Racial Differences in Atrial Cardiopathy Phenotypes in Patients With Ischemic Stroke

Interrelations between albuminuria, electrocardiographic left atrial abnormality, and incident atrial fibrillation in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort

BACKGROUND

The objective of the study was to examine the joint associations of albuminuria and electrocardiographic left atrial abnormality (ECG-LAA) with incident atrial fibrillation (AF) and whether this relationship varies by race.

METHODS

This analysis included 6670 participants free of clinical cardiovascular disease (CVD), including atrial fibrillation (AF), from the Multi-Ethnic Study of Atherosclerosis. ECG-LAA was defined as P-wave terminal force in V1 [PTFV1] >5000 μV × ms. Albuminuria was defined as urine albumin-creatinine ratio (UACR) ≥30 mg/g. Incident AF events through 2015 were ascertained from hospital discharge records and study-scheduled electrocardiograms. Cox proportional hazard models were used to examine the association of "no albuminuria + no ECG-LAA (reference)", "isolated albuminuria", "isolated ECG-LAA" and "albuminuria + ECG-LAA" with incident AF.

RESULTS

Over a median follow-up of 13.8 years, 979 incident cases of AF occurred. In adjusted models, the concomitant presence of ECG-LAA and albuminuria was associated with a higher risk of AF than either ECG-LAA or albuminuria in isolation (HR (95% CI): 2.43 (1.65-3.58), 1.33 (1.05-1.69), and 1.55 (1.27-1.88), respectively (interaction p-value = 0.50). Effect modification by race was observed with a 4-fold greater AF risk in Black participants with albuminuria + ECG-LAA (HR (95%CI): 4.37 (2.38-8.01) but no significant association in White participants (HR (95% CI) 0.60 (0.19-1.92) respectively; (interaction p-value for race x albuminuria-ECG-LAA combination = 0.05).

CONCLUSIONS

Concomitant presence of ECG-LAA and albuminuria confers a higher risk of AF compared to either one in isolation with a stronger association in Blacks than Whites.

Atrial Fibrillation Detected After Stroke and Transient Ischemic Attack: A Novel Clinical Concept Challenging Current Views

Atrial fibrillation (AF) can be newly detected in approximately one-fourth of patients with ischemic stroke and transient ischemic attack without previously recognized AF. We present updated evidence supporting that AF detected after stroke or transient ischemic attack (AFDAS) may be a distinct clinical entity from AF known before stroke occurrence (known atrial fibrillation). Data suggest that AFDAS can arise from the interplay of cardiogenic and neurogenic forces. The embolic risk of AFDAS can be understood as a gradient defined by the prevalence of vascular comorbidities, the burden of AF, neurogenic autonomic changes, and the severity of atrial cardiopathy. The balance of existing data indicates that AFDAS has a lower prevalence of cardiovascular comorbidities, a lower degree of cardiac abnormalities than known atrial fibrillation, a high proportion (52%) of very brief (<30 seconds) AF paroxysms, and is more frequently associated with insular brain infarction. These distinctive features of AFDAS may explain its recently observed lower associated risk of stroke than known atrial fibrillation. We present an updated ad-hoc meta-analysis of randomized clinical trials in which the association between prolonged cardiac monitoring and reduced risk of ischemic stroke was nonsignificant (incidence rate ratio, 0.90 [95% CI, 0.71-1.15]). These findings highlight that larger and sufficiently powered randomized controlled trials of prolonged cardiac monitoring assessing the risk of stroke recurrence are needed. Meanwhile, we call for further research on AFDAS and stroke recurrence, and a tailored approach when using prolonged cardiac monitoring after ischemic stroke or transient ischemic attack, focusing on patients at higher risk of AFDAS and, more importantly, at higher risk of cardiac embolism.

Prognostic value of left atrial size in hypertensive African Americans undergoing stress echocardiography

BACKGROUND

Left atrial (LA) enlargement is a marker of increased risk in the general population undergoing stress echocardiography. African American (AA) patients with hypertension are known to have less atrial remodeling than whites with hypertension. The prognostic impact of LA enlargement in AA with hypertension undergoing stress echocardiography is uncertain.

AIM

To investigate the prognostic value of LA size in hypertensive AA patients undergoing stress echocardiography.

METHODS

This retrospective outcomes study enrolled 583 consecutive hypertensive AA patients who underwent stress echocardiography over a 2.5-year period. Clinical characteristics including cardiovascular risk factors, stress and echocardiographic data were collected from the electronic health record of a large community hospital. Treadmill exercise and Dobutamine protocols were conducted based on standard practices. Patients were followed for all-cause mortality. The optimal cutoff value of antero-posterior LA diameter for mortality was assessed by receiver operating characteristic analysis. Cox regression was used to determine variables associated with outcome.

RESULTS

The mean age was 57 ± 12 years. LA dilatation was present in 9% (54) of patients (LA anteroposterior ≥ 2.4 cm/m²). There were 85 deaths (15%) during 4.5 ± 1.7 years of follow-up. LA diameter indexed for body surface area had an area under the curve of 0.72 ± 0.03 (optimal cut-point of 2.05 cm/m²). Variables independently associated with mortality included age [P = 0.004, hazard ratio (HR) 1.34 (1.10-1.64)], tobacco use [P = 0.001, HR 2.59 (1.51-4.44)], left ventricular hypertrophy [P = 0.001 , HR 2.14 (1.35-3.39)], Dobutamine stress [P = 0.003, HR 2.12 (1.29-3.47)], heart failure history [P = 0.031, HR 1.76 (1.05-2.94)], LA diameter ≥ 2.05 cm/m² [P = 0.027, HR 1.73 (1.06-2.82)], and an abnormal stress echocardiogram [P = 0.033, HR 1.67 (1.04-2.68)]. LA diameter as a continuous variable was also independently associated with mortality but LA size ≥ 2.40 cm/m² was not.

CONCLUSION

LA enlargement is infrequent in hypertensive AA patients when traditional reference values are used. LA enlargement is independently associated with mortality when a lower than “normal” threshold (≥ 2.05 cm/m²) is used.