In this study we looked for the impact of COVID-19 pandemic on heart failure hospitalizations in California. Trends in heart failure hospitalizations remained lower during 2020, compared to 2019. Adverse clinical outcomes such as in-hospital mortality, vasopressor use, mechanical ventilation, and ARDS were significantly higher among heart failure hospitalizations in 2020, compared to 2019.
We found that heart failure hospitalization rates were lower during 2020 and in spite of increasing trends in the latter half of the period, did not catch up with pre-COVID levels. These findings have been observed in other studies as well, which showed decreasing hospitalizations for cardiac conditions including heart failure due to COVID-19 pandemic [4, 12, 13]. A number of factors associated with COVID-19 pandemic could be responsible for these findings. Majority of the patients with heart failure could have willfully delayed treatment due to the fear of contracting COVID-19 during treatment encounters [14, 15]. In addition, the policy of diverting resources and healthcare personnel for COVID-19 management measures such as shelter-in-place and restructuring could have significantly decreased delivery of treatments and managements for non-COVID conditions such as heart failure [16, 17]. Monthly trends in hospitalization rates for heart failure showed a uniform and smooth decline during March to August of 2019 and a smooth but steeper increase during August to December of 2019. Such seasonal variations have been observed in other studies as well, which have reported increasing admissions during winter months and decreasing admissions during summer months [18–20]. Though we observed these seasonal variations in 2020 as well, the decline in hospitalization rates observed during April to July 2020 were much steeper compared to the decrease in 2019. This decline was observed subsequent to postponement of all major events and stay-at-home order issued by the government of California for the months of March and April of 2020 [21, 22]. Subsequently, after the release of a reopening plan, hospitalization rates for heart failure started to increase after a lag of 2–3 months. Nevertheless, in spite of reimposition of restrictions in the succeeding months, hospitalization rates for heart failure showed increasing trends. These increases in heart failure hospitalizations could be due to encouragements to seek care for cardiovascular conditions in spite of existing restrictions for containment of COVID-19 pandemic [23].
We observed that in-hospital mortality was significantly higher among heart failure hospitalizations in 2020, compared to 2019. Similar to our findings, a study among 1,372 heart failure patients reported that in-hospital mortality was significantly higher among patients hospitalized in 2020 (hazard ratio 2.23, P = 0.002). Similarly a large scale study among 101,433 patients hospitalized in 24 cardiology departments showed that in-hospital mortality rates were significantly higher among heart failure patients admitted during the pandemic [4]. A number of reasons could be responsible for these findings. It could be possible that more sicker patients with advanced stages of the disease presented for admissions during the pandemic. A previous study by Bromage at al. reported that heart failure patients admitted during 2020 were sicker and had worse New York Heart Association (NYHA) classifications, compared to the previous year, thereby resulting in higher in-hospital mortality [24]. In addition, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could have also directly affect the cardiovascular system and precipitated new onset heart failure leading to higher mortality rates [25]. However, the number of patients who experienced new onset heart failure after SARS-CoV-2 infection were relatively small and would not have substantially contributed to the higher mortality rates observed in 2020 [25]. Nevertheless, some studies have also reported that concomitant presence of COVID-19 and heart failure irrespective of which condition preceded one another, collectively increased the risk for mortality, especially when combined with old age and preexisting lung disease [26, 27].
We observed that vasopressor use, mechanical ventilation, and ARDS were significantly higher among heart failure hospitalizations in 2020. In the majority of COVID-19 patients, vasopressors are used to treat hypotension from sedation. It could also be used for hypotension caused by sepsis due to SARS-CoV-2 infection or concomitant bacterial infections [28, 29]. Heart failure patients with COVID-19 and experiencing hypotension are clinically managed using inotropic/vasopressor and diuretic medications [30]. However, among patients not amenable to these treatments, mechanical circulatory support is recommended as a life saving measure [30]. In our study, though we found that vasopressor use was significantly higher compared to pre-COVID-19 levels, corresponding increases in mechanical circulatory support was not observed in 2020. Therefore, we could infer that though the severity of heart failure among patients admitted in 2020 was greater than that compared to pre-COVID-19 levels, the rates of severe heart failures requiring mechanical circulatory support did not differ between the two-time frames. Increased rates of mechanical ventilation and ARDS during 2020 was not a surprising finding. Most patients with COVID-19 ARDS are managed with mechanical ventilation and evidence-based ARDS strategies [31]. In addition, mechanical ventilation could alter intrapleural and intrathoracic pressures, which could have adverse effects on cardiovascular functions such as atrial preload, ventricular afterload, heart rate, and myocardial contractility [32]. In our study, these functional deficits could also be partially responsible for greater requirements of vasopressor medications among heart failure patients who could have been mechanically ventilated.
Limitations
Our study has some limitations. We used ICD-10 codes for identifying diagnosis and procedures, which could have led to some levels of misclassification bias due to errors in coding. The distinction between index cases and readmitted cases cannot be ascertained in SID because it deletes all personal identifiers for ensuring confidentiality of the collected data and every admission is considered an independent new admission. Consequently, our study may have overestimated hospitalization rates. SID being an administrative database, it does not have information on factors such as medication, functional classification, and left ventricular functions. We could, therefore, not ascertain the effects of these factors on our outcomes. In this study the COVID-19 data available to us was collected during 2020. There have been significant changes in understanding the pathophysiological mechanisms and management of COVID-19 since this period. Therefore, the findings in our study should be cautiously interpreted.