Seasonal trends of incidence and outcomes of cardiogenic shock : findings from a large, nationwide inpatients sample with 441,696 cases

© The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. The Creative Commons Public Domain Dedication waiver (http:// creat iveco mmons. org/ publi cdoma in/ zero/1. 0/) applies to the data made available in this article, unless otherwise stated in a credit line to the data. Research letter An increase in the annual incidence of cardiogenic shock (CS) and a growing sub-population of patients without acute myocardial infarction (AMI) was documented in Germany [1]. However, contemporary data regarding seasonal trends of CS irrespective of the underlying cause are rare. In this study, we aimed to analyze seasonal trends of (i) incidence; (ii) patient characteristics; and (iii) outcomes in a nation-wide sample of more than 400,000 CS cases between 2005 and 2017 in Germany. For the present analyses, all CS cases (ICD-10-GM code R57.0) in patients ≥ 18 years between 2005 and 2017 in Germany were included. Patients were categorized based on admission in one of four groups: spring, summer, fall, and winter. Temperature-related morbidity and mortality is a growing public health issue. Several studies outside Germany demonstrated more fatal and nonfatal cardiovascular events in the winter than in the summer [2], but contemporary data is missing. We show in our study: the highest incidence of CS was recorded during the winter, while the lowest incidence of CS was observed in the summer. The number of patients admitted with CS in the winter exceeded those in the summer by almost 10,000 (Table 1). Our study also revealed that in-hospital mortality of CS patients was higher in the winter than in the summer (winter vs. summer, n = 70,727 (61.1%) vs. n = 62,379 (58.8%), p < 0.001) (Fig. 1). Additionally, we found that patients admitted with CS in the winter were slightly older than in those admitted in the summer (winter vs. summer, mean age 71.1 (± 13.6) vs. 70.8 (± 13.8), whereas sex did not differ over the seasons (p = 0.8). Notably, incidence of AMI, pre-hospital and in-hospital cardiac arrest among CS patients varied across seasons as well (p < 0.001). This is in line with previous studies showing increased incidence of sudden cardiac death in the winter [3]. The field of temporary mechanical circulatory support (MCS) to manage patients with CS enhanced in the last decade [4]. In this study, intra-aortic balloon pump (IABP) was the most used assist device, followed by veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and left ventricular assist device (LVAD) in CS patients, illustrating the perceived clinical need for MCS devices. Open Access


Research letter
An increase in the annual incidence of cardiogenic shock (CS) and a growing sub-population of patients without acute myocardial infarction (AMI) was documented in Germany [1]. However, contemporary data regarding seasonal trends of CS irrespective of the underlying cause are rare.
In this study, we aimed to analyze seasonal trends of (i) incidence; (ii) patient characteristics; and (iii) outcomes in a nation-wide sample of more than 400,000 CS cases between 2005 and 2017 in Germany.
For the present analyses, all CS cases (ICD-10-GM code R57.0) in patients ≥ 18 years between 2005 and 2017 in Germany were included. Patients were categorized based on admission in one of four groups: spring, summer, fall, and winter.
Temperature-related morbidity and mortality is a growing public health issue. Several studies outside Germany demonstrated more fatal and nonfatal cardiovascular events in the winter than in the summer [2], but contemporary data is missing. We show in our study: the highest incidence of CS was recorded during the winter, while the lowest incidence of CS was observed in the summer. The number of patients admitted with CS in the winter exceeded those in the summer by almost 10,000 (Table 1). Our study also revealed that in-hospital mortality of CS patients was higher in the winter than in the summer (winter vs. summer, n = 70,727 (61.1%) vs. n = 62,379 (58.8%), p < 0.001) (Fig. 1). Additionally, we found that patients admitted with CS in the winter were slightly older than in those admitted in the summer (winter vs. summer, mean age 71.1 (± 13.6) vs. 70.8 (± 13.8), whereas sex did not differ over the seasons (p = 0.8).
Notably, incidence of AMI, pre-hospital and in-hospital cardiac arrest among CS patients varied across seasons as well (p < 0.001). This is in line with previous studies showing increased incidence of sudden cardiac death in the winter [3].
The field of temporary mechanical circulatory support (MCS) to manage patients with CS enhanced in the last decade [4]. In this study, intra-aortic balloon pump (IABP) was the most used assist device, followed by veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and left ventricular assist device (LVAD) in CS patients, illustrating the perceived clinical need for MCS devices. The multidisciplinary shock team approach utilizing protocol-driven care appears to be feasible and to reduce mortality in patients with refractory CS [5,6]. However, the extent to which the shock team approach and associated outcomes are affected by seasonal variations remains unclear. Further studies have to elucidate whether prolonged transport time due to adverse weather conditions, atherosclerotic/thrombotic incidences in terms of AMI, and time-dependent care processes are influenced by seasonal variations and/or lower temperatures.

Open Access
The strengths of this study are the large sample size and the well-validated database. Clinical variables such as laboratory values, physiological markers and followup data beyond the hospital stay were unfortunately not available in this administrative dataset. The exact time course of the different diagnoses e.g. being prevalent at admission or incident during the hospital stay was not possible to assess in this administrative dataset. This potential bias/confounding has to be taken under consideration when interpreting our results. Finally, validation of our results outside of Germany is needed.
In this nation-wide cohort of more than 400,000 CS patients, incidence and in-hospital mortality of CS varied substantially by season, with lowest incidence/mortality during the summer and highest incidence/mortality during the winter. A better understanding of these seasonal trends, and especially if these can be attributed to temperature changes or factors related to quality of care, needs to be evaluated in future research. This might have important implications for the care of CS patients and could help to improve outcomes.