First we feast: a narrative review of postprandial assessment of left ventricular outflow tract obstruction in hypertrophic cardiomyopathy.

BACKGROUND: Dynamic left ventricular outflow tract (LVOT) obstruction is a common and consequential feature of hypertrophic cardiomyopathy (HCM), present in a majority of patients at rest or with provocation, and it directly influences symptom burden and eligibility for therapy. When obstruction is absent at rest it can be provoked by physiologic stimuli, including the ingestion of a meal, a phenomenon patients have reported for decades. Whether postprandial assessment improves detection of obstructive physiology over conventional provocative testing has not been systematically examined. METHODS: We searched PubMed/MEDLINE, Embase, the Cochrane Library, and Web of Science from inception through June 2025. Study quality was assessed with the Newcastle-Ottawa Scale. Because of substantial heterogeneity in study protocols and outcome definitions, we performed a narrative synthesis rather than a meta-analysis. RESULTS: Seven studies met inclusion criteria, published between 1991 and 2024 across three countries. Across these studies, postprandial assessment consistently provoked higher LVOT gradients than fasting measurement and identified obstructive physiology in patients with no obstruction on conventional testing. In the most rigorous comparative study, postprandial echocardiography identified gradients ≥ 30 mmHg in 74% of patients with no resting obstruction, compared with 23% by Valsalva maneuver (p < 0.001). In the largest cohort (n = 252), postprandial testing identified gradients ≥ 50 mmHg in an additional 35.7% of patients who did not reach that threshold under routine conditions. Invasive hemodynamic data provide a mechanistic basis: meal ingestion reduced systemic vascular resistance and raised cardiac filling pressures, conditions that favor dynamic obstruction. CONCLUSIONS: Postprandial LVOT assessment identifies obstructive physiology that conventional provocative maneuvers miss. As approved medical therapies targeting LVOT obstruction reshape HCM management, accurate identification of the obstructive phenotype carries direct therapeutic consequences. Standardized multicenter validation is needed, but existing evidence supports consideration of postprandial testing in symptomatic patients who remain without obstruction on conventional assessment.