Rationale With the advent of primary PCI (PPCI), reperfusion is achieved in almost all patients presenting with acute myocardial infarction. However, despite multiple trials, reperfusion injury has not been successfully dealt with so far. In mouse models, CD4+ T lymphocytes (T cells) have been shown to be crucial instigators of reperfusion injury. Objective Our goal was to investigate the role of CD4+ T cells during myocardial reperfusion following PPCI by developing a protocol for high-throughput multiplexed flow cytometric analysis and multivariate flow clustering. Methods and Results 13-parameter immunophenotyping and hierarchical cluster analysis (HCA) identified a unique CD4+CD57+ T-cell population in PPCI patients that reflected acute proliferation in the CD4+ T-cell compartment. CD4+CCR7+ T cells were specifically depleted from peripheral blood during the first 30 min of myocardial reperfusion after PPCI, suggesting a potential role for the chemokine receptor CCR7 in T-cell redistribution to either peripheral tissues or migration to the infarcted heart during ischemia/reperfusion following PPCI. Conclusions High-throughput polychromatic flow cytometry and HCA are capable of objective, time and cost efficient assessment of the individual T-cell immune profile in different stages of coronary heart disease and have broad applications in clinical trials.