Association Between Coronary Assessment in Heart Failure and Clinical Outcomes Within a Safety-Net Setting Using a Target Trial Emulation Observational Design

Abstract

Background: Ischemic cardiomyopathy is the leading cause of heart failure (HF). Most patients do not undergo coronary assessment after HF diagnosis. There are no randomized clinical trials of coronary assessment after HF diagnosis.

Methods: Using an electronic health record cohort of all individuals with HF within the San Francisco Health Network from 2001 to 2019, we identified factors associated with coronary assessment. Then, we studied the association of coronary assessment within 30 days of HF diagnosis with all-cause mortality and a composite of mortality and emergent angiography using a target trial emulation observational comparative-effectiveness approach. Target trial emulation is an approach to causal inference based on creating a hypothetical randomized clinical trial protocol and using observational data to emulate the protocol. We used propensity scores for covariate adjustment. We used national death records to improve the ascertainment of mortality and included falsification end points for the cause of death.

Results: Among 14 829 individuals with HF (median, 62 years old; 5855 [40%] women), 3987 (26.9%) ever completed coronary assessment, with 2467/13 301 (18.5%) with unknown coronary artery disease status at HF diagnosis assessed. Women, older individuals, and people without stable housing were less likely to complete coronary assessment. Among 5972 eligible persons of whom 627 underwent early elective coronary assessment, coronary assessment was associated with lower mortality (hazard ratio, 0.84 [95% CI, 0.72-0.97]; P=0.025), reduced risk of the composite outcome (hazard ratio, 0.86 [95% CI, 0.73-1.00]), higher rates of revascularization (odds ratio, 7.6 [95% CI, 5.4-10.6]), and higher use of medical therapy (odds ratio, 2.5 [95% CI, 1.7-3.6]), but not the falsification end points.

Conclusions: In a safety-net population, disparities in coronary assessment after HF diagnosis are not fully explained by coronary artery disease risk factors. Early coronary assessment is associated with improved HF outcomes possibly related to higher rates of revascularization and guideline-directed medical therapy but with low certainty that this finding is not attributable to unmeasured confounding.

Keywords: angiography; coronary artery disease; disparities; heart failure; mortality.

Figure 1.

Trends in echocardiography and coronary assessment by year. The proportion of individuals with incident heart failure who completed coronary assessment (navy) and echocardiogram (lavender) within 30 days of diagnosis and the proportion hospitalized with heart failure with reduced ejection fraction at the time of diagnosis prescribed outpatient guideline-directed medical therapy (GDMT) at hospital discharge (orange) by year. There was a statistically significant trend for less coronary assessment completed over time and much higher rates of GDMT prescription in the more recent years of the study. HF indicates heart failure.

Figure 2.

Consort diagram for target trial of elective coronary assessment at the time of heart failure (HF) diagnosis. To make good use of our observational data, we emulated a randomized controlled trial of elective coronary assessment at the time of heart failure diagnosis by creating a hypothetical trial of individuals “assigned” to early coronary assessment compared to those assigned to not undergo coronary assessment. This figure shows how we excluded individuals prevalent heart failure, with known coronary artery disease (CAD), competing diagnoses (cirrhosis/cancer), then by timing of coronary assessment, and finally excluding those whose initial presentation necessitated emergent coronary angiography (who would be more likely to benefit). CABG indicates coronary artery bypass graft; NSTEMI, non-ST elevation myocardial infarction; PCI, percutaneous coronary intervention; and STEMI, ST elevation myocardial infarction.

Figure 3.

Association of early coronary assessment in heart failure (HF) with outcomes. After defining the target trial, we adjusted for age, sex, propensity for coronary assessment as a restricted cubic spline, and HF hospitalization before testing and show the adjusted survival curves by concurrent coronary assessment. Hazard ratios (HRs) are comparing those who completed early coronary assessment to those who did not, with the bottom two additionally adjusting for revascularization (bottom left) and use of guideline-directed medical therapy (GDMT) among hospitalized patients with heart failure with reduced ejection fraction (bottom right). At-risk tables are shown below each. CA indicates coronary assessment.