ST-segment analysis with ambulatory ECG monitoring: are solid state recorders better than tape cassettes?

To assess the benefit of solid-state electrocardiogram (ECG) versus cassette recording in ambulatory monitoring, the fidelity of ST-segment analysis was investigated in solid-state systems and cassette recording systems. Three systems were equipped with a solid-state recorder, three with a direct-recording cassette recorder and one with a frequency-modulated cassette recorder. The amplitude and phase responses were measured using sinus waves and a phase-sensitive waveform. Additionally, an artificial ECG test signal with predetermined horizontal ST-segment depressions from 0.0 to 0.5 mV was produced to assess the reproducibility of ST-segment changes. The test parameters and procedures are given in detail. The reproducibility of predetermined ST-depressions was good with all systems. Solid-state recorders were not found to be superior to modern cassette-based ambulatory ECG monitoring systems