Black patients with implantable cardioverter defibrillators (ICDs) have a significantly higher burden of disease than white patients with the identical device, in accordance with a recent study from University of Rochester Medical Center (URMC) cardiology researchers. Analyzing data from clinical trials conducted over a 20-year period by the Clinical Cardiovascular Research Center (CCRC) at URMC, investigators concluded that not only did Black patients with ICDs are likely to be significantly younger than white patients, but in addition they had a better rate of post-implant cardiac events and risk of death.

When a patient is in danger for cardiac arrest, an ICD helps to observe their heart rhythm, and if an abnormality is detected, the device delivers a shock of electricity to reset the heartbeat to a standard rhythm. The study, published in Circulation, examines the speed of events that a patient experiences after their ICD is implanted. After three years of monitoring, the danger of ventricular arrhythmia (sustained rapid heartbeat that may result in sudden cardiac death) was 20 percent for white patients, but 31 percent for Black patients. The opposite significant findings were that Black patients requiring an ICD appeared at younger ages, by five to 10 years, and the danger of death for Black patients, despite having an ICD to guard them, is 2 times higher.

There are two forms of heart failure. In a single, a heart attack can leave a scar, which develops the potential for future heart failure. That is ischemic cardiomyopathy (ICM). In the opposite, heart failure is attributable to comorbidities, corresponding to diabetes and hypertension. That is non-ischemic cardiomyopathy (NICM). An interesting note within the study shows there was virtually no difference in results for Black and white patients with ICM since the scar is basically the identical in each races, subsequently they’ve the identical issues and receive the identical treatment. It’s only in patients with NICM that there are stark differences between Black and white patients.

These results beg the query: why? Principal investigator Ilan Goldenberg, MD, said they will hypothesize some reasons for the differences, but not fully draw solid conclusions. “It is feasible that Black patients are usually not managed in addition to white patients due to health care disparities, but we didn’t discover any significant differences in our study. We did discover that after one yr, Black patients were more prone to discontinue some medications, but the explanations for which are unknown as well. The younger age of onset and the increased rate of comorbidities, corresponding to diabetes and hypertension, amongst Black patients with NICM is striking and will contribute to the more serious outcomes attributable to more advanced heart disease.”

The authors applied the Gini Index to their results. This index looks at zip codes across the country to check its residents wealth to areas surrounding it. For this particular study, the index scores for patients indicated that Black patients did are likely to come from areas with lower socioeconomic status. “Future studies should examine closely social determinants of health, which weren’t captured in our clinical trials, to see why these findings occurred,” said Goldenberg.

Lead writer Arwa Younis, MD, is a former research fellow from the URMC Clinical Cardiovascular Research Center who’s now on the Cleveland Clinic and still holds an adjunct position with URMC. Younis knew going into the study that there have been differences between racial groups with ICDs, but he was surprised by the extent of the outcomes. “There’s nothing worse than getting a shock for a patient,” said Younis. “And it’s difficult to see a patient proceed to receive shocks despite being on optimal medical therapy. In our study, we assessed patient compliance on the one-year mark and greater than 85 percent of patients remained compliant. So, despite being on optimal medical therapy and having a high compliance rate, the burden of disease remained very high for Black patients.”

In response to Younis, these results mean that Black patients with an ICD should receive aggressive positive treatment as early as possible. This implies monitoring patients closely, referring to specialists as needed, and implanting devices earlier on.

We consider the important implication of this study is that because we now know that Black patients who’ve heart failure usually tend to have more advanced arrhythmias, they must be considered earlier for an ICD defibrillator to guard them from sudden cardiac death.”

Ilan Goldenberg, MD, Principal Investigator

He also notes that primary prevention and treatment of comorbidities corresponding to diabetes and hypertension could also be one option to help prevent the burden of cardiac disease in Black patients.

Additional co-authors of the study from URMC include Sanah Ali, MD, Ido Goldenberg, MD, Scott McNitt, MS, Bronislava Polonsky, MS, Mehmet Aktas, MD, Valentina Kutyifa, MD, PhD, and Wojciech Zareba, MD, PhD. Co-authors from the Cleveland Clinic include Eileen Hsich, MD, and Oussama Wazni, MD, MBA.

Source:

University of Rochester Medical Center

Journal reference:

Younis, A., et al. (2023) Arrhythmia and Survival Outcomes Amongst Black Patients and White Patients With a Primary Prevention Defibrillator. Circulation. doi.org/10.1161/CIRCULATIONAHA.123.065367.