Cardiovascular disease disproportionately affects Black and Native American adults, undocumented immigrants, and Hispanic individuals, while cultural and language barriers in underserved clinics hinder health equity.1,2
Cardiovascular magnetic resonance (CMR), the standard for evaluating heart function and fibrosis, faces implementation challenges, including cost, lack of expertise, and coordination issues, compounded by longer scan times for non-English speakers despite advancements in free-breathing, motion-corrected techniques.3, 4, 5
Our institution’s imaging program serves a diverse group of patients, regardless of insurance status. This study assessed CMR's clinical utility in an underserved, uninsured U.S. population and the differences between evaluations in underserved clinics vs standard health care offices. In our study, “underserved clinics” are defined as those that serve uninsured patients. Those patients who are able pay a nominal co-pay to help defray the clinic expenses; patients who are unable, do not pay any fees. It also examined the efficacy of fully free-breathing CMR exams.
All participants in this prospective study consented to an Institutional Review Board-approved protocol, allowing for technical development in imaging and observational study of cardiovascular disease (NCT00027170). Non-English speakers gave informed consent via interpreters, using translated or short-form consents.
Over 4 years, outpatient referrals for clinically indicated CMR from local community physicians and 2 underserved health clinics formed the patient base.
CMR exams using a 1.5-T magnetic resonance imaging scanner evaluated cardiac structure, ventricular function, and myocardial scarring, incorporating additional techniques like stress perfusion and magnetic resonance angiography as needed, while accommodating patients with language barriers, breath-holding issues, or irregular heart rhythms using free-breathing, motion-corrected sequences.
Patient history and clinical data, including age, sex, race, body mass index (BMI), language, comorbidities, medications, blood pressure, heart rate, electrocardiograms, and scan duration, were collected.
For statistical analysis, unpaired t-tests were used to compare normally distributed data between groups, including categorical data. The Mann-Whitney test was used to analyze non-normal distributions. Categorical data were presented as counts and percentages, and continuous data as median (IQR). Analyses were executed using MedCalc, version 12 (statistical significance set at P < 0.05).
In a cohort analysis of 179 patients (after removal of 4 claustrophobic subjects), final analysis included 76 referred from underserved clinics and 103 from traditional payer health settings. Compared to those from traditional payer clinics, demographics showed those from underserved clinics were more likely Asian (23.7% vs 5.8%, respectively) or Black/African-American (52.6% vs 9.7%, respectively) (P < 0.001), non-English speakers (46.0% vs 1.9%, respectively; P < 0.001), and had higher instances of hypertension (79.0% vs 48.5%, respectively; P < 0.001), hyperlipidemia (59.2% vs 39.8%, respectively; P = 0.011), diabetes mellitus (31.6% vs 15.5%, respectively; P = 0.012), and greater BMI (29.6 vs 26.6 kg/m2, P < 0.001). There was no significant difference in the past occurrence of coronary artery disease (9.2% vs 9.7%, P = 0.913) and revascularizations (11.8% vs 7.7%, P = 0.372) between patients who received treatment from underserved clinics and those who did not.
CMR referrals from underserved clinics were often for ischemia or scar (75%, P < 0.001), and free-breathing scans were shorter than breath-held scans, with underserved clinic referrals being notably quicker (44.5 minutes vs 55.4 minutes, respectively; P < 0.001). Underserved clinic patients exhibited a higher prevalence of abnormal stress perfusion (24/40 stresses, 60% vs 5/15 stresses, 33.3% for the payer group), dilated cardiomyopathy (38.2% vs 11.7%), and myocardial fibrosis (39.5% vs 14.2%) (P < 0.001 for all). They had higher rates of left ventricular hypertrophy (35.5% vs 16.5%, P = 0.004). Two patients from the underserved clinics had newly diagnosed intracardiac shunts. Table 1 summarizes key CMR findings.
Table 1.
Cardiovascular Magnetic Resonance Findings
| Underserved Clinic Referrals (n = 76) | Traditional Payer Community Clinic Referrals (n = 103) | P Value | |
|---|---|---|---|
| Age (y), median (IQR) | 62 (20.0) | 60.5 (25.3) | 0.082 |
| Female | 38 (50.0) | 45 (43.7) | 0.402 |
| BMI (kg/m2), median (IQR) | 29.57 (7.5) | 26.63 (5.3) | <0.001 |
| Length of scan (min) | 46.46 ± 9.0 | 61.52 ± 14.8 | <0.001 |
| Stress perfusion | 40 (54.8) | 15 (14.6) | <0.001 |
| Abnormal stress perfusion | 24 (31.6) | 5 (5.8) | <0.001 |
| Late gadolinium enhancement | |||
| Enhancement present | 30 (39.5) | 14 (14.2) | <0.001 |
| Myocardial infarction pattern | 23 (30.3) | 7 (7.6) | <0.001 |
| Atypical pattern | 7 (9.2) | 7 (6.6) | 0.566 |
| Structural abnormalities noted | |||
| Left ventricular hypertrophy | 27 (35.5) | 17 (16.5) | 0.004 |
| Dilated cardiomyopathy | 29 (38.2) | 12 (11.7) | <0.001 |
| Valvular | 4 (5.3) | 9 (8.7) | 0.394 |
| Mass | 1 (1.3) | 1 (1.0) | 0.859 |
| Congenital (eg, ASD, VSD, coarctation of aorta) | 3 (4.0) | 19 (18.5) | 0.004 |
| Vascular (eg, dilated aorta, dilated pulmonary artery) | 4 (5.3) | 5 (4.9) | 0.907 |
| Functional metrics, median (IQR) | |||
| LVEDV indexed (mL/m2) | 85.64 (33.0) | 84.77 (27.5) | 0.749 |
| LVESV indexed (mL/m2) | 34.14 (23.8) | 35.48 (17.0) | 0.729 |
| LVSV | 83.1 (33.9) | 88.9 (29.8) | 0.25 |
| LVEF (%) | 57.71 (13.0) | 56.84 (8.6) | 0.611 |
| LV mass indexed (g/m2) | 50.72 (20.3) | 49.12 (17.1) | 0.428 |
| RVEDV indexed (mL/m2) | 73.94 (22.4) | 81.37 (29.7) | 0.095 |
| RVESV indexed (mL/m2) | 28.64 (13.5) | 33.74 (14.8) | 0.08 |
| RVSV | 81.9 (29.7) | 88.3 (32.4) | 0.115 |
| RVEF (%) | 58.86 (12.5) | 58.61 (9.1) | 0.382 |
| Reason for free-breathing scan, (of all 70 free-breathing scans) | |||
| Arrhythmia | 7 (0.1) | 15 (21.4) | 0.069 |
| Non-English speaking | 38 (54.3) | 1 (1.4) | <0.001 |
| Claustrophobia/Anxiety | 2 (2.9) | 3 (4.3) | 0.678 |
| Other | 3 (4.3) | 1 (1.4) | 0.364 |
Values are n (%) or mean ± SD unless otherwise indicated. Bold values indicated P value < 0.05 and is considered statistically significant.
ASD = atrial septal defect; BMI = body mass index; CMR = cardiovascular magnetic resonance; LV = left ventricular; LVEDV = left ventricular end-diastolic volume; LVEF = left ventricular ejection fraction; LVESV = left ventricular end-systolic volume; LVSV = left ventricular stroke volume; RVEDV = right ventricular end-diastolic volume; RVEF = right ventricular ejection fraction; RVESV = right ventricular end-systolic volume; RVSV = right ventricular stroke volume; VSD = ventricular septal defect.
Electrocardiograms indicated that patients from underserved clinics showed more nonspecific ST-T-wave changes and possible ischemic changes (31.6% vs 14.6%, P = 0.007), and atrioventricular block and ventricular ectopy (11.8% vs 2.9%, P = 0.023).
We acknowledge that there may be factors such as referral bias that account for differences in the indications for CMR between underserved clinics and traditional payer settings. However, this study confirms existing data indicating that individuals with constrained health care access exhibit elevated BMIs and baseline blood pressures, which heightens their risk of developing cardiovascular risks like hypertension, hyperlipidemia, and diabetes compared to those with traditional health care coverage. Such patients are at an increased risk of cardiac complications, as revealed by abnormal baseline electrocardiograms and CMR findings of left ventricular hypertrophy, dilated cardiomyopathies, ischemia, and myocardial infarction (MI). Despite having similar rates of past coronary artery disease history as the traditional payer group, patients from underserved clinics had more CMR diagnosis of MI.
In conclusion, our study highlights the modern persistence of health care disparities seen in minorities and those with inadequate access to health care with a high burden of cardiovascular risk and pathology identified by CMR. Significantly, this research also introduces free-breathing CMR as a time-efficient and patient-friendly alternative to the conventional breath-held approach, while still preserving diagnostic image quality, offering particular benefit to patients who are not proficient in English, are unable to breath-hold, or have irregular baseline rhythms. In a high-risk group of patients, CMR demonstrates its strengths in providing a comprehensive assessment of cardiovascular pathophysiology, which may alter management, for example, implementation of guideline-directed medical therapy in subclinical MI, undiagnosed ischemia, or cardiomyopathy, and thus potentially affect outcomes and prognosis in patients.
Footnotes
This research was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health Intramural Research Program (1ZIAHL006220).
Disclaimer: The content of this manuscript is solely the responsibility of the authors and does not necessarily reflect the official views of the National Heart, Lung, and Blood Institute, National Institutes of Health, or the United States Department of Health and Human Services. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
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