PROMIS-HFpEF, the largest prospective multinational study ever conducted to assess the prevalence of coronary microvascular dysfunction (CMD) in HFpEF patients, demonstrates that this condition is associated with systemic endothelial dysfunction, heart failure severity, and myocardial dysfunction. Hence, coronary microvascular dysfunction may be a composite risk marker and a potential therapeutic target in HFpEF. Carolyn S.P. Lam (National Heart Centre, Duke-NUS Medical School, Singapore) reports on the results of the PROMIS-HFpEF trial at ESC18, the annual meeting of the European Society of Cardiology.