There are many tests and investigations that are used commonly in cardiology. The exact tests required vary according to your symptoms and the possible diagnosis. Even when people have similar symptoms the tests can vary and different tests can be used to look for certain diagnoses.

24 hour ECG (Holter Monitoring), Event Recorders and Reveal Implants
Transthoracic echocardiogram (echo)
Transoesophageal echocardiogram (TOE)
Cardiac MRI (CMR)
CT coronary angiogram
Coronary angiogram and percutaneous coronary intervention (PCI or angioplasty)
Pacemakers, pacemaker checks and other pacing devices
EP studies and ablation
Chest X-Ray
Nuclear perfusion studies
Exercise tolerance test
Carotid ultrasound