New dedicated cardiac gamma cameras using CZT detectors have shown significant improvement over the Anger camera regarding physical parameters, and their diagnostic performances have been validated in clinical studies. To date, few studies have evaluated the prognostic value of a low to intermediate risk single-photon emission tomography (SPECT) myocardial perfusion imaging (MPI) with these cameras, and only one with a HSDI stress thallium-201/rest Technetium-99m protocol on a CZT camera.

The study included patients who had no or minimal perfusion defects (<10% of the LV myocardium) on a HS-DI MPI following a symptom-limited treadmill test or a pharmacological stress testing. These 578 patients were followed for 3.3±0.4 years (95% complete). The main endpoint was the occurrence a hard cardiac event (cardiac death or nonfatal myocardial infarction).

212 patients (37%) underwent exercise stress and 366 (63%) had pharmacological stress (of which 89% had dipyridamole and 11% had dobutamine). Mean summed stress score was 0.95±1.2 [0-5]. During the follow-up period 25 hard cardiac events occurred. Annualized event rate was 1.3%/y. In the subgroup of patients undergoing exercise stress test, annualized event rate was 0.43%/y. Multivariate Cox analysis identified age (HR 1.14 [1.08; 1.20], p<0.0001) and rest LVEF (HR 0.95 [0.92; 0.98], p=0.008) as independent predictors of cardiac death or myocardial infarction. Survival analysis showed that the occurrence of cardiac events was significantly higher in patients who had an altered LVEF compared to patients with a normal LVEF (16% vs. 3.8%, p=0.003).

The use of a HS-DI protocol on a CZT camera provides prognostic information, comparable to single-isotope protocols on conventional Anger camera, while reducing imaging time and without increasing the injected activity.

The author hereby declares no conflict of interest