1. A method of classifying a cardiac response to one or more pacing pulses, comprising: sensing one or more intrinsic composite cardiac signals, each intrinsic composite cardiac signal indicative of intrinsic cardiac activity and sensed using at least three spatially distributed implantable electrodes; performing source separation using the sensed one or more intrinsic composite cardiac signals, the source separation separating one or more components of the intrinsic composite signal according to correlation between components of common cardiac origin; producing one or more intrinsic cardiac signal vectors representative of all or a portion of one or more intrinsic cardiac activation sequences based on the separated one or more components of the intrinsic composite cardiac signal; sensing one or more paced composite cardiac signals, each paced composite cardiac signal indicative of cardiac activity following delivery of pacing energy and sensed using at least three spatially distributed implantable electrodes; performing source separation using the sensed one or more paced composite cardiac signals, the source separation separating one or more components of the paced composite signal according to correlation between components of common cardiac origin; producing one or more paced cardiac signal vectors representative of all or a portion of one or more cardiac activation sequences based on the separated one or more components of the paced composite signal; establishing a vector orientation criterion based on respective orientations of the one or more intrinsic cardiac signal vectors and the one or more paced cardiac signal vectors; delivering a cardiac pacing pulse; sensing one or more composite cardiac signals following delivery of the cardiac pacing pulse using at least three spatially distributed implantable electrodes; performing source separation using the sensed one or more composite cardiac signals, the source separation separating one or more components of the composite cardiac signal according to correlation between components of common cardiac origin; producing one or more cardiac signal vectors representative of all or a portion of one or more cardiac activation sequences based on the separated one or more components of the composite cardiac signal; and classifying a cardiac response to the pacing pulse as capture or non-capture based on at least a comparison of orientation of the one or more cardiac signal vectors with the vector orientation criterion.