Aims: Assess the relationship between New York Heart Association (NYHA) functional class and cardiovascular (CV) outcomes in obstructive hypertrophic cardiomyopathy (HCM).
Materials and methods: This retrospective cohort study used the Optum Market Clarity database with linked claims and electronic health records. Adults (aged ≥18 years) with obstructive HCM and ≥1 NYHA class assessment after first HCM diagnosis were eligible (selection period: 2007-2021). Thirteen outcomes were assessed following the index date (first documented NYHA class assessment after first HCM diagnosis in the study period): all-cause mortality; first occurrences of all-cause hospitalization; CV-related hospitalization; primary ischemic stroke or transient ischemic attack (TIA); myocardial infarction (MI); deep vein thrombosis (DVT) or pulmonary embolism (PE); and major adverse CV event (MACE); as well as first incident events of atrial fibrillation or flutter; primary ischemic stroke or TIA; heart failure; acute MI; DVT/PE; and a composite endpoint of pacemaker and cardiac resynchronization therapy. Their associations with the index NYHA class were described using the Kaplan-Meier method (mortality) or cumulative incidence functions (other outcomes). Hazard ratios between NYHA class over time and outcomes were evaluated using time-varying Cox models, adjusting for age at first observed HCM diagnosis, sex, and race.
Results: Among 4,631 eligible patients, the mean age was 59 years at the first observed HCM diagnosis (female, 47%; White, 77%). The risks of all outcomes increased with worse (higher) index NYHA class and worsening NYHA class over time. Deterioration in the NYHA class from the index date was associated with increased risks of outcomes.
Limitations: The study population may not be representative of all patients with obstructive HCM in the real world. Documented NYHA classes may not fully reflect the longitudinal variation of NYHA class for each patient.
Conclusions: Worsening NYHA class was associated with increased risks of all-cause mortality and CV outcomes in obstructive HCM.
Keywords: Atrial fibrillation; I; I1; I10; I19; New York Heart Association (NYHA) class; cardiovascular outcomes; heart failure; hospitalization; major adverse cardiovascular event (MACE); mortality; myocardial infarction; obstructive hypertrophic cardiomyopathy; stroke.
The New York Heart Association (NYHA) class is a simple way for doctors to measure how bad a patient’s heart failure is by how it affects a person’s ability to do everyday activities. It is a 4-point scale from 1, indicating no limitations on activity and no shortness of breath, to 4, at which patients have symptoms even at rest and any activity leaves people struggling to catch their breath. NYHA class is also used to assess patients with obstructive hypertrophic cardiomyopathy (HCM), a disease that causes thickening of the heart muscle. While doctors know that as obstructive HCM becomes worse, patients are at greater risk of having to go to the hospital, getting other conditions (like atrial fibrillation or heart failure), having to have more treatments (like surgery), or even death, doctors and researchers do not know how much risk the patient has and how it changes as the disease changes over time. Although there have been some smaller studies that have estimated this risk, we studied a large, national database and found that patients with worse (higher) NYHA class over time had an increased risk of dying, having to go to the hospital for heart-related care, and developing other heart-related conditions. This finding suggests that it is important for doctors to follow up patients with obstructive HCM carefully and to adjust treatments in order to help patients to stay at lower NYHA classes to improve long-term outcomes.