Thank you for your query.
There are many risk factor for blockage(ischemic heart disease
The common are diabetes mellitus
This problem can be identified by complaints of the patient(central chest pain,exersional breathlessness) & some relevant investigation(ecg,echo,angiogram).
In case of your father,if ecg indicate some blockage then angiogram can be done to confirm & intensification of the problem.
There are some treatment option for this.
Medical management,per cutaneous intervention & angioplasty
are common among them.
Pacemaker usually prescribed for a patient having cardiac conduction defect like AV block,sick sinus disease etc.
An ECG is sometimes enough for diagnosis of this cases.
If these diseases are symptomatic then permanent pacemaker is mandatory.
I hope I have some help of your query.