(1) Background: The aim of the study was to assess the risk of heart failure (HF) in elderly treated hypertensive patients with white coat uncontrolled hypertension (WUCH), ambulatory nonresistant hypertension (ANRH) and ambulatory resistant hypertension (ARH), when compared to those with controlled hypertension (CH). (2) We studied 745 treated hypertensive subjects older than 65 years. CH was defined as clinic blood pressure (BP) < 140/90 mmHg and 24-h BP < 130/80 mmHg; WUCH was defined as clinic BP ≥ 140/90 mmHg and 24-h BP < 130/80 mmHg; ANRH was defined as 24-h BP ≥ 130/80 mmHg in patients receiving ≤2 antihypertensive drugs; ARH was defined as 24-h BP ≥ 130/80 mmHg in patients receiving ≥3 antihypertensive drugs. (3) Results: 153 patients had CH, 153 had WUCH, 307 had ANRH and 132 (18%) had ARH. During the follow-up (8.4 ± 4.8 years), 82 HF events occurred. After adjustment for various covariates, when compared to CH, the hazard ratio (95% confidence interval) for HF was 1.30 (0.51-3.32), 2.14 (1.03-4.43) and 3.52 (1.56-7.96) in WUCH, ANRH and ARH, respectively. (4) Conclusions: among elderly treated hypertensive patients, those with ARH are at a considerably higher risk of developing HF when compared to CH.