https://orcid.org/0000-0003-1080-7425
Introduction
Ventricular arrhythmias (VAs) represent a serious complication of acute myocardial infarction (AMI). While data regarding SCD and VAs after AMI in patients with implantable cardioverter defibrillator (ICD) are well described, data regarding the incidence of readmissions for VAs in patients without ICD implantation criteria after a first AMI are scarce, as well as the impact of sex on their occurrence.1,2 This study aims to investigate the impact of sex on VA occurrences in post-AMI patients without ICD.
Methods
Study design and data source
We conducted a nationwide, population-based, retrospective cohort study between 2014 and 2020 using data extracted from the French National Health Data System. This national data system includes several databases linked by an anonymous number for each beneficiary identifier, including the National Hospital Discharge Database (PMSI). The PMSI database is a comprehensive claims database that includes information on diagnoses and procedures in all public and private hospitals in France. Diagnoses are coded according to the International Classification of Diseases version 10 (ICD-10). This study was conducted in compliance with all French laws and regulations and the Declaration of Helsinki, and was notified to the French Data Protection Agency.
Study population and outcomes
We searched the PMSI database for patient discharges from healthcare facilities between 1 January 2014 and 31 December 2015, for AMI (PMSI codes: I21, corresponding to both ST-elevation and non-ST-elevation MI). Patients with a history of AMI, ICD implantation, and those who underwent primary and secondary ICD implantation after the AMI episode were excluded from the analysis. Readmission for sustained VA (PMSI codes I47.2, I49) until 31 December 2020 was then searched for in the PMSI for all patients who met the inclusion criteria (Figure 1).
Relative incidence of readmission for VA over a 7-year follow-up after AMI in men and women without implantable cardioverter defibrillator.
Statistical analysis
Multivariable logistic regression analyses were performed to identify independent factors associated with the risk of VA readmission in men and women. Results are expressed as adjusted odds ratios (aOR) with their respective 95% confidence intervals (95% CI). All data underlying this publication were provided by the Agence Technique de l’Information sur l’Hospitalisation (ATIH). Data analyses were performed using the SQL server software.
Results
Between 1 January 2014 and 31 December 2015, a total of 137 736 patients were hospitalized in France with a diagnosis of AMI. Among these patients, 25 271 were excluded for prior history of AMI. Moreover, 6836 patients were excluded due to the presence of an ICD before the hospitalization, or due to ICD implantation for primary and secondary prevention after the AMI episode. Of the remaining 105 629 patients, 1600 (1.51%) were rehospitalized for VA over the 7-year follow-up, with a median delay of 505 days (110–1208) after the AMI.
Among the 72 103 men included, 1240 (1.72%) were rehospitalized for VA over the 7-year follow-up, with a median delay of 514 days (107–1212). Factors independently associated with readmission for VA in men were previous atrial fibrillation (aOR 1.91, 95% CI 1.66–2.21), previous vascular disease (aOR 1.28, 95% CI 1.10–1.50), absence of coronary angioplasty at the time of AMI (aOR 1.28, 95% CI 1.10–1.50), previous diabetes (aOR 1.19, 95% CI 1.04–1.36), previous hypertension (aOR 1.19, 95% CI 1.05–1.34), and previous or in-hospital congestive heart failure (aOR 1.47, 95% CI 1.03–2.08 and aOR 1.65, 95% CI 1.32–2.07). Among the 33 526 women included, 360 (1.07%) were rehospitalized for VA over the 7-year follow-up, with a median delay of 461 days (116–1159). Factors independently associated with readmission for VA in women were previous atrial fibrillation (aOR 1.68, 95% CI 1.30–2.18) and previous vascular disease (aOR 1.37, 95% CI 1.01–1.84).
After adjusting for confounding variables, men had almost twice the risk of readmission for VA than women (aOR 1.88, 95% CI 1.65–2.14; P < 0.0001).
Discussion
Prediction of VAs in post-AMI patients represents a major clinical problem, especially in patients with left ventricular ejection fraction > 35%.3–5
As outlined in the scientific statement from the American Heart Association on AMI in women, limited data exist regarding the influence of sex on the risk of life-threatening VA after AMI.6 This nationwide cohort study sheds light on the significant disparity in the risk of readmission for VAs following a first AMI in men and women in whom an ICD implantation was not performed after the index event. While several studies have shown that rates of rehospitalization after AMI are higher among women than men, these results indicate that readmissions for VAs are more frequent in men.7 Moreover, predictive factors for VA readmission also differ according to sex. These disparities are thought to be partly related to the differences in the underlying substrate after AMI in men and women (e.g. more extensive coronary artery disease and scar formation in men, greater role of microvascular disease among women), as well as a lower susceptibility to arrhythmia triggers in women.8,9
Hence, these findings suggest that sex-specific VA risk stratification may be warranted in the population considered to be at low risk of malignant arrhythmias after an initial AMI.
Limitations
The current study is subject to certain limitations inherent in retrospective electronic health record data analysis, including the potential risk of missing data and coding errors. Notably, the coding process was conducted by the treating physicians, thus relying solely on their accuracy. Specifically, while ICD-10 codes used for VA identification are intended to capture sustained arrhythmias, there remains a possibility that non-sustained ventricular tachycardia episodes were misclassified under these codes. Moreover, the PMSI database lacks detailed coding for cardiac arrest events. While some instances may be coded under a general cardiac arrest code, this does not specify the underlying cause, limiting our ability to distinguish between VA and other causes of cardiac arrest. Consequently, our reliance on specific VA codes alone may not encompass the full spectrum of VA occurring post-MI.
Conclusion
The long-term risk of readmission for VAs after a first AMI appears to be significantly lower in women than in men, with distinct predictive factors depending on sex. These findings suggest that sex-specific VA risk stratification may be warranted in patients considered to be at low risk of VAs after an initial AMI.
Funding
Authors received no specific funding for this work.
Data availability
The data that support the findings of this study are available from the corresponding author upon reasonable request.
References
Author notes
Conflict of interest: none declared.
