CCT (CCI): Bruce Protocol With a Beta Blocker On Board

Beta blocker taken this morning - the biggest one. Metoprolol blunts heart rate and can mask ischemia by preventing the rate-pressure product from rising; a test that stops at 70% of age-predicted heart rate is often non-diagnostic. The lab's protocol usually calls for holding it 24–48 hours, but you never instruct a patient to stop a cardiac medication yourself. Contact the ordering provider, present the situation, and document the decision (proceed with a blunted-heart-rate caveat, or reschedule).

LVH with 1 mm downsloping ST depression at rest. This is a baseline abnormality that reduces the specificity of ST-segment interpretation - LVH with a strain pattern produces exactly the ST depression you would otherwise call ischemia. It must be documented as baseline, and the interpreting physician may want an imaging modality rather than a plain treadmill. Nothing to "fix" at the bedside, but it changes how the result will be read.

BP 166/94. Recheck after 10 minutes of quiet seated rest, and confirm with a properly sized cuff on a supported arm. It is high but below the usual threshold for cancelling; a value that stays above roughly 200/110 is a reason not to start.

Large breakfast 90 minutes ago. Food shifts blood to the splanchnic bed, causes nausea and poor effort, and can distort the ECG. Most labs want 2–3 hours fasting; either allow more rest time or reschedule.

Cigarette in the parking lot. Smoking within a few hours raises heart rate and BP, causes vasoconstriction and raises carboxyhemoglobin, all of which distort the hemodynamic response. Note it, and consider a delay or reschedule per lab policy.

Answer to his question: possibly yes - but that is the ordering provider's call, not yours alone. Present the combined picture and the recommendation; do not silently proceed on a test that is likely to be submaximal and uninterpretable.

Continue - with coaching - provided nothing else has appeared.

Why not stop:

• Fatigue at RPE 13 is not an indication for termination. The standard end points are symptoms (angina, severe dyspnea, dizziness), ECG changes (significant ST elevation/depression, serious ventricular ectopy, new bundle branch block), a fall in systolic BP, or hypertensive response above roughly 250 systolic / 115 diastolic. None of these are present.
• He is submaximal: 118/159 ≈ 74% of age-predicted maximum, below the ~85% (about 135 bpm) generally needed for an adequate diagnostic study. Stopping now produces a test that cannot answer the question.
• Beta blockade matters for interpretation: 118 bpm on metoprolol may reflect a higher workload than the number implies. Note the resting rate and the chronotropic response in the report.
• BP 192/90 is high but not a stop criterion; recheck it at the next stage and watch the trend. A fall in systolic pressure with increasing workload would be a stop.

What to do in the next 30 seconds:

1. Check the tracing, not just the screen - confirm the "no ST change" is real and not masked by a noisy lead or a wandering baseline.
2. Correct handrail technique - leaning on the rails offloads body weight, lowers the true workload and heart rate, and can raise BP. Have him walk with arms swinging if he is steady.
3. Coach: encourage, tell him the time and how he is doing, ask about chest pain and dyspnea specifically rather than "how are you."
4. Continue to symptom limitation, target heart rate, or a true end point.

Stop immediately if: chest pain, ≥1–2 mm of new horizontal/downsloping ST change, a drop in systolic BP, complex ventricular ectopy, lightheadedness, or if he cannot continue despite coaching.

Treat it as unproven until the technical explanation is excluded - but do not dismiss it either.

Features favouring artifact:

• The change tracks the respiratory cycle - the baseline rolls and the apparent ST level moves with it.
• It appears in only one or two leads without a contiguous, anatomically sensible pattern, and V5 (the lead most sensitive to lateral ischemia) is unchanged.
• Slight upsloping ST depression in V2–V3 during heavy hyperventilation and tachycardia is common and usually non-ischemic.
• It coincides with breathlessness, motion, and a change in baseline - all of which shift the isoelectric reference point. ST level must be measured relative to the PR segment, not to a drifting baseline.

Features favouring true ischemia:

• Horizontal or downsloping ST depression that is beat-to-beat consistent across several complexes.
• Present in contiguous leads (e.g., V4–V6, or II/III/aVF), with reciprocal change.
• Accompanied by chest pain, a fall in systolic BP, or ventricular ectopy.

What you do:

1. Do not stop the test on a single noisy complex, and do not declare it positive either.
2. Ask him to keep breathing steadily and to avoid gripping the rails; take a fresh tracing at the same stage.
3. Re-check the V2–V3 electrodes (loose, over muscle, sweat) and re-prep if needed.
4. Compare the same leads at rest, at each stage, and in recovery - a change that is present at rest is baseline; one that appears and progresses with workload is meaningful.
5. If the change persists and becomes horizontal/downsloping in contiguous leads, stop the test and report it; if it disappears with a cleaner tracing, document that it was respiratory/motion artifact so the reader is not misled by the raw strip.