The Significance of Equivocal Exercise Treadmill ECG for Intermediate Risk Chest Pain Assessment - Insight From Coronary CT Angiography Data.

BACKGROUND

Exercise treadmill test (ETT) is commonly the first-line investigation in troponin-negative chest pain patients. Inconclusive results are common and often lead to repeated functional testings. Coronary computed tomographic angiography (CCTA) has excellent negative predictive value for coronary artery disease detection and may play an important role in their diagnostic workup. We aim to analyse ETT and CCTA findings to understand their modern roles in intermediate risk chest pain population with inconclusive ETT.

METHODS

Patients who underwent both ETT and CCTA at our institution between August 2011 and February 2013 were retrospectively investigated. The ETTs were blindly reviewed, with equivocal ETTs defined as any indeterminate results not strictly adhering to ACC/AHA guidelines for positive ETT. Baseline demographics, clinical characteristics and investigation results were collated. Follow-up outcome data for subsequent investigations, representations, major cardiac adverse events (MACE) and unexpected revascularisations were also analysed.

RESULTS

346 consecutive patients were identified (age 57±10years, 53% females, body mass index (BMI) 28±4, Dukes Clinical Score 48±30%, mean follow-up 2.1±0.4years). The ETT was positive in 31%, equivocal in 54% and negative in 15%. Obstructive coronary artery disease (CAD) prevalence was 25% (29% males, 13% females). Those with negative ETTs had obstructive CAD in 8%, with no adverse outcomes during follow-up. Obstructive CAD was seen in 20% with "equivocal" ETTs and 29% with "positive" ETTs. In females, obstructive CAD prevalence was low, and similar in those with equivocal or positive ETT (16% and 11% respectively). In males, obstructive CAD was almost 50% in those with positive ETT (p=0.005).

CONCLUSIONS

Obstructive CAD was found in one in five "equivocal" ETTs, hence, not all should be considered negative. Obstructive CAD was only found in one in three "positive" ETTs, hence not all should proceed to invasive angiography. CCTA may be an important gatekeeper test in those with low-intermediate pre-test probability of obstructive CAD.