Background

Accurate non-invasive risk stratification may management and impact survival of CAD patients. Stress perfusion CMR reliably assesses ventricular function, viability and myocardial ischemia in a single examination. While prognostic information may be derived from individual components of a comprehensive CMR exam, evidence that they provide complementary prognostic information is still limited. We sought to determine whether the presence of myocardial ischemia by stress perfusion CMR provides incremental prognostic information for major adverse cardiovascular events (MACE) beyond ventricular function, the presence of myocardial scar and traditional risk factors in a large cohort of patients referred for non-invasive assessment of CAD.

Methods and results

Stress perfusion CMR was performed in 711 consecutive patients (297 females, mean age 56±15 years) referred to assess myocardial ischemia with an intermediate pre-test likelihood of CAD (mean pre-test likelihood of CAD 22±18%). Rest and vasodilator stress perfusion CMR were performed each using a 0.1mmol/Kg bolus infusion of gadolinium, followed by cine function imaging and late gadolinium enhancement (LGE) 10 minutes after a cumulative dose of 0.2mmol/Kg of gadolinium. The presence of myocardial ischemia was defined by a segmental stress-induced perfusion defect without matching segmental LGE. At a median follow-up of 21.4 months (range 2.5 months to 8.2 years), 52 MACE (8%) had occurred (29 cardiac deaths and 28 acute nonfatal MI). By univariable analysis, the presence of ischemia and LGE portended to > 11-fold and > 3-fold increases in MACE (LRχ2, 51.62 and 17.02, both P<0.0001, table1), respectively. Adjusting for age, LVEF, presence LGE and resting ST segment changes, presence of ischemia maintains a strong adjusted association with MACE (adjusted LRχ2 26.1, HR 7.4, P<0.0001). By stepwise forward selection (table 2) considering all pertinent clinical, CMR and ECG variables, presence of ischemia remained the strongest predictor of MACE in the best-overall model. A stress perfusion CMR study without ischemia and LGE predicted a very low negative annual MACE rate (0.6%, figure 1). In addition, the presence of ischemia was strongly associated with a reduced MACE-free survival (figure 2).

Table 1 Univariable prognostic association with MACE
Table 2 Best Overall model for MACE
Figure 1
figure 1

Cardiac Death/MI

Figure 2
figure 2

Cardiac Death/MI

Conclusion

The presence of ischemia by stress perfusion CMR provides robust prognostic information for MACE beyond the presence of scar, LVEF, and classical clinical and ECG markers of cardiac prognosis.. The combined absence of ischemia by myocardial perfusion imaging and scar by LGE imaging identifies a very low risk population.