Cardiological Diagnostic and Therapeutic Selection Parameters
The selection of appropriate diagnostic and therapeutic tools in cardiology should be based on evidence-based guidelines from the American College of Cardiology (ACC) and European Society of Cardiology (ESC), with careful consideration of patient-specific factors to optimize morbidity and mortality outcomes. 1
Diagnostic Test Selection Parameters
Stress ECG vs CT Coronary Angiography vs Stress Echo
| Parameter | Stress ECG | CT Coronary Angiography | Stress Echo |
|---|---|---|---|
| Pretest Probability of CAD | Intermediate | Low to intermediate | Intermediate to high |
| ECG Interpretability | Requires interpretable ECG | Not dependent on ECG interpretability | Used when ECG uninterpretable |
| Physical Functioning | Requires moderate physical functioning | No physical exertion needed | Moderate physical functioning required (pharmacologic stress if limited) |
| Prior Test Results | Initial test | After inconclusive stress ECG | After inconclusive stress ECG |
| Comorbidities | No disabling comorbidity | Suitable for patients with comorbidities limiting exercise | Pharmacologic stress if exercise limited |
| Contraindications | Uninterpretable ECG, inability to exercise | Severe renal dysfunction, contrast allergy, irregular heart rhythm, high calcium score | Poor acoustic window, severe valvular disease |
| Radiation Exposure | None | Moderate | None |
Strong recommendation: Standard exercise ECG is the preferred initial diagnostic test for patients with intermediate pretest probability of ischemic heart disease who have an interpretable ECG and at least moderate physical functioning. 1
Revascularization Decision Parameters: PCI vs CABG
| Parameter | PCI Preferred | CABG Preferred |
|---|---|---|
| Coronary Anatomy | Single or two-vessel disease | Left main disease, three-vessel disease |
| SYNTAX Score | Low (≤22) | High (>32) |
| SYNTAX Score II | Favors PCI | Favors CABG |
| Diabetes Status | Non-diabetic | Diabetic patients |
| LV Function | Preserved EF | Reduced EF (<35%) |
| Comorbidities | High surgical risk | Lower surgical risk |
| Age | Advanced age with frailty | Younger patients with longer life expectancy |
| Lesion Complexity | Simple lesions | Complex lesions, chronic total occlusions |
| Technical Feasibility | Technically feasible | Not suitable for PCI |
| Patient Preference | Prefers less invasive approach | Accepts more invasive approach for durability |
FFR (Fractional Flow Reserve) is indicated for assessment of intermediate coronary lesions (40-70% stenosis) when functional significance is uncertain, with values ≤0.80 indicating hemodynamically significant stenosis requiring intervention.
Device Therapy Selection Parameters
CRT Devices
| Parameter | Indication |
|---|---|
| QRS Duration | ≥130 ms (especially LBBB) |
| LVEF | ≤35% |
| NYHA Class | II-IV despite optimal medical therapy |
| Sinus Rhythm | Preferred (though can be used in AF with adequate rate control) |
| Life Expectancy | >1 year |
| Contraindications | Mechanical right heart valve, tricuspid valve replacement, expected heart transplant within 6 months |
ICD Devices
| Parameter | Indication |
|---|---|
| Primary Prevention | LVEF ≤35% despite optimal medical therapy (≥40 days post-MI), NYHA II-III |
| Secondary Prevention | Survived cardiac arrest, sustained VT with structural heart disease |
| Genetic Disorders | Brugada syndrome, Long QT syndrome, HCM with high risk features |
| Life Expectancy | >1 year with good functional status |
| Contraindications | Terminal illness, psychiatric illness affecting compliance, incessant VT/VF, NYHA IV not candidate for transplant/CRT |
Pacemakers
| Parameter | Permanent Pacemaker | Temporary Pacemaker |
|---|---|---|
| Indications | Symptomatic bradycardia, high-grade AV block, symptomatic sinus node dysfunction | Acute MI with high-grade AV block, drug overdose with bradycardia, temporary support during procedures |
| Duration | Long-term management | Short-term management (days) |
| Contraindications | Active systemic infection, expected resolution of bradycardia | Severe coagulopathy (relative) |
Monitoring Device Selection Parameters
| Parameter | Holter Monitor | Ambulatory BP Monitor | Implantable Loop Recorder |
|---|---|---|---|
| Duration | 24-48 hours | 24 hours | Up to 3 years |
| Symptoms | Frequent symptoms (daily/weekly) | Suspected white coat/masked hypertension | Infrequent symptoms (monthly) |
| Diagnostic Yield | Moderate for frequent arrhythmias | High for BP patterns | High for infrequent arrhythmias |
| Indications | Palpitations, syncope evaluation, AF detection | Hypertension diagnosis/management | Unexplained syncope, cryptogenic stroke |
| Contraindications | Skin allergies to adhesives | Severe arm tremor, very irregular pulse | Active infection at implant site |
Ablation Therapy Selection Parameters
| Parameter | AF Ablation | PVC Ablation | SVT Ablation |
|---|---|---|---|
| Indications | Symptomatic AF refractory to ≥1 antiarrhythmic drug, selected patients as first-line therapy | Symptomatic PVCs >10,000/day, PVC-induced cardiomyopathy | Symptomatic SVT after failed drug therapy, patient preference over lifelong medication |
| 3D Mapping | Recommended for all AF ablations | Recommended for complex PVCs (outflow tract, epicardial) | Recommended for complex SVTs, congenital heart disease |
| Success Rate | 60-80% (higher for paroxysmal) | 80-95% | 95-98% |
| Contraindications | LA thrombus, active infection, severe valvular disease, pregnancy | Active infection, proximity to coronary arteries, pregnancy | Active infection, pregnancy |
Common Pitfalls and Caveats
Pretest Probability Assessment: Failing to assess pretest probability before selecting diagnostic tests can lead to unnecessary testing and false positives.
SYNTAX Score Limitations: SYNTAX score alone may not be sufficient; consider SYNTAX Score II which incorporates clinical variables for better decision-making between PCI and CABG.
Device Selection: Selecting devices based solely on ejection fraction without considering QRS morphology, etiology of heart failure, and comorbidities can lead to suboptimal outcomes.
Monitoring Duration: Matching monitoring duration to symptom frequency is critical - using short-term monitoring for infrequent symptoms leads to missed diagnoses.
Ablation Candidate Selection: Patient selection for ablation procedures significantly impacts success rates; thorough pre-procedural imaging and assessment is essential.
By following these evidence-based parameters for selecting diagnostic and therapeutic tools in cardiology, clinicians can optimize patient outcomes while minimizing unnecessary procedures and their associated risks.