Sudden cardiac death after manual or automated snow removal

Physical activity, cardiorespiratory fitness, and cardiovascular health: A clinical practice statement of the ASPC Part I: Bioenergetics, contemporary physical activity recommendations, benefits, risks, extreme exercise regimens, potential maladaptations

Regular moderate-to-vigorous physical activity (PA) and increased levels of cardiorespiratory fitness (CRF) or aerobic capacity are widely promoted as cardioprotective measures in the primary and secondary prevention of atherosclerotic cardiovascular (CV) disease (CVD). Nevertheless, physical inactivity and sedentary behaviors remain a worldwide concern. The continuing coronavirus (COVID-19) pandemic has been especially devastating to patients with known or occult CVD since sitting time and recreational PA have been reported to increase and decrease by 28% and 33%, respectively. Herein, in this first of a 2-part series, we discuss foundational factors in exercise programming, with specific reference to energy metabolism, contemporary PA recommendations, the dose-response relationship of exercise as medicine, the benefits of regular exercise training, including the exercise preconditioning cardioprotective phenotype, as well as the CV risks of PA. Finally, we discuss the 'extreme exercise hypothesis,' specifically the potential maladaptations resulting from high-volume, high-intensity training programs, including accelerated coronary artery calcification and incident atrial fibrillation. The latter is commonly depicted by a reverse J-shaped or U-shaped curve. On the other hand, longevity data argue against this relationship, as elite endurance athletes live 3-6 years longer than the general population.

High level physical activity in cardiac rehabilitation: Implications for exercise training and leisure-time pursuits

IMPORTANCE

Regular moderate-to-vigorous physical activity and increased levels of cardiorespiratory fitness (CRF) are widely promoted as cardioprotective measures in secondary prevention interventions.

OBSERVATIONS

A low level of CRF increases the risk of cardiovascular disease (CVD) to a greater extent than merely being physically inactive. An exercise capacity <5 metabolic equivalents (METs), generally corresponding to the bottom 20% of the fitness continuum, indicates a higher mortality group. Accordingly, a key objective in early cardiac rehabilitation (CR) is to increase the intensity of training to >3 METs, to empower patients to vacate this "high risk" group. Moreover, a "good" exercise capacity, expressed as peak METs, identifies individuals with a favorable long-term prognosis, regardless of the underlying extent of coronary disease. On the other hand, vigorous-to-high intensity physical activity, particularly when unaccustomed, and some competitive sports are associated with a greater incidence of acute cardiovascular events. Marathon and triathlon training/competition also have limited applicability and value in CR, are associated with acute cardiac events each year, and do not necessarily provide immunity to the development of or the progression of CVD. Furthermore, extreme endurance exercise regimens are associated with an increased incidence of atrial fibrillation and accelerated coronary artery calcification.

CONCLUSIONS AND RELEVANCE

High-intensity training offers a time-saving alternative to moderate intensity continuous training, as well as other potential advantages. Additional long-term studies assessing safety, adherence, and morbidity and mortality are required before high-intensity CR training can be more widely recommended, especially in previously sedentary patients with known or suspected CVD exercising in non-medically supervised settings.

Chronic Stress, Exercise and Cardiovascular Disease: Placing the Benefits and Risks of Physical Activity into Perspective

Chronic stress, which has been exacerbated worldwide by the lingering COVID pandemic, has been strongly linked to cardiovascular disease (CVD). In addition, autonomic dysregulation via sustained sympathetic activity has been shown to increase the risk of arrhythmias, platelet aggregation, acute coronary syndromes and heart failure. Fortunately, effective coping strategies have been shown to attenuate the magnitude of hyperarousal associated with the stress response, including moderate-to-vigorous lifestyle activity and/or structured exercise. A good-to-excellent level of cardiorespiratory fitness also appears to be highly cardioprotective. These beneficial effects have been substantiated by numerous studies that have evaluated the levels of stress reactivity and stress recovery in physically active individuals versus matched sedentary controls, as well as before and after exercise interventions. On the other hand, unaccustomed strenuous exercise in habitually sedentary persons with underlying CVD is associated with a disproportionate incidence of acute cardiac events. Moreover, extreme exercise regimens appear to increase coronary calcification and the likelihood of developing atrial fibrillation. This review summarizes these relations and more, with specific reference to placing the benefits and risks of physical activity into perspective.

Events Due to Snowblower Use Seen in US Emergency Departments From 2003 Through 2018

Objective To comprehensively analyze emergency department (ED) visits associated with snowblower use in the United States. Methods Data on National Electronic Injury Surveillance System ED visits due to snow blowers from 2003 through 2018 were analyzed by age, sex, diagnosis, anatomic location of the injury, and year, month, or weekday. The mechanism of injury and alcohol use were noted. Statistical analyses were performed, accounting for the weighted, stratified nature of the data. Results There were an estimated 91,451 patients with an average age of 51 years; 91.2% were male. Amputation, fracture, or laceration accounted for 43,524 (47.6%) of the ED visits. The mechanism of injury was placing the hand into the chute (44.5%), a fall/slip (13.3%), medical events (6.1%), and miscellaneous (33.8%). Most (68.9%) occurred at home. Alcohol was rarely involved (0.4%). There were 648 deaths; 647 were due to cardiac events. The five major injury diagnoses were fracture (25.9%), laceration (20.2%), strain/sprain (15.0%), amputation (11.2%), and contusion/abrasion (10.2%); 99.8% of the amputations involved fingers. The incidence of ED snowblower visits was 1.845 per 100,000 US population with no change over time. There was a general correlation between the number of visits and the annual snow cover. Conclusions Ample opportunity for injury prevention exists, as there was no change in the incidence over time. Cardiac events accounted for essentially all of the deaths.

Snowfall, Temperature, and the Risk of Death From Myocardial Infarction: A Case-Crossover Study

Previous research has associated snowfall with risk of myocardial infarction (MI). Most studies have been conducted in regions with harsh winters; it remains unclear whether snowfall is associated with risk of MI in regions with milder or more varied climates. A case-crossover design was used to investigate the association between snowfall and death from MI in British Columbia, Canada. Deaths from MI among British Columbia residents between October 15 and March 31 from 2009 to 2017 were identified. The day of each death from MI was treated as the case day, and each case day was matched to control days drawn from the same day of the week during the same month. Daily snowfall amount was assigned to case and control days at the residential address, using weather stations within 15 km of the residence and 100 m in elevation. In total, 3,300 MI case days were matched to 10,441 control days. Compared with days that had no snowfall, odds of death from MI increased 34% (95% confidence interval: 0%, 80%) on days with heavy snowfall (≥5 cm). In stratified analysis of deaths from MI as a function of both maximum temperature and snowfall, risk was significantly increased on snowfall days when the temperature was warmer.

Exercise-Related Acute Cardiovascular Events and Potential Deleterious Adaptations Following Long-Term Exercise Training: Placing the Risks Into Perspective-An Update: A Scientific Statement From the American Heart Association

Epidemiological and biological plausibility studies support a cause-and-effect relationship between increased levels of physical activity or cardiorespiratory fitness and reduced coronary heart disease events. These data, plus the well-documented anti-aging effects of exercise, have likely contributed to the escalating numbers of adults who have embraced the notion that "more exercise is better." As a result, worldwide participation in endurance training, competitive long distance endurance events, and high-intensity interval training has increased markedly since the previous American Heart Association statement on exercise risk. On the other hand, vigorous physical activity, particularly when performed by unfit individuals, can acutely increase the risk of sudden cardiac death and acute myocardial infarction in susceptible people. Recent studies have also shown that large exercise volumes and vigorous intensities are both associated with potential cardiac maladaptations, including accelerated coronary artery calcification, exercise-induced cardiac biomarker release, myocardial fibrosis, and atrial fibrillation. The relationship between these maladaptive responses and physical activity often forms a U- or reverse J-shaped dose-response curve. This scientific statement discusses the cardiovascular and health implications for moderate to vigorous physical activity, as well as high-volume, high-intensity exercise regimens, based on current understanding of the associated risks and benefits. The goal is to provide healthcare professionals with updated information to advise patients on appropriate preparticipation screening and the benefits and risks of physical activity or physical exertion in varied environments and during competitive events.

Sudden cardiac death during physical exercise: Characteristics of victims and autopsy findings

OBJECTIVE

To provide data on the risk factors and characteristics of subjects who experience sudden cardiac death (SCD) during physical exercise.

METHODS AND RESULTS

We assessed the characteristics and the medico-legal autopsy findings of SCD victims who had experienced a witnessed fatal cardiac arrest at rest (n = 876) or in relation to physical exercise (n = 328) in the Finnish Study of Genotype and Phenotype Characteristics of SCD (FinGesture). A total of 876 (73%) witnessed SCDs occurred at rest (R group) and 328 (27%) during or immediately after physical exercise (PE group). Male gender was more common in the PE group compared to the R group (309/328, 94% versus 678/876, 77%, P < 0.001). Coronary artery disease was a more common structural heart disease than non-ischemic disease at autopsy when SCD was exercise-triggered (299/328, 91% versus 657/876, 75%, P < 0.001). Myocardial scarring and cardiac hypertrophy were more commonly found at autopsy in the PE group (194/328, 59% versus 370/876, 42%, P < 0.001; 243/328, 74% versus 585/876, 67%, P = 0.012, respectively). Skiing, cycling, and snow shoveling were the most common modes of exercise at the time of SCD.

CONCLUSIONS

SCD during or immediately after exercise is related to male gender, ischemic heart disease, cardiac hypertrophy, and myocardial scarring.

Coronary responses to cold air inhalation following afferent and efferent blockade

Cardiac ischemia and angina pectoris are commonly experienced during exertion in a cold environment. In the current study we tested the hypotheses that oropharyngeal afferent blockade (i.e., local anesthesia of the upper airway with lidocaine) as well as systemic β-adrenergic receptor blockade (i.e., intravenous propranolol) would improve the balance between myocardial oxygen supply and demand in response to the combined stimulus of cold air inhalation (-15 to -30°C) and isometric handgrip exercise (Cold + Grip). Young healthy subjects underwent Cold + Grip following lidocaine, propranolol, and control (no drug). Heart rate, blood pressure, and coronary blood flow velocity (CBV, from Doppler echocardiography) were continuously measured. Rate-pressure product (RPP) was calculated, and changes from baseline were compared between treatments. The change in RPP at the end of Cold + Grip was not different between lidocaine (2,441 ± 376) and control conditions (3,159 ± 626); CBV responses were also not different between treatments. With propranolol, heart rate (8 ± 1 vs. 14 ± 3 beats/min) and RPP responses to Cold + Grip were significantly attenuated. However, at peak exercise propranolol also resulted in a smaller ΔCBV (1.4 ± 0.8 vs. 5.3 ± 1.4 cm/s, P = 0.035), such that the relationship between coronary flow and cardiac metabolism was impaired under propranolol (0.43 ± 0.37 vs. 2.1 ± 0.63 arbitrary units). These data suggest that cold air breathing and isometric exercise significantly influence efferent control of coronary blood flow. Additionally, β-adrenergic vasodilation may play a significant role in coronary regulation during exercise.

Putting the benefits and risks of aerobic exercise in perspective

Although considerable epidemiologic and clinical evidence suggests that structured exercise, increased lifestyle activity, or both are cardioprotective, the absolute and relative risk of cardiovascular and musculoskeletal complications appear to increase transiently during vigorous physical activity. The estimated relative risk of exercise-related cardiac events ranges from 2.1 to 56 and is highest among habitually sedentary individuals with underlying cardiovascular disease who were performing unaccustomed vigorous physical exertion. Moreover, an estimated 7 million Americans receive medical attention for sports and recreation-related injuries each year. These risks, and their modulators, should be considered when endorsing strenuous leisure time or exercise interventions. If the current mantra "exercise is medicine" is embraced, underdosing and overdosing are possible. Thus, exercise may have a typical dose-response curve with a plateau in benefit or even adverse effects, in some individuals, at more extreme levels.

Firefighters' physical activity: relation to fitness and cardiovascular disease risk

PURPOSE

Cardiovascular disease (CVD) accounts for 44% of on-duty deaths among US firefighters with a markedly higher event risk during strenuous duties compared with nonemergencies. Sedentary persons are most susceptible to such CVD "event-triggering" due to irregular bouts of vigorous physical activity (PA). Conversely, regular PA and increased levels of cardiorespiratory fitness (CRF) protect against CVD triggering. Therefore, the present study evaluates PA measures in structural firefighters and their relationship to CRF and CVD risk factors.

METHODS

Cross-sectional cohort study of 527 Midwestern career firefighters. PA frequency, duration, and intensity measures from a questionnaire along with total weekly aerobic exercise were analyzed. CRF was measured by maximal exercise tolerance testing. CVD risk parameters included body composition, blood pressure, and metabolic profiles. Group differences were compared using general linear models.

RESULTS

Measures of increasing frequency, duration, intensity of PA, and total weekly exercise (min) were significantly associated with higher CRF (P < 0.001) after adjustment for age, body mass index (BMI), and smoking status. After multivariate adjustment, increasing PA frequency was significantly associated with reduced total cholesterol-HDL ratio, triglycerides, and glucose, as well as HDL increments. Increasing BMI category was associated with significant decrements in CRF and unfavorable dose-response trends in CVD risk factors (P < 0.001), even for those reporting very frequent, sustained, and intense PA.

CONCLUSIONS

Increasing PA has beneficial independent effects on CRF, and PA frequency has similar favorable effects on CVD risk profiles. Whereas PA was beneficial regardless of BMI category, increasing BMI category had strong independent unfavorable effects. PA should be strongly encouraged for all firefighters with the highest priority given to PA frequency, followed by PA duration and intensity.

Effect of cold air inhalation and isometric exercise on coronary blood flow and myocardial function in humans

The effects of cold air inhalation and isometric exercise on coronary blood flow are currently unknown, despite the fact that both cold air and acute exertion trigger angina in clinical populations. In this study, we used transthoracic Doppler echocardiography to measure coronary blood flow velocity (CBV; left anterior descending coronary artery) and myocardial function during cold air inhalation and handgrip exercise. Ten young healthy subjects underwent the following protocols: 5 min of inhaling cold air (cold air protocol), 5 min of inhaling thermoneutral air (sham protocol), 2 min of isometric handgrip at 30% of maximal voluntary contraction (grip protocol), and 5 min of isometric handgrip at 30% maximal voluntary contraction while breathing cold air (cold + grip protocol). Heart rate, blood pressure, inspired air temperature, CBV, myocardial function (tissue Doppler imaging), O(2) saturation, and pulmonary function were measured. The rate-pressure product (RPP) was used as an index of myocardial O(2) demand, whereas CBV was used as an index of myocardial O(2) supply. Compared with the sham protocol, the cold air protocol caused a significantly higher RPP, but there was a significant reduction in CBV. The cold + grip protocol caused a significantly greater increase in RPP compared with the grip protocol (P = 0.045), but the increase in CBV was significantly less (P = 0.039). However, myocardial function was not impaired during the cold + grip protocol relative to the grip protocol alone. Collectively, these data indicate that there is a supply-demand mismatch in the coronary vascular bed when cold ambient air is breathed during acute exertion but myocardial function is preserved, suggesting an adequate redistribution of blood flow.

Triggers of acute cardiovascular events and potential preventive strategies: prophylactic role of regular exercise

There is now considerable evidence to suggest that acute myocardial infarction, sudden cardiac death, and stroke can be triggered by physical, chemical, and psychological stressors, including heavy physical exertion and situations that create heightened emotional stress. The increased risk appears to be largely limited to a susceptible subset of the population, that is, individuals with known or occult cardiovascular (CV) disease. In this article, we summarize the evidence supporting the impact of selected triggers in the pathogenesis of acute CV events, as well as the potential role of various preventive strategies, especially regular exercise training and improvements in cardiorespiratory fitness to reduce the CV risk imposed by various triggers.

The snow-shoveler's ST elevation myocardial infarction

Heavy snowfall, cold temperatures, and low atmospheric pressure during the winter months have been associated with increased adverse cardiovascular events. However, only a few cases of the "snow shoveler's infarction" have been reported. The investigators describe their experience with 6 patients presenting with ST elevation myocardial infarctions, all within a 24-hour period during an unprecedented snowfall (4 of whom were shoveling snow), and provide a detailed review of previously reported cases of snow shoveler's infarction. Consistent with other reports, most patients reported here had the traditional cardiac risk factors of hypertension, hyperlipidemia, diabetes mellitus, tobacco use, and sedentary lifestyle. Unique to this case series, however, was that the 4 patients who had histories of coronary artery disease and previous coronary artery stenting all presented with subacute stent thromboses documented on coronary angiography performed emergently. Moreover, these patients constituted 25% of all subacute stent thromboses diagnosed in the cardiac catheterization laboratory in the preceding 12 months. In conclusion, these findings suggest that in typically sedentary individuals with cardiac risk factors or histories of coronary artery disease, snow shoveling may trigger ST elevation myocardial infarction and therefore should be avoided. This may be most critical in patients with histories of coronary stent placement, considering that these findings suggest that snow shoveling may precipitate subacute stent thrombosis.

The Risk in Exercise Training

Although exercise training is unequivocally of benefit relative to the risk of cardiovascular disease, there is a definable risk of complications during exercise training. In younger individuals, the risk is almost exclusively related to the presence of congenital abnormalities, whereas in older (∼40 years) individuals, the risk is largely related to atherosclerotic disease. In both groups, the risk of the underlying pathology leading to clinical presentation is increased by higher intensity exercise. In older individuals, preexercise screening is of potential benefit but is not generally well done. Exercise prescription should favor lower intensity exercise during the early weeks of an exercise program. Subjective methods, which do not rely on the results of an exercise test, including the Rating of Perceived Exertion and the Talk Test, are to be recommended because preliminary exercise testing is performed inconsistently. There are inadequate data regarding the spontaneous exercise training intensity in both healthy individuals and patients.