['Coronary microvascular resistance is increased after primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI), which may be related in part to changed left ventricular (LV) dynamics. Therefore we studied the coronary microcirculation in relation to systolic and diastolic LV function after STEMI.', 'The study cohort consisted of 12 consecutive patients, all treated with primary PCI for a first anterior wall STEMI. At 4\xa0months, we assessed pressure-volume loops. Subsequently, we measured intracoronary pressure and flow velocity and calculated coronary microvascular resistance. Infarct size and LV mass were assessed using magnetic resonance imaging.', 'Patients with an impaired systolic LV function due to a larger myocardial infarction showed a higher baseline average peak flow velocity (APV) than the other patients (26\u2009±\u20097 versus 17\u2009±\u20095\xa0cm/s, p\u2009=\u20090.003, respectively), and showed an impaired variable microvascular resistance index (2.1\u2009±\u20091.0 versus 4.1\u2009±\u20091.3\xa0mmHg\u2009cm(-1)∙s(-1), p\u2009=\u20090.003, respectively). Impaired diastolic relaxation time was inversely correlated with hyperaemic APV (r\u2009=\u2009-0.56, p\u2009=\u20090.003) and positively correlated with hyperaemic microvascular resistance (r\u2009=\u20090.48, p\u2009=\u20090.01). LV dilatation was associated with a reduced variable microvascular resistance index (r\u2009=\u20090.78, p\u2009=\u20090.006).'] Is coronary microcirculatory dysfunction associated with left ventricular dysfunction during follow-up after STEMI?