Cardiac resynchronization therapy is the guideline-directed treatment option in selected heart failure with reduced left ventricular ejection fraction patients. Data regarding the contemporary clinical practice of cardiac resynchronization therapy in Turkey have been published recently. This sub-study aims to compare clinical and periprocedural characteristics between cardiac resynchronization therapy upgrade and de novo implantations. Turkish arm of the Cardiac Resynchronization Therapy Survey-II was conducted between October 1, 2015, and December 31, 2016, at 16 centers. All consecutive patients who underwent an upgrade to cardiac resynchronization therapy system (n=60) or de novo cardiac resynchronization therapy implantation (n=335) were eligible. Distribution of age, gender, and heart failure etiology were similar in the 2 groups. Atrial fibrillation, valvular heart disease, and chronic kidney disease were more common in cardiac resynchronization therapy upgrade patients. Narrow intrinsic QRS duration and left ventricular ejection fraction being 75% in both groups, and only beta-blockers were prescribed at rates of >90% in both groups. Cardiac resynchronization therapy upgrades are performed with high procedural success rates and without excess periprocedural complication risk. Feared complications of cardiac resynchronization therapy upgrades due to the pre-existing device should not delay the procedure if indicated.