Slovak conductor, composer and teacher studied both conducting and composition at Academy of Music and Performing Arts, Bratislava with Ondrej Lenárd and Vladimír Bokes. Subsequently he took master classes by numerous master conductors such as Zsolt Nagy, Günter Herbig, Peter Eötvos, Iván Fischer and by composers such as Tristan Murail, Erich Urbanner, Klaus Huber, Christian Wolff and many others.
As conductor within last 15 years Lejava has premiered more than 100 works of chamber, orchestral and stage music of both domestic and foreign composers, many of them with close and personal collaborations (E.Sharp, D.Dramm, I.Matsushita, V.Cordero, numerous Slovak composers and many others).
Guest conductor in Slovak national theatre since 2006, Slovak Philharmony since 2007, State philharmony Košice since 2011 and State opera Košice since 2014.
Since 2014 he is principal conductor of Prague Modern ensemble. He was former principal conductor of Melos Etos ensemble (2005-7) and VENI ensemble (1999-2009).
Inventor, founder and conductor of VENI ACADEMY (2010-2015) – platform for education of young generation of musicians in contemporary music. He has won RADIO_HEAD AWARDS 2013 for Best album of the year in Classical Music category for double album VENI ACADEMY “Rolling Tones/In Zarter Bewegung” and recently and RADIO_HEAD AWARDS 2016 for Best album of the year in Classical Music category for album „Szymanowski/Berg violin concertos“ with violinist Milan Pala and Slovak Radio Symphony Orchestra.
As conductor, he has travelled over the Europe, Japan and China with both concerts and opera performances.
Lejava has participated on more than 20 CDs (Naxos and Slovak labels) mostly of contemporary music including world premieres and recorded “Chant d´Amour” CD (2006) with his own chamber music.
Between 2007-14 he was head and conductor of Opera studio at Academy of Music and Performing Arts in Bratislava and since 2007 he teaches both conducting and composition. He also gave lectures in Music department of Faculty of Philosophy at Komensky University in Bratislava (musical analysis) and lectured both conducting and composition at Academy in Aveiro (Portugal) and AMU Prague (Czech Republic).