You need to review your source of information. This is not correct.
The heart has a rhythmical rate of 40 to about 200 BPM which corresponds to 0.67 Hz to 3.33 Hz. Normal is 80 to 120 BMP. There are other frequencies involved but they are very minor.
If the heart was sensitive to 1 Mhz, then AM radio ( 610 kHz to 1.6 Mhz ) would quickly kill us.