The Veteran's claim for an increased rating for residuals of submucous resection was denied as the maximum schedular rating has been assigned. The claims of service connection for endocarditis, atrial fibrillation, neuromuscular disease of the left and right lower extremities, and macular degeneration were all denied due to lack of evidence linking these conditions to his active military service.

The Board has remanded the claim of entitlement to SMC based on the need for aid and attendance for the Veteran's spouse due to conflicting information in the June 2025 examination. A VA examination is needed to determine if the spouse requires regular aid and attendance.

The Board has determined that the Veteran's cause of death (acute respiratory failure, atrial fibrillation, and/or hypertension) is related to his active duty service, including from exposure to toxins and chemicals from open burn pits during the harsh winters in Korea. The Board finds a pre-decisional duty to assist error and remands for obtaining a VA medical opinion.

The Veteran's death was caused by cardiopulmonary arrest, with congestive heart failure, atrial fibrillation, and coronary artery disease presence of stent as the underlying cause. The Board has determined that there is a need for additional medical opinion regarding whether the Veteran's hypertension, which he had during service, contributed to his death.

The Board denied the Veteran's claim of service connection for cause of death, finding that his service-connected conditions did not contribute to his death. The evidence showed well-controlled heart symptoms prior to death and no causal relationship between anxiety and cardiopulmonary disease or renal failure.