Seasonal variation in sudden cardiac death after experimental myocardial infarction

Unmet needs for emergency care and prevention of prehospital death in acute myocardial infarction

INTRODUCTION

Percutaneous coronary intervention (PCI) has successfully reduced the mortality of patients with acute myocardial infarction (AMI). However, patients with out-of-hospital cardiac arrest have high mortality, which is difficult to control by hospital staff. In this study, we investigated the prevalence of prehospital death (PHD) in patients with AMI. Furthermore, we investigated the risk factors associated with 30-day mortality in patients with AMI who survived PHD.

METHODS

We investigated the prevalence of PHD using data from the Yamagata AMI registry and from death certification of the entire Yamagata Prefecture in Japan between 2010 and 2015. Furthermore, we investigated the risk factors for 30-day mortality in patients who survived PHD, using data from the Yamagata AMI registry from 1993 to 2015. AMI was identified by the International Classification of Diseases, 10th revision code I21.

RESULTS

Out of the 6984 patients with AMI, 3771 patients had PHD. Patients with PHD were older and more likely to be women than those without PHD. More PHD occurred in winter and spring than in summer or autumn. Multivariate regression analysis showed that age, female sex, and winter onset were independently associated with PHD. We also investigated the risk factors associated with 30-day mortality in 9675 patients who survived PHD. The rate of PCI was remarkably lower in patients with acute death than in those without acute death. Multivariate regression analysis showed that age, anterior infarction, estimated glomerular filtration rate, Killip class, and PCI were independently associated with 30-day mortality after adjusting for confounding factors.

CONCLUSION

Approximately half of the patients with AMI died before they could reach the destination hospital. Although emergency PCI is the most important factor in reducing 30-day mortality in patients with AMI, attempts to reduce patient delay and system delay are possibly needed to further reduce PHD.

Winter cardiovascular diseases phenomenon

This paper review seasonal patterns across twelve cardiovascular diseases: Deep venous thrombosis, pulmonary embolism, aortic dissection and rupture, stroke, intracerebral hemorrhage, hypertension, heart failure, angina pectoris, myocardial infarction, sudden cardiac death, venricular arrythmia and atrial fibrillation, and discuss a possible cause of the occurrence of these diseases. There is a clear seasonal trend of cardiovascular diseases, with the highest incidence occurring during the colder winter months, which have been described in many countries. This phenomenon likely contributes to the numbers of deaths occurring in winter. The implications of this finding are important for testing the relative importance of the proposed mechanisms. Understanding the influence of season and other factors is essential when seeking to implement effective public health measures.

Seasonal variation influences outcomes following lung cancer resections

OBJECTIVE

The effect of seasonal variation on postoperative outcomes following lung cancer resections is unknown. We hypothesized that postoperative outcomes following surgical resection for lung cancer within the United States would not be impacted by operative season.

METHODS

From 2002 to 2007, 182507 isolated lung cancer resections (lobectomy (n = 147 937), sublobar resection (n = 21650), and pneumonectomy (n = 13916)) were evaluated using the Nationwide Inpatient Sample (NIS) database. Patients were stratified according to operative season: spring (n = 47382), summer (n = 46131), fall (n = 45370) and winter (n = 43624). Multivariate regression models were applied to assess the effect of operative season on adjusted postoperative outcomes.

RESULTS

Patient co-morbidities and risk factors were similar despite the operative season. Lobectomy was the most common operation performed: spring (80.0%), summer (81.3%), fall (81.8%), and winter (81.1%). Lung cancer resections were more commonly performed at large, high-volume (>75th percentile operative volume) centers (P < 0.001). Unadjusted mortality was lowest during the spring (2.6%, P < 0.001) season compared with summer (3.1%), fall (3.0%) and winter (3.2%), while complications were most common in the fall (31.7%, P < 0.001). Hospital length of stay was longest for operations performed in the winter season (8.92 ± 0.11 days, P < 0.001). Importantly, multivariable logistic regression revealed that operative season was an independent predictor of in-hospital mortality (P < 0.001) and of postoperative complications (P < 0.001). Risk-adjusted odds of in-hospital mortality were increased for lung cancer resections occurring during all other seasons compared with those occurring in the spring.

CONCLUSIONS

Outcomes following surgical resection for lung cancer are independently influenced by time of year. Risk-adjusted in-hospital mortality and hospital length of stay were lowest during the spring season.

Sudden cardiac death after manual or automated snow removal

To examine the proximate circumstances of sudden cardiac death (SCD) in the setting of major snowstorms, we reviewed records from the medical examiners' offices of 3 counties in the weeks before, during, and after 2 heavy snowfalls that occurred in the greater metropolitan Detroit area. Of those who experienced SCD due to atherosclerotic cardiovascular disease (n = 271), 36 (33 men, 3 women) were engaged in snow removal, representing the largest number of exertion-related deaths after heavy snowfalls reported to date.

Gender and seasonally related differences in myocardial recovery and susceptibility to sotalol-induced arrhythmias in isolated rabbit hearts

INTRODUCTION

Gender differences and seasonal variations in cardiac electrophysiology and susceptibility to arrhythmias have been described clinically. The present study was undertaken to determine if there are similar gender and seasonally related differences in the electrophysiology of the rabbit heart.

METHODS AND RESULTS

We analyzed epicardial electrograms, left ventricular endocardial monophasic action potentials (MAPs), and simulated X and Y lead ECGs from 145 isolated rabbit hearts studied over a period of 41 months. Hearts from males had seasonal increases in the duration of myocardial recovery. During the months of June to September compared with October to January and February to May, epicardial activation-recovery intervals (231.6+/-23.4 vs 215.6+/-19.2 and 213.5+/-18.8 msec, P = 0.003), MAP durations (256.5+/-25.4 vs 237.0+/-19.6 and 230.7+/-26.4 msec, P < 0.001), and QT intervals (278.3+/-25.6 vs 267.3+/-11.8 and 261.3+/-13.0 msec, P = 0.037) were longer. Overall, hearts from females had shorter QT intervals than males (257.7+/-15.7 vs 270.1+/-20.3 msec, P < 0.001), and this difference was reflected in their shorter epicardial activation-recovery intervals and MAP durations. However, hearts from females showed a greater prolongation of epicardial recovery (P = 0.007) and greater incidence of arrhythmias (P < 0.001) with sotalol than males. Also, the incidence of arrhythmias was greater in the winter months October to May (P < 0.001).

CONCLUSION

The isolated rabbit heart provides a spontaneous model of gender and seasonally related differences in cardiac electrophysiology and arrhythmia susceptibility. These differences may be related to variation in the expression of or regulation of the membrane ion channels mediating repolarization.

Chronobiological patterns of onset of acute cerebrovascular diseases

There is a considerable amount of data indicating that several major unfavorable cerebrovascular events are not randomly distributed over time, but show a peculiar distribution along the day, the week, and the months of the year. The authors review the available evidence on the chronobiological (circadian, weekly, and seasonal) patterns of onset of acute cerebrovascular diseases and variations in their possible triggering mechanisms. The existence of a peculiar chronobiological pattern in the onset of acute cerebrovascular disease, characterized by both circadian (morning and evening occurrence), circaseptan (last and first days of the week), and circannual (especially in winter) is confirmed, although differences depending on biological (gender, age), pathological (diabetes, hypertension, smoke, alcohol), cultural, social, and environmental factors exist. A deeper knowledge of the underlying pathophysiologic mechanisms could provide more effective insights for both preventive strategies and optimization of therapeutic approach.

Inherited ventricular arrhythmias and sudden death in German shepherd dogs

OBJECTIVES

This report describes a unique group of German shepherd dogs with inherited ventricular arrhythmias and sudden death. Before death, these dogs have no evidence of cardiovascular failure.

BACKGROUND

There are few spontaneous animal models of sudden death that permit intensive investigation.

METHODS

To determine the temporal evolution of ventricular arrhythmias and to characterize the syndrome of sudden cardiac death in these dogs, 24-h ambulatory electrocardiographic (ECG) monitoring, echocardiograms, electrophysiologic testing and breeding studies were conducted.

RESULTS

The 24-h ambulatory ECGs from dogs that died showed frequent ventricular arrhythmias with rapid polymorphic ventricular tachycardia (rates > 480 beats/min). Affected dogs had a window of vulnerability for arrhythmias, with the highest incidence and severity of arrhythmias between 20 to 30 and 40 to 50 weeks of age. Affected dogs that died did not have prolongation of the QT interval over a spectrum of heart rates compared with unaffected dogs. The clinical arrhythmia was not induced in dogs during programmed electrical stimulation. Severely affected dogs monitored > 5 years did not develop any evidence of heart failure or cardiomyopathy, and no histopathologic abnormalities existed. Seventeen dogs died suddenly (age 4 to 30 months) and were either 1) found dead at first observation in the morning (n = 8), 2) observed to die during sleep (n = 4), 3) observed to die while resting after exercise (n = 3), or 4) observed to die during exercise (n = 2). All sudden deaths occurred between the end of September and April, with most (n = 11) during January and February.

CONCLUSIONS

The cause of the inherited severe ventricular arrhythmias and sudden death in these young German shepherd dogs is still undetermined. A purely arrhythmic disorder is supported by the lack of cardiac pathology. Moreover, the window of vulnerability to ventricular arrhythmias and the age and circumstances of death invite speculation about the role of the autonomic nervous system.

Composition of seasonality of disease

The composition of the seasonality of total death was ascertained. Vascular disease seasonality constitutes more than half. The remaining seasonality is influenced by respiratory disease. Surprisingly and of possible importance cancer mortality was not seasonal. Deaths from 'all other disease' and from 'injuries' is seasonal. Seasonality increases with age. In coronary and cerebrovascular disease death has a large seasonal fluctuation. On the other hand hospital admissions and survivors have a minor seasonal fluctuation--only cerebrovascular admissions reaching the chosen level of significance with a small seasonal amplitude. For vascular disease the ranking of seasonal fluctuation from greatest to least is--death outside hospital, total death, death inside hospital, admissions, survivors. It is death outside hospital presumably 'sudden' that imposes seasonality on coronary disease in general. For respiratory diseases not only death but hospital admissions and survivors have high amplitude seasonality with a much greater fluctuation than for death in vascular disease.