Lead aVR predicts early revascularization but not long-term events in patients referred for stress electrocardiography

Abstract

Background: Exercise stress electrocardiography (ExECG) is recommended as a first-line tool to assess ischemia, but standard ST-analysis has limited diagnostic accuracy. ST elevation in lead aVR has been associated with left main and LAD disease in the population undergoing coronary angiography but has not been studied in the general population undergoing stress testing for the initial evaluation of CAD without coronary angiography. We sought to determine the predictive value of lead aVR elevation for ischemia, early revascularization, and subsequent cardiac events in consecutive patients undergoing ExECG.

Methods and results: The study cohort included 641 subjects referred for ExECG who were dichotomized by presence or absence of aVR elevation ≥1mm and compared for prevalence and predictors of ischemia and a composite of cardiac death, nonfatal myocardial infarction, and late revascularization. The cohort had a median age of 57 and 57% were male. The prevalence of aVR elevation was 11.5%. The prevalence of significant ischemia on patients who received imaging was significantly higher with aVR elevation (14.3% vs 2.3%, p<0.001). Early revascularization occurred in 10.9% with vs 0.2% without aVR elevation, p<0.001. No subjects without aVR elevation or ST-depression underwent early revascularization. However, cardiac event rates were similar over a median 4.0 years of follow-up with and without aVR elevation (2.8% vs. 2.6%, p = 0.80). aVR elevation did not predict long-term cardiac events by Kaplan-Meier survival analysis (p = 0.94) or Cox proportional hazards modeling (p = 0.35).

Conclusions: aVR elevation during ExECG predicts ischemia on imaging and early revascularization but not long-term outcomes and could serve as a useful adjunct to standard ST-analysis and potentially reduce the need for concurrent imaging.

Fig 1. Patient flow diagram depicting the derivation of the study cohort.

Fig 2

Examples of aVR elevation during stress electrocardiography with (A) and without (B) ST depression in lead V5. Note the subtle ST depression in tracing B does not meet criteria for ST depression on stress electrocardiography (defined as ≥1mm horizontal or down-sloping depression of the ST segment ≥80ms after the J-point for 3 consecutive beats).

Fig 3. Prevalence of ischemia on SPECT myocardial perfusion imaging by the presence or absence of ≥1mm ST-depression in all leads and ≥1mm elevation in lead aVR.

There was a significant difference in prevalence by presence of absence of aVR elevation, but no significant difference by ST-depression within each aVR subgroup.

Fig 4. Lead aVR results in those with and without ST-depression and rates of early revascularization.

In those without ST-depression, the rate of early revascularization was significantly higher in those with aVR elevation (p<0.001). In those with ST-depression, the subgroup with aVR elevation had a higher rate that was non-significant (p = 0.18) possibly due to reduced power from low numbers with ST-depression.

Fig 5. Kaplan-Meier survival analysis for freedom from cardiac events stratified by ≥1mm of aVR elevation.

The presence or absence of ≥1mm elevation in lead aVR did not increase the risk of the composite outcome of cardiac death, nonfatal myocardial infarction, or late revascularization over a median 4.0 years of follow-up (p = 0.94).