Forgot to answer part two of your question:
A cardiologist will:
Get a history and perform a physical exam including auscultation (listening with a stethoscope). He is listening for a murmur, any irregular heart rate, and any lung sounds.
If needed, do a two view chest x-ray to determine heart size, condition of lungs (whether or not there is fluid in or around lungs), look for the presence of other lung disease such as COPD, look to see if enlarged heart is pressing against the main airway, look at the great vessels, etc.
If needed, do an echocardiogram with color doppler - which is an ultrasound of the heart that shows exact chamber sizes, condition and functioning of the valves, whether there are ruptured chords (chordae tendineae), measures regurgitant blood flow velocity and amount, measures contractility (pumping strength of the heart), looks for pulmonary hypertension (high blood pressure in the vasculature of the lungs only versus systemic blood pressure) and more.
If needed (because he hears an irregular heartbeat) do an ECG - electrocardiogram - which measures heart rhythm and looks for arrhythmias (irregular heart rate - too slow, too fast, or other irregularity).
If needed, check blood pressure.
None of these tests require sedation and none are invasive.
On the basis of the test results, the cardiologist will "stage" the disease, give a prognosis, and determine if and what meds are indicated.
BTW, Rod I noticed a typo on your "a few words about pimobendan" - the word is "contractility" not "contractibility." (pointing out in a friendly and not a critical way!!)
Pat