The decision rests on CHADS-65, which is a sequential algorithm, not a score. The first question is age ≥65 — she is 68, and that single fact settles it. It is tempting to tally the familiar risk factors, find none, and conclude she is low risk; the algorithm deliberately asks about age first, before anything else.

Apixaban 5 mg twice daily is correct because DOACs are preferred over warfarin in non-valvular AF, and her echo shows no significant valvular disease. She meets none of the dose-reduction criteria — two or more of age ≥80, weight ≤60 kg, or creatinine ≥133 µmol/L — so full dose applies.

A is tempting precisely because she has no hypertension, diabetes, heart failure or prior stroke, but those questions sit below age in the algorithm and are never reached. B reflects older teaching that ASA is acceptable in “low-risk” AF; AVERROES showed apixaban superior to ASA, and ASA is not stroke prevention in AF. D is right in principle but wrong in agent — warfarin is reserved for valvular AF, meaning a mechanical valve or moderate-to-severe mitral stenosis, neither of which she has.

Takeaway: In AF, check the age before counting anything else.

Two findings place him in the high-risk group: a rise in troponin consistent with MI, and dynamic ST changes not present on a prior tracing. That combination earns angiography within 24 hours. The reasoning to practise is separating high risk from very high risk, because the two look similar and the timing differs by an order of magnitude.

A is tempting because a rising troponin with dynamic changes feels like an emergency, but immediate angiography is reserved for hemodynamic instability or cardiogenic shock, refractory or recurrent pain despite therapy, life-threatening arrhythmia, mechanical complications, or acute heart failure related to the ACS. He has none of these. C is the error of downgrading on comfort — he is pain-free and stable, which tempts learners toward the lower-risk pathway, but a troponin rise with dynamic ECG changes is disqualifying. D belongs to the initial conservative approach for genuinely lower-risk patients, and here would delay revascularization in someone with objective evidence of infarction.

Takeaway: Stability makes a patient high risk, not lower risk, when troponin is rising and the ECG is dynamic.

Three findings carry the reasoning: a ventricular rate uncontrolled for two years, a dilated ventricle with an ejection fraction of 30%, and a clean coronary angiogram. A prolonged uncontrolled tachyarrhythmia can itself produce left ventricular systolic dysfunction, and it is one of the few causes of HFrEF that is frequently reversible — with rate or rhythm control the ejection fraction can recover substantially.

He should still receive guideline-directed therapy for HFrEF, but naming the arrhythmia as the driver changes both the prognosis and the urgency of rate control.

C is the most tempting answer, and reasonably so — ischemic heart disease is the commonest cause of HFrEF in developed countries, and every new heart failure patient should be assessed for coronary disease. That assessment has already been done here, and the angiogram is what excludes it. B is tempting because chronic pressure overload is a major contributor to heart failure, but his blood pressure is 118/74 with no history of hypertension. A is worth considering in any new cardiomyopathy since it reverses with abstinence, but two beers weekly is far below a causative intake.

Takeaway: In new HFrEF with a fast ventricular rate and clean coronaries, treat the rhythm as the cause until proven otherwise.

His blood pressure exceeds 140/90, so pharmacotherapy is indicated regardless of cardiovascular risk. The point being tested is what to start: HC 2025 step therapy opens with a dual combination — an ACE inhibitor or ARB paired with a thiazide/thiazide-like diuretic or a calcium channel blocker — with a single-pill combination preferred for adherence.

B and C both reflect the older sequential habit of starting one agent and titrating it before adding a second. Neither drug is wrong in itself — both classes appear in step 1 — the error is choosing monotherapy when the recommended starting point is a dual combination. D correctly recognises that two agents are needed but pairs two renin–angiotensin blockers; ONTARGET established that ACE inhibitors and ARBs should not be combined.

Takeaway: At diagnosis above target, start two agents in one pill rather than climbing the dose of one.

Four ECG features settle this, and they are the ones worth committing to memory: the ST elevation is diffuse rather than territorial, concave rather than convex, accompanied by PR depression with reciprocal PR elevation in aVR, and there are no reciprocal ST depressions. Add positional pleuritic pain and a friction rub and the picture is complete.

B is the answer that matters to exclude, and the reason this question exists — ST elevation triggers a reflex toward cath lab activation. STEMI elevation is confined to a coronary territory, convex, and accompanied by reciprocal change in opposing leads, none of which is present here. A is tempting given the viral prodrome, and pericarditis and myocarditis overlap considerably, but myocardial involvement would be expected to raise troponin; his is normal. D produces ST elevation and appears on the differential for infarction without obstructive coronaries, but it classically follows acute emotional or physical stress and would also elevate troponin.

Takeaway: Diffuse, concave, PR depression, no reciprocal change — that combination is not a cath lab call.

The decisive fact is duration: four days, so beyond 48 hours. Above that threshold sinus rhythm cannot be restored without either three weeks of prior anticoagulation or a transesophageal echocardiogram excluding left atrial appendage thrombus. Because she wants same-day treatment, TEE is the route that permits it.

A is the error of letting stability and symptom burden override duration — she is well and keen, which makes proceeding feel safe, but thrombus risk is a function of how long she has been in AF, not how she looks. B is defensible management and not dangerous, but it abandons her stated goal without addressing whether cardioversion is safely achievable. C captures the right principle, that anticoagulation precedes cardioversion, but badly underestimates the interval; the requirement is three weeks, not 24 hours, unless a TEE substitutes for it.

Takeaway: Ask how long, not how unwell, before cardioverting.

One feature drives the whole answer: this is a prosthetic valve. Empiric regimens in endocarditis are chosen by valve type, and prosthetic valve infection requires vancomycin, gentamicin and rifampin, for a minimum of six weeks. Cultures are already drawn, so therapy can begin.

C is the single most instructive distractor because it is exactly right for a native valve — vancomycin plus ceftriaxone is the correct empiric pairing there. Choosing it means the valve type never registered, which is the commonest error in this scenario. A reflects anchoring on a streptococcal cause, where ceftriaxone is appropriate definitive therapy; empiric cover must include staphylococci, including MRSA, before organisms are known. D covers MSSA and adds an aminoglycoside, so it looks plausible to a learner reasoning about staphylococci, but it misses MRSA and omits rifampin, which is added specifically for staphylococcal prosthetic valve infection.

Takeaway: In endocarditis, establish the valve type before choosing the regimen.

ST depression in V1–V3 accompanied by tall R waves is the mirror image of posterior ST elevation. Because the standard twelve leads face the heart anteriorly, a posterior infarct appears inverted; posterior leads V7–V9 record it directly and convert a puzzling tracing into a STEMI equivalent requiring reperfusion.

A is the error this question is built around: ST depression is the textbook NSTEMI pattern, so taking the tracing at face value is entirely natural — and it consigns a patient with an occluded vessel to a 24-hour pathway. B is the cautious default for evolving pain with a non-diagnostic ECG and is reasonable in many presentations, but here it delays reperfusion when one additional tracing would resolve the question in minutes. D shows the right instinct, that this is reperfusion territory, but a PCI centre is 20 minutes away, comfortably within the 120-minute target, which makes primary PCI the preferred strategy.

Takeaway: Anterior ST depression with tall R waves earns posterior leads before it earns an NSTEMI label.

Her ejection fraction is 55%, placing her in the non-reduced group, and that classification changes which therapies carry evidence. SGLT2 inhibitors hold a strong recommendation across HFnrEF, supported by EMPEROR-Preserved and DELIVER, and require no titration.

B is the most revealing wrong answer: beta-blockers are one of the four pillars, and transplanting the HFrEF regimen wholesale onto preserved ejection fraction is the central error this question targets. The four pillars are defined for HFrEF and do not transfer intact. C is tempting for the same reason with an extra wrinkle — ARNi does appear in HFnrEF recommendations, but only weakly, on the strength of PARAGON-HF, so it is not the change most likely to keep her out of hospital. D treats the congestion in front of you, and diuretics remain central to volume management, but adjusting the diuretic manages symptoms rather than reducing hospitalization risk.

Takeaway: Read the ejection fraction before reaching for the pillars.

This is a hypertensive emergency because there is acute end-organ damage, and the damage is an acute coronary syndrome with pulmonary congestion. Agent choice in a hypertensive emergency follows the organ involved rather than the blood pressure number, and nitroglycerin is preferred in both ACS and acute pulmonary edema — the two problems he has.

A is the reflex reach for a quick intravenous antihypertensive, and is precisely the wrong one here: hydralazine is avoided in coronary disease because reflex tachycardia raises myocardial oxygen demand in a heart that is already ischemic. C is a legitimate titratable agent, but its stated preference is stroke, and it addresses neither his coronary ischemia nor his preload. D appeals because rate control seems attractive in ACS, but esmolol’s role is aortic dissection — excluded here by equal pressures and no back pain — and beta-blockade is avoided in decompensated heart failure, which his crackles and congestion indicate.

Takeaway: In a hypertensive emergency, the damaged organ picks the drug.