There is no way to prevent a heart block from occurring in a healthy person. A test called an electrocardiogram, or ECG , can diagnose the disorder. Heart blocks often have a certain pattern that the ECG machine traces on special paper. In some instances, special tests using probes placed into the heart can measure the flow and direction of electricity. The long-term effects of heart block depend on the underlying heart disease.
Heart block is an indicator of the disease process.
If the underlying disease does not get worse, then the heart block is of no real import. If a new heart block appears suddenly where none existed before it can indicate a heart attack . In summary, the worse the underlying disease the worse the block. The worse the block the slower the heart rate. The slower the rate the worse the symptoms.