cardiovascular costs of working memory performance: effects of age and performance feedback

Ageing is associated with impaired working memory (WM) performance that may increase cardiovascular costs in older workers. Performance feedback (FB) was assumed to compensate for performance decline and reduce cardiovascular costs. Forty-eight younger (29 ± 3 yr) and 45 older (55 ± 4 yr) healthy workers had to perform a 0-back task (low WM load), 2-back task (high WM load) and 2-back task with FB (high WM load & FB). Age-related performance decline and enhanced blood pressure (BP) reactivity to WM load were found. The baroreflex sensitivity (BRS) decreased under high WM load in older workers compared to younger workers. The FB abolished age differences in omission rate and increased low frequency heart rate variability (HRV) in both age groups. Moreover, FB reduced heart rate in older workers and increased BRS as well as high frequency HRV in younger workers. The results suggest that older workers compensate for WM performance decline at cost of heightened BP due to age-related reductions of vagal tone and impairments of the baroreflex mechanism. The performance FB helps older workers to partly compensate for performance deficits and reduce cardiovascular costs by moderate decreases in sympathetic tone.