ATRIAL FIBRILLATION OR ATRIAL FLUTTER

Summary

The Veteran, a U.S. Navy Veteran who served from September 1968 to August 1972, appeals the denial of service connection for atrial fibrillation, left carotid artery stenosis, cerebrovascular accident (CVA) residuals, and valvular heart disease. The Veteran claims these conditions are related to presumed herbicide agent exposure during his Vietnam service. The Board found favorable evidence for the existence of the current disabilities and the in-service herbicide exposure for all four conditions. The primary issue was establishing a medical nexus between the exposure and the claimed cardiovascular and cerebrovascular conditions. The Board considered a VA medical opinion that found the conditions less likely than not related to herbicide exposure, attributing them to general risk factors like age and hypertension. However, the Board found a private medical opinion highly probative, which linked herbicide exposure and TCDD toxicity to endothelial dysfunction, inflammation, oxidative stress, and metabolic disruption, contributing to vascular injury and systemic atherosclerotic disease, manifesting as the Veteran's conditions. This private opinion also rebutted the VA opinion's reliance on general risk factors. Applying the benefit of the doubt doctrine, the Board found the evidence in approximate balance for all four conditions, granting service connection for atrial fibrillation, left carotid artery stenosis, CVA residuals, and valvular heart disease.

Rationale

Favorable finding of current disability diagnosis; Favorable finding of presumed in-service herbicide exposure; Private medical opinion found highly probative for nexus; Benefit of the doubt applied due to approximate balance of evidence

Full Decision Text

Citation Nr: A26027979
Decision Date: 03/27/26	Archive Date: 03/27/26

DOCKET NO. 250708-561578
DATE: March 27, 2026

ORDER

Entitlement to service connection for atrial fibrillation is granted.

Entitlement to service connection for left carotid artery stenosis is granted.

Entitlement to service connection for cerebrovascular accident residuals is granted.

Entitlement to service connection for valvular heart disease (also claimed as mitral regurgitation and tricuspid) is granted.

FINDINGS OF FACT

1. The evidence is in at least approximate balance that there is a medical nexus between the Veteran's current atrial fibrillation and his in-service herbicide agent exposure.

2. The evidence is in at least approximate balance that there is a medical nexus between the Veteran's current left carotid artery stenosis and his in-service herbicide agent exposure.

3. The evidence is in at least approximate balance that there is a medical nexus between the Veteran's current cerebrovascular accident residuals and his in-service herbicide agent exposure.

4. The evidence is in at least approximate balance that there is a medical nexus between the Veteran's current valvular heart disease and his in-service herbicide agent exposure.

CONCLUSIONS OF LAW

1. The criteria for entitlement to service connection for atrial fibrillation have been met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.304.

2. The criteria for entitlement to service connection for left carotid artery stenosis have been met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.304.

3. The criteria for entitlement to service connection for cerebrovascular accident have been met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.304.

4. The criteria for entitlement to service connection for valvular heart disease have been met. 38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.303, 3.304.

REASONS AND BASES FOR FINDINGS AND CONCLUSIONS

The Veteran served in the U.S. Navy from September 1968 to August 1972.

A July 7, 2024 rating decision denied service connection for atrial fibrillation, cerebrovascular accident, left carotid artery stenosis, and valvular heart disease. The Veteran requested a Higher-Level Review (HLR) and received a decision on January 13, 2025. The Agency of Original Jurisdiction (AOJ) remanded the claims to remedy pre-decisional duty-to-assist errors. Upon completing these tasks, a May 21, 2025 rating decision again denied service connection for atrial fibrillation, cerebrovascular accident, left carotid artery stenosis, and valvular heart disease. The Veteran timely appealed this decision to the Board by requesting the Appeals Modernization Act (AMA) Hearing Lane for a reevaluation of the evidence considered by the AOJ. See July 2025 VA Form 10182. As this is a Hearing appeal under the AMA, the record closed on the date of the May 2025 rating decision, reopened on the date of the December 11, 2025 hearing, and would close 90 days after the hearing on March 11, 2026 unless otherwise waived. See 38 C.F.R. § 20.302. However, because the Veteran waived the remainder of the evidence submission period on March 9, 2026, the record closed on that date. If evidence was associated with the claims file during a period of time when additional evidence was not allowed, the Board has not considered it in its decision on the claims on appeal. 38 C.F.R. § 20.300.

Service Connection

Service connection may be granted for disability resulting from disease or injury incurred in or aggravated by active service. See 38 U.S.C. § 1110; 38 C.F.R. § 3.303. The three-element test for service connection requires evidence of: (1) a current disability; (2) in-service incurrence or aggravation of a disease or injury, and; (3) a causal relationship between the current disability and the in-service disease or injury. See Shedden v. Principi, 381 F.3d 1163, 1166-67 (Fed. Cir. 2004
 on the claims on appeal. 38 C.F.R. § 20.300.

Service Connection

Service connection may be granted for disability resulting from disease or injury incurred in or aggravated by active service. See 38 U.S.C. § 1110; 38 C.F.R. § 3.303. The three-element test for service connection requires evidence of: (1) a current disability; (2) in-service incurrence or aggravation of a disease or injury, and; (3) a causal relationship between the current disability and the in-service disease or injury. See Shedden v. Principi, 381 F.3d 1163, 1166-67 (Fed. Cir. 2004).

When there is an approximate balance of positive and negative evidence regarding any issue material to the determination of a matter, VA shall give the benefit of the doubt to the claimant. 38 U.S.C. § 5107(b). It follows, that when the evidence persuasively favors one side or the other, the benefit-of-the-doubt rule is not applied. Lynch v. McDonough, 21 F.4th 776 (Fed. Cir. 2021).

1. Entitlement to service connection for atrial fibrillation is granted.

The Veteran contends that his current atrial fibrillation is related to his exposure to herbicide agents during his Vietnam service. See, e.g., December 2025 Hearing Transcript, p. 3.

The AOJ made the favorable findings that the Veteran has a current disability diagnosis of atrial fibrillation, also recorded as "supraventricular arrhythmia (supraventricular tachycardia), cardiomyopathy, and left bundle branch block," and the Veteran had an in-service injury of presumed exposure to herbicide agents during his Vietnam active-duty service. See May 2025 Rating Decision. See also January 12, 2023 Private Treatment Record. Therefore, the Board finds these elements of service connection have been established.

The Board next considers whether there is sufficient evidence to establish a medical nexus between the Veteran's atrial fibrillation disability and his in-service herbicide agent exposure.

In a February 2025 VA medical opinion, the examiner opined that the Veteran's atrial fibrillation disability is less likely than not related to his herbicide agent exposure during service because "there is no medical or scientific evidence available that provides any indication of a relationship between the development" of atrial fibrillation and herbicide agent exposure, instead attributing the Veteran's disability to the potential applicability of the risk factors of "advanced age, high blood pressure, underlying heart and lung disease, congenital heart disease, and increased alcohol consumption." The Board assigns this opinion probative weight to the nexus at issue.

In a March 2026 private medical opinion, the examining physician opined that although atrial fibrillation is not listed as a disability presumptively related to herbicide agent exposure, "the absence of a presumptive designation does not preclude direct service connection when the available medical evidence supports a causal relationship between toxic exposure and the development of disease." He explained that "from a pathophysiologic standpoint, herbicide exposure and TCDD toxicity have been associated in experimental and epidemiologic studies with endothelial dysfunction, chronic inflammatory activation, oxidative stress, and metabolic disruption," these processes contribute to vascular injury and the development of systemic atherosclerotic disease, and "peripheral arterial disease and carotid artery disease represent manifestations of systemic atherosclerosis affecting the peripheral and cerebrovascular circulation." This pathology also led to the Veteran subsequently developing atrial fibrillation. The examining physician also opined that "while age and hypertension are recognized contributors to cardiovascular disease in the general population, the presence of these risk factors does not exclude the role of toxic exposure," highlighting that for a nexus to be established for VA compensation purposes, "the question is not whether herbicide exposure was the sole cause of the condition, but whether it contributed to the development of the disease to a degree that is at least as likely as not." Finally, the examiner specifically rebuts the VA medical opinion of record, indication its rationale "relies primarily on general population risk factors and does not meaningfully address the veteran's confirmed herbicide exposure or the medical literature describing cardiovascular effects associated with TCDD exposure." The Board finds this opinion highly probative to the medical nexus at issue.

Giving the benefit of the doubt to the Veteran, the Board finds that the evidence is at least in approximate balance that the Veteran's atrial fibrillation disability is related to his in-service herbicide agent exposure. 38 U.S.C. § 5107; 38 C.F.R. § 3.102.

Therefore, entitlement to service connection for atrial fibrillation is granted.

2. Entitlement to service connection for left carotid artery stenosis
 record, indication its rationale "relies primarily on general population risk factors and does not meaningfully address the veteran's confirmed herbicide exposure or the medical literature describing cardiovascular effects associated with TCDD exposure." The Board finds this opinion highly probative to the medical nexus at issue.

Giving the benefit of the doubt to the Veteran, the Board finds that the evidence is at least in approximate balance that the Veteran's atrial fibrillation disability is related to his in-service herbicide agent exposure. 38 U.S.C. § 5107; 38 C.F.R. § 3.102.

Therefore, entitlement to service connection for atrial fibrillation is granted.

2. Entitlement to service connection for left carotid artery stenosis is granted.

The Veteran contends that his current left carotid artery stenosis is related to his exposure to herbicide agents during his Vietnam service. See, e.g., December 2025 Hearing Transcript, p. 3.

The AOJ made the favorable findings that the Veteran has a current disability diagnosis of left carotid artery stenosis, also recorded as peripheral arterial disease, and the in-service injury of presumed exposure to herbicide agents during his Vietnam active-duty service. See May 2025 Rating Decision. See also September 8, 2011 Private Treatment Record ("The patient recently had a left carotid endarterectomy . . . It felt to be prudent to take care of this early as it a significant stenosis contralateral to his most recent CVA."). Therefore, the Board finds these elements of service connection have been established.

The Board next considers whether there is sufficient evidence to establish a medical nexus between the Veteran's left carotid artery stenosis disability and his in-service herbicide agent exposure.

In a February 2025 VA medical opinion, the examiner opined the Veteran's current left carotid artery stenosis was "less likely than not" related to his in-service herbicide agent exposure because "there is no medical or scientific evidence available that provides any indication of a relationship between the development of the condition(s) at issue and the TERA." Instead, the examiner attributed the Veteran's carotid disability to systemic atherosclerotic disease, and the Veteran's potential risk factors of "smoking, hyperlipidemia, male gender, and increased age." The Board assigns this opinion some probative weight, reduced somewhat because the rationale does not appear to contemplate whether the systemic atherosclerotic disease could be related to his herbicide agent exposure.

In a March 2026 private medical opinion, the examining physician opined that although peripheral arterial disease is not listed as a disability presumptively related to herbicide agent exposure, "the absence of a presumptive designation does not preclude direct service connection when the available medical evidence supports a causal relationship between toxic exposure and the development of disease." He explained that "from a pathophysiologic standpoint, herbicide exposure and TCDD toxicity have been associated in experimental and epidemiologic studies with endothelial dysfunction, chronic inflammatory activation, oxidative stress, and metabolic disruption," these processes contribute to vascular injury and the development of systemic atherosclerotic disease, and "peripheral arterial disease and carotid artery disease represent manifestations of systemic atherosclerosis affecting the peripheral and cerebrovascular circulation." The examining physician also opined that "while age and hypertension are recognized contributors to cardiovascular disease in the general population, the presence of these risk factors does not exclude the role of toxic exposure," highlighting that for a nexus to be established for VA compensation purposes, "the question is not whether herbicide exposure was the sole cause of the condition, but whether it contributed to the development of the disease to a degree that is at least as likely as not." Finally, the examiner specifically rebuts the VA medical opinion of record, indication its rationale "relies primarily on general population risk factors and does not meaningfully address the veteran's confirmed herbicide exposure or the medical literature describing cardiovascular effects associated with TCDD exposure." The Board finds this opinion highly probative to the medical nexus at issue.

Giving the benefit of the doubt to the Veteran, the Board finds that the evidence is at least in approximate balance that the Veteran's left carotid artery stenosis disability is related to his in-service herbicide agent exposure. 38 U.S.C. § 5107; 38 C.F.R. § 3.102.

Therefore, entitlement to service connection for left carotid artery stenosis is granted.

3. Entitlement to service connection for cerebrovascular accident residuals is granted.

The Veteran contends that his cerebrovascular accident is related to his exposure to herbicide agents during his Vietnam service. See, e.g., December 2025 Hearing Transcript, p. 3.

The AOJ made the favorable findings that the Veteran has a current disability diagnosis of a cerebrovascular
 that the evidence is at least in approximate balance that the Veteran's left carotid artery stenosis disability is related to his in-service herbicide agent exposure. 38 U.S.C. § 5107; 38 C.F.R. § 3.102.

Therefore, entitlement to service connection for left carotid artery stenosis is granted.

3. Entitlement to service connection for cerebrovascular accident residuals is granted.

The Veteran contends that his cerebrovascular accident is related to his exposure to herbicide agents during his Vietnam service. See, e.g., December 2025 Hearing Transcript, p. 3.

The AOJ made the favorable findings that the Veteran has a current disability diagnosis of a cerebrovascular accident (CVA) residuals, also recorded as a "thrombosis, TIA or cerebral infarction," and the in-service injury of presumed exposure to herbicide agents during his Vietnam active-duty service. See May 2025 Rating Decision. See also September 8, 2011 Private Treatment Record (discussing possible complications of the Veteran's "most recent CVA"). Therefore, the Board finds these elements of service connection have been established.

The Board next considers whether there is sufficient evidence to establish a medical nexus between the Veteran's CVA residuals disability and his in-service herbicide agent exposure.

In a February 2025 VA medical opinion, the examiner opined the Veteran's CVA residuals are "less likely than not" related to his in-service herbicide agent exposure because "there are risk factors outside of military service" which "far outweigh the factors identified in the TERA [memorandum]," instead attributing the disability to the "underlying risk factors of carotid artery stenosis and atrial fibrillation." The Board finds this opinion probative to the nexus at issue, but that in the context of the Board's above grants of service connection for atrial fibrillation and left carotid artery stenosis, it is actually supportive of a grant of service connection, albeit on a secondary basis.

In a March 2026 private medical opinion, the examining physician opined that "from a pathophysiologic standpoint, herbicide exposure and TCDD toxicity have been associated in experimental and epidemiologic studies with endothelial dysfunction, chronic inflammatory activation, oxidative stress, and metabolic disruption," these processes contribute to vascular injury and the development of systemic atherosclerotic disease, and "peripheral arterial disease and carotid artery disease represent manifestations of systemic atherosclerosis affecting the peripheral and cerebrovascular circulation." He indicated that subsequently, the Veteran also developed atrial fibrillation and cardiomyopathy, "conditions that frequently arise in the setting of chronic structural cardiac disease and vascular pathology" and that "significantly increase the risk of thromboembolic complications, including cerebrovascular accident, which occurred in this case." The examining physician also opined that "while age and hypertension are recognized contributors to cardiovascular disease in the general population, the presence of these risk factors does not exclude the role of toxic exposure," highlighting that for a nexus to be established for VA compensation purposes, "the question is not whether herbicide exposure was the sole cause of the condition, but whether it contributed to the development of the disease to a degree that is at least as likely as not." Finally, the examiner specifically rebuts the VA medical opinion of record, indication its rationale "relies primarily on general population risk factors and does not meaningfully address the veteran's confirmed herbicide exposure or the medical literature describing cardiovascular effects associated with TCDD exposure." The Board finds this opinion highly probative to the medical nexus at issue.

Giving the benefit of the doubt to the Veteran, the Board finds that the evidence is at least in approximate balance that the Veteran's CVA residuals disability is related to his in-service herbicide agent exposure. 38 U.S.C. § 5107; 38 C.F.R. § 3.102.

Therefore, entitlement to service connection for CVA residuals is granted.

4. Entitlement to service connection for valvular heart disease (also claimed as mitral regurgitation and tricuspid) is granted.

The Veteran contends that his current valvular heart disease is related to his exposure to herbicide agents during his Vietnam service. See, e.g., December 2025 Hearing Transcript, p. 3.

The AOJ made the favorable finding that the Veteran incurred the in-service injury of presumed exposure to herbicide agents during his Vietnam active-duty service. See May 2025 Rating Decision. Therefore, the Board finds this element of service connection has been established.

The Board next considers whether there is sufficient evidence to establish the Veteran has a current valvular heart disease diagnosis.

In a September 2011 private treatment record, the Veteran's treating cardiologist recorded that his cardiac symptomology included "mild mitral regurgitation"
 granted.

The Veteran contends that his current valvular heart disease is related to his exposure to herbicide agents during his Vietnam service. See, e.g., December 2025 Hearing Transcript, p. 3.

The AOJ made the favorable finding that the Veteran incurred the in-service injury of presumed exposure to herbicide agents during his Vietnam active-duty service. See May 2025 Rating Decision. Therefore, the Board finds this element of service connection has been established.

The Board next considers whether there is sufficient evidence to establish the Veteran has a current valvular heart disease diagnosis.

In a September 2011 private treatment record, the Veteran's treating cardiologist recorded that his cardiac symptomology included "mild mitral regurgitation" and "mild tricuspid regurgitation." See September 30, 2011 Private Treatment Record. The result of a December 2010 echocardiogram also recorded an impression including "+1" mitral and tricuspid regurgitation. See December 22, 2010 Private Treatment Record. See also March 2026 Private Cardiac Examination (listing mitral regurgitation and tricuspid regurgitation in Veteran's medical history); id. ("The veteran has also demonstrated structural cardiac abnormalities including reduced left ventricular systolic function and chamber dilation.") Alternatively, during his February 2025 VA Heart Condition examination, the examiner concluded the Veteran had the cardiological diagnoses of supraventricular arrhythmia, cardiomyopathy, and left bundle branch block, but no valvular heart disease nor other heart valve conditions.

Giving the Veteran the benefit of the doubt, the Board finds the evidence is in at least approximate balance that the Veteran has a valvular heart disease diagnosis, specifically one pertaining to mitral and tricuspid dysfunction.

The Board next considers whether there is sufficient evidence to establish a medical nexus between the Veteran's valvular heart disease disability and his in-service herbicide agent exposure.

On a February 2025 VA medical opinion form, the examiner indicated that no opinion was rendered for the Veteran's valvular heart disease disability because "there was no pathology to render a diagnosis." As the previous does not discuss the medical nexus at issue, the Board assigns it no probative weight.

In a March 2026 private medical opinion, the examining physician opined that medical scholarship has "identified associations between herbicide exposure and the later development of cardiovascular disease, particularly ischemic heart disease and other manifestations of systemic vascular injury." He also argued that "the absence of a presumptive designation does not preclude direct service connection when the available medical evidence supports a causal relationship between toxic exposure and the development of disease." He explained that "from a pathophysiologic standpoint, herbicide exposure and TCDD toxicity have been associated in experimental and epidemiologic studies with endothelial dysfunction, chronic inflammatory activation, oxidative stress, and metabolic disruption," these processes contribute to vascular injury and the development of systemic atherosclerotic disease. The examining physician also opined that "while age and hypertension are recognized contributors to cardiovascular disease in the general population, the presence of these risk factors does not exclude the role of toxic exposure," highlighting that for a nexus to be established for VA compensation purposes, "the question is not whether herbicide exposure was the sole cause of the condition, but whether it contributed to the development of the disease to a degree that is at least as likely as not." The Board finds this opinion highly probative to the medical nexus at issue.

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Giving the benefit of the doubt to the Veteran, the Board finds that the evidence is at least in approximate balance that the Veteran's valvular heart disease disability is related to his in-service herbicide agent exposure. 38 U.S.C. § 5107; 38 C.F.R. § 3.102.

Therefore, entitlement to service connection for valvular heart disease is granted.

 

 

Martin T. Mitchell

Veterans Law Judge

Board of Veterans' Appeals

Attorney for the Board	Galik, E.

The Board's decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.